514
ACUS11 KWNS 301703
SWOMCD
SPC MCD 301702
INZ000-MIZ000-ILZ000-301930-
MESOSCALE DISCUSSION 1847
NWS STORM PREDICTION CENTER NORMAN OK
1202 PM CDT WED JUL 30 2025
AREAS AFFECTED...PARTS OF SOUTH CENTRAL/EASTERN ILLINOIS INTO
NORTHWESTERN INDIANA AND SOUTHWESTERN LOWER MICHIGAN
CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY
VALID 301702Z - 301930Z
PROBABILITY OF WATCH ISSUANCE...20 PERCENT
SUMMARY...A LINE OF THUNDERSTORMS MAY UNDERGO GRADUAL
INTENSIFICATION WITH INCREASING POTENTIAL FOR LOCALLY STRONG TO
SEVERE WIND GUSTS WHILE ADVANCING EASTWARD AROUND 20-30 KT, INTO AND
THROUGH MID TO LATE AFTERNOON (2-4 PM CDT/3-5 PM EDT). IT IS STILL
NOT CLEAR THAT A SEVERE WEATHER WATCH IS NEEDED, BUT TRENDS WILL BE
MONITORED.
DISCUSSION...THUNDERSTORM DEVELOPMENT ALONG A MODEST EASTWARD
PROPAGATING CONVECTIVE COLD POOL HAS UNDERGONE RECENT RENEWED
INTENSIFICATION, LIKELY AIDED BY EASTERLY LOW-LEVEL UPDRAFT INFLOW
OF DESTABILIZING BOUNDARY-LAYER AIR CHARACTERIZED BY SEASONABLY HIGH
MOISTURE CONTENT (INCLUDING MID/UPPER 70S SURFACE DEW POINTS). THE
BOUNDARY-LAYER MOISTURE MAY BE CONTRIBUTING TO CAPE IN EXCESS OF
2000 J/KG, FORECAST SOUNDINGS INDICATE THAT LAPSE RATES IN
MID/UPPER-LEVELS ARE MODEST TO WEAK.
ALTHOUGH A BELT OF SOUTHWESTERLY FLOW ON THE ORDER OF 30-40 KTS IN
THE 700-500 MB LAYER MAY BE CONTRIBUTING TO AT LEAST MODERATELY
STRONG DEEP-LAYER SHEAR, DEEPER-LAYER MEAN FLOW REMAINS A RATHER
MODEST TO WEAK 15-25 KTS. STILL, THE SHEAR AND FORCING FOR ASCENT
ASSOCIATED WITH A SUPPORTING UPSTREAM MID-LEVEL TROUGH MAY BE
SUFFICIENT TO MAINTAIN ONGOING ACTIVITY THROUGH THIS AFTERNOON.
GRADUALLY, FURTHER INSOLATION, BOUNDARY-LAYER WARMING AND STEEPENING
OF LOW-LEVEL LAPSE RATES COULD CONTRIBUTE TO FURTHER INTENSIFICATION
OF CONVECTION DEVELOPMENT, WITH POSSIBLE DEVELOPING EMBEDDED
MESOSCALE CYCLONIC CIRCULATIONS AND A STRENGTHENING COLD POOL,
ACCOMPANIED BY INCREASING POTENTIAL FOR LOCALLY STRONG TO SEVERE
SURFACE GUSTS.
..KERR/SMITH.. 07/30/2025
..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...IWX...IND...PAH...LOT...ILX...LSX...
LAT...LON 41768740 41838540 40718550 38748726 38348881 38878987
39638908 40318882 41768740
MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 95 MPH
MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN
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