Valid 251630Z – 261200Z
…THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER SOUTHERN
ARIZONA AND SOUTHEAST CALIFORNIA…AND OVER PARTS OF THE CENTRAL
UNITED STATES…
…SUMMARY…
Isolated severe winds and hail are possible this afternoon and
evening from the Ozarks westward over parts of Oklahoma and Kansas,
as well as parts of Arizona and southeastern California.
…AZ/CA…
A cut-off upper low over northwest Mexico is expected to move slowly
northward into the Lower Colorado Valley later today. This area
should see strong heating this afternoon as temperatures climb into
the 80s and lower 90s. A pocket of cooler midlevel temperatures
will accompany the low, resulting in steepening lapse rates and
increasing CAPE this afternoon. 12z CAM solutions agree on the
development of scattered thunderstorms in this region, with hail and
gusty winds possible in the strongest cells. The main period of
risk will be between 20-04z.
…OK/KS/MO/AR…
Scattered pockets of remnant precipitation and mid clouds persist
today over this region, where dewpoints are in the 70s. Relatively
strong heating will occur this afternoon, yielding afternoon MLCAPE
values over 3000 J/kg. Strong instability and steep midlevel lapse
rates would support vigorous up/downdrafts in a few storms – with a
risk of hail and gusty winds. Forcing is weak and confidence in
significant coverage of thunderstorms before 00z is not particularly
high. However, the combination of isolated strong storms this
afternoon and more widespread convection after dark are sufficient
to maintain the ongoing MRGL risk with no changes.
..Hart/Bentley.. 09/25/2019
$$