ACUS11 KWNS 010934
SWOMCD
SPC MCD 010934=20
CAZ000-011330-
Mesoscale Discussion 0212
NWS Storm Prediction Center Norman OK
0334 AM CST Wed Mar 01 2023
Areas affected...the San Gabriel...San Bernardino and San Jacinto
Mountains vicinity
Concerning...Heavy snow=20
Valid 010934Z - 011330Z
SUMMARY...Heavy snow is expected to continue developing across the
higher terrain through daybreak, with rates peaking up to 2-4 inches
per hour across parts of the San Bernardino into San Jacinto
Mountains around 4-7 AM PST.
DISCUSSION...Deepening mid-level troughing, with a developing
embedded low, continues to dig inland of the Pacific coast, with the
exit region of an intense jet streak (in excess of 110 kt around 500
mb) still offshore of the coast nosing toward the LA Basin through
daybreak. Aided by increasing forcing for ascent, likely largely
still due to low-level warm advection, moderate to locally heavy
precipitation has already been overspreading much of southern
California coastal areas into the western slopes of the adjacent
mountains.
Forecast soundings suggest that the dendritic growth layer, which is
roughly centered near or below the 600 mb level, remains
unsaturated. However, with continuing mid-level height falls and
strengthening divergence aloft this is forecast to change during the
next few hours. As west-southwesterly flow in the 4000-8000+ foot
layer strengthens to 40-50+ kt, increasing orographic forcing for
ascent on the windward-facing mountain slopes is expected to
contribute to intensify snow rates, in the presence of precipitable
water increasing in excess of .60 inches. Rapid Refresh forecast
soundings and High Resolution Ensemble output suggest snow rates may
maximize on the order of 2-4 inches per hour in the 12-15Z time
frame across the San Bernardino into San Jacinto Mountains. During
this time, freezing levels across lower elevations may slowly rise
toward 5000 ft, before falling again later this morning. However,
due to the heavy snow rates, and cooling due to melting, snow levels
might be maintained at 3500-4000 feet.
..Kerr.. 03/01/2023
...Please see
https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!8CcvjlDMjiRQEPFeYExvWjELVvkLIIBb7NjUh-fXN7pqUAaENmRWevtndlLSBGIjKsidT4YVw= tRwtMvGP-TrrUDzKnI$ for graphic product...
ATTN...WFO...PSR...VEF...SGX...LOX...
LAT...LON 34371772 34191642 33381625 33161651 33421680 33991699
34371772=20
=3D =3D =3D
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