689
ACUS01 KWNS 071946
SWODY1
SPC AC 071945

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0245 PM CDT Tue May 07 2024

Valid 072000Z - 081200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR
INDIANA...WESTERN AND CENTRAL OHIO...AND NORTHERN KENTUCKY...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS
SOUTH-CENTRAL TEXAS...

...SUMMARY...
Scattered severe thunderstorms are expected across the southern
Great Lakes and Ohio Valley through evening.  A few tornadoes (some
strong), large to very large hail, and severe/damaging winds all
appear possible.

...20z Update...

Most of the ongoing outlook remains on track and reasoning has not
changed from the previous forecast. See Tornado Watch 195 and any
forthcoming MCDs regarding short term severe potential across parts
of the Midwest.

A small Slight risk (level 2 of 5) has been added over portions of
central TX. A few storms capable of large hail (2.5+ inches
diameter) appear possible through evening. Agitated cumulus in a
very moist/unstable environment amid modest low-level convergence
continue to deepen this afternoon. Forecast soundings depict a
favorable environment for isolated but possible significant hail.
While this risk is somewhat conditional/isolated, given the
possibility for 2.5+ inch hail an upgrade to 15% SIG hail
probabilities appears warranted. For more details, see MCD 678.

..Leitman.. 05/07/2024

.PREV DISCUSSION... /ISSUED 1136 AM CDT Tue May 07 2024/

...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.

$$