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Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0750 PM CDT Wed Jun 29 2022

Valid 300100Z - 301200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
SOUTH DAKOTA...

...SUMMARY...
Severe storms will be possible across parts of the northern Plains
this evening. Isolated large hail may occur in parts of eastern
North Dakota, with a potential for damaging wind gusts across South
Dakota, some of which could be greater than 65 knots.

...Northern Plains...
Latest water vapor imagery shows a low-amplitude upper-level ridge
over the north-central U.S., with a shortwave trough embedded in
west-southwesterly mid-level flow over far eastern Montana and far
western South Dakota. At the surface, a 1002 mb low is analyzed
across far northern South Dakota, with a surface trough extending
southward across east-central South Dakota. This area is located to
the south of a corridor of maximized low-level moisture, extending
from southern Minnesota northwestward into eastern North Dakota.
Thunderstorms are ongoing to the south of this moist axis across
parts of western and central South Dakota, where surface
temperature-dewpoint spreads exceed 40 degrees F in some locations.
As a result, near dry adiabatic conditions are present, with
forecast soundings in central South Dakota showing 0-3 km lapse
rates in the 9 to 10 C/km range. These steep lapse rates will aid
downdraft acceleration, making severe wind gusts likely with the
stronger downdrafts. A few wind gusts of greater than 65 knots could
occur with the more intense short line segments.

Further to the north into parts of central and eastern North Dakota,
a moderately unstable airmass is in place, where MLCAPE is estimated
by the RAP to be in the 2000 to 3000 J/kg range. Forecast soundings
across central and eastern North Dakota show a capping inversion
just above 850 mb. This should limit convective potential for a few
more hours. But later this evening, the cap is forecast to weaken,
suggesting isolated to scattered thunderstorm development should
take place. The moderate instability co*bined with 0-6 km shear in
the 45 to 55 kt range, should be enough for supercells with large
hail. Supercells with hailstones greater than 2 inches in diameter
will be possible.

...Intermountain West/Central Rockies...
The latest mosaic radar imagery shows scattered thunderstorms
ongoing across parts of the Intermountain West into the central
Rockies, mostly in the higher terrain. Weak instability is analyzed
from northern Utah eastward into northern Colorado and eastern
Wyoming, where the RAP has MLCAPE generally in the 250 to 500 J/kg
range. This co*bined with moderate deep-layer shear and very steep
lapse rates, evident on forecast soundings, could be enough for an
isolated and marginal wind-damage threat for a few more hours this
evening.

...New England...
A shortwave trough is evident on water vapor imagery over the
Northeast. Ahead of the trough, scattered thunderstorms are ongoing
across parts of New England. Although instability is weak, forecast
soundings show steep lapse rates, in excess of 8.0 C/km, from the
surface to 850 mb. This could be enough for a marginal wind-damage
threat with the stronger downdrafts. The threat may persist for a
couple more hours as the severe threat gradually transitions
eastward into parts of western and northern Maine.

..Broyles.. 06/30/2022