SPC Jun 3, 2025 1630 UTC Day 1 Convective Outlook

SPC 1630Z Day 1 Outlook

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1127 AM CDT Tue Jun 03 2025

Valid 031630Z - 041200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PORTIONS OF
THE CENTRAL AND SOUTHERN PLAINS INTO THE MIDWEST...

...SUMMARY...
Scattered severe thunderstorms are possible from the southern Great
Plains to the Midwest. Damaging winds and large hail are the primary
concerns.

...Central/Southern Plains into the Midwest...
Water-vapor imagery late this morning shows a mid-level shortwave
trough over the central Great Plains, embedded within larger upper
troughing centered over MT/WY and the Dakotas that extends over much
of the north-central U.S.  A cold front extends from the western
Great Lakes southwestward to a weak low near the OK/KS/TX Panhandle
region.  An extensive area of showers and thunderstorms exists from
KS eastward into the mid MS Valley near the frontal zone.  

A low-predictability forecast scenario regarding specific details of
storm evolution is expected this afternoon into the evening.  A
relatively weak capping inversion was sampled by the 12 UTC Norman,
OK and Fort Worth/Midland, TX raobs (9 to 10 deg C at 700 mb) over
the southern Great Plains.  Heating in wake of morning convection
and related cloud debris will promote a very unstable boundary layer
by early to mid afternoon.  Expecting a diurnal increase in
low-level moisture coincident with the evapotranspiration cycle and 
lowest 100-mb mean mixing ratios increasing from 14-15 to 16-17 g/kg
(translated to surface dewpoints rising from 68-70 to 72-76 deg F). 
Forecast soundings show 2500-3500 J/kg MLCAPE from southwest MO into
central TX.  The 12 UTC model run of the NAM appears to be an
unrealistic outlier solution showing enhanced low-level shear across
OK during the afternoon.  As convective inhibition erodes across the
southern Great Plains east of a dryline/cold front and south of
reinforced outflow draped across southern KS into northern MO,
expecting scattered to numerous thunderstorms to develop during the
afternoon into the evening period.  Severe gusts and large hail
appear to be the primary severe hazards.  Strong to occasionally
severe thunderstorms should continue along the front as it moves
into TX Hill Country tonight.  An elongated corridor of low-tornado
potential will be maintained this outlook update from the southern
Great Plains northeastward through the lower MO Valley and into the
western Great Lakes.  A belt of 40-kt 2 km southwesterly flow will
be maintained across western into northern MO and spatially
overlapping outflow in the lower MO Valley.  Limited heating will
temper the overall buoyancy across the northern half of MO into IA,
likely tempering the overall severe risk.  Additionally, with the
line-parallel orientation of the deep-layer shear across this
region, the expectation is for a predominantly linear storm mode,
with occasional bowing segments capable of producing damaging gusts.

..Smith/Flournoy.. 06/03/2025

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