From Dumas Walker@21:1/175 to All on Tue May 7 14:02:00 2024
ACUS01 KWNS 071637
SWODY1
SPC AC 071636
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1136 AM CDT Tue May 07 2024
Valid 071630Z - 081200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR
INDIANA...WESTERN AND CENTRAL OHIO...AND NORTHERN KENTUCKY...
...SUMMARY...
Scattered severe thunderstorms are expected across the southern
Great Lakes and Ohio Valley this afternoon and evening. A few
tornadoes (some strong), large to very large hail, and
severe/damaging winds all appear possible.
...Southern Great Lakes/Ohio Valley and vicinity...
Considerable uncertainty remains for this forecast due largely in
part to an ongoing broken squall line moving east across KY/IN/Lake
Michigan and the related influences for airmass destabilization in
its wake. However, clearing skies in the MCS' wake will result in a
seemingly sufficient period of heating during the afternoon.
Water-vapor imagery shows the deep-layer cyclone centered over the
northern Great Plains. A mid-level speed max rotating through the
base of the larger-scale trough will move from the mid MS Valley
late this morning into the southern Great Lakes by early evening.
Rapid strengthening of southwesterly 500-mb flow is forecast over
northern IL into the northern half of IN through the mid-late
afternoon. As an effective warm frontal zone becomes draped across
the southern Great Lakes/OH Valley regions, curved low-level
hodographs beneath a lengthening of the mid and upper part of the
hodograph will support a supercell risk. It seems most probable
based on morning model guidance that storms will initially develop
across central/northern IL and move northeast into northern IN.
Isolated to scattered storms are forecast to eventually develop this
afternoon across parts of the OH Valley in association with
warm/moist-air advection---although considerable uncertainty remains
regarding this scenario. The stronger storms (i.e., supercells)
will be potentially capable of a large to very large hail threat, in
addition to several tornadoes (perhaps a few which may be strong).
...Arklatex to north-central and south-central TX...
Not much change in the forecast thinking across the Mid South
southwestward into parts of TX. Isolated severe thunderstorms are
possible during mid/late afternoon. Damaging gusts and large hail
would be the main concerns. The threat over the area is conditional
-- more due to weak lift than thermodynamic considerations. Surface
dewpoints commonly in the 70s F will underlie a deep troposphere and
enough middle-level lapse rates for MLCAPE in the 3500-4500 J/kg
range. Weak low-level winds will constrain hodograph size and
boundary- layer shear. However, enough mid/upper flow remains to
support around 45-55 kt effective-shear magnitudes, yielding a
conditional supercell environment. In the absence of meaningful
large-scale support, and with shallower overall lift near the
front/dryline, convective coverage over this region is more in
question and likely isolated. Additional convection may form
overnight in a warm-advection plume near and southeast of the front,
across parts of the Mid-South to Arklatex regions. Marginal hail
and isolated damaging gusts would be the main concerns.
...Southeast KS late tonight...
A strengthening LLJ and associated warm-air advection will be
focused over the northeast OK/southeast KS region late tonight.
Forecast soundings show large MUCAPE amidst strong deep-layer shear.
Large hail may accompany a stronger storm or two that manages to
develop/become sustained during the 08-12z period.