Severe Storm Outlook Narrative (AC)
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ACUS11 KWNS 041856
SWOMCD
SPC MCD 041856
ILZ000-IAZ000-042030-
Mesoscale Discussion 0630
NWS Storm Prediction Center Norman OK
0156 PM CDT Sat May 04 2024
Areas affected...northern and western Illinois.
Concerning...Severe potential...Watch possible
Valid 041856Z - 042030Z
Probability of Watch Issuance...40 percent
SUMMARY...There is an increased threat for damaging wind gusts from
thunderstorms for several hours this afternoon/evening.
DISCUSSION...RAP mesoanalysis shows a mostly uncapped airmass ahead
of a cold front moving across the Midwest. Expect destabilization to
increase through the afternoon as mid-60s dewpoints continue to
advect into the region and temperatures warm into the low 80s.
Substantial instability (~1500-2000 J/kg MLCAPE) and modest
deep-layer shear (25-30 knots per DVN VWP) will lead to some loosely
organized multicell thunderstorms along the front later this
afternoon. Near peak heating (~21Z), there may be a few hour window
with strong to severe thunderstorms with a primary threat of
damaging wind gusts. However, this threat is expected to be mainly
driven by daytime heating and therefore, the threat should wane by
dusk. Convective trends will be monitored, and if decent storm
coverage and intensity appears imminent, a severe thunderstorm watch
will be considered.
..Bentley/Smith.. 05/04/2024
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...LOT...ILX...LSX...DVN...
LAT...LON 39139043 39429084 39919124 40479132 41029104 41959038
42318962 42348840 40638832 39188944 39139043