Severe Storm Outlook Narrative (AC)
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000
ACUS11 KWNS 251811
SWOMCD
SPC MCD 251810
INZ000-MIZ000-ILZ000-252015-

MESOSCALE DISCUSSION 1614
NWS STORM PREDICTION CENTER NORMAN OK
0110 PM CDT MON AUG 25 2014

AREAS AFFECTED...NORTHERN IL/NORTHERN INDIANA AND SOUTHWEST LOWER MI

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 251810Z - 252015Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...ISOLATED INSTANCES OF DAMAGING WINDS/SOME HAIL WILL BE
POSSIBLE THIS AFTERNOON ACROSS NORTHERN IL/NORTHERN INDIANA AND
POSSIBLY PORTIONS OF LOWER MI. WHILE A WATCH IS NOT CURRENTLY
ANTICIPATED...CONVECTIVE TRENDS WILL MONITORED THIS AFTERNOON FOR A
POSSIBLE SLIGHT RISK UPGRADE/SEVERE THUNDERSTORM WATCH.

DISCUSSION...THUNDERSTORMS HAVE SHOWN SOME RECENT SIGNS OF
INTENSIFICATION IN A NORTHEAST-SOUTHWEST ORIENTED CORRIDOR ACROSS
FAR SOUTHERN LOWER MI AND THE CHICAGOLAND VICINITY. THESE STORMS ARE
FOCUSED ALONG SOUTHEASTWARD-SPREADING OUTFLOW...AS IT INTERCEPTS A
VERY MOIST/UNSTABLE BOUNDARY LAYER ACROSS NORTHERN IL/INDIANA INTO
SOUTHWEST LOWER MI. IN THIS CORRIDOR...70S F SURFACE DEWPOINTS AND
AMPLE INSOLATION ARE ALREADY CONTRIBUTING TO AS MUCH AS 3500-4000
J/KG OF MLCAPE. LARGE-SCALE INFLUENCES ARE WEAK ASIDE FROM THE
AFOREMENTIONED BOUNDARY...WHILE VERTICAL SHEAR IS ALSO LIMITED
/20-25 KT 0-6 KM CHICAGO WSR-88D VWP/. HOWEVER...ADDITIONAL
DESTABILIZATION AND STORM DEVELOPMENT/MERGERS MAY LEAD TO GRADUAL
UPSCALE GROWTH/ORGANIZATION...WITH SOME DEGREE OF FORWARD
ACCELERATION/PROPAGATION AS A SOUTHEASTWARD-MOVING CONVECTIVE LINE.
THIS IS A SCENARIO WELL-SUPPORTED BY LATEST HRRR RUNS AND THE 12Z
WRF-NSSL. STEEPENING LOW-LEVEL LAPSE RATES AND AMPLE
MOISTURE/BUOYANCY WILL BE SUPPORTIVE OF MICROBURST POTENTIAL WITH AT
LEAST LOCALLY DAMAGING WINDS POSSIBLE THROUGH EARLY EVENING.

..GUYER/MEAD.. 08/25/2014

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...IWX...GRR...IND...LOT...ILX...DVN...

LAT...LON   41458861 42148714 42388540 41028504 40448556 40308696
            40348834 41098918 41458861



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