SPC AC 220528
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1228 AM CDT Sun Sep 22 2019
Valid 231200Z - 241200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER MUCH OF
CENTRAL AND SOUTHERN ARIZONA...
Scattered storms, some severe with damaging wind and hail, are
expected over much of Arizona Monday.
An upper low will drop south from NV toward the lower Colorado River
Valley, providing large-scale lift as well as increasing shear
profiles. At the surface, southern winds will persist over southeast
CA into southern AZ ahead of the developing cold front. Heating as
well as gulf moisture with 60s F dewpoints will result in MLCAPE on
the order of 1000-1500 J/kg with little if any capping. Severe
storms, including damaging wind gusts and hail, will develop during
the afternoon over southern and central AZ, and possibly extreme
eastern CA and southern NV where heating will be maximized.
Low-level winds will be generally weak, but beneath increasing
southwesterlies aloft. This will elongate hodographs, which will be
mainly straight-line, supporting splitting cells capable of hail.
Some cells may bow and produce damaging winds as well. Sporadic
strong to severe storms will be possible late into the night over
southern AZ as the air mass remains unstable prior to the cold front
A potent shortwave trough will move rapidly east from the Great
Lakes into the Northeast, providing increasing deep-layer shear as
well as lift. At the surface, a narrow plume of low 60s F dewpoints
will spread northward ahead of a cold front which will move across
NY and PA during the day, and across New England overnight. Despite
increasing wind fields, instability is forecast to be weak,
averaging just a few hundred J/kg, and with poor deep-layer lapse
rates. This should result in primarily non-severe storms along the
cold front, capable of a few strong wind gusts as low-level mean
winds average around 35 kt.
...MAXIMUM RISK BY HAZARD...
Tornado: 2% - Marginal
Wind: 15% - Slight
Hail: 15% - Slight
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NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z