Subj : DAY1SVR: Day 1 Convective Outlook
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Tue Feb 20 2024 00:52:01

ACUS01 KWNS 200051
SWODY1
SPC AC 200050

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0650 PM CST Mon Feb 19 2024

Valid 200100Z - 201200Z

....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
THE SACRAMENTO VALLEY IN NORTHERN CALIFORNIA...

....SUMMARY...
A couple of strong storms may impact parts of the Sacramento Valley
through the evening hours, and perhaps pose at least some risk for
producing a tornado or two.

....Synopsis...
Over the past 1-2 hours, several weak, low-topped supercells have
been observed along the central CA coast and within the northern
Sacramento Valley. The duration and overall intensity of these
storms has been limited, but organized mid-level mesocyclones noted
in regional velocity data suggest the kinematic environment remains
supportive of at least a low-end tornado threat in the near-term
(next 1-2 hours). However, this threat is expected to gradually
diminish through late evening and overnight hours. Recent RAP/HRRR
runs appear to be initializing too warm/moist at the surface based
on recent observations and the 00 UTC OAK sounding, resulting in a
slight over-estimation of environmental buoyancy. This
consideration, combined with the expectation of diminishing SBCAPE
with the onset of nocturnal cooling, suggests that the thermodynamic
environment will become increasingly prohibitive of robust
convection heading into the overnight hours. Furthermore, surface
winds are beginning to back across the western half of the
Sacramento Valley, which should lead to diminishing low-level shear
across portions of the effective warm sector. For this reason, the
5% tornado probabilities have been removed, though a low-end severe
threat will persist given potential for additional shallow/weak
supercells.

...Moore.. 02/20/2024

$$

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