SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0748 AM CDT Wed Aug 03 2022
Valid 031300Z - 041200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
THROUGH LATE EVENING FROM CENTRAL MO TO SOUTHERN LOWER MI...
...SUMMARY...
Scattered storms, some severe, are most probable from Lower Michigan
into the Mid Mississippi Valley, with at least isolated severe
possibly extending southwestward across Missouri and into eastern
Kansas.
...Mid MS Valley to Lower Mi through tonight...
A midlevel shortwave trough will move eastward from northern MN
across Lake Superior and Upper MI, as other smaller-scale
perturbations likewise move eastward from SD/NE toward northern
IL/Lower MI by this evening. A surface cold front will translate
southeastward across the upper MS Valley and central Plains, and the
front will be preceded by outflow from overnight convection across
WI/northern Lower MI, and related differential heating zones. Away
from lingering debris cloudiness, strong surface heating and
boundary-layer dewpoints in the low 70s will contribute to a
corridor of strong buoyancy (MLCAPE of 2500-4000 J/kg) from the mid
MS Valley into Lower MI. Midlevel westerly flow will be stronger
over Lower MI (30-40 kt), and will tend to weaken with southwest
extent toward MO.
Isolated strong storms will be possible this morning through midday
from IA to southern WI, near the leading edge of the thicker cloud
band and outflow boundaries. The primary severe threat is expected
to materialize this afternoon along the lingering
outflow/differential heating zone from northern MO across northern
IL to central/southern Lower MI. A mix of multicell clusters and
line segments is expected to be the primary convective mode, with
large buoyancy and DCAPE in excess of 1200 J/kg supporting the
threat for damaging gusts. The severe threat is expected to
diminish by late evening from southeast Lower MI into IN, but strong
storms may linger into the overnight hours while developing
southward into the richer moisture/larger buoyancy toward southeast
MO.
...Southeast AZ this afternoon/evening...
Despite weakening of an overnight MCS across Sonora, other
convection persists this morning across southeast AZ. Gradual
clearing of clouds is expected by afternoon, but the rate of
clearing will control surface heating/destabilization and the
potential for additional afternoon storms over the higher terrain of
southeast AZ. East to east-southeasterly midlevel flow south of the
midlevel ridge will steer convection westward toward the lower
deserts, though lingering convective inhibition over the lower
deserts casts doubt on how far west the storms can persist.
Assuming sufficient duration of clearing in the wake of the morning
clouds/convection, inverted-v profiles and DCAPE in excess of 1000
J/kg will support isolated strong-severe outflow gusts for a few
hours this afternoon/evening.
...Savannah River Valley this afternoon...
Scattered thunderstorms are expected to develop by early-mid
afternoon in association with a differential heating zone, local sea
breeze circulations, and a lingering front. Thermodynamic profiles
will be sufficient for a few strong/damaging downbursts, with
convection expected to be focused near the northeast edge of the
thicker clouds and very moist profiles associated with a weak
midlevel trough over GA.
..Thompson/Kerr.. 08/03/2022
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