SPC MD 688

MD 0688 CONCERNING TORNADO WATCH 232…234… FOR NRN MO/SRN AND SERN IA AND WRN/NRN IL


MESOSCALE DISCUSSION 0688
NWS STORM PREDICTION CENTER NORMAN OK
1118 PM CDT THU MAY 03 2012

AREAS AFFECTED...NRN MO/SRN AND SERN IA AND WRN/NRN IL

CONCERNING...TORNADO WATCH 232...234...

VALID 040418Z - 040445Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 232...234...CONTINUES.

SUMMARY...ONGOING TSTM CLUSTER LOCATED OVER SERN IA INTO NWRN IL
WILL CONTINUE TO MOVE ESE DURING THE LATE EVENING/EARLY OVERNIGHT
PERIOD WITH A NEW WW POSSIBLE BY 05Z AS WW 232 AND WW 233 ARE
SCHEDULED TO EXPIRE AT THAT TIME.  IN ADDITION TO A THREAT FOR SVR
STORMS WITH THIS COMPLEX...HEAVY RAIN RATES OF 1-2+ INCH PER HOUR
WILL PERSIST AS STORMS TRAIN ESE WITHIN A 35 MILE WIDE CORRIDOR
EXTENDING FROM LOUISA COUNTY IA TO LA SALLE COUNTY IL.

TSTMS HAVE CONTINUED TO INCREASE IN COVERAGE AND INTENSITY ACROSS
NWRN MO INTO FAR NERN KS.  A TORNADO THREAT AND POTENTIAL FOR LARGE
HAIL AND DAMAGING WINDS ARE POSSIBLE WITH THIS ACTIVITY.

DISCUSSION...LATE EVENING SURFACE ANALYSIS SHOWED A ZONE OF LOW
LEVEL CONVERGENCE EXTENDING FROM NEAR CHICAGO SWWD INTO WEST CENTRAL
IL AND THEN WWD THROUGH FAR NRN MO.  OBJECTIVE ANALYSES INDICATED
EFFECTIVE SRH OF 100-200 M2/S2 INVOF THE CONVERGENCE ZONE WHERE A
SSWLY 30-40 KT LLJ WAS OBSERVED PER WIND PROFILERS AND WSR-88D VWP
DATA.  THIS SUGGESTS THE TORNADO THREAT REMAINS NONZERO WITH THE
GREATEST TORNADO THREAT POTENTIAL ATTENDANT TO THE DISCRETE STORMS
IN NWRN MO/FAR NERN KS...THOUGH THE TORNADO THREAT CANNOT BE RULED
OUT WITH THE ACTIVITY ALONG THE SRN EXTENT OF THE SERN IA/NWRN IL
TSTM COMPLEX.

IN ADDITION...RECENT RADAR IMAGERY OVER NWRN IL INDICATED A N-S LINE
OF TSTMS DEVELOPING FROM HENRY COUNTY TO MERCER COUNTY...WHICH MAY
BE THE BEGINNING OF A DAMAGING WIND THREAT AS THIS LINE ADVANCES
EWD.  GIVEN A SSWLY LLJ WILL CONTINUE TO FEED MODERATE INSTABILITY
INTO THE SWRN-SRN EXTENT OF THIS TSTM COMPLEX MAINTAINING NEW
DEVELOPMENT...A NEW WW WILL LIKELY BE COORDINATED SOON FOR PARTS OF
NRN/CENTRAL IL.

..PETERS.. 05/04/2012

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

ATTN...WFO...LOT...ILX...LSX...DVN...DMX...EAX...OAX...TOP...

LAT...LON   40599574 40659487 41499514 41559157 41879131 41809025
            41618978 41558918 40928900 40368801 39878929 39489069
            39159132 39299261 39309328 39199418 39459442 39559511
            39699532 40599574

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