Subj : MESO: Mesoscale Discussion 0283
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Sun Mar 12 2023 20:51:08

ACUS11 KWNS 122051
SWOMCD
SPC MCD 122050=20
CAZ000-122315-

Mesoscale Discussion 0283
NWS Storm Prediction Center Norman OK
0350 PM CDT Sun Mar 12 2023

Areas affected...portions of Central Valley California

Concerning...Severe potential...Watch unlikely=20

Valid 122050Z - 122315Z

Probability of Watch Issuance...20 percent

SUMMARY...A couple instances of marginally severe hail and perhaps a
brief tornado are possible through the afternoon and early evening
hours. A WW issuance is not expected.

DISCUSSION...Cumulus/showers continue to gradually deepen across the
Central Valley region of California as occasional breaks in cloud
cover allows some surface heating to occur, with a couple of
lightning flashes already noted. With continued heating, low-level
lapse rates should continue to steepen, fostering adequate low-level
CAPE amid 40+ kts of effective bulk shear to support isolated,
low-topped supercells. Supercell initiation will most likely occur
in the next few hours with CU embedded within or immediately ahead
of a confluence band moving ashore from Monterey Bay. Modified RAP
forecast soundings suggest that temperatures only need to warm into
the lower 60s F to support strong to potentially severe storms.
Current observations show such temperatures already in place from
Merced County southward, with 20Z mesoanalysis also depicting up to
8.5 C/km 0-3 km lapse rates. Here, MLCAPE is approaching 500 J/kg.
High-resolution model guidance has also persistently shown areas
near and south of MOD to have the best chance at experiencing a
discrete, sustained supercell. Nonetheless, a severe threat may
still exist farther north toward Sacramento if surface-based
buoyancy materializes later this afternoon.

Through the Central Valley, the presence of cooler temperatures
aloft will promote hail production with the more persistent storms,
with a couple brief instances of 1 inch diameter hail possible.
Furthermore, steep low-level lapse rates and 175+ J/kg 0-3 km CAPE
may also encourage stretching of low-level vertically oriented
(terrain-induced) vorticity to support a brief tornado or two. Any
severe threat that develops should wane with the loss of daytime
heating. Given the isolated and marginal nature of the severe
threat, a WW issuance is not expected.

...Squitieri.. 03/12/2023

....Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj=
g!45WTpUX79xXeJRjVT3C-lQXQ4TEBM304xQpoHPVsxTNCVRGj-LtRQvQnZhxyPh0SZCwnMofCM=
9GCcFmQWYjF0M5tdcA$  for graphic product...

ATTN...WFO...HNX...STO...

LAT...LON   37642118 38712174 39032143 39062105 38312051 37701987
            37131933 36781937 36571963 36622023 36752052 37642118=20


=3D =3D =3D
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