Day 1 Convective Outlook CORR 1
NWS Storm Prediction Center Norman OK
1231 AM CDT Fri Jul 26 2024
Valid 261200Z - 271200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS LATE THIS
AFTERNOON AND EVENING ACROSS PARTS OF SOUTHEASTERN ARIZONA AND
ADJACENT SOUTHWESTERN NEW MEXICO...PARTS OF NORTHEASTERN NEVADA INTO
WESTERN UTAH...PARTS OF WESTERN NEBRASKA AND ADJACENT SOUTHEASTERN
WYOMING INTO CENTRAL SOUTH DAKOTA...AND PARTS OF EASTERN NORTH
DAKOTA INTO NORTHWESTERN MINNESOTA...
CORRECTED FOR GEN THUNDER LINE/NDFD GRAPHIC
...SUMMARY...
The risk for severe thunderstorms appears seasonably low across much
of the U.S. today through tonight.
...Discussion...
A significant inland migrating mid-level trough (and embedded low)
is now progressing east-northeast of the Canadian and northern U.S.
Rockies, and forecast to continue eastward across the Canadian
Prairies today through tonight. While stronger mid-level height
falls likely remain focused well to the north of the international
border area, models indicate that mid-level heights will continue to
fall across much of the West into the northern Great Plains, as weak
trailing troughing develops inland of the Pacific coast and
downstream ridging becomes increasingly suppressed. In lower
levels, to the south of a deepening surface cyclone associated with
the primary short wave perturbation, a modest cold front may advance
east of the northern Rockies, before stalling and weakening across
the northern Great Plains into northern portions of the Great Basin.
As this regime evolves, destabilization associated with strong
daytime heating and remnant monsoonal moisture appears likely to
support considerable thunderstorm development this afternoon and
evening across the higher terrain of eastern Arizona through the
southern Rockies, and near lee surface troughing across the north
central high plains. Additional, more widely scattered,
thunderstorm activity may focus near/just ahead of the surface front
across the northern Great Basin through portions of the northern
Rockies and northern Great Plains. Some of the stronger, more
persistent convection will probably overspread, or develop above,
more strongly heated and deeply mixed (with large developing surface
temperature-dew point spreads) lower elevations, accompanied by a
risk for strong to locally severe wind gusts.
...Eastern North Dakota/Northwestern Minnesota...
Beneath a plume of very warm and capping elevated mixed-layer air,
which will continue to advect northeastward across the northern
Great Plains through the day, models indicate that seasonably moist
boundary-layer air may support a narrow corridor of large potential
instability across the Red River Valley vicinity into the stalling
weakening frontal zone across northwestern Minnesota/southeastern
Manitoba/adjacent northwest Ontario by early evening. Downstream of
the base of the short wave perturbation crossing the Canadian
Prairies, forcing for ascent may support isolated to widely
scattered thunderstorm development. In the presence of at least
30-40 kt deep-layer shear, and modest clockwise-curved low-level
hodographs, one or two supercells appear possible to the south of
the international border, perhaps as far southwest as areas
near/west of Grand Forks and Fargo.
..Kerr.. 07/26/2024
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