MESO: Mesoscale Discussion 2038

ACUS11 KWNS 272233
SWOMCD
SPC MCD 272232
INZ000-ILZ000-WIZ000-IAZ000-280000-

MESOSCALE DISCUSSION 2038
NWS STORM PREDICTION CENTER NORMAN OK
0532 PM CDT SUN SEP 27 2009

AREAS AFFECTED...SRN WI...EXTREME ERN IA...NRN AND CNTRL IL AND NWRN
IND

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 272232Z - 280000Z

THUNDERSTORMS ARE EXPECTED TO INCREASE IN COVERAGE AND INTENSITY
NEXT FEW HOURS ACROSS SRN WI...BUT WITH SWD DEVELOPMENT INTO ERN IA
AND NRN IL POSSIBLE. BOTH SUPERCELLS AND LINE SEGMENTS ARE LIKELY
WITH DAMAGING WIND AND LARGE HAIL THE MAIN THREATS...BUT AN ISOLATED
TORNADO OR TWO CANNOT BE RULED OUT. A WW WILL LIKELY BE NEEDED
BEFORE 00Z.

A PRE-FRONTAL BOUNDARY EXTENDS FROM SWRN WI SWWD THROUGH ERN IA NWRN
MO INTO ERN KS WITH A COLD FRONT A LITTLE FARTHER UPSTREAM FROM NWRN
WI SWWD THROUGH E CNTRL IA INTO NERN KS. LATEST OBJECTIVE ANALYSIS
INDICATES A NARROW AXIS OF MARGINAL INSTABILITY WITH 500 J/KG MLCAPE
FROM NRN MO NEWD THROUGH ERN IA INTO WI WHERE PLUME OF STEEP MID
LEVEL LAPSE RATES HAVE OVERSPREAD THE THETA-E AXIS WITH DEWPOINTS
GENERALLY IN THE MID 50S. SOME FURTHER DESTABILIZATION IS
POSSIBLE...ESPECIALLY ACROSS PARTS OF IL THIS EVENING AS THE
STRENGTHENING LOW LEVEL JET ADVECTS SLIGHTLY RICHER MOISTURE NWD.
STORMS ARE ALREADY DEVELOPING ALONG PRE-FRONTAL BOUNDARY OVER SRN WI
WITHIN ZONE OF INCREASING ASCENT WITHIN EXIT REGION OF ESEWD MOVING
UPPER JET. ADDITIONAL STORMS WILL LIKELY DEVELOP SWD WITH TIME AS
THE COLD FRONT ACCOMPANIED BY DEEP ASCENT CONTINUES ESEWD INTO IL.
SWLY BULK SHEAR INCREASING TO 45+ KT WILL SUPPORT ORGANIZED STORMS
INCLUDING BOTH LINE SEGMENTS AND SUPERCELLS WITH LARGE HAIL AND
DAMAGING WIND THE PRIMARY THREATS. HODOGRAPH SIZE WILL INCREASE
SUBSTANTIALLY THIS EVENING...SUPPORTING A CONDITIONAL THREAT OF
ISOLATED TORNADOES...PARTICULARLY IF STORMS CAN DEVELOP FARTHER SWD
INTO NRN AND CNTRL IL. PRIMARY LIMITING FACTOR FOR A MORE ROBUST
TORNADO THREAT IS LIMITED LOW LEVEL MOISTURE AND TENDENCY FOR THE
BOUNDARY LAYER TO DECOUPLE AFTER SUNSET.

..DIAL.. 09/27/2009

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

ATTN...WFO...LOT...ILX...MKX...LSX...DVN...ARX...

LAT...LON 43218809 41138716 39908835 39999081 41259169 43369019
43218809

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
To unsubscribe from WX-STORM send e-mail to LISTSERV@LISTSERV.ILLINOIS.EDU with
"unsub wx-storm" in the body of your message. For more information write cnovy@cox.net.