372
ACUS01 KWNS 090601
SWODY1
SPC AC 090600

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0100 AM CDT Wed Jul 09 2025

Valid 091200Z - 101200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CAROLINAS INTO THE MID-ATLANTIC...AND PORTIONS OF THE
NORTHERN/CENTRAL PLAINS...

...SUMMARY...
Scattered damaging winds are possible this afternoon to early
evening from parts of the Carolinas to the Mid-Atlantic. Large hail
and severe gusts are also possible across parts of the
northern/central Plains beginning late this afternoon and continuing
into the evening.

...Southeast into the Mid-Atlantic...
A weak mid-level trough will move slowly eastward today across the
Great Lakes/OH Valley. A belt of modestly enhanced southwesterly
mid-level flow will remain over the Mid-Atlantic through this
evening, diminishing with southward extent in the Southeast.
Scattered to numerous thunderstorms are once again expected to
develop this afternoon over the southern Appalachians and Blue Ridge
Mountains, and then spread eastward towards the coast. The presence
of rich low-level moisture will compensate for poor lapse rates
aloft to support MLCAPE generally around 1500-3000 J/kg across lower
elevations. A few loosely organized clusters may eventually develop
from parts of VA towards the DelMarVa Peninsula and vicinity owing
to somewhat more favorable deep-layer shear across these regions.
Isolated hail may occur initially with the more cellular/discrete
convection, before scattered severe/damaging winds becomes the
primary risk with eastward extent as multiple clusters potentially
develop. Generally minor adjustments have been made to the ongoing
Marginal/Slight Risk areas to account for latest guidance trends.

...Northern/Central Plains...
Downstream of a low-amplitude mid-level ridge emanating from an
upper-level anticyclone over the Southwest, most guidance continues
to suggest that isolated to scattered thunderstorms should form by
late this afternoon along a weak surface trough. Ample low-level
moisture ahead of this trough will gradually build beneath a stout
EML. A corridor of strong to very strong instability will likely
exist by late afternoon/early evening from parts of western/central
ND into NE, aided by daytime heating and steep lapse rates aloft.
Despite modest mid-level west-northwesterlies owing to the proximity
of the upper ridge, stronger upper-level westerlies will support
adequate deep-layer shear for a few supercells initially, with
associated threat for large to isolated very large hail.
Outflow-dominated downdrafts should foster clustering
east-southeastward across the Dakotas and perhaps parts of NE, with
a risk for scattered severe gusts, some of which could be 75+ mph on
an isolated basis given the rather favorable thermodynamic
environment forecast.

While confidence is somewhat lower regarding convective coverage
with southward extent across the central Plains (into KS and
vicinity), a conditionally favorable environment for at least
isolated severe convection will be in place. Have therefore expanded
the Marginal Risk southward to account for this potential.

...Interior Northwest/Northern Rockies...
Downstream of a shortwave trough moving eastward across northern CA
into the northwest Great Basin, an elongated belt of enhanced
southwesterly mid-level flow will exist across the northern Great
Basin/Rockies. Within this favorable flow regime amid steepened
low-level lapse rates through daytime heating, scattered
thunderstorms should foster strong to isolated severe gusts from
parts of eastern OR into MT.

...Lower Michigan into Northwest Ohio...
Isolated/marginally severe hail and locally damaging winds appear
possible this afternoon across parts of Lower Michigan and northwest
OH as scattered thunderstorms develop beneath a weak upper trough,
supported by a modest combination of instability and deep-layer
shear.

..Gleason/Weinman.. 07/09/2025

$$