SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0219 PM CDT Thu Jul 07 2022
Valid 072000Z - 081200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER MUCH OF
MONTANA...AND PARTS OF THE LOWER MISSOURI VALLEY AND SOUTHEAST...
...SUMMARY...
Scattered damaging winds will be possible from parts of the
Southeast to the Lower Missouri Valley this afternoon and evening.
Scattered large hail and severe wind gusts are also possible in
Montana from late afternoon through the evening.
No updates are needed for the 20Z outlook.
..Jewell.. 07/07/2022
.PREV DISCUSSION... /ISSUED 1123 AM CDT Thu Jul 07 2022/
...MT and vicinity...
The continued presence of mid 50s to low 60s surface dew points
banked along the northern Rockies will support another round of
scattered thunderstorms off the higher terrain by late afternoon.
Amid low-amplitude mid-level ridging from the central Rockies to the
Prairie Provinces, a belt of moderate southwesterlies/westerlies
atop weak low-level easterlies will yield sufficient bulk shear for
a few initial supercells centered on central MT that should
consolidate into a couple eastward-moving clusters this evening.
With 1500-2000 J/kg of MLCAPE becoming common, large hail will be
the primary initial hazard transitioning to predominantly severe
wind gusts in time. Overall severe threat will gradually diminish
overnight as MLCIN strengthens across eastern MT into the western
Dakotas.
...Lower OH Valley to the Southeast...
To the southeast of a decaying non-severe MCS over IL, robust
boundary-layer heating and very rich low-level moisture will support
a broad area of scattered thunderstorms this afternoon. This
activity should tend to focus along residual outflow boundaries, the
higher terrain of the southern Appalachians, and a weak cold front
sinking south in VA. Relative maxima of large buoyancy will be
centered on middle TN and separately along the Carolina coastal
plain, while very poor mid-level lapse rates with 700-500 mb values
less than 5 C/km will be prevalent from VA north, east of the
Appalachians.
Deep-tropospheric flow will be quite weak with effective bulk shear
largely around 10-15 kt. This will favor extensive disorganized
pulse convection with wet microbursts capable of localized damaging
winds. It's plausible that weakly organized multicell clustering may
occur within mesoscale corridors, mainly during the late afternoon
and early evening, which would temporarily increase the wind damage
threat.
...Lower MO Valley...
Convective outflow in the wake of a decaying MCS has pushed as far
south as southwest MO. This boundary should wash out or effectively
consolidate north across northern portions of KS/MO as a warm front
by early evening with pronounced differential heating across it.
Modest low-level warm advection and an upstream MCV drifting east
from central NE should aid in scattered thunderstorm development
during the evening. With a confined corridor of large buoyancy
expected along and just south of the front, coincident with enhanced
0-3 km SRH along and just north of it, an organized multicell
cluster may develop and gradually spread east-southeast. Damaging
winds should be the main threat, but a tornado will also be possible
before convection weakens overnight.
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