388
ACUS01 KWNS 091633
SWODY1
SPC AC 091631

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1131 AM CDT Wed Jul 09 2025

Valid 091630Z - 101200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS CENTRAL
SD AND FAR NORTH-CENTRAL NE AND SOUTH-CENTRAL MT...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE
MID-ATLANTIC STATES AND CAROLINAS...

...SUMMARY...
Severe wind gusts and isolated large hail are possible across parts
of the northern/central Plains late this afternoon into evening.
Scattered damaging winds are possible this afternoon to early
evening from parts of the Carolinas to the Mid-Atlantic as well as
over central Montana.

...Northern/Central Plains...
A reservoir of ample low-level moisture currently exists from the
central Plains back northwestward into eastern MT, with upper 60s
dewpoints in NE and mid 60s dewpoints as far northwest as DIK in
southwest ND. Steep mid-level lapse rates extend over the
westernmost portions of this greater low-level moisture, which will
support the development of strong to very strong buoyancy later this
afternoon. Thunderstorms are not expected to develop within this
area of strong buoyancy, but instead will likely initiate farther
west (from southeast MT/northeast WY into the NE Panhandle) amid a
combination of weak lee troughing and subtle ascent attendant to
low-amplitude shortwave trough. Here, modest buoyancy, high cloud
bases, and moderate westerly flow aloft will result in
outflow-dominant storm structures which will quickly move into the
more buoyant airmass downstream. Given the ample buoyancy and
moderate vertical shear, updrafts should persist along this
fast-moving outflow, resulting in more progressive convective
clusters. Severe gusts will be possible as these clusters move
eastward/southeastward, with some potential for gusts over 75 mph.
Recent guidance has provided more confidence in higher severe wind
coverage, meriting the introduction of 30% wind probabilities and
southeastward expansion of the 15% wind probabilities past the MO
River in NE/IA.

...Mid-Atlantic/Southeast States...
Recent satellite imagery shows a shortwave trough extending from
southern Ontario through the Lower OH Valley. Morning soundings and
recent mesoanalysis both show moderate mid-level flow (i.e. 30 to 40
kt at 500 mb) throughout the base of this shortwave. Expectation is
for this wave to continue eastward/northeastward through the OH
Valley, reaching the Mid-Atlantic by late afternoon. The airmass
preceding this wave across the Mid-Atlantic is very moist, with
dewpoints ranging from the upper 60s/low 70s from eastern PA/NJ to
the mid 70s across the eastern Carolina. This ample low-level
moisture will result in quick airmass destabilization amid strong
daytime heating. Limited remaining convective inhibition on recent
mesoanalysis indicates this destabilization is already firmly
underway.

Large-scale lift attendant to the approaching shortwave (augmented
by orographic ascent) coupled with airmass destabilization will
result in scattered to numerous thunderstorms development this
afternoon over the southern Appalachians and Blue Ridge Mountains.
This initial, more cellular development could produce isolated hail.
These storms should then spread eastward towards the coast with some
increasing coverage possible. The strongest mid-level flow (and
greatest vertical shear) this afternoon will extend from WV across
northern VA/southern PA and NJ. The greatest buoyancy will be
farther south, across the Carolinas and GA. Even with this
displacement, there is enough overlap between the buoyancy and shear
to support loosely organized strong to severe storms. The highest
concentration of severe storms is anticipated from southeast
PA/southern NJ southward across central VA and the Delmarva into
central NC. In this region, numerous thunderstorms coupled with
moderate shear should result in several cold-pool-dominated,
forward-propagating convective clusters. Damaging gusts will be the
primary risk within this more linear activity.

...Northern Intermountain West/Rockies and Northern Great Basin...
A shortwave trough is currently moving through northern CA. An
elongated belt of enhanced southwesterly mid-level flow exists from
the base of this shortwave (over northern CA/northwest NV)
northeastward across the northern Great Basin/Rockies. Scattered
thunderstorm development is anticipated within this favorable flow
regime. Daytime heating and steepened low-level lapse rates coupled
with this enhanced mid-level flow should support a strong to severe
wind gusts from parts of eastern Oregon into Idaho/Montana and
possibly northern Utah. Highest coverage is expected over
south-central MT.

...Lower Michigan to northwest Ohio...
Scattered thunderstorms are forecast develop this afternoon beneath
a weak upper trough across parts of Lower Michigan and northwest
Ohio. A modest combination of instability and deep-layer shear will
support isolated/marginally severe hail and locally damaging winds
with the strongest updrafts.

..Mosier/Moore.. 07/09/2025

$$