MESO: Mesoscale Discussion 1995

ACUS11 KWNS 172045
SWOMCD
SPC MCD 172044
ILZ000-WIZ000-IAZ000-MOZ000-172215-

MESOSCALE DISCUSSION 1995
NWS STORM PREDICTION CENTER NORMAN OK
0344 PM CDT WED AUG 17 2011

AREAS AFFECTED...CNTRL/NRN IL...FAR NERN MO...FAR ERN IA...FAR SRN
WI

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 172044Z - 172215Z

A FEW STORMS COULD PRODUCE DMGG WIND GUSTS AND/OR LARGE HAIL THIS
AFTERNOON INTO THE EVENING. HOWEVER...THE ANTICIPATED ISOLATED
NATURE OF THE SVR THREAT IS EXPECTED TO PRECLUDE THE NEED FOR A WW.

MID-AFTERNOON SFC MESOANALYSIS DEPICTS A COLD FRONT EXTENDING FROM
SWRN WI INTO CNTRL IA...ACROSS WHICH A MODEST THERMAL GRADIENT
EXISTS -- I.E. TEMPERATURES IN THE UPPER 70S AND LOWER 80S IN ITS
WAKE AND IN THE MID AND UPPER 80S PRECEDING IT. A PREFRONTAL WIND
SHIFT AXIS LIES NEAR THE IL/IA BORDER...SEPARATING NWLY FLOW TO ITS
WEST FROM FLOW WITH MORE OF A SLY COMPONENT TO ITS EAST. MODIFIED
12Z DAVENPORT RAOB FOR CURRENT CONDITIONS SUGGESTS MLCAPE VALUES ON
THE ORDER OF 1500-2000 J/KG INVOF THE WIND SHIFT AXIS...ALONG WHICH
WEAK SFC CONVERGENCE COULD SUPPORT THE DEVELOPMENT OF ISOLATED TO
SCATTERED CONVECTION DURING THE NEXT FEW HOURS. THE AFOREMENTIONED
BUOYANCY COMBINED WITH 30-45 KT OF EFFECTIVE BULK SHEAR BENEATH A
MID-LEVEL WNWLY/NWLY SPEED MAX OVER THE MID-MISSISSIPPI VALLEY
REGION...COULD SUPPORT A FEW SUSTAINED/ORGANIZED STORM STRUCTURES
WITH AN ATTENDANT THREAT FOR LARGE HAIL AND/OR DMGG WIND GUSTS.
HOWEVER...SFC OBS...ALONG WITH DAVENPORT/ST LOUIS/CHICAGO VWP
DATA...DEPICT WEAK LOW-LEVEL FLOW ACROSS THE REGION -- I.E. WIND
SPEEDS AOB 10 KT BELOW THE 1-KM-AGL-LEVEL -- OFFERING RATHER WEAK
CONVERGENCE ALONG THE AFOREMENTIONED SFC FEATURES. THIS SHOULD LIMIT
STORM COVERAGE TO SOME DEGREE. FURTHERMORE...THE SHALLOW/WEAK NATURE
OF THE CONVERGENCE AND RECENT INFLUX OF A MID-LEVEL DRY SLOT PER
WATER VAPOR IMAGERY SHOULD MITIGATE THE SVR POTENTIAL...WITH THE SVR
THREAT EXPECTED TO REMAIN ISOLATED.

..COHEN.. 08/17/2011

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

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

LAT...LON 41458760 40318817 39338952 39159068 39479139 40249180
40879154 42349026 42698873 42458779 41458760

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
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.