AWUS01 KWNH 031910
FFGMPD
VAZ000-NCZ000-GAZ000-TNZ000-KYZ000-ALZ000-MSZ000-040108-

Mesoscale Precipitation Discussion 0031
NWS Weather Prediction Center College Park MD
209 PM EST Thu Feb 03 2022

Areas affected...northern/central Alabama, middle Tennessee,
southeastern Kentucky, northwestern Georgia

Concerning...Heavy rainfall...Flash flooding possible

Valid 031908Z - 040108Z

Summary...Indications are that heavier rainfall rates will
overspread the discussion area from west to east over time, with
sensitive ground conditions potentially supporting a flash flood
risk through 01Z.

Discussion...Radar mosaic imagery and MRMS data indicate gradually
increasing convection and heavier rain rates developing from near
Muscle Shoals to Meridian/Tuscaloosa. Deeper, more intense
convection was also ongoing south of I-20 in MS/AL. These
convective trends were likely occurring as a result of gradually
increasing instability due to warm/moist advection ahead of a
strong cold front just west of the MS/AL border area from near
Columbus to near Meridian. Southerly flow was maintaining an axis
of 1.2-1.6 inch PW values just ahead of the front along with about
250-500 J/kg MUCAPE.

Models (particularly the HREF) suggest that these trends will
continue through the next 6 hours or so, with a consolidating band
of rain rates approaching 0.5-1 inch/hr sweeping through much of
the discussion area (highest in central Alabama). The band will
be fairly progressive and have less available moisture/instability
compared to areas farther south, which should temper rain rates
overall. However, ground conditions are much more sensitive, with
higher soil moisture content and FFGs in the 0.75-1.5 inch/hr
range - locally lowest near sensitive areas. As this band
continues to consolidate, at least minor flooding issues are
expected to materialize. Areas of 1-2.5 inches of rain area
expected over the next 6 hours or so.

Cook

ATTN...WFO...BMX...FFC...GSP...HUN...JAN...JKL...LMK...MRX...
OHX...

ATTN...RFC...LMRFC...OHRFC...SERFC...NWC...

LAT...LON 37758382 37658288 37188269 36148336 35188421
34298436 33348451 32518539 32358719 32418800
32708839 35078733 36018639 37188500
$$
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AWUS01 KWNH 032122
FFGMPD
FLZ000-GAZ000-ALZ000-MSZ000-LAZ000-040319-

Mesoscale Precipitation Discussion 0032
NWS Weather Prediction Center College Park MD
420 PM EST Thu Feb 03 2022

Areas affected...far southeastern Louisiana, southern Mississippi,
southern Alabama, west-central Georgia

Concerning...Heavy rainfall...Flash flooding likely

Valid 032119Z - 040319Z

Summary...Storms across southwestern Alabama, southeastern
Mississippi, and southeastern Louisiana have taken on a somewhat
more favorable orientation for training and flash flood potential
over the past 1-2 hours. The ongoing trajectory of the storms
should spread flash flood potential into more of southern Alabama
over the next several hours.

Discussion...Vigorous convection has organized into a series of
clusters and linear segments that are focused along an axis from
just southwest of Selma to Lake Pontchartrain. Storms are now
nearly parallel to steering flow aloft and are remaining just out
ahead of a strong cold front. The orientation of this front was
also parallel to upper flow aloft in that region, allowing for
slower southeastward progress compared to areas farther north.
The environment supporting the storms (characterized by 1000+ J/kg
MLCAPE and 1.8 inch PW values) supports efficient rain rates,
while localized training within the convective axis was allowing
for occasional rain rates exceeding 2.5 inches/hr at times. Gauge
data from Weather Underground suggested 4+ inches of rainfall fell
in a few spots across southeastern Louisiana and southern
Mississippi earlier this afternoon.

Observational trends suggest that the ongoing band of convection
(and associated flash flood potential) will gradually extend
east-northeastward into more of southern Alabama and perhaps far
west-central Georgia through 03Z. Moist, southerly flow will
maintain buoyancy to sustain heavier rainfall rates, and local
areas of 3-4 inch rainfall amounts cannot be completely ruled out.
These rain totals will exceed FFG thresholds in a few areas. The
most likely corridor for flash flooding will exist from near/north
of Mobile to Montgomery and perhaps extend into west-central
Georgia by around 00Z.

Cook

ATTN...WFO...BMX...FFC...JAN...LIX...MOB...TAE...

ATTN...RFC...LMRFC...SERFC...NWC...

LAT...LON 33758491 33528418 32888411 31858472 31098620
30508702 30088803 30178885 29188914 29018960
29299060 29409090 30209088 30839010 31698924
32658763 33138736 33628617

$$
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AWUS01 KWNH 172008
FFGMPD
PAZ000-WVZ000-OHZ000-KYZ000-INZ000-180215-

Mesoscale Precipitation Discussion 0036
NWS Weather Prediction Center College Park MD
307 PM EST Thu Feb 17 2022

Areas affected...Western to Northern KY...Far Southern
IND...Southern OH...Western PA...ext Northwest WV...

Concerning...Heavy rainfall...Flash flooding possible

Valid 172015Z - 180215Z

SUMMARY...Reducing rainfall rates but cells moving toward
saturated ground conditions and ongoing flooding. Increased
runoff may pose isolated flash flooding conditions through early
overnight hours.

DISCUSSION...GOES-E WV suite depicts the southern stream shortwave
starting to elongate/shear out of eastern KS through the toward
southeast IA/western IL, in advance of strengthening northern
stream larger synoptic trof across the Upper Midwest. In
response, the low level return moisture stream/warm conveyor is
starting to flatten across the Ohio River Valley, this has reduced
overall available instability across the MPD area, yet, low level
moisture flux convergence continues to be very strong along and
east of the cold front, particularly enhanced on remaining outflow
boundary across north-central KY. Surface Tds into the 50s and
Total PWats within the core of the warm conveyor near 1.5" will
continue to support greatest rainfall rates down-shear of the
surface wave inflection along the Ohio River.

Initially, due to confluent 65-80kt 85H flux should support some
shallow upglide cells capable of 1"/hr across NW KY; but as
instability and moisture stream slackens slightly after 00z, cells
will diminish toward .5-.75"/hr across N KY into S OH. Though
southerly low level flow is expected to expand and area of upglide
will expand downstream across central OH into E OH/W PA with
.25-.5"/hr rates. NASA LIS 0-40cm soil saturation ratios over 80%
and cold grounds are likely to act hydrophobic and much of the
rain will runoff. FFG values are low enough (<1" from 1 to 6hrs)
across much of Ohio into the foothills of W PA/NW WV, it is
increasingly possible the scattered swaths of 1-2" totals may
induce localized flash flooding or at least aggravate already
swollen rivers/streams in the area (as corroborated by NWC
forecasters and NWM).

Gallina

ATTN...WFO...CLE...ILN...IND...JKL...LMK...PAH...PBZ...RLX...

ATTN...RFC...OHRFC...NWC...

LAT...LON 41157998 40428003 39428072 38568218 38118354
37538501 36768760 37908792 38618676 39508534
40368334 41108117
$$
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AWUS01 KWNH 061523
FFGMPD
TNZ000-KYZ000-INZ000-ILZ000-MOZ000-ARZ000-062120-

Mesoscale Precipitation Discussion 0052
NWS Weather Prediction Center College Park MD
1021 AM EST Sun Mar 06 2022

Areas affected...Much of west-central Kentucky...Missouri
Bootheel...Far northwest Tennessee

Concerning...Heavy rainfall...Flash flooding possible

Valid 061520Z - 062120Z

Summary...Training convection with rainfall rates of 1-2"/hr will
lead to localized totals of 2-3 inches. Isolated instances of
flash flooding are possible.

Discussion...A relatively narrow corridor of deep layer moisture
flux convergence has taken shape across much of the state of
Kentucky, oriented from the ESE to the WNW ahead of an approaching
cold front. The position of this corridor looks to remain somewhat
stalled as one upper-level shortwave departs (lifts to the north
into SE Canada and New England) while a more substantial second
shortwave approaches from the west (also lifting, but acting to
flatten the large scale ridge across the SE US). This synoptic
dance between the shortwaves should maintain a broad warm sector
over the region through the afternoon with the aforementioned
corridor of deep layer moisture flux convergence presenting a
flash flooding threat with the potential for training convection.
The mesoscale environment over Kentucky is characterized by PWATs
of 1.2-1.4 inches (near the max moving average per BNA sounding
climatology), ML CAPE of 250-500 J/kg, and effective bulk shear of
50-60 kts (parallel to and of similar magnitude to the deep layer
mean wind).

Hi-res guidance is in rather good agreement concerning expected
QPF through 21z with rainfall rates currently maxing out around
1"/hr increasing to 1-2"/hr this afternoon. This should result in
localized totals of 2-3 inches where the most idealized training
is able to occur (per HREF 2" exceedance probabilities over 3-hr
of 10-15%). Corresponding Flash Flood Guidance (FFG) over much of
the highlighted region is as low as 2" over the same 3-hr period.

Churchill

ATTN...WFO...JKL...LMK...MEG...OHX...PAH...

ATTN...RFC...LMRFC...OHRFC...NWC...

LAT...LON 38248403 37598410 37238497 36938609 36458765
35858922 35969038 36609046 37138945 37708774
38198549
$$
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AWUS01 KWNH 062321
FFGMPD
KYZ000-INZ000-ILZ000-MOZ000-ARZ000-OKZ000-KSZ000-070500-

Mesoscale Precipitation Discussion 0054
NWS Weather Prediction Center College Park MD
619 PM EST Sun Mar 06 2022

Areas affected...Mid Mississippi Valley

Concerning...Heavy rainfall...Flash flooding possible

Valid 062318Z - 070500Z

Summary...Convection capable of 1-2"/hr rainfall rates will result
in localized accumulations of 2-4 inches over the next 3-6 hours
over portions of the mid-Mississippi Valley. Flash flooding is
possible.

Discussion...A potent upper-level shortwave trough is driving a
deepening low pressure system near the OK/AR border late this
afternoon, sending a warm front slowly northward across southern
Missouri. The air mass south of the warm front is characterized by
PWATs of 1.2-1.6 inches as shown by mid-afternoon special
soundings from SGF/LZK/JAN, ML CAPE of 500-2500 J/kg, and 50 to 70
knots of bulk shear. Rainfall rates in the vicinity of the front
have already approached 1"/hr, and rates as high as 2"/hr are
expected with more vigorous convective cores to develop as
boundary layer moisture flux covergence becomes more pronounced
along and north of the warm front. Given that the deep layer mean
wind nearly parallel to the postion of the warm front (and with
little additional northward progress expected), training of cells
may result in localized totals of 2-4 inches over the next 3-6
hours.

Out of the avaliable CAM guidance, the more recent runs of the
HRRR seem to be matching observational trends the best (while also
depicting the highest totals of the hi-res guidance). This would
suggest that the peak of the activity is likely to occur around
03-06z with 3-hr totals approaching 3" locally.

Bann

ATTN...WFO...ILX...IND...LMK...LSX...LZK...MEG...PAH...SGF...
TSA...

ATTN...RFC...ABRFC...LMRFC...MBRFC...NCRFC...OHRFC...NWC...

LAT...LON 39328822 38818662 38178645 37628705 36808890
35319357 36109498 37329448 38519228
$$
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AWUS01 KWNH 051836
FFGMPD
NCZ000-SCZ000-GAZ000-060033-

Mesoscale Precipitation Discussion 0102
NWS Weather Prediction Center College Park MD
235 PM EDT Tue Apr 05 2022

Areas affected...South Carolina, eastern Georgia, southern North
Carolina

Concerning...Heavy rainfall...Flash flooding possible

Valid 051833Z - 060033Z

Summary...A complicated convective scenario is evolving across the
discussion area that could lead to flash flooding especially in
central and upstate South Carolina.

Discussion...A complicated flash-flood scenario is evolving
particularly across South Carolina. Isentropic lift associated
with strong low-level warm advection combined with marginal
mid-level instability has contributed to a gradual expansion of upright/lightning-producing convection in northeastward-moving
bands between the GA/SC border to the I-26 corridor. The bands
are progressive, although a tendency for redevelopment from south
to north across the area is contributing to increasing rain rates
- now approaching 1 inch/hr southwest of Columbia. Meanwhile, a
mature MCS was holding together in west-central Georgia and
vicinity in an environment characterized by marginal surface-based
instability (especially in northern Georgia), but appreciable
forcing associated with a mid-level wave centered over middle
Tennessee and Kentucky.

The weak instability in northern/central Georgia hints at some
concern on MCS maintenance through the discussion area over the
next couple hours, although strong 850-925 flow (>30 knots) and
heating in southern Georgia may be enough to help with airmass
recovery and some continuation of heavy rain potential as the
complex migrates into South Carolina later this afternoon. This
MCS, along with developing convection out ahead, should result in
rounds of heavy rainfall and a few areas of 2-3 inches of rainfall
through just after 0030Z. These rain totals could lead to areas
of localized/isolated flash flooding - especially if heavier rain
rates become more established in sensitive areas of central and
upstate South Carolina where FFGs are appreciably lower (1.5-2
inches/hr, 2-3 inches/3-hr thresholds).

Cook

ATTN...WFO...CAE...FFC...GSP...ILM...RAH...

ATTN...RFC...SERFC...NWC...

LAT...LON 35448047 35347952 34967930 34357957 33738067
33188193 33238300 33878339 34398309 34838258
35308135

$$
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AWUS01 KWNH 111757
FFGMPD
TNZ000-KYZ000-INZ000-ILZ000-MOZ000-ARZ000-112351-

Mesoscale Precipitation Discussion 0107
NWS Weather Prediction Center College Park MD
152 PM EDT Mon Apr 11 2022

Areas affected...Mid-MS River Valley

Concerning...Heavy rainfall...Flash flooding possible

Valid 111751Z - 112351Z

Summary...Rounds of moderate to locally heavy rainfall through the
afternoon across the Mid-MS River Valley may lead to isolated to
scattered instances of flash flooding.

Discussion...As of 17Z, an area of low pressure was analyzed
across eastern Oklahoma with a frontal boundary extending
northeast through southern to central Missouri. Meanwhile, water
vapor imagery showed a shortwave trough quickly moving eastward
through southern Kansas. This forcing for ascent and lift along
the stationary boundary has led to widespread loosely organized
showers and isolated thunderstorms since this morning. The airmass
along/ahead of the boundary in the warm sector is characterized by
dewpoints in the 50s to near 60F and precipitable water values
approaching 1.2-1.3", which is +2 sigma above the climatological
normal. The better instability axis lies to the south/southwest
with values approaching 1000-1500 J/kg MUCAPE. With a steady
southwest low level inflow approaching 40 kts at 850 mb and max
diurnal heating, this instability axis will expand northeast
across the outlook area. Convection should begin to blossom
along/ahead of the boundary at the nose of the better moisture
transport axis. Meanwhile, residual outflow boundaries from
earlier should lead to additional convection this afternoon to the
east. As the flow begins to align more parallel to the expected
storm motion this afternoon, there's some potential for east-west
oriented line segments that favor repeating rounds or training.
Overall, isolated max rain rates up to 2"/hr will be possible with
isolated 3-4" totals possible through 00Z. This could lead to
isolated to scattered instances of flash flooding.


Taylor

ATTN...WFO...LSX...LZK...MEG...OHX...PAH...SGF...TSA...

ATTN...RFC...ABRFC...LMRFC...MBRFC...NCRFC...OHRFC...NWC...

LAT...LON 38528788 37828742 36548781 35498933 35309155
35669342 36759441 37919352 38458993
$$
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AWUS01 KWNH 131737
FFGMPD
TNZ000-KYZ000-INZ000-ILZ000-MSZ000-MOZ000-ARZ000-132330-

Mesoscale Precipitation Discussion 0113
NWS Weather Prediction Center College Park MD
137 PM EDT Wed Apr 13 2022

Areas affected...Mid-Mississippi River Valley

Concerning...Heavy rainfall...Flash flooding possible

Valid 131736Z - 132330Z

Summary...Widespread showers and thunderstorms with rain rates
reaching 2"/hr will continue to move across the Mid-Mississippi
River Valley through the evening. 2-3" of rainfall with locally
higher amounts may produce flash flooding.

Discussion...GOES-E IR imagery this aftn shows an expansive area
of cooling cloud tops stretching from southern Arkansas northeast
into southern Illinois. These cloud tops are associated with
strengthening convection along and ahead of a cold front, and
recent 1-hr rainfall has been measured at several stations across
AR of over 1.5", closely matching radar estimates from KLZK
WSR-88D. As this cold front continues to push eastward through the
aftn, these rain rates will likely continue, and may increase
towards 2"/hr near the Mississippi River.

This cold front is being driven eastward by robust height falls
downstream of the parent longwave trough, and a potent vorticity
impulse swinging through to the east. The amplification of this
feature is driving impressive RRQ upper diffluence as well, the
result of which is producing strong deep layer ascent to expand
thunderstorm coverage. Ahead of the front, strong thermodynamic
advection noted by RAP 850mb winds from the S/SW at 50-60kts
according to SPC mesoanalysis is driving PWs towards 1.5" and
MUCape above 2000 J/kg in the pre-convective environment. The
overlap of the strong forcing into the impressive thermodynamics
should allow for a continued increase in updraft strength
supporting rain rates that may eclipse 2"/hr as shown by HREF
probabilities.

The high-res guidance, most notably the HRRR and ARW which are
handling the current situation the best, suggest the thunderstorms
along the northern edge of the instability pool may begin to race
faster to the east, limiting the temporal duration of heavy rain
rates. However, mean cloud layer flow which is parallel to the
front should allow storms which initiate in the greater
instability to still train south to north, leading to repeated
rounds of heavy rainfall in some locations which could accumulate
to 2-3" or more. Parts of the region, especially near the Bootheel
of MO, have received more than 300% of normal rainfall the past 7
days which has resulted in 40cm soil moisture that is above the
90th percentile according to NASA SPoRT, and severely compromised
FFG. In this area, HREF exceedance probabilities for 3-hr FFG
reach above 40%. While the greatest flash flood risk will be
across these saturated soils, any location that receives training
of these heavy rain rates could experience flash flooding this
aftn.

Weiss

ATTN...WFO...ILX...IND...JAN...LSX...LZK...MEG...OHX...PAH...
SGF...

ATTN...RFC...ABRFC...LMRFC...MBRFC...NCRFC...OHRFC...NWC...

LAT...LON 39098907 38998826 38508768 38198755 37548763
36808790 35978834 35298880 34298940 33798982
33459042 33359099 33349163 33479235 33739298
34379320 35209313 36299266 36519253 37009220
37959151 38679061 38919000

$$
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AWUS01 KWNH 251632
FFGMPD
TXZ000-252229-

Mesoscale Precipitation Discussion 0140
NWS Weather Prediction Center College Park MD
1231 PM EDT Mon Apr 25 2022

Areas affected...portions of southeast Texas

Concerning...Heavy rainfall...Flash flooding possible

Valid 251629Z - 252229Z

Summary...A slowing linear MCS could contribute to a few instances
of runoff especially near urbanized and/or sensitive areas.

Discussion...An elongated MCS continues its forward progress
across much of the southern Plains and Lower Mississippi Valley.
Concern exists that portions of this MCS have begun to slow its
forward progress (to around 10-15 knots) near the College Station
vicinity. The stalling boundary and persistent isentropic lift
along it has begun to enhance rain rates on a very localized
basis, with MRMS data suggesting 1-2.5 inch/hr rain rates beneath
the more persistent convection. Antecedent conditions have been
fairly dry across southeast Texas, suggesting that most areas can
handle the rainfall although moderate MRMS Flash responses have
peaked near the College Station vicinity over the past hour.

Some concern exists that heavier rainfall (with rates exceeding 1
inch/hr) will overspread sensitive, urbanized areas of the Houston
Metro beginning around/after 18Z. The risk of flash flooding will
increase if this somewhat conditional heavy rain threat
materializes. Localized instances of 2-3.5 inches of rainfall are
possible beneath the heavier activity, although current trends
suggest that the heavier rates should stay relatively focused and
not become widespread.

Cook


ATTN...WFO...CRP...EWX...FWD...HGX...LCH...SHV...

ATTN...RFC...WGRFC...NWC...

LAT...LON 31389543 31379482 31199437 30839416 30289408
29799417 29629456 28889560 28669661 28759712
29109733 29719753 30639737 30959689 31219607

$$
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AWUS01 KWNH 292149
FFGMPD
NEZ000-300300-

Mesoscale Precipitation Discussion 0146
NWS Weather Prediction Center College Park MD
547 PM EDT Fri Apr 29 2022

Areas affected...Eastern Nebraska

Concerning...Heavy rainfall...Flash flooding possible

Valid 292145Z - 300300Z

SUMMARY...Robust convection tracking through eastern Nebraska this
afternoon and evening may produce excessive rainfall rates that
could possibly lead to areas of flash flooding.

DISCUSSION...A deepening surface low in northern Kansas contains a
lifting warm front that is crossing into southeast Nebraska this
afternoon. Aloft, 500mb height falls are being observed ahead of a
vigorous 500mb trough approaching from the Rockies. At 250mb, the
left exit region of a jet streak atop the Central Rockies is
providing impressive diffluence in the upper levels while moist
850mb flow is streaming north from the South-Central U.S. While
surface dew points are generally in the 60s, precipitable water
levels up to 1.25" (roughly +1.5-2.0 sigma) and 850mb moisture
flux anomalies peaking up to +4.0 sigma over eastern Kansas feed
directly beneath the diffluent left-exit region this evening.
Along with an intensifying low level jet of 50-60 knots by 02Z in
eastern Kansas, and MLCAPE of 2,000-2,500 J/kg in place, the
ingredients are there for organized deep moist convection to
persist into the evening hours.

It is worth noting that drier RH levels at mid-levels and colder
temperatures aloft as the upper trough approaches increase the
potential for dry air entrainment, as well as a favorable hail
growth zone within maturing convection. The mean flow within the
LCL-EL layer in 20Z HRRR area averaged soundings in southeast
Nebraska around 00Z is >30 kts and Corfidi shear vectors are >15
kts. These factors do limit the extent of flash flooding, however
there has also been convection in parts of the region from last
night. Much of the region remains mired in drought, but the areas
most at risk for potential flooding would be in areas where hourly
FFG is under 1.5"/hr.

Latest 18Z HREF indicates there are 10-20% probabilities of 1-hr
rainfall totals exceeding 1-hr FFGs in the the eastern periphery
of this MPD. Similar probabilities are shown for 3-hr totals
exceeding 3-hr FFGs as well. The fast storm motions and drier air
aloft will limit the extent to which warm rain processes
transpire. That said, rainfall rates could approach FFG levels in
parts of eastern Nebraska with the areas most at risk where
rainfall occurred within the last 24 hours.

Mullinax

ATTN...WFO...GID...LBF...OAX...

ATTN...RFC...MBRFC...NWC...

LAT...LON 42339777 42199705 41969657 41409628 40699648
40259690 40059763 40009905 40359960 40839906
41469860 41979837
$$
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AWUS01 KWNH 232017
FFGMPD
VAZ000-NCZ000-240204-

Mesoscale Precipitation Discussion 0234...Corrected
NWS Weather Prediction Center College Park MD
416 PM EDT Mon May 23 2022

Corrected for Lat/Lon Points

Areas affected...Central/Northern NC and South-Central VA

Concerning...Heavy rainfall...Flash flooding likely

Valid 232004Z - 240204Z

SUMMARY...Showers and thunderstorms with very heavy rainfall rates
are expected to become a bit more expansive and focused going
through the late-afternoon and early evening hours. Very heavy
rainfall rates and locally repeating rounds of convection will
promote some areas of flash flooding. This will especially be the
case across areas of central NC and around the Raleigh-Durham
metropolitan area.

DISCUSSION...The latest radar imagery shows heavy showers and
thunderstorms generally expanding in coverage across areas of
central and northern NC as a very moist and unstable airmass
lifting northeast up across Southeast coastal plain and overruns a
well-defined front attempting to lift north into the southern
Mid-Atlantic as low pressure rides northeast up across southwest
NC.

There is the nose of a 30 to 40+ kt southwest low-level riding up
across western and central SC which will aim into areas of
southern and central NC over the next few hours and favor strong
low-level moisture and instability transport into this strong
frontal zone. Isentropic ascent coupled with the instability and
locally strong frontal convergence/forcing will likely set the
stage for some additional expansion of heavy showers and
thunderstorms over the next few hours, including the potential for
repeated development/rounds in vicinity of the front.

The 12Z HREF guidance suggests high probabilities of seeing some 2
to 3 inch/hour rainfall rates, and with some 6-hour QPFs on the
order of 3 to 5 inches across central NC in particular going
through 00Z. In fact, the HREF is supporting greater than 50%
probabilities of seeing 6-hour QPF amounts exceed the 10-year ARI
across parts of central NC in the 21Z to 00Z time frame.

Areas of flash flooding are generally going to be expected over
the next several hours given the set-up, with a notable concern
for the more urbanized Raleigh-Durham metropolitan area and
adjacent suburbs. Some of these heavy rains may result in runoff
concerns farther north across northern NC and areas of far
south-central VA as well.

Orrison

ATTN...WFO...AKQ...GSP...MHX...RAH...RNK...

ATTN...RFC...OHRFC...SERFC...NWC...

LAT...LON 36917997 36917855 36507733 35957693 35277707
34897760 34937852 35397993 35838076 36568076

$$
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AWUS01 KWNH 301738
FFGMPD
MNZ000-IAZ000-NEZ000-SDZ000-NDZ000-302335-

Mesoscale Precipitation Discussion 0268
NWS Weather Prediction Center College Park MD
136 PM EDT Mon May 30 2022

Areas affected...Southeastern ND...Eastern SD...West-Central
MN...Northeastern NE

Concerning...Heavy rainfall...Flash flooding possible

Valid 301735Z - 302335Z

Summary...Convection is expected to rapidly expand northward this
afternoon, bringing nearly widespread coverage of heavy rainfall
with rates of 1-2"+/hr. Localized accumulations as high as 3-5"
may lead to isolated to scattered instances of flash flooding.

Discussion...Deep convection has begun to initiate in portions of
SD/NE, along and east of a stationary front that is currently
draped from eastern ND southwestward through SD into central NE. A
fairly broad area of low pressure exists across the region,
expected to deepen this afternoon in response to a potent
shortwave trough currently ejecting northward out of western NE.
Instability across the region is rapidly increasing from 1000-2000
J/kg of SB CAPE to 2000-3000 J/kg by 20z. This is due to a
combination of height falls aloft (increasing lapse rates) and
peak diurnal heating. Precipitable water values range from 1.2-1.5
inches, but may reach as high as 1.6 inches this afternoon
(between the 90th percentile and record highs, per OAX/ABR
sounding climatology). A strong gradient of deep layer wind shear
exists, from 20-30 kts near the ND/MN border to a staggering 50-70
kts farther south near the intersection of SD/MN/IA/NE. Given
strong forcing and overall model agreement, deep convection should
have no problem organizing and moving rapidly NNE with the mean
wind this afternoon.

Rainfall rates in association with deep convection should have no
trouble reaching 1-2"/hr, though instantaneous rates will be
higher with the potential for sub-hourly accumulations of 1"+. The
overall fast movement of convective activity should largely limit
significant rainfall accumulations, though localized 3-6 hour
totals of 3-5" seem plausible with the potential for some
north-to-south training/repeating along the nearly stationary
front. The forcing via the shortwave should become so strong that
a deepening low should start to overtake the placement/existence
of the front, allowing an ending of precipitation from south to
north as a dry slot/subsidence rapidly develops. Any instances of
flash flooding are expected to remain fairly isolated to widely
scattered through 00z, though subsequent MPD issuance is likely
through the evening with the potential for more
widespread/significant flash flooding farther north into ND/MN
(where FFG is lower and the length of the event may be more
prolonged).

Churchill

ATTN...WFO...ABR...BIS...DLH...FGF...FSD...LBF...MPX...OAX...
UNR...

ATTN...RFC...MBRFC...NCRFC...NWC...

LAT...LON 48009550 47739358 46189437 44909539 43499637
41969731 41819837 41979881 42259929 42549968
43280013 44250012 45319978 46549885 47709721


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AWUS01 KWNH 112226
FFGMPD
MOZ000-IAZ000-KSZ000-NEZ000-120400-

Mesoscale Precipitation Discussion 0341
NWS Weather Prediction Center College Park MD
624 PM EDT Sat Jun 11 2022

Areas affected...Southeastern NE...Northeastern KS...Northwestern
MO

Concerning...Heavy rainfall...Flash flooding possible

Valid 112223Z - 120400Z

Summary...Training/repeating of 1-2"/hr rainfall rates may lead to
localized instances of flash flooding, short-term totals of 2-4".

Discussion...Discrete convection has manifested in the form of
supercells this afternoon in the vicinity of a surface low
pressure system and its associated warm front. In addition to very
large hail, these supercells will produce rainfall rates of
1-2"/hr with precipitable water values of 1.5-1.8" per SPC
mesoscale analysis (at or above the 90th percentile, per OAX/TOP
sounding climatology). In addition, very high instability/shear
(SB CAPE of 3000-6000 J/kg and effective bulk shear of 40-60 kts)
is expected to maintain supercell storm structure. This highly
favorable parameter space for heavy rainfall will coincide with
the potential for repeating/training of discrete cells, as the
deep layer mean wind and bunkers right mover vectors are mostly
parallel with the surface boundary/axis of storm initiation
(orthoganal to the low-level inflow/moisture transport). So
despite the fairly unfavorable, relatively fast storm motion (deep
layer mean wind ~30 kts), the act of training may allow for
successive hours of 1-2"/hr rates (in addition to the tendency for
storms to become right movers, favoring a slower storm motion of
15-20 kts). This discrete convection should gradually merge and
form a forward propagating mesoscale convective system (MCS),
eventually lessening the threat of flash flooding due to a more
progressive, southerly motion.

Hydrologically, the region is not particularly susceptible with
regard to antecedent conditions with NASA SPoRT-LIS 0-40 cm soil
moisture indicated to be near normal or just above normal (near
the 50-70th percentile). Even so, flash flood guidance (FFG) is
indicated to be as low as 1.5" (but more generally ~2.0") over a
3-hr period. Hi-res CAM guidance (as well as the current trends
detailed above) would support localized totals of 2-4" over as
little as 1-2 hours, so flash flooding is considered possible
where the training of supercells is able to locally occur.

Churchill

ATTN...WFO...DMX...EAX...OAX...TOP...

ATTN...RFC...ABRFC...MBRFC...NWC...

LAT...LON 41679629 41369522 40829441 39999355 39369353
38889401 38679481 38749641 39119679 39769711
40309729 40949694

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AWUS01 KWNH 191803
FFGMPD
TXZ000-NMZ000-AZZ000-200000-

Mesoscale Precipitation Discussion 0377
NWS Weather Prediction Center College Park MD
200 PM EDT Sun Jun 19 2022

Areas affected...Far Southeast AZ...Much of NM

Concerning...Heavy rainfall...Flash flooding possible

Valid 191800Z - 200000Z

SUMMARY...Scattered areas of showers and thunderstorms today will
foster an isolated concern for some flash flooding. Dry washes and
burn scars will again be the more vulnerable locations for runoff
problems.

DISCUSSION...Monsoonal moisture continues to pool across portions
of the Southwest as deep layer south-southwest flow in between an
upper-level trough over the Intermountain West, and a strong ridge
of high pressure over the Plains, transports moisture northward
from Mexico.

The PW anomalies today are somewhat lower compared to yesterday
and also oriented a bit farther east, but still as much as 2 to
2.5 standard deviations above normal from far southeast AZ through
southwest and central NM. It should be noted that the latest
CIRA-ALPW data shows some of the mid-level moisture over the
region having at least some origin to the eastern tropical Pacific.

Extensive cloudiness throughout the morning had been limiting
boundary layer heating to an extent, but over the next few hours
there should be sufficient surface-based heating/instability to
promote scattered areas of orographically enhanced showers and
thunderstorms across the region.

The 12Z HREF guidance favors some hourly rainfall amounts of as
much as 1.5 inches with the stronger cells, and localized storm
totals going through late afternoon of 2 to 2.5 inches. The
heaviest rainfall amounts today should target the higher terrain
of central and southern NM, with the Sacramento Mountains of
south-central NM in particular seeing a favorable setup for heavy
amounts given a combination of upslope flow, moisture transport,
and instability.

The flash flood threat overall will be isolated, but the area dry
washes and burn scar locations will again be susceptible to seeing
runoff problems with some of these heavier showers and
thunderstorms that materialize.

Orrison

ATTN...WFO...ABQ...EPZ...FGZ...TWC...

ATTN...RFC...ABRFC...CBRFC...WGRFC...NWC...

LAT...LON 36830645 36430475 34870463 33510510 32720542
32060591 31710656 31730778 31370892 31501023
32770999 34090929 35790795

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AWUS01 KWNH 222058
FFGMPD
NYZ000-PAZ000-MDZ000-VAZ000-WVZ000-230300-

Mesoscale Precipitation Discussion 0391
NWS Weather Prediction Center College Park MD
456 PM EDT Wed Jun 22 2022

Areas affected...Interior Northeast and Mid-Atlantic states

Concerning...Heavy rainfall...Flash flooding possible

Valid 222100Z - 230300Z

Summary...Thunderstorms developing along a stationary front will
expand in coverage through this evening. Rainfall rates of 1-2"/hr
are likely, which through training could produce 2-3" of rainfall.
Flash flooding is possible.

Discussion...GOES-E WV imagery depicts an anomalous closed low
retrograding east of New England, while a mid-level ridge expands
across the Mid-South. At the same time, a surface cold front
analyzed by WPC and noted by rapidly deepening convection on the
IR imagery is dropping across the Great Lakes. Between all of
these features, the Mid-Atlantic and interior Northeast are being
sandwiched between moist unstable air to the west, and cooler more
stable air to the east, with a stationary boundary serving as the
demarcation line. It is along this stationary boundary that
low-level convergence is focusing more enhanced ascent, leading to
increasing coverage of showers and thunderstorms across the area.

The environment in the vicinity of this stationary boundary varies
considerably from west to east due to a sharp moisture and
instability gradient. Within the warm sector along and west of the
boundary, RAP analyzed SBCAPE is above 3000 J/kg, with PWs of
1.75-2 inches fueled by 850mb dew point temperatures of +17C,
above the daily record according to the SPC sounding climatology.
With warm cloud depths forecast to rise to near 13,000 ft, these
parameters together suggest increasingly efficient warm rain
processes which can support rainfall rates of 1-2"/hr as progged
by the HREF probabilities, and already being estimated by the
local radars.

Although the 0-6km mean wind is likely to remain quick from north
to south on deep nearly unidirectional flow, this will be parallel
to the boundary, suggesting an increasing training potential. As
storms fire anywhere within the warm sector, they will likely drop
southward over similar areas, and the high-res guidance is in
decent agreement in a narrow corridor of heavy rain along the best instability/moisture gradient. With rainfall rates of 1-2"/hr,
some locations that receive multiple rounds of convection could
accumulate up to 3" of rain. Where this heaviest rain occurs,
isolated flash flooding is possible as HREF exceedance
probabilities for 3-hr FFG reaches 20-40% despite locally higher
FFG due to antecedent dry conditions. The most likely locations
for any flash flooding will be across any urban areas or sensitive
terrain, but any enhanced training could lead to isolated impacts
anywhere within the discussion area until instability wanes this
evening.


Weiss

ATTN...WFO...AKQ...BGM...BUF...CTP...LWX...PBZ...RNK...

ATTN...RFC...MARFC...NERFC...OHRFC...NWC...

LAT...LON 43377670 43157633 42537631 41317665 39927704
38637749 37497810 37447869 37727921 38897916
40387884 41737849 42747803 43187752 43367704


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AWUS01 KWNH 261814
FFGMPD
COZ000-NMZ000-AZZ000-UTZ000-270012-

Mesoscale Precipitation Discussion 0411
NWS Weather Prediction Center College Park MD
213 PM EDT Sun Jun 26 2022

Areas affected...portions of Utah, northern Arizona, and
western/central Colorado

Concerning...Heavy rainfall...Flash flooding possible

Valid 261812Z - 270012Z

Summary...Areas of 0.5 inch/hr rain rates (locally heavier)
beneath slow-moving thunderstorms could cause a few areas of flash
flooding at times this afternoon and early evening.

Discussion...Solar insolation has allowed for enough mid-level
instability to foster isolated thunderstorm development over the
past hour or so across the discussion area. These storms are in a steep-lapse-rate environment, with mid-level moisture lingering
across the region bolstering PW values into the 0.5-0.75 inch
range across the discussion area. Additionally, very weak
tropospheric wind fields (less than 20 knots beneath 300mb),
allowing for mostly outflow-dominant storms with very erratic and
slow storm motions. The slow storm motions will allow for
occasional rain rates exceeding 0.5 inch/hr at times as convective
coverage expands through peak heating. These rates could be
enough to result in flash flooding in sensitive, terrain-favored
areas and especially near burn scars.

Convective coverage should continue to expand through peak heating
hours and persist well after 00Z as the strength of updrafts are
modulated by insolation and resultant instability. The attendant
flash flood threat will exist through that time as well - albeit
on an isolated basis.

Cook

ATTN...WFO...ABQ...BOU...FGZ...GJT...PSR...PUB...SLC...VEF...

ATTN...RFC...ABRFC...CBRFC...MBRFC...WGRFC...NWC...

LAT...LON 40370736 40350632 39890566 39420547 38640603
37210761 36560903 35520970 33911020 33721093
34071239 35201385 36631404 37551388 39051300
39871204 40171080 40320895

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AWUS01 KWNH 020902
FFGMPD
LAZ000-TXZ000-021500-

Mesoscale Precipitation Discussion 0431
NWS Weather Prediction Center College Park MD
500 AM EDT Sat Jul 02 2022

Areas affected...Far Eastern TX...Northwest LA

Concerning...Heavy rainfall...Flash flooding possible

Valid 020900Z - 021500Z

SUMMARY...Concerns will exist this morning for developing and
expanding areas of backbuilding and training convection with
extremely heavy rainfall rates. Some areas of flash flooding will
be possible.

DISCUSSION...A long-lived MCV which was instrumental in driving
yesterday morning's heavy to excessive rainfall event across far
southwest LA and adjacent areas of the upper TX coast is now
situated over northern LA with a very slow drift off to the
northeast.

Some very warm-topped convection has begun to develop near the
vort center over the last couple of hours, and the concern going
through the early and mid-morning hours will be for there to be
additional development and expansion of this convection as
southerly low-level flow increases into proximity of the
tightening mid-level vort center dynamics.

The latest RAP forecast does show a stronger pooling of
instability and convergence around the western and southern flanks
of a weak 500/700 mb low circulation over northwest LA this
morning, and there is an environment conducive for backbuilding
and training convection with the Corfidi vectors oriented along
and opposite of the 850/300 mb mean layer flow.

PWs over the region are very high and tropical in nature with 2.25
inch values noted in the latest NESDIS Blended-TPW product. The
CIRA-ALPW data sets show some particularly strong concentrations
of moisture in the 700/300 mb layer.

The environment is strongly conducive for enhanced rainfall
efficiency with warm rain processes dominating the vertical
hydrometeor profile. Expect convection this morning to be
relatively low-topped in the short-term, with some stronger
vertical development in time as somewhat stronger instability
pools into the region. Extremely high rainfall rates are possible,
with 3+ inch/hour rainfall rates not out of the question with some
of these backbuilding and training convective cells that set up.

The models are highly uncertain with the exact axis of heavier
rainfall potential stretching from far eastern TX into northwest
LA, but overall, some rainfall totals going through mid-morning
may approach or locally exceed 5 inches. Areas of flash flooding
will be possible as a result.

Orrison

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!DZ3fjg!5Fyx7WOAXMVl8VMIR324FAwIk3mSW8UTf8gj7NIH808C1N8b7EXkhx5g5sK37Qhp5G4aCiJUkmw8Pp9y56BmhpduYNQ$
for graphic product...

ATTN...WFO...FWD...HGX...SHV...

ATTN...RFC...LMRFC...WGRFC...NWC...

LAT...LON 32849292 32679241 32359225 31829242 31439358
31319487 31549546 31879557 32199537 32479482
32679419 32789363
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AWUS01 KWNH 021150
FFGMPD
MOZ000-KSZ000-NEZ000-021630-

Mesoscale Precipitation Discussion 0432
NWS Weather Prediction Center College Park MD
749 AM EDT Sat Jul 02 2022

Areas affected...Eastern Kansas, Western Missouri

Concerning...Heavy rainfall...Flash flooding possible

Valid 021148Z - 021630Z

Summary...Showers and thunderstorms training north of a warm front
will produce rounds of heavy rainfall through late morning.
Rainfall rates in excess of 1"/hr are likely, which may produce
flash flooding.

Discussion...The regional radar mosaic this morning depicts a
large area of showers with embedded thunderstorms moving across
eastern Kansas. This activity was associated with an 850mb LLJ of
35 kts noted via the KICT VWP surging out of the south, driving
PWs to more than 2 inches according to recent GPS observations. A
warm front analyzed by WPC was laying just north of the KS/OK
border, which was acting as a boundary into which the LLJ was
isentropically ascending across much of eastern Kansas. This
ascent within the very moist environment is leading to sustained
convection across the region despite modest instability, and an
MCV was noted via KTWX radar, embedded within this larger
precipitation shield. Rainfall rates estimated by local radars
were 1-1.5"/hr in pockets stronger reflectivity.

As the warm front lifts slowly northward this morning, it will
continue to serve as the impetus for shower and thunderstorm
development within the WAA lifting from the south. The LLJ, which
is likely to continue as the primary driver of ascent through the
morning, is progged to veer and weaken in the next few hours.
However, at least modest diffluence in the RRQ of a distant upper
jet streak, and the MCV which should push eastward, will somewhat
offset the reduction in lift caused by the weakening LLJ. At the
same time, a sharp instability gradient is likely to persist along
the boundary itself, with MUCAPE of 500-1000 J/kg serving to
resupply favorable thermodynamics into KS and MO. This suggests
that convection will only slowly wane in intensity while shifting
eastward, a pattern that is echoed by most available high-res
guidance. The HRRR is the weakest of the solutions this morning,
but appears to be under-doing the current convective activity, and
has also exhibited a subtle increase in its simulated reflectivity
during the past few runs. Noting this, and comparing to current
radar, the flash flood risk will likely extend downstream well
into Missouri, which is supported by moderate to high
probabilities of both 1"/hr rainfall and 3-hr FFG exceedance in
the HREF.

The greatest risk for flash flooding will likely remain across
Kansas during the next few hours due to the stronger moisture
transport and ascent on the LLJ, with training of heavy rain
likely from west to east. This is also where AHPS 14-day rainfall
has been above normal leading to near normal 40cm soil moisture
and FFG as low as 1.5"/3hrs. However, downstream into Missouri
despite higher FFG, a lesser but still elevated flash flood risk
will exist until the LLJ weakens and veers to the west by late
morning.


Weiss

ATTN...WFO...EAX...GID...ICT...LSX...OAX...SGF...TOP...

ATTN...RFC...ABRFC...MBRFC...NCRFC...NWC...

LAT...LON 40059691 40039587 39989491 39749360 39389254
39009180 38369109 37839114 37729136 37639171
37649225 37679290 37779362 37879430 37999565
38119647 38639749 39139808 39569832 39949834
40049779

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AWUS01 KWNH 051751
FFGMPD
ALZ000-MSZ000-LAZ000-052247-

Mesoscale Precipitation Discussion 0447
NWS Weather Prediction Center College Park MD
150 PM EDT Tue Jul 05 2022

Areas affected...Southeastern LA...Southern MS/AL

Concerning...Heavy rainfall...Flash flooding possible

Valid 051747Z - 052247Z

Summary...Heavy rainfall rates (1-3"/hr) with relatively slow
storm motions may lead to localized totals of 4-6", isolated
instances of flash flooding.

Discussion...A weak, retrograding shortwave trough along the Gulf
Coast is resulting in a rather expansive area of showers and
thunderstorms across much of southeastern LA and southern MS/AL
early this afternoon. The mesoscale enviornment is characterized
by ML CAPE of 2000-3000 J/kg, precipitable water values of 2.2-2.4
inches (above the 90th percentile and near the max moving average,
per LIX sounding climatology), and effective bulk shear near 20
kts. While convection is expected to continue to be fairly
unorganized in this enviornment (relatively low shear), the
anomolous moisture content and weak steering flow (850-300 mb mean
winds near 5 kts) will allow for wide-ranging heavy rainfall rates
of 1-3"/hr. While most localities can take up to 3" of rain in an
hour, a few spots may approach totals of 4-6" in as little as 2-3
hours. An isolated instance or two of flash flooding is possible,
particularly if training occurs over more urbanized terrain.

Churchill

ATTN...WFO...JAN...LCH...LIX...MOB...

ATTN...RFC...LMRFC...SERFC...NWC...

LAT...LON 31728908 31618828 31308770 30648778 30288816
30278877 30118964 29918994 29499066 29289133
29649185 29969203 30499209 31049160 31449080
31649000

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AWUS01 KWNH 051844
FFGMPD
VAZ000-NCZ000-WVZ000-OHZ000-TNZ000-KYZ000-INZ000-060030-

Mesoscale Precipitation Discussion 0448
NWS Weather Prediction Center College Park MD
243 PM EDT Tue Jul 05 2022

Areas affected...Ohio Valley and Central Appalachians

Concerning...Heavy rainfall...Flash flooding possible

Valid 051841Z - 060030Z

Summary...Showers and thunderstorms developing within a warm
sector behind a slow moving warm front will expand through the
evening. Rainfall rates of 1-2"/hr are likely, which could create
flash flooding, especially in any sensitive terrain.

Discussion...The regional radar mosaic this aftn depicts rapidly
increasing convection behind a warm front and along a surface
trough/outflow boundary draped from southern IN through WV. Both
the intensity and coverage of this convection is increasing in
response to an extremely favorable thermodynamic environment. PWs
measured by GPS are as high as 1.75-2 inches, with SPC RAP
analyzed MLCAPE as high as 3000 J/kg. Low-level flow is generally
out of the west, supplying renewed and favorable moisture and
instability into the region ahead of the trough, within which
convection will likely persist through the evening. Recent
radar-estimated rain rates were as high as 1.5"/hr according to
the KJKL WSR-88D, and these rates are forecast to continue for
several more hours.

A weak shortwave dropping southeast across the region will help
enhance ascent, and the high-res simulated reflectivity suggests
showers and thunderstorms will be widespread this aftn and
evening, despite initializing with less coverage that currently
occurring. As the low-level flow remains favorable for resupply of thermodynamics, rainfall rates are expected to persist at 1-2"/hr
through loss of diurnal heating. This will pose an increasing
flash flood risk as 0-6km mean winds of 10-20kts remain parallel
to both the surface trough and the Corfidi vectors, indicating a
likelihood for training from west to east as the boundary drops
southward. Training of these impressive rainfall rates could
produce 1-3" of rainfall, with locally higher amounts, through the
evening.

FFG across the region is generally 2"/3hrs, but has pockets as low
as 1.5"/3hrs. This is due to recent rainfall that is as high as
150% of normal in the past 7 days in parts of KY and WV, leading
to slightly above normal soil moisture according to NASA SPoRT.
Due to the under-representative nature of the high-res in terms of
convective coverage, the HREF exceedance probabilities that are
just around 20% could be too low. With favorable ingredients
persisting, and impressive rainfall rates training, flash flooding
is possible through the evening, with the greatest chance atop the
most sensitive soils due to antecedent rainfall or terrain
features.


Weiss

ATTN...WFO...AKQ...ILN...IND...JKL...LMK...LWX...MRX...RAH...
RLX...RNK...

ATTN...RFC...LMRFC...MARFC...OHRFC...SERFC...NWC...

LAT...LON 39558495 39528449 39198372 38918322 38698224
38548098 38417959 38247828 37757754 37297759
36857796 36567852 36377892 36277943 36288040
36418160 36728282 37188429 38028536 38578563
39148547

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AWUS01 KWNH 112108
FFGMPD
FLZ000-GAZ000-ALZ000-MSZ000-120230-

Mesoscale Precipitation Discussion 0482
NWS Weather Prediction Center College Park MD
507 PM EDT Mon Jul 11 2022

Areas affected...Southern GA...Northern FL & Panhandle...Southern
AL...Southern MS

Concerning...Heavy rainfall...Flash flooding possible

Valid 112110Z - 120230Z

SUMMARY...A few more hours of slow moving highly efficient
rainfall producing thunderstorms seeking out remaining pockets of
instability.

DISCUSSION...GOES-E Visible and Regional RADAR loop depict peak
thunderstorm activity along the stationary front extending from
the GA/FL coast and across to central LA just a county or so
onshore with little weak areas of low pressure near JAX and back
toward GZH in S AL. Very rich deep moisture pooled along the
front is due to deep layer trof vertically stacked through much of
the lower and middle troposphere with total PWat values of
2.25-2.5". Even with saturated profiles, high solar angle was
able to generate ample sfc heating to produce narrow skinny
profiles of 2000-3000 J/kg. Current activity is doing a good job
on overturning a large area generally 70 miles on either side of
the boundary with weak steering flow to support some weak
organization, more than up/down pulse convection. Propagation
along outflows, intersecting mergers will turn over the remaining
pockets of instability in sometimes larger slabs allowing for
increased breadth of the subsequent downdrafts and capable of 2-3"
hourly rain totals with a bulk of it coming in sub-hourly time
frames. As a result, localized rapid inundation flooding remains
possible through the late evening hours with greater potential
near those weak sfc to 85H circulations that may help some storm
scale inflow for locally enhanced totals up to 4".

Only sizable forecast change was weak retrograding of a surface to
85H wave from SE AL/W FL panhandle westward toward Mobile and even
as far west as coastal MS...this area has been spared but
increased moisture flux and MLCAPEs to 3000 J/kg should expand on
outflows over areas that have seen recently heavy rainfall over
the last day or two (ie Mobile).

Gallina

ATTN...WFO...CHS...JAN...JAX...LIX...MOB...TAE...

ATTN...RFC...LMRFC...SERFC...NWC...

LAT...LON 32138140 31938094 30908130 29948117 29628220
29858322 29978414 29638470 29578532 30048584
30278667 30138783 30228902 30788926 31408882
31668710 31558584 31678430 31758268 31968202


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AWUS01 KWNH 162110
FFGMPD
NVZ000-CAZ000-170210-

Mesoscale Precipitation Discussion 0515
NWS Weather Prediction Center College Park MD
510 PM EDT Sat Jul 16 2022

Areas affected...Southern Sierra Nevada Mtns in California...

Concerning...Heavy rainfall...Flash flooding possible

Valid 162110Z - 170210Z

SUMMARY...Enhanced moisture at cloud base and slow motions/upslope redevelopment pose hourly rates of .5-.75" and localized totals of
1"+ resulting in possible localized flash flooding.

DISCUSSION...RAP 7H analysis denotes an bubble of increased
moisture with Tds to 7C which appears to be corroborated by CIRA
LPW denoting a bubble of enhanced moisture advecting from the
south with .5-.6" Pwat values. HNX VWP suggests 7H flow is
supportive of western upslope while along the far western edge of
the 5-3H elongated ridge. Jet over N CA, may provide some
additional upper level support with weak divergence for any cell
that does develop. Yet 85-7H flow is 15-20kts at cloud base from
the south-southwest which may further support longer
duration/redevelopment potential along the peak/ridge lines to
maintain some duration for stronger updrafts that are expected to
blossom over the next 1-2 hours. While total PWat values are
about .75-.9", this is generally 90-95th percentile of moisture at
the higher elevation and that it is fluxed at general cloud base
should allow for rain rates of .5-.75"/hr. This may result in
similar or totals up to 1". 18z HREF probability of 1"+ is about
40-45% with 1"/3hrs around 25-30%. This is in the range of FFG
values (.5/hr or 1-1.5/3hrs) in complex terrain and with some
spots receiving rainfall yesterday, localized streams may be a bit
higher than in recent weeks. As such, flash flooding is
considered possible through late evening.

Gallina

ATTN...WFO...HNX...REV...VEF...

ATTN...RFC...CNRFC...NWC...

LAT...LON 38171874 37491816 36521785 36011774 35821809
36021843 36651875 37471946 38151945

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AWUS01 KWNH 032029
FFGMPD
MSZ000-LAZ000-TXZ000-040215-

Mesoscale Precipitation Discussion 0932
NWS Weather Prediction Center College Park MD
428 PM EDT Sat Sep 03 2022

Areas affected...South Texas through Far Southern Mississippi

Concerning...Heavy rainfall...Flash flooding possible

Valid 032026Z - 040215Z

Summary...Thunderstorms continue to develop along an surface
trough inland from the western to central Gulf Coast along with
further activity near the coast. Very efficient warm rain
processes will continue to support rainfall rates of 2-3" per
hour, which could cause flash flooding into the evening.

Discussion...Afternoon regional NEXRAD and GOES-16 IR imagery
depict swaths of heavy thunderstorms with 1.5-3" hourly rainfall
estimates from the Lower Rio Grande Valley up through South Texas,
over south-central TX east through southwest LA and over southern
MS. This expansive area of activity is associated with broad
onshore flow from the western Gulf along with a surface trough
that has pushed inland. Efficient rainfall production is occurring
with 2500-3000 J/kg SBCAPE, PWATs of 2.2-2.5" per GPS sensors and
the 18Z KBRO raob, and warm cloud depth exceeding 10,000 feet.
Deep layer mean flow is at most 5 kts over TX, increasing to
around 10kt out of the west over LA/MS which is aligned with the
surface trough. As a result, activity is slow moving...generally
sagging south over east TX to into LA with more outflow driven
motion in MS and far south TX. Given the ample instability and
presence of the surface trough, heavy, slow-moving convection is
expected to last into the evening.

3hr FFGs are generally 2.5-3" in TX (the south Texas Sand
Sheet/King Ranch was avoided given its higher FFG) and 2.5-4" in
LA/MS), which could continued to be breached by the slow moving
activity. Of particular note is areas that received heavy rain
earlier such as south-central LA and Corpus Christi should
generally avoid another round of heavy rain into this evening and
have been left out of the threat area.

Jackson

ATTN...WFO...BRO...CRP...EWX...HGX...JAN...LCH...LIX...MOB...

ATTN...RFC...LMRFC...WGRFC...NWC...

LAT...LON 31519045 31418937 31158855 30558850 30458868
30168917 29698997 30449138 29949288 29299455
28749559 28289734 27449772 27179843 26669808
26429760 26019762 26219898 28100008 29299868
29959778 30439683 30559526 30969312

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AWUS01 KWNH 272228
FFGMPD
FLZ000-280359-

Mesoscale Precipitation Discussion 1043
NWS Weather Prediction Center College Park MD
624 PM EDT Tue Sep 27 2022

Areas affected...Southwestern and Southeast Florida

Concerning...Heavy rainfall...Flash flooding possible

Valid 272224Z - 280359Z

SUMMARY...Rainfall intensity associated with convection in some of
the outer bands of Hurricane Ian will increase and expand in
coverage through the evening hours across portions of South
Florida.

DISCUSSION...Recent GOES-16 infrared and regional Doppler radars
are indicating in increase of heavy convection in the outer rain
bands oriented from the greater Miami metro area northwestward to
near Fort Myers. There has been repeated upstream development of
new convective cells over the southern Everglades and adjacent
coastal waters, and these cells are feeding into training
corridors as low level moisture convergence increases within a
highly anomalous PW environment, with highly efficient rainfall
processes at work.

The more organized rainbands are expected to produce rainfall
rates on the order of 1-2 inches in 30 minutes, and with localized cell-training concerns, some additional storm total amounts of 2
to 5 inches will be possible going through the late evening hours
based on the latest CAM guidance suite. Farther east along the
urban corridor of southeast Florida, coverage is expected to
generally be more scattered, but antecedent rainfall from earlier
today will lead to slightly more susceptible conditions for
additional flooding.

Hamrick

ATTN...WFO...MFL...TBW...

ATTN...RFC...SERFC...NWC...

LAT...LON 27228163 27198135 27108106 26868099 26738086
26638071 26538051 26378011 26218002 25868012
25708020 25548028 25508037 25528049 25528062
25528072 25468091 25468104 25478115 25498119
25758145 25848173 26098185 26328190 26368207
26518219 26718215 26828211 27028211 27068206
27218178

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AWUS01 KWNH 152146
FFGMPD
ILZ000-MOZ000-160300-

Mesoscale Precipitation Discussion 0189
NWS Weather Prediction Center College Park MD
545 PM EDT Sat Apr 15 2023

Areas affected...central/southern MO into central/southern IL

Concerning...Heavy rainfall...Flash flooding possible

Valid 152144Z - 160300Z

Summary...1 to 2.5 inches of rain will be possible from portions
of central/southern MO into south-central IL over the next few
hours. Localized flash flooding will be possible with peak
rainfall rates of 1 to 2 in/hr.

Discussion...Thunderstorms were ongoing at 2120Z, just ahead of a
cold front that stretched from western IL into southwestern MO and
just north of a low level convergence axis, enhanced by
thunderstorm outflow that extended from just north of TBN to just
south of STL. The environment was characterized by precipitable
water values just over 1 inch and MLCAPE of 1000-2000 J/kg (per
SPC mesoanalysis data), resulting in MRMS-derived rainfall rates
of 1-2 in/hr at times.

Steering flow was southwest to northeast, or quasi-parallel to the
pre-frontal convergence axis which could allow for some training
and/or repeating of storms. Short term forecasts from the RAP
support enhancement to lift leading up to and just beyond 00Z as
an 80-100 kt jet streak develops across the MO/IA border with
divergence and diffluence aloft increasing over the mid-MS Valley. Thunderstorms are expected to continue to follow the cold front as
it tracks east through 03Z, with the orientation of the cold front
somewhat normal to storm movement limiting the degree of flash
flooding. However, where storms align from southwest to northeast,
initially along the convergence axis in MO, and possibly later on
as thunderstorms moving into IL, brief training could allow for a
quick 1.5 to 2.5 inches of rain. 3-hr flash flood guidance of 1.5
to 2.0 inches for a large portion of the discussion area in MO and
IL could be exceeded in a couple of locations, resulting in
localized flash flooding.

Otto

ATTN...WFO...ILX...LSX...PAH...SGF...

ATTN...RFC...LMRFC...MBRFC...NCRFC...OHRFC...NWC...

LAT...LON 40218949 39818879 38958871 38108935 37039150
36809325 37609310 38009270 39199137 39849053


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AWUS01 KWNH 021938
FFGMPD
MTZ000-WYZ000-030137-

Mesoscale Precipitation Discussion 0411
NWS Weather Prediction Center College Park MD
338 PM EDT Fri Jun 02 2023

Areas affected...central/eastern Montana

Concerning...Heavy rainfall...Flash flooding likely

Valid 021937Z - 030137Z

Summary...Deepening convection in eastern Montana will migrate
northwestward into areas of very wet ground conditions. Flash
flood potential is likely to increase through the afternoon and
evening.

Discussion...A broad axis of light to moderate precipitation was
ongoing across portions of the discussion area - generally along
and west of a surface trough/stationary front located from near
Billings to just northwest of Glasgow. Just east of this trough,
surface heating and warm/moist advection has maintained 500-1500
J/kg MLCAPE and 1-1.3 inch PW values. Thunderstorms were
deepening within this airmass, with southeasterly
mid-level/steering flow helping to move that convection westward
toward the surface trough. Additionally, ongoing and prior
rainfall (estimated at 2+ inches in many areas per AHPS) have
moistened soils considerably, and FFG thresholds are quite low
across the region (ranging from 0.25 inch/hr near the surface
trough to around 1 inch/hr along the eastern MT/ND border.)

Models/observations are consistent in depicting a continued
expansion of convective coverage east of the trough along with a
modest increase in precip rates near the trough over the next 4-6
hours. With low FFGs and wet soils, the risk of flash flooding is
expected to increase through the evening especially 1) near the
surface trough and 2) near any training convection that can
prolong rain fall rates east of the trough. This risk is expected
to persist through 02Z and beyond - the surface trough and warm
advection regime in eastern Montana is not expected to change
dramatically during the valid MPD timeframe.

Cook

ATTN...WFO...BYZ...GGW...RIW...TFX...

ATTN...RFC...MBRFC...NWC...

LAT...LON 48990822 48980495 48330407 45990414 45050418
44970867 45260965 46270979 47510958 48480900


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AWUS01 KWNH 261826
FFGMPD
MAZ000-NHZ000-VTZ000-NYZ000-270015-

Mesoscale Precipitation Discussion 0590
NWS Weather Prediction Center College Park MD
225 PM EDT Mon Jun 26 2023

Areas affected...New England

Concerning...Heavy rainfall...Flash flooding possible

Valid 261825Z - 270015Z

SUMMARY...Heavy thunderstorms containing 2"/hr rainfall rates may
result in areas of flash flooding this afternoon.

DISCUSSION...Doppler Radar showed scatted thunderstorms across
interior New England tracking NNE this afternoon. The region
resides ahead of the mean 250-500mb trough axis to the southwest,
placing favorable upper level divergence overhead this afternoon.
There is also a potent 500mb vorticity maximum making its way
through northern VA and act as a trigger for thunderstorms in ther
northern Mid-Atlantic. Mean 850-300mb flow is out of the SSW,
which may direct ongoing storms unfolding near the Catskills and
eastern PA towards the region later this afternoon.

There is a steady stream of southerly 850mb moisture flux being
directed north into the northern Appalachians and along a frontal
boundary positioned over NH and northern VT. PWATs are forecast to
reach at least 1.5" and may even top 1.75" in the Hudson Valley
and Champlain Valley. The warm front has lifted north into
southeast Canada and the warm sector has steadily destabilized.
3-hr MLCAPE change ranges between 200-400 J/kg from the western
half of VT to northern NY with values topping 1,000 J/kg in most
areas. The atmospheric column is also quite saturated, as evidence
by the 80-90% RH values within the 1000-500mb layer. Warm cloud
layers are likely to be 10,000' in depth in some areas, providing
storms with the tools to maintain efficient warm rain processes.

While much of the region can use the rain, these are still storms
containing almost tropical-like characteristics in areas that are
not as adept to handling 2"/hr rainfall rates. In fact, 1-hr FFGs
are as low as 1.0-1.5" and many areas are below 2"/hr. The steady
SSW flow through the depth of the column will also support
possible backbuilding convection, especially in favored upslope
areas and as evidence by upshear Corfidi vectors <10 knots. There
is the potential for flash flooding this afternoon with urbanized
communities and low-lying/poor drainage areas most at-risk.

Mullinax

ATTN...WFO...ALY...BOX...BTV...GYX...

ATTN...RFC...NERFC...NWC...

LAT...LON 45137339 45127225 45137155 44467157 43847155
42597130 42557214 43057323 43277489 44147488
44857439

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AWUS01 KWNH 121124
FFGMPD
MSZ000-LAZ000-ARZ000-TXZ000-121500-

Mesoscale Precipitation Discussion 0705...Corrected
NWS Weather Prediction Center College Park MD
723 AM EDT Wed Jul 12 2023

Corrected for flash flooding tag

Areas affected...Southern Arkansas... Northern Louisiana...Adj Far
NE Texas...Northwest Mississippi...

Concerning...Heavy rainfall...Flash flooding likely

Valid 121122Z - 121500Z

SUMMARY...Extreme rain-rates and totals pressing 8-10" in portions
of Southwest Arkansas will continue to produce significant flash
flooding. Scattered downstream cells into NW MS may have 2-3"+ and
isolated lower end flash flooding thru 15z.

DISCUSSION...GOES-E 1-minute 10.3um EIR shows MCC across southern
AR with two main cooling/overshooting tops (-75C). RADAR depicts
this a a mature arc of convection from Desha/Drew to Bradley and
then back to Miller/Lafayette county. Evolution of the MCC
depicts the combination of MCV and parent mid-level shortwave near
Cleveland county lifting northward. DPVA and low level moisture
convergence from southwesterly overrunning is becoming
increasingly distant from pool of instability across NE TX into N
LA, but given deep 2.25-2.5" total PWats and deep warm layer,
rainfall efficiency has been strong to support 2-2.5"/hr rates.
Forward (northeast) cell motion ahead of the shortwave and weak
propagation should maintain a more scattered appearance lifting
into NW MS over the next few hours, spots of 2-4" are possible in
an hour or two and may result in possible flash flooding, but more
scattered in nature relative to the upwind edge of the complex, so
have extended the MPD into NW MS on this lower-end risk.

RADAR trends show a bit more southward propagation of the upwind
edge of the MCC across SW AR. CIRA LPW denoted a small wedge of
drier air across SW OK that may have mixed into the mid-levels to
allow for increased cold pool generation over the last few hours.
However, 850-700mb moisture channel appears to becoming
increasingly confluent/convergent in the vicinity of Hempstead
county allowing for continued backbuilding and with 2.5" total
PWat values along 20kt southwesterly 850mb flow (64 to 68F Tds)
veering to 25-30kts at 700mb (45-50F Tds) should continue to
support efficient rainfall production of 3-3.5"/hr. Southward
propagation may alleviate the areas of Ouachita/Nevada/Union
counties of receiving more rain, but localized totals of 8-10"
remain probable even with some southward propagation, though more
likely a broader area of 4-6" will occur perhaps into the first
row of NW LA parishes. Flash flooding is likely to continue with
some rural spots experiencing significant flooding still through
the early morning hours (14-15z).

Gallina

ATTN...WFO...JAN...LZK...MEG...SHV...

ATTN...RFC...ABRFC...LMRFC...NWC...

LAT...LON 34669058 34318998 33799002 33269050 32669156
32489247 32659353 33299433 33889441 34439431
34379367 33779293 33769238 33949188 34339152
34589122

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