Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0100 AM CDT Tue Apr 02 2024
Valid 021200Z - 031200Z
...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS THE OHIO
VALLEY...
...SUMMARY...
A potentially substantial severe weather outbreak -- possibly
including a few significant/long-track tornadoes -- is anticipated
this afternoon and evening, with the highest probability centered
over the Ohio Valley. Severe risk exists as far south as the Gulf
Coast, and as far east as western portions of Virginia and the
Carolinas.
...Discussion...
Strong northern-stream upper low, currently located over southern
MB, is forecast to drop south across MN into northern IL late in the
period. This evolution is driven in part by a 500mb speed max that
will translate across the central Plains, increasing to near 100kt
over eastern KS/OK by 03/12z. Intense 12hr midlevel height falls are
forecast across much of the Great Lakes, OH/TN Valley, and the
northern Gulf States, where values in excess of 200m are expected
during the latter half of the period. Synoptic front that is
currently draped across the OH Valley will be encouraged to
gradually advance north due to the digging trough; however, an
extensive corridor of convection currently extends across the MS
Valley into the OH valley, which is maintaining cool boundary-layer
conditions north of I-70.
Latest water-vapor imagery suggests a southern-stream short-wave
trough is progressing across eastern KS/eastern OK. This feature
will progress downstream and likely aid early-day thunderstorm
development near the confluence of the MS/OH Rivers. Seasonally high
PW airmass currently extends across northern AR/southern MO into
southern IL. NAM forecast sounding for JBR at 15z exhibits 60kt
surface-6km bulk shear with SBCAPE on the order of 1500 J/kg.
Discrete supercells may evolve ahead of this feature then
spread/develop northeast across southern IN/KY into OH. Some
uncertainty exists across northern OH/IN regarding destabilization.
It's not entirely clear if ongoing convection will allow the warm
front to lift appreciably north of its current position. However,
large-scale pattern is quite dynamic and favors surface low
deepening over southern Lake MI during the latter half of the
pattern. NAM struggles to reflect this scenario, thus weaker
instability is forecast at higher latitudes. Tornadoes, damaging
winds, and large hail are expected with supercells that evolve
across the warm sector. Some tornadoes may be long-lived and strong.
Farther south, a bimodal severe threat may ultimately evolve with a
secondary corridor of more concentrated severe across portions of
the northern Gulf States. 500mb speed max is forecast to eject
across northern Mexico into TX by 03/00z. This feature will
intensify as it translates across LA into eastern TN by the end of
the period. There is some concern that severe probabilities may need
to be increased across this region to account for this low-latitude
speed max during the evening/overnight hours. Strong shear will
support supercells along with a threat for tornadoes, damaging
winds, and hail.
..Darrow/Bentley.. 04/02/2024
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