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Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0242 PM CDT Fri Jul 22 2022

Valid 222000Z - 231200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
CENTRAL PLAINS TO THE UPPER MIDWEST...NORTHERN PLAINS...UPPER OH
RIVER VALLEY...AND NORTHERN UTAH......

...SUMMARY...
Isolated strong to severe thunderstorms may occur from parts of the
central and northern Plains into the Upper Midwest, separately over
parts of northern Utah, and the upper Ohio Valley/north-central
Appalachians region.

...North Dakota...

Some consideration was given to introducing a narrow Slight risk for
hail/wind across parts of northern ND. One or two cells are expected
to develop by evening and may pose a threat for large hail and
strong gusts. However, confidence in the exact, very focused
corridor is low and will maintain the Marginal risk with the 20z
update. 

...Northern IL/IN...

Some consideration was given for an upgrade to Slight risk across
parts of northeast IL into northern IN for overnight wind/hail
potential late in the forecast period. However, forecast soundings
show very strong boundary-layer inhibition during the
overnight/early morning period despite an otherwise favorable
environment. This should act to limit severe wind potential.
Furthermore, storm mode is expected to be unfavorable for large hail
as clusters quickly develop. For these reasons, will maintain the
Marginal risk for now.

Elsewhere, the outlook remains on track and no changes have been
made.

..Leitman.. 07/22/2022

.PREV DISCUSSION... /ISSUED 1119 AM CDT Fri Jul 22 2022/

...Synopsis...
Mid-morning water vapor imagery continues to track a stout upper
ridge over AZ as well as several shortwave perturbations embedded
within a swath of relatively strong zonal flow across the northern
tier of the CONUS. Of these, the shortwave troughs translating
across the Pacific Northwest and across the upper Midwest/Great
Lakes regions are notable and will likely drive severe weather
potential for parts of the Northern Plains and upper OH River Valley
this afternoon and/or tonight. Other notable surface features
(outlined below) will support additional severe weather concerns
this afternoon. 

...Central Plains into the Midwest...
A residual outflow boundary from overnight and early-morning
convection is noted across eastern IA with a weak surface
trough/warm front draped across NE into eastern CO/western KS.
Although gradual clearing is noted in latest visible imagery across
parts of eastern NE and IA, weakening convection and showers are
stunting daytime heating with temperatures struggling to climb past
the mid-70s. A region of dry, subsident air is gradually moving into
the region behind the Midwest/Great Lakes shortwave trough, and
should aid in continued clearing and gradual destabilization through
the day. Thunderstorm potential will likely be greatest this evening
as the low-level jet increases in response to the approaching
disturbance from the Pacific Northwest, boosting isentropic ascent
over the residual boundary/weak warm front in the process.
Thunderstorm coverage remains somewhat unclear given spread in
latest hi-res guidance, though 30-40 knot northwesterly flow aloft
should support some storm organization and the potential for
wind/hail. Severe wind potential may be locally maximized across
northern IL into northern IN overnight if an organized cluster/line
can beco*e established and propagate east along the outflow/warm
frontal boundary. However, this potential remains too conditional to
warrant higher probabilities at this time.

...Upper OH River Valley/Central Appalachians...
Building cumulus is noted across eastern OH into northern PA ahead
of an upper level disturbance and weak surface pressure trough
approaching from the west. Destabilization will continue through the
late morning/early afternoon as temperatures climb into the upper
80s. Although mid-level lapse rates sampled by regional 12 UTC
soundings are modest, rich boundary-layer moisture co*bined with
diurnal heating should yield 1000-1500 J/kg MLCAPE by early
afternoon with limited inhibition. 30 knot winds in the lowest 3 km
(sampled by regional VWPs) coupled with steep low-level lapse rates
should support a damaging wind potential across the region as
isolated to scattered thunderstorms develop through the afternoon.

...Northern Plains...
Surface pressure falls are noted across the northern High Plains
this morning as the Pacific Northwest disturbance approaches the
northern Rockies. This trend will continue through the day and help
consolidate a broad frontal zone draped along the international
border. Thunderstorm development remains possible in the vicinity of
a developing triple point this evening as the upper low shifts into
the Plains. Warm temperatures between 850-700 mb sampled by the 12
UTC BIS and GGW soundings and modest boundary-layer moisture will
act as a mitigating factors for storm coverage and intensity despite
strong dynamic ascent. However, storms that can mature may beco*e
organized given the elongated forecast hodographs, and could support
a hail/wind threat. A zone of enhanced ascent appears probable early
Saturday morning along the ND/SD border either along the surface
cold front, along an outflow boundary from tonight's convection,
within a zone of strong isentropic ascent, or a co*bination of these
factors. Regardless, many CAMs show this potential for additional
development, which may pose a severe risk prior to sunrise for parts
of the lower Red River Valley. 

...Northern Utah...
The 12 UTC soundings from SLC sampled a dry boundary layer along
with adequate mid-level moisture and lapse rates to support around
100 J/kg MUCAPE. Mostly clear skies will support deep boundary-layer
mixing and inverted-v profiles favorable for strong to severe
downbursts by mid/late afternoon. Isolated to scattered
thunderstorms are expected across the region as ascent from the
passing Pacific Northwest disturbance glances the region to the
north, supporting the severe wind potential.