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Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0250 PM CDT Sun Jul 17 2022

Valid 172000Z - 181200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS LATE THIS
AFTERNOON AND EVENING ACROSS PARTS OF SOUTHERN MISSOURI AND
NORTHEASTERN ARKANSAS INTO WESTERN KENTUCKY AND TENNESSEE...AND
PARTS OF EASTERN KENTUCKY...SOUTHEASTERN OHIO...WEST
VIRGINIA...WESTERN MARYLAND AND SOUTHWESTERN PENNSYLVANIA...

...SUMMARY...
Thunderstorms capable of producing potentially damaging wind gusts
and perhaps some hail appear mostly likely across parts of the Ozark
Plateau into Mid South and portions of the Allegheny Plateau late
this afternoon and evening.

...20Z Outlook Update...
Categorical and probabilistic lines have been adjusted, generally to
account for the progression of synoptic and sub-synoptic features
and the latest trends concerning destabilization.

Please refer to the prior discussion appended below, and the latest
SPC Mesoscale Discussions for information concerning the anticipated
severe weather potential for the remainder of this period.

..Kerr.. 07/17/2022

.PREV DISCUSSION... /ISSUED 1130 AM CDT Sun Jul 17 2022/

...Synopsis...
A pair of weak upper-level disturbances/MCVs remain evident in
mid-level reflectivity mosaics across central IL and the upper OH
River Valley. Embedded within a broad trough across the great Great
Lakes region, these features are expected to continue to propagate
to the east/northeast through the day. Widespread stratiform rain
with embedded convection in the vicinity of these two features is
diabatically reinforcing a stalled cold front draped through the OH
River Valley into the southern Plains. This front is expected to
gradually migrate southward through the day and will likely be the
impetus for thunderstorm development and/or intensification later
this afternoon. Across the west, ample monsoonal moisture across the
Great Four Corners region and into the northern Rockies will support
scattered thunderstorm development with the potential for severe
downburst winds. 

...Upper OH River Valley...
The ongoing showers and thunderstorms across the mid to upper OH
River Valley are limiting the potential for daytime heating across
the region. Temperatures are currently struggling to climb above the
mid 70s with few breaks in cloud cover expected through at least mid
afternoon. With lift and modest, but sufficient, deep-layer flow
already in place ahead of the MCVs, the greater severe threat will
likely reside along and south of the OH River Valley where some
destabilization is already noted. Latest CAMs support this idea and
show clusters developing by late afternoon through the region.
Severe probabilities have been adjusted southward to reflect this
trend. 

...Ozark Plateau into the lower OH River Valley...
Morning showers and thunderstorms across southern MO and into
adjacent parts of AR, IL, and KY will likely limit diurnal heating
through at least early afternoon. Some guidance suggests sufficient
clearing can take place to allow thunderstorm development across
central to southern MO by mid-afternoon, and latest visible
satellite imagery and surface temperature trends across western MO
support this idea, but the degree of destabilization that can occur
remains uncertain. Confidence in storm development is higher to the
south across AR and into the mid-MS River Valley where
destabilization is already ongoing with temperatures climbing into
the low/mid 80s. While mid to upper-level flow will be modest,
adequate deep-layer shear should be in place to support
semi-discrete storms to clusters from western AR into western KY/TN
to support an isolated hail/severe wind threat. A brief tornado or
two appears possible across the mid-MS River Valley region where
low-level helicity along and just ahead of the front will be
maximized, but confidence in storm mode and coverage remains too
limited for higher probabilities. 

...Red River Valley of the North...
Latest surface observations across northeast ND into northwest MN
show surface pressure falling over the past several hours, which is
resulting in a slight bolstering of generally southerly low-level
flow through the region. In turn, dewpoints have increased into the
70s through the region, which is boosting MLCAPE estimates to over
2000 J/kg. Despite the improving buoyancy, 12 UTC soundings from BIS
and ABR reveal some mixed-layer inhibition, which remains a concern
for convective potential later this afternoon. Forecast soundings
suggest this inhibition may beco*e negligible by this afternoon, and
several CAMs show discrete supercell potential as storms develop
along a weak surface trough. However, some spread in guidance
remains with other solutions showing little to no activity south of
the international border. The Marginal risk has been expanded south
to enco*pass much of the Red River Valley, but this is to more
accurately address spatial extent of the severe threat rather than
indicate an increase in the probability for thunderstorms. 

...Montana...
Morning soundings from MT and ID sampled 50-60 knot winds aloft
ahead of a shortwave trough located across the Pacific Northwest.
These soundings also sampled mid-level monsoonal moisture and fairly
dry boundary layers. With daytime heating already underway,
thermodynamic profiles across southern MT should be favorable for
thunderstorms with strong to severe downbursts by late this
afternoon. co*bined ascent ahead of the shortwave trough and via
orographic ascent should support isolated to scattered thunderstorms
across the region. 

...Nevada/Utah...
Similar to southern MT, 12 UTC soundings from LKN, VEF, and SLC all
sampled dry boundary layers with adequate mid-level monsoonal
moisture to support thunderstorms by this afternoon. Forecast
soundings show 2 to 3 km deep sub-cloud layers with steep low-level
lapse rates that will be supportive of strong to severe downburst
winds. Latest CAM guidance shows a strong convective signal across
northeast NV into northwest UT this afternoon, which gives
sufficient confidence to introduce severe wind probabilities given
the expected thermodynamic environment.