457
ACUS01 KWNS 010549
SWODY1
SPC AC 010548

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1248 AM CDT Tue Jul 01 2025

Valid 011200Z - 021200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE MIDDLE
ATLANTIC REGION...

...SUMMARY...
Scattered strong to severe storms are possible across parts of the
Mid-Atlantic into the Northeast this afternoon/evening. An isolated
severe storm may also occur over parts of the High Plains.

...Middle Atlantic...

Upper trough currently located over the upper Great Lakes, extending
into central MO, is forecast to shift into the OH Valley by late
afternoon before advancing across the northern/central Appalachians
by the end of the period. At the surface, a cold front will progress
into the upper OH Valley early in the period and this will serve as
the focus for scattered thunderstorms by mid day.

Early this morning, water-vapor imagery suggests a weak
low-amplitude short-wave trough is embedded within the base of the
larger trough along the IL/IN border. Radar data supports this with
a few clusters of thunderstorms extending from western IN into
western TN. Current speed/movement of this feature would place this
short wave into southern OH/eastern KY by 18z. While low-level lapse
rates are not forecast to be that steep across the Middle Atlantic,
modest southwesterly mid-level flow will contribute to adequate
shear, supporting organized line segments/clusters. Current thinking
is scattered thunderstorms will readily develop ahead of this
feature, and a marked increase in convection should be noted into
the mid afternoon across southern PA into northern VA. Latest HREF
guidance supports this scenario, and forecast soundings favor
damaging winds with convection that develops within a high-PW air
mass, despite marginal lapse rates/instability. Strong-severe
convection should spread off the Middle Atlantic Coast during the
evening.

...High Plains...

A weak short-wave trough appears to be topping the Rockies ridge
over eastern ID/southern MT early this morning. This feature will
begin to dig southeast toward the Black Hills, eventually migrating
into the lower MO Valley by the end of the period. As a result, a
weak lee trough should extend across eastern WY during the late
afternoon and isolated thunderstorms are expected to develop across
the High Plains of western SD into the NE Panhandle/northeast CO.
Some consideration was given to a SLGT Risk across this region but
activity may prove too sparse to warrant higher severe
probabilities. Even so, wind profiles suggest a few slow-moving
supercells could develop. With LLJ expected to strengthen across
this region after sunset, this would favor a few longer-lived
storms. If it appears coverage will be a bit more expansive then
currently forecast, a SLGT Risk may be warranted.

..Darrow/Halbert.. 07/01/2025

$$