ACUS01 KWNS 080602
SWODY1
SPC AC 080600
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0100 AM CDT Sun Jun 08 2025
Valid 081200Z - 091200Z
...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF SOUTHERN OKLAHOMA INTO NORTHERN TEXAS...
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SEPARATELY ALONG
THE EAST COAST...
...SUMMARY...
A severe weather outbreak is possible across the southern Plains
today. A few tornadoes, destructive wind gusts of 80-100 mph, and
giant hail up to 5 inches in diameter are likely. Strong gusts, and
perhaps a couple of tornadoes, are also possible along portions of
the East Coast.
...Synopsis...
***A severe weather outbreak is possible across the southern Plains
today***
A broad mid-level trough will deepen across the Great Lakes into the
OH Valley, with multiple embedded mid-level impulses poised to pivot
around the upper trough across the southern Plains to the Southeast
and Atlantic Seaboard today. A broad northwesterly upper-flow regime
will become established across the Plains States into the MS Valley,
with modest mid-level flow contributing to strong deep-layer shear.
Beneath this stronger flow/shear and cold temperatures aloft will be
rich low-level moisture, which will support extreme instability,
especially in the southern Plains. Here, a volatile setup for severe
weather will exist. All severe hazards are expected, with
destructive wind gusts and giant hail likely. The severe threat
should persist to some degree into the Lower MS Valley after dark. A
severe risk will also accompany storms along parts of the East
Coast, as passing mid-level impulses provide enough lift and shear
atop a moist, unstable airmass.
...Southern Plains into the Lower MS Valley...
A diffuse baroclinic zone will be positioned across the TX
Panhandle, southeast into central or southern OK at the start of the
period. It is unclear how prolific convection will be during the
morning to early afternoon. Latest high-resolution model guidance
consensus suggests that these storms should not be overly intense,
nor should their impact on the free warm sector be overly
detrimental. Assuming this is the case, strong daytime heating, amid
some high level cirrus clouds, should support surface temperatures
reaching 90 F amid mid 70s F dewpoints. Given robust boundary layer
heating of this moisture beneath 8-9 C/km mid-level lapse rates,
widespread extreme buoyancy should develop by afternoon. Forecast
soundings show deep, wide CAPE profiles, with over 5000 J/kg MLCAPE
possible (perhaps locally higher in spots). At the same time, modest
veering with height in the lowest few hundred mb, and northwesterly
flow in the 500-200 mb increasing to 50-70 kts, will promote 50+ kts
of effective bulk shear (elongated hodographs with small low-level
curvature).
A quasi-stationary cold front will be draped somewhere along the
KS/OK border into MO, with a dryline positioned in far western TX
during the afternoon. With maximum daytime heating and minimal
MLCINH, robust convective initiation is expected along these
boundaries around mid-afternoon. Given the extreme buoyancy/shear
parameter space, the more isolated, discrete storms should quickly
become intense supercells capable of a few tornadoes, severe gusts
(perhaps exceeding 75 mph), and large hail. 2+ inch diameter hail
should become commonplace if multiple supercells can sustain
themselves, with giant hail (perhaps over 5 inches in diameter)
possible. Though much more conditional, an intense tornado could
develop somewhere in the eastern TX Panhandle if a longer-lived, inflow-dominant supercell manages to materialize and optimally
ingest the extreme buoyancy while also traversing the diffuse
baroclinic boundary. However, confidence in this scenario is too low
for the introduction of higher tornado probabilities at this time.
At some point during the afternoon early evening, supercell cold
pool mergers should support the development of either one intense
MCS (perhaps in the form of a bow echo), or multiple small but
intense bowing segments. Should a bow echo form, widespread severe
winds are likely. In either scenario, gust magnitudes may
potentially reaching 80-100 mph, hence the maintenance of a Category
4/Moderate Risk. An MCS should progress toward the lower MS Valley
during the evening into the overnight, with a lingering severe wind
threat that should gradually subside with time.
...Portions of the Mid Atlantic...
By early afternoon, thunderstorms should increase in both coverage
and intensity ahead of a weak surface low and associated weak
mid-level impulse. These storms will move into an airmass
characterized by mid to upper 70s F temperatures and 70 F dewpoints,
overspread by modest mid-level lapse rates (resulting in over 1500
J/kg MLCAPE). Considerable veering with height will support
elongated hodographs with appreciable low-level curvature, with
multicells and supercells the expected storm mode. Damaging gusts
and large hail may accompany the stronger storms. A few tornadoes
may occur with any supercells that interact with a baroclinic
boundary across eastern VA.
...Portions of the Southeast Atlantic Coastline...
From mid morning to early afternoon, diurnal heating of a moist,
weakly capped boundary layer will result in surface temperatures
reaching 90 F amid 70 F surface dewpoints, with MLCAPE exceeding
2000 J/kg in spots. Overall deep-layer flow/shear should be modest
at best, with forecast soundings showing predominantly short
hodographs. Given the moderate to strong instability in place,
multicells are the expected mode of convection. While some hail
cannot be ruled out with the stronger storms (given modest mid-level
lapse rates), the main threat with these storms should be strong
wind gusts.
..Squitieri/Kerr.. 06/08/2025
$$
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