MESO: Mesoscale Discussion 0617

ACUS11 KWNS 292052
SWOMCD
SPC MCD 292052
ILZ000-WIZ000-IAZ000-MNZ000-292215-

MESOSCALE DISCUSSION 0617
NWS STORM PREDICTION CENTER NORMAN OK
0352 PM CDT SUN APR 29 2007

AREAS AFFECTED...NERN IA...SRN WI...FAR NRN IL

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 292052Z - 292215Z

ISOLATED TO WIDELY SCATTERED HIGH-BASED TSTMS SHOULD CONTINUE TO
DEVELOP ALONG PRE-FRONTAL SURFACE TROUGH OVER THE NEXT FEW HOURS.
ALTHOUGH DEEP-LAYER SHEAR PROFILES ARE SUFFICIENT FOR ROTATING
UPDRAFTS...RELATIVELY WEAK FORCING AND LIMITED INSTABILITY WILL
LIKELY MITIGATE A MORE WIDESPREAD SEVERE WEATHER THREAT. THUS...A WW
APPEARS UNLIKELY ATTM...BUT TRENDS WILL CONTINUE TO BE MONITORED.

ISOLATED TSTMS HAVE RECENTLY DEVELOPED ALONG AN E-W ORIENTED SURFACE
TROUGH FROM AROUND 40 S RST TO 40 S LSE. TEMPERATURES WITHIN THIS
AXIS HAVE REACHED THE MIDDLE TO UPPER 80S WHILE ASOS REPORTED DEW
POINTS HAVE MIXED TO THE MIDDLE TO UPPER 40S. GIVEN THE NEARLY 40
DEGREE DEW POINT DEPRESSIONS...STEEP LOW-LEVEL LAPSE RATES MAY
CONTRIBUTE TO A DRY MICROBURST THREAT AS THE TSTMS MATURE SEWD.
STRONG 0-6 KM SHEAR OF 40 TO 45 KTS /AS SAMPLED BY THE LA CROSSE VAD
PROFILER/...WILL BE ADEQUATE FOR LARGE HAIL DEVELOPMENT AS WELL.
HOWEVER...THE STRONGEST FORCING WILL REMAIN WELL NORTHEAST OF THE
AREA IN ASSOCIATION WITH A MID-LEVEL SHORT WAVE TROUGH MOVING SEWD
NE OF LK SUPERIOR. IN ADDITION...CONVECTIVE COVERAGE SHOULD LARGELY
BE DRIVEN BY RELATIVELY WEAK CONVERGENCE ALONG THE SURFACE TROUGH
AND/OR COLD FRONT. TO THE S OF THE SURFACE TROUGH...LATEST OBJECTIVE
ANALYSIS INDICATES A CAPPING INVERSION REMAINS WITH LIMITED
INSTABILITY /MLCAPES AOB 500 J/KG/.

.GRAMS.. 04/29/2007

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

ATTN...WFO...LOT...MKX...DVN...ARX...DMX...

42088805 42179040 42429189 42679303 42939350 43429395
43469337 43489169 43669032 43708828 42918790

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