SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0254 PM CDT Mon Aug 29 2022
Valid 292000Z - 301200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
NORTHERN INDIANA...FAR SOUTHERN LOWER MICHIGAN...AND NORTHWESTERN
OHIO...
...SUMMARY...
Scattered to numerous severe thunderstorm winds should continue
through this evening across parts of the mid Mississippi Valley into
Lower Michigan.
...20Z Update...
The main change with this update was to adjust severe wind
probabilities across the Midwest and Lower MI to account for an
ongoing cluster of thunderstorms extending across Lower MI into IN.
With a moist and rather unstable airmass present ahead of it,
scattered to numerous severe/damaging winds should continue to be
the main threat with this MCS as it moves eastward through the rest
of the afternoon and into the early evening.
The potential for additional robust convective development later
this afternoon and evening along/ahead of the surface cold front in
northern MO and central IL remains unclear. If thunderstorms can
develop across this region, then both damaging winds and isolated
severe hail may occur given the strong buoyancy and moderate
deep-layer shear present.
The Marginal Risk has been expanded into western NY based on an
ongoing cluster of thunderstorms moving from western PA into this
region. Occasional damaging winds appear possible with this
convection through the early evening as it moves northeastward into
a moderately unstable airmass with modest deep-layer shear.
..Gleason.. 08/29/2022
.PREV DISCUSSION... /ISSUED 1123 AM CDT Mon Aug 29 2022/
...Northeast MO across IL to Lower MI through late evening...
A midlevel trough will move eastward from the upper MS Valley to the
Great Lakes, with some modest amplification expected from IA to IL
as an embedded mid-upper speed max digs southeastward from the
northern Plains. An associated surface cold front will likewise
move eastward/southeastward from IA/WI to MO/IL/Lower MI by tonight.
Convective clusters are ongoing this morning across northwest IL,
apparently in conjunction with an undular bore ahead of the surface
cold front. Given an environment with MLCAPE near 3000 J/kg,
midlevel lapse rates at or above 8 C/km, DCAPE > 1000 J/kg and 35-45
kt midlevel flow, the ongoing storms should eventually produce a
stronger cold pool and there will be and attendant increase in the
threat for damaging winds by early afternoon.
The ongoing convection will modulate the severe threat area later
this afternoon, with potential stabilization across northern IL in
the wake of the storms, and outflow to focus the threat a bit
farther south by mid-late afternoon. Additional storms that form
this afternoon along the front/outflow will have the potential to
produce occasional damaging outflow gusts and isolated large hail
from northeast MO across central IL into northern IN and southern
Lower MI.
...West TX to the OH Valley this afternoon/evening...
A few thunderstorm clusters are ongoing from northern OK to southern
IL and northern OH in association with subtle midlevel vorticity
maxima and within a moisture plume with PW > 1.75 inches. Mid-upper
flow weakens with southward and westward extent, but precipitation
loading within multicell clusters will support the potential for
isolated wind damage this afternoon. Additional storms will likely
form along the surface cold front in KS, and in the area of strong
surface heating east of a subtle midlevel trough over northeast NM.
Relatively deep mixing and moderate-strong buoyancy will support
downburst potential this afternoon/evening from west TX into KS.
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