876
ACUS01 KWNS 041252
SWODY1
SPC AC 041251

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0751 AM CDT Tue Jun 04 2024

Valid 041300Z - 051200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THROUGH TONIGHT
FROM THE LOWER MS VALLEY TO OK...THEN NORTHWARD ACROSS EASTERN
KS...IA AND MN...

...SUMMARY...
Scattered strong-severe storms with wind damage and large hail will
be possible this afternoon/evening from the middle Missouri Valley
to the upper Mississippi Valley.  An ongoing storm cluster near the
Arklatex could persist through the day with some damaging-wind
threat, and storms will be capable of producing isolated very large
hail and severe outflow winds of 60-80 mph this evening into tonight
across Oklahoma.

...Southern Plains to lower MS Valley through tonight...
Another in a series of overnight MCSs is moving southeastward near
the Arklatex, though the bowing system appears to have weakened
prior to sunrise.  The MCS is moving into an area overturned
yesterday across LA/AR, with the primary moisture/buoyancy feed into
the MCS from the south-southwest from the unstable warm sector in
TX.  There will still be some potential for eventual intensification
of the storms as the low levels warm and moisten during the day, and
the stronger embedded storms could produce damaging winds.

Outflow from the morning storms will reinforce a composite outflow
boundary, though the outflow is already somewhat diffuse with
west/northwestward extent.  It appears that the outflow air mass
will modify through the day across OK during the day.  There will be
the potential for isolated thunderstorm development later this
afternoon along the west edge of the richer moisture (near the
western OK/TX border) where MLCAPE could exceed 5000 J/kg with only
small convective inhibition.  However, forcing for ascent will be
rather nebulous and storm initiation/coverage are both in question.
If storms form, there will be just enough vertical shear for
supercells capable of producing isolated very large hail, and
perhaps an isolated tornado. Confidence is greater in renewed
thunderstorm development across KS this afternoon and into OK late
this evening 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.  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 (60-80 mph) as storms grow
upscale into another MCS tonight.

...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.
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.

..Thompson/Grams.. 06/04/2024

$$