984
ACUS01 KWNS 041631
SWODY1
SPC AC 041629

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1129 AM CDT Tue Jun 04 2024

Valid 041630Z - 051200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
CENTRAL AND EASTERN OKLAHOMA...

...SUMMARY...
Scattered severe thunderstorms are probable across central and
eastern Oklahoma this evening.  A tornado and large to very large
hail will be possible this evening, before severe outflow winds of
60-85 mph potentially accompany the more intense downdrafts this
evening into tonight.

...Southern Plains to lower MS Valley through tonight...
Radar/satellite imagery late this morning shows a
south-southeastward moving MCS along the TX/LA border.  Heating of
the airmass ahead of the MCS will continue to lead to strong
destabilization.  A rejuvenation of storm intensity along the
western flank of the MCS is possible where a reservoir of very rich
low-level moisture and steep 700-500 mb lapse rates will aid in
strong/severe storm potential.  Damaging gusts and perhaps large
hail will be the primary hazards with the stronger storms.

Outflow from the morning storms will reinforce a composite outflow
boundary across north TX northward into OK.  It appears that the
outflow air mass will modify through the day across OK.  Surface
dewpoints are forecast to increase into the mid 70s across
central-southern OK where isolated thunderstorm development is
forecast by late this afternoon/early evening along the edge of
richer moisture.  Forecast soundings show MLCAPE could exceed 5000
J/kg with only small convective inhibition.  However, forcing for
ascent will be rather nebulous and storm initiation/initial coverage
is uncertain.  Nonetheless, a short window of opportunity may exist
for a tornado risk if a quasi-discrete mode can occur early in the
convective life cycle.  Very large buoyancy and nearly dry adiabatic
lapse rates across OK will support large/tall storms capable of
producing isolated very large hail initially, and an increase in the
threat for damaging winds (60-85 mph) as storms grow upscale into
another MCS tonight.  Have opted to upgrade to a 30-percent
significant wind area for greater confidence in a severe MCS across
central/eastern OK.  Farther north, thunderstorms for forecast to
develop across KS this afternoon into early tonight, as a weak
surface cold front and associated midlevel trough will move
southeastward and impinge on the very moist/unstable warm sector.
Hail/wind will be the primary risks with those stronger storms.

...Mid MO to upper MS Valleys this afternoon/evening...
A midlevel shortwave trough and associated cold front will move
eastward from NE/Dakotas to eastern KS/IA and WI by the end of the
period.  The richest low-level moisture will remain farther south,
but surface heating in pre-frontal cloud breaks and boundary-layer
dewpoints in the 60s will contribute to MLCAPE of 1000-2000 J/kg.
Some low-level hodographs enlargement in northern MN may aid in some
brief updraft rotation potential before an extensive band of storms
becomes outflow dominant.  Vertical shear will be relatively weak in
the warm sector which will primarily support multicell clusters and
line segments capable of producing occasional wind damage and
marginally severe hail.

...MO/IL today...
A midlevel low over west central MO this morning will move
northeastward toward central/northern IL by this evening.  Lingering
clouds will tend to slow surface heating, though cloud breaks could
allow modest destabilization and support a few strong thunderstorm
clusters capable of producing isolated strong/damaging outflow gusts
and marginally severe hail.

..Smith/Barnes.. 06/04/2024

$$