MESO: Mesoscale Discussion 1681

ACUS11 KWNS 220009
SWOMCD
SPC MCD 220009
ILZ000-IAZ000-MOZ000-220145-

MESOSCALE DISCUSSION 1681
NWS STORM PREDICTION CENTER NORMAN OK
0709 PM CDT THU JUL 21 2011

AREAS AFFECTED...SRN IA...W-CNTRL IL...FAR NRN MO

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 220009Z - 220145Z

AN ISOLATED THREAT FOR STRONG STORMS WILL OCCUR THROUGH EARLY
EVENING. WHILE CONVECTIVE TRENDS WILL CONTINUE TO BE MONITORED...THE
ISOLATED NATURE OF ANY SVR THREAT WILL LIKELY PRECLUDE THE NEED FOR
A WW.

EARLY EVENING MESOANALYSIS AND VISIBLE SATELLITE IMAGES REVEAL A
NWD-MOVING WARM FRONT DRAPED ACROSS SRN IA INTO W-CNTRL IL. AREAS OF
PRECIPITATION ON THE COOL SIDE OF THIS BOUNDARY ACROSS CNTRL IA ARE
MAINTAINING ITS BAROCLINICITY. SUFFICIENT MOISTURE CONVERGENCE ALONG
THIS BOUNDARY...AIDED BY DIVERGENT FLOW SOUTH OF A 1012-MB MESOHIGH
CENTERED OVER N-CNTRL IA...HAS PROMPTED THE INITIATION OF STRONG
CONVECTION EARLIER OVER MONROE COUNTY IA...WITH ADDITIONAL ATTEMPTS
AT INITIATION FARTHER WEST INTO LUCAS COUNTY...AND ACROSS LOUISA
COUNTY IA. DESPITE MODEST MID-LEVEL LAPSE RATES EVIDENT IN THE 00Z
DAVENPORT IA SOUNDING...THE COMBINATION OF SFC TEMPERATURES IN THE
LOWER TO MIDDLE 90S AND DEWPOINTS IN THE LOWER/MIDDLE 70S IS
SUPPORTING MODERATE INSTABILITY NEAR AND SOUTH OF THE WARM FRONT.
THIS COULD SUPPORT VIGOROUS CONVECTION...AIDED BY 34 KT OF 0-6-KM
BULK SHEAR EVIDENT IN THE 00Z DAVENPORT SOUNDING. GIVEN THESE
PARAMETERS...LARGE HAIL AND DMGG WIND GUSTS COULD OCCUR IN
ASSOCIATION WITH GENERALLY MULTICELLULAR CONVECTION. HOWEVER...THE
LACK OF MID-LEVEL FORCING FOR ASCENT AND THE ABSENCE OF STRONG
LOW-LEVEL INFLOW SHOULD LIMIT THE COVERAGE OF ANY SVR THREAT TO
ISOLATED.

..COHEN.. 07/22/2011

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

ATTN...WFO...ILX...DVN...DMX...EAX...

LAT...LON 40529045 40319283 40509447 40999485 41419435 41689238
41559038 40928983 40529045

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