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Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1250 AM CDT Fri Jul 22 2022

Valid 221200Z - 231200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHEAST AND NORTHERN PLAINS INTO THE UPPER MIDWEST REGION...

...SUMMARY...
Isolated strong to severe thunderstorms may occur Friday into Friday
night from parts of the central and northern Plains into the Upper
Midwest, and over portions of the Ohio Valley/northern Middle
Atlantic.

...OH Valley/Northern Middle Atlantic...

Large-scale flow will beco*e a bit more zonal across the northern
tier of the CONUS during the day1 period as weak height rises are
noted across the lower Great Lakes into the Northeast. Despite the
height rises, broad cyclonic flow will persist across southeastern
Canada, and a minor disturbance will translate across lower MI into
the upper OH Valley later this afternoon. This feature will likely
aid scattered convection, though strong boundary-layer heating will
prove instrumental in destabilization necessary for robust updrafts.
Gusty winds may acco*pany scattered convection across this region.

...Northern Plains into the Upper Midwest...

Early-morning water-vapor imagery depicts a notable short-wave
trough approaching the WA/OR coast. This feature will progress
across the northern Rockies into western MT by 23/00z, then lose its
amplitude as it translates to near the MT/ND by the end of the
period. In response to this feature, lee surface trough will shift
east across MT as a weak low migrates into northwestern ND. Latest
model guidance suggests a warm front will advance north to near the
international border by late afternoon, then sag south after dark as
the short wave approaches. Forecast soundings across the northern
Plains suggest convective temperatures will be breached across
eastern MT/western ND by 21z; however, temp/dew point spreads will
be large. Any convection that evolves across this region will be
high based, and likely isolated in nature due to limited moisture.
Given the approaching short wave and frontal structure, there is
some concern that a few severe storms could evolve over southeast
SK, just north of the surface low, then track southeast along the
boundary. If this materializes, a narrow corridor of higher severe
probabilities may be warranted into the evening hours.

Farther south, predictability is considerably lower. The
evolution/demise of early-day convection across the lower MO Valley
will largely dictate/influence possible redevelopment within a warm
advection zone along the eastern plume of steep lapse rates.
Multiple scenarios exist within the latest hr** guidance, but a
signal for possible strong convection is noted. One consistent
signal is the influence of strong heating along the lee trough which
should lead to isolated high-based storms by late afternoon. LLJ
bifurcates across the central Plains, with one branch holding across
the High Plains and a secondary, more veered branch focused across
southern IA into northern IL late evening. This secondary branch may
aid elevated convection after dark. Strength of this activity
remains questionable, and for this reason will maintain a Marginal
Risk across this region.

..Darrow/Weinman.. 07/22/2022