SPC Jul 1, 2025 1630 UTC Day 1 Convective Outlook

SPC 1630Z Day 1 Outlook

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1104 AM CDT Tue Jul 01 2025

Valid 011630Z - 021200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE
MID-ATLANTIC REGION AND ACROSS WESTERN PORTIONS OF NEBRASKA AND
SOUTH DAKOTA...

...SUMMARY...
Scattered strong to severe storms are possible across parts of the
Mid-Atlantic into the Northeast this afternoon/evening.  A few
severe thunderstorms are possible over western parts of Nebraska and
South Dakota.

...Mid-Atlantic into the Northeast...
Recent satellite imagery shows a well-defined shortwave trough
extending from western QC through the middle OH Valley into the Mid
MS Valley. Regional radar imagery depicts showers and thunderstorms
preceding this wave from across the mid/upper OH Valley, with the
stronger storms occurring along an associated cold front that
extends from far western NY southwestward across western PA and
along the WV/OH border through eastern KY.

The general expectation throughout the day is for this shortwave
trough and associated cold front to progress eastward into the
increasingly moist and unstable airmass downstream, promoting
widespread thunderstorm development this afternoon. Moderate
mid-level flow extends through the eastern periphery of this wave,
with the strongest flow (i.e. around 40 kt at 500 mb) expected to
move across NY and New England. Given the more northern trajectory
of the stronger flow, there will be limited overlap between the
strongest flow and the better buoyancy, which will remain farther
south across the Mid-Atlantic. Even so, the overall environment will
support some organization of storms into line segments/clusters.
Scattered thunderstorms will increase in coverage with time and
numerous thunderstorms are expected by mid-late afternoon while
moving east from PA/WV in NJ/VA/MD. Recently issued MCD #1529 also
addresses the severe potential in this region. More limited storm
coverage is anticipated farther north. Strong to severe gusts (50-65
mph) are possible with the stronger downdrafts.

...Black Hills/SD into the Central High Plains... 
A weak shortwave trough is currently progressing through eastern MT
and eastern WY, throughout the northern periphery of the upper
ridging that extends from the southern Plains through the northern
Rockies. This wave is forecast to continue eastward/southeastward,
eventually interacting with the moderate low-level moisture expected
to advect northward across western portions of KS, NE and SD. Ascent
attendant to this wave will augment low-level convergence near an
associated surface low to foster afternoon thunderstorm development.
Low-level southerly flow veering to northwesterly aloft will foster
moderate effective shear (i.e. 30 to 40 kt) and the potential for a
couple of supercells. Large hail will be the primary risk with these
storms.

Some additional thunderstorms are possible later tonight across far
southern ND and central/eastern SD as a strengthening low-level jet
contributes to warm-air advection across a developing warm frontal
zone. Moderate shear and steep mid-level lapse rates will support a
few stronger storms capable of producing isolated large hail.

...Central Appalachians into the Southeast...
Afternoon thunderstorms are expected across a large area from the
central Appalachians and Carolinas southwestward into the Southeast,
along or just ahead of a weak, eastward-progressing cold front.
Limited vertical shear should promote less organized storms,
although a few strong, water-loaded downdrafts capable of producing
damaging winds are possible.

..Mosier/Karstens.. 07/01/2025

StormPrep