Subj : DAY2SVR: Nws Storm Prediction Center Norman Ok
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Sun Feb 18 2024 07:02:14

ACUS02 KWNS 180702
SWODY2
SPC AC 180700

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
0100 AM CST Sun Feb 18 2024

Valid 191200Z - 201200Z

....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR A PORTION OF
THE CENTRAL VALLEY OF CALIFORNIA...

....SUMMARY...
An isolated risk for a tornado is forecast across the Central Valley
of California on Monday afternoon and early evening.

....Synopsis...
A mid-level low located over the eastern Pacific to the west of the
CA/OR border will move little during the period.  A belt of strong
southwesterly 500-mb flow will extend from the base of the
larger-scale eastern Pacific trough and into CA/NV.  In the low
levels, a surface low will meander to the west of the northern CA/OR
coast.

....Central Valley of CA...
Several members of the latest HREF convection-allowing model
ensemble show cellular storms developing during peak heating in the
Central Valley.  The NAM model appears to be consistently exhibiting
a surface-temperature cool bias of several degrees F compared to
expected high temperatures (e.g., 55-60 deg F vs. 60-65 deg F).
Model data also shows some erosion of low clouds during the day over
the valley and would align with slightly warmer temperatures than
the NAM model forecast.  When modifying forecast soundings for
slightly warmer surface temperatures, it seems probable 250-500 J/kg
MLCAPE will develop during the afternoon.  The 18/03z RAP model
shows some veering of surface winds (south-southwesterly) that
appears incongruent with the terrain-channeled flow (surface winds
south-southeasterly) that typically occurs with these types of
setups.  Large 0-3 km MLCAPE (150 J/kg) co-located with very
favorably curved and elongated hodographs amidst a moist boundary
layer (dewpoints in the upper 40s to low-mid 50s), indicate an
environment favorable for shallow rotating cells (i.e., transient
supercells).  The more robust storms will potentially yield an
isolated threat for a tornado in addition to localized gusts.  This
activity will likely dissipate by the early evening as instability
wanes.

...Smith.. 02/18/2024

$$

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