LIVE MAP (ABOVE) ... SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1121 AM CDT Mon Jul 31 2023
Valid 311630Z - 011200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
MO...LA...THE SOUTHEAST ATLANTIC STATES...AZ AND FROM NORTHEAST CO
TO ND...
...SUMMARY...
Isolated severe thunderstorms are possible over portions of the
northern/central Plains, coastal Southeast, lower Missouri Valley to
west-central Gulf Coast, and Arizona.
...MO to LA this afternoon into tonight...
Multiple thunderstorm clusters occurred overnight, and the remnants
of convection with outflow and debris clouds persist from southern
AR into LA, and across northwest MO. The relatively widespread
convective overturning/modification suggests the environment will
not have sufficient time to recover by this afternoon. There will
be some potential for additional development along the outflow
boundary moving southward into southern LA this afternoon, where
isolated downbursts may occur. Otherwise, the more probable
scenario is for slightly elevated storms to form again tonight in
the strengthening warm advection zone across MO. Lapse rates will
not be as steep as prior days and midlevel temperatures will be
relatively warm in proximity to the southern Plains ridge, so any
hail/wind threat should remain marginal.
...Dakotas to northeast CO this afternoon into tonight...
Lingering low-level moisture in a weak upslope flow regime will
support scattered thunderstorm development this afternoon/evening
from the Front Range in northeast CO northward into eastern WY.
Midlevel lapse rates will not be as steep as prior days as a result
of the monsoonal moisture plume spreading northeastward across
UT/CO/WY, and flow aloft will also be relatively weak. Thus,
primarily multicell clusters with isolated strong-severe outflow
gusts will be the main threat as convection spreads eastward toward
western NE and vicinity by tonight.
Farther north into ND, the focus for storm development will be
nebulous at best. There will be a small chance for diurnal storms
in the differential heating zone across far southwest ND by late
afternoon, and a storm or two could approach the international
border from SK tonight. However, confidence in either scenario is
low.
...Fl to Carolinas this afternoon/evening...
A weak midlevel trough over the southeast Atlantic states and
daytime heating in cloud breaks will drive diurnal convection this
afternoon. The primary wind shift/front extends across north FL and
off the coasts of the Carolinas, leaving terrain influences and a
weak outflow boundary to focus thunderstorm development this
afternoon. Lapse rates aloft are poor and buoyancy will be rather
modest by summer standards - both of which suggest today is a
low-end downburst day (at best) into the Carolinas. Stronger
surface heating and destabilization will occur farther south into
FL, where a few pulse severe storms with downburst winds will be
possible this afternoon.
...AZ this afternoon/evening...
With prior convection and the approach of a weak wave from northwest
Mexico, there's been an increase in low-level moisture and a
decrease in low-midlevel lapse rates since yesterday across southern
AZ. Still, isolated strong outflow gusts will be possible with
convection from southeast AZ northwestward in the vicinity of the
Mogollon Rim, which is where the weaker convective inhibition is
expected this afternoon/evening.
..Thompson/Squitieri.. 07/31/2023
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