LIVE MAP (ABOVE) ... SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1116 AM CDT Fri Sep 01 2023
Valid 011630Z - 021200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM SOUTHERN AZ
AND SOUTHEASTERN CA INTO SOUTHEAST ID...
...SUMMARY...
Isolated severe gusts and hail will be possible today into this
evening, from southern Arizona and southeastern California to
southern Idaho.
...AZ/Southeastern CA into Eastern Great Basin...
Morning satellite and radar imagery shows showers and isolated
thunderstorms from southern NV into western UT, within a band of
clouds arcing from western AZ through eastern NV/western UT and into
WY. This band and associated showers are expected to gradually shift
eastward/northeastward throughout the day. Additional thunderstorm
development is anticipated later this afternoon to the west of this
band, where the airmass is expected to destabilize amid daytime
heating and ample low/mid-level moisture. Ascent for this
thunderstorm development will be provide by broad low-level
convergence between the upper low drifting southwestward towards
northern CA and the persistent upper ridging over the
central/southern Plains.
Moderate mid-level flow will exist between these two features,
supporting enough vertical shear for some briefly organized storm
structures, and any stronger/more persistent updrafts could produce
isolated hail. Cloud bases are not expected to be high by western
CONUS standards, but steep low-level lapse rates could still support
strong downbursts in areas where clouds clear and some heating is
realized.
...Elsewhere...
Scattered to numerous thunderstorms are expected across the
Southeast, where ample low-level moisture and strong heating will
destabilize the airmass in the vicinity of an easterly wave moving
across the region. Weak vertical shear will limit storm organization
and severity, with an outflow-dominant, multicell mode anticipated.
Even so, a damaging gust or two is possible amid strong water
loading and forward-propagating storm structures.
Ongoing cluster of showers and thunderstorms across SD may persist
for the next hour or two, before dissipating as it the low-level jet
weakens and the cluster continues northeastward.
A few elevated thunderstorms are also possible early tomorrow
morning across the Upper Midwest, forced by a strong low-level jet
and related warm-air advection (and perhaps weak ascent attendant to
a convectively augmented shortwave trough).
..Mosier/Weinman.. 09/01/2023
Read more CHECK UPDATE ZOOM GRAPHIC
http://dlvr.it/SvVjrR
