Subj : DAY1SVR: Day 1 Convective Outlook
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Mon Feb 19 2024 16:22:55

ACUS01 KWNS 191622
SWODY1
SPC AC 191621

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1021 AM CST Mon Feb 19 2024

Valid 191630Z - 201200Z

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

....SUMMARY...
A tornado or two may occur in the Sacramento Valley region of
California today.

....Synopsis...
A pronounced mid-level trough and associated surface low continue to
impinge on the West Coast, supporting a continued northward
transport of moisture over California into southern portions of the
Pacific Northwest. 12Z observed soundings for sites along the
California coast already show cooler mid-level temperatures
overspreading inland, suggesting that marginal buoyancy should
already be present across central into northern CA. With time,
insolation will support locally higher amounts of buoyancy amid a
highly sheared environment to support low-topped but organized
thunderstorms capable of producing severe hazards over portions of
central into northern CA this afternoon.

....Portions of central into northern CA...
Low-level warm-air advection has encouraged surface temperatures to
warm into the mid 50s F across southern portions of the Sacramento
Valley prior to diurnal heating. By afternoon, 52-54 F surface
dewpoints beneath 7.5+ C/km mid-level lapse rates will boost tall
but thin SBCAPE to the 500-750 J/kg range. The BBX VAD currently
depicts a sizable, curved low-level hodograph, with over 300 m2/s2
of 0-3 km SRH, and these favorable low-level shear trends are
expected to persist through the day as the surface low continues to
meander just offshore. Modifying RAP forecast soundings suggest that
surface dewpoints need to rise at least into the 53-54F range to
support efficient ingesting of SRH for tornadogenesis. It is unclear
how widespread 53-54 F dewpoints will become by afternoon, with the
tornado threat more conditional on these dewpoints being realized.
Nonetheless, a couple of low-topped supercells are possible this
afternoon, likely accompanied by at least a marginal severe
hail/wind threat.

...Squitieri.. 02/19/2024

$$

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