743
ACUS01 KWNS 021244
SWODY1
SPC AC 021242

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0742 AM CDT Sun Jun 02 2024

Valid 021300Z - 031200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
INTO EARLY TONIGHT ACROSS NE AND NORTHERN KS...

...SUMMARY...
Scattered severe thunderstorms are forecast across much of the
Plains region this afternoon and evening, especially across the
central Plains of Nebraska and northwest Kansas. Very large hail of
2-3 inches in diameter, severe gusts of 60-80 mph, and a couple of
tornadoes are expected.

...Central Plains through tonight...
Within generally zonal flow aloft, a low amplitude shortwave trough
will progress eastward from the northern Rockies to the northern
Plains through tonight.  Lee cyclogenesis is expected across western
NE/northeast CO near the southern influence of this midlevel trough,
with a weak cold front farther north into the Dakotas.  The surface
front/cyclone, as well as a lee trough farther to the south will
help focus thunderstorm development this afternoon and storms will
spread eastward through tonight.

Slightly elevated thunderstorms are ongoing in clusters this morning
from eastern NE to eastern KS in association with low-level warm
advection on the edge of the surface warm sector.  These storms
could pose a marginal hail/wind threat before weakening later this
morning.  Farther west, a few thunderstorm clusters persist from
central NE to the TX Panhandle.  Like the elevated storms to the
east, these storms are also expected to weaken later this morning.
In the wake of the morning storms, surface temperatures will warm
into the 80s with boundary-layer dewpoints mainly in the upper 50s
to lower 60s, beneath steep midlevel lapse rates.  The net result
will be a corridor of large buoyancy (MLCAPE of 2500-4000 J/kg) and
minimal convective inhibition by mid afternoon from west TX to NE to
the east of the lee trough/dryline, when thunderstorm development is
expected.

Somewhat stronger forcing for ascent will contribute to storm
clustering/upscale growth from western into central NE, where MCS
development is likely.  The initial storms in western NE into
northwest KS could be supercells capable of producing isolated very
large hail (2-3 inches in diameter), before upscale growth leads to
an increasing threat for damaging winds of 60-80 mph as storms surge
eastward during the late afternoon/evening.  Any tornado threat will
be tied to the more discrete initial supercells, or fortuitous storm
interactions.

...Northern Plains this afternoon/evening...
The warm sector will narrow and buoyancy will weaken with northward
extent from SD into ND, ahead of the surface cold front.  This
front, and ascent related to the approaching midlevel trough, will
help focus a line of thunderstorms along the front in central ND by
early-mid afternoon (possibly evolving from the ongoing storms near
the southwest ND border), and storms will subsequently spread
eastward toward western MN in the evening and develop southward into
SD.  The initial storms, or any embedded supercells, will pose a
threat for large hail of 1-1.75 inches in diameter, while damaging
gusts of 60-70 mph will become the more common threat once a linear
mode is established (and before the storms move too far east of the
primary buoyancy corridor).

...Southern High Plains this afternoon into tonight...
The ongoing storm cluster in the eastern TX Panhandle may persist
for a few hours this morning, though its longevity and influence on
afternoon convection are uncertain.  At least widely scattered
storms are expected by mid-late afternoon along the dryline from the
TX Panhandle into west central TX, potentially aided by a subtle
southern-stream shortwave trough moving over NM this morning.  40-50
kt flow above the 500 mb level will help elongate hodographs and
favor supercells capable of producing isolated very large hail (2-3
inches in diameter).  Though storm coverage will be a primary driver
of any damaging-wind threat, thermodynamic profiles will favor
intense downdrafts capable of producing isolated significant outflow
gusts of 75-80 mph.  The afternoon/evening storms will spread
eastward into northwest TX and western OK before beginning to weaken
late tonight.

...Southern LA to central/north TX this afternoon...
Scattered thunderstorm development will be possible in a loosely
focused corridor from southern LA into parts of southeast, central
and north TX along a remnant outflow/returning moisture gradient.
Though storm development in any particular area is low confidence, a
few storms in this area could pose a threat for isolated large
hail/wind damage given large CAPE and sufficient deep-layer
shear/hodograph length for at least some supercell potential.

..Thompson/Grams.. 06/02/2024

$$