SPC AC 261615
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1115 AM CDT Sun Sep 26 2021
Valid 261630Z - 271200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS
AFTERNOON/EVENING ACROSS SOUTHEAST AZ AND SOUTHWEST NM...
Isolated severe hail and/or gusts are possible this afternoon and
evening across southeast Arizona and southwest New Mexico.
A closed midlevel low over the northern Gulf of CA will move slowly
eastward near the southern AZ border through tonight. Surface
heating in cloud breaks across southeast AZ/southwest NM, and ascent
northeast of the midlevel low will support scattered thunderstorm
development this afternoon into this evening. Moderate buoyancy
(MLCAPE near 1000 J/kg) and effective bulk shear of 25-30 kt will
support the potential for a few semi-organized storm clusters.
Isolated strong outflow gusts will be possible with the stronger
storms given steepening low-level lapse rates. Though lapse rates
aloft will not be particularly steep, the moderate buoyancy and
vertical shear may support isolated, marginally severe hail.
Otherwise, isolated lightning flashes will be possible through mid
afternoon with elevated convection over eastern ME with an ejecting
shortwave trough. A few thunderstorms are expected this afternoon
across southwest FL with a weak backdoor cold front and local sea
breeze circulations. Overnight, isolated lightning flashes may
occur with weak elevated convection in the warm conveyor belt over
northwest WA, immediately in advance of a midlevel trough and
baroclinic zone moving eastward over the southeast Gulf of Alaska.
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NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z