Severe Storm Outlook Narrative (AC)
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000
ACUS11 KWNS 261434
SWOMCD
SPC MCD 261434
INZ000-ILZ000-WIZ000-261630-

MESOSCALE DISCUSSION 1620
NWS STORM PREDICTION CENTER NORMAN OK
0934 AM CDT TUE AUG 26 2014

AREAS AFFECTED...PORTIONS OF NRN IL...NWRN INDIANA...SERN WI

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 261434Z - 261630Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...THUNDERSTORMS CROSSING THE REGION THIS MORNING COULD
PRODUCE ISOLATED MARGINALLY SVR WIND/HAIL. WHILE CONVECTIVE TRENDS
WILL CONTINUE TO BE MONITORED...WW ISSUANCE IS CURRENTLY UNLIKELY.

DISCUSSION...THE REMNANTS OF NOCTURNAL CONVECTION THAT EVOLVED FROM
ERN NEB TO IA HAVE CROSSED THE MS RIVER...PRESENTLY REACHING A LINE
FROM ROCKFORD TO MOLINE. CAPPI DATA AT 9 KM INDICATE SUSTENANCE OF
ONGOING MULTICELL CLUSTERS...WHICH ARE APPROACHING A SFC BOUNDARY
DRAPED FROM THE CHICAGO AREA INTO W-CNTRL IL. THE 12Z ILX RAOB AND
SFC OBSERVATIONS SUGGEST RICH BOUNDARY-LAYER MOISTURE IN PROXIMITY
TO AND ON THE WARM SIDE OF THIS BOUNDARY -- E.G. LOWEST-100-MB MEAN
MIXING RATIO AROUND 16 G/KG. DIURNAL HEATING OF THIS MOISTURE WILL
BOOST BUOYANCY...WITH MLCAPE LIKELY REACHING 1500-2500 J/KG DURING
THE NEXT FEW HOURS.

ONGOING MULTICELL CLUSTERS WILL APPROACH/CROSS THE BOUNDARY --
INCLUDING THE CHICAGO AREA IN THE 1545-1700Z TIME FRAME -- AND A
RISK FOR INTENSE UPDRAFTS/DOWNDRAFTS WILL EXIST. LOT AND MKX VWPS
SAMPLE 25-30 KT WLYS IN THE 1-4-KM LAYER...WHICH WILL BOLSTER
CONVECTIVE MOMENTUM TRANSPORT TO POTENTIALLY YIELD ISOLATED DMGG
WIND GUSTS. ISOLATED MARGINALLY SVR HAIL CANNOT BE RULED OUT.
HOWEVER...ONLY MODEST MID-LEVEL FLOW/DEEP SHEAR YIELD UNCERTAINTY IN
A MORE ORGANIZED...SUSTAINED SVR RISK. NEVERTHELESS...CONVECTIVE
TRENDS WILL CONTINUE TO BE MONITORED.

..COHEN/MEAD.. 08/26/2014

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

ATTN...WFO...LOT...MKX...DVN...

LAT...LON   42718878 42768753 41468694 40878805 41458932 42718878



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