MESO: Mesoscale Discussion 1263

ACUS11 KWNS 211923
SWOMCD
SPC MCD 211923
INZ000-ILZ000-212100-

MESOSCALE DISCUSSION 1263
NWS STORM PREDICTION CENTER NORMAN OK
0223 PM CDT SUN JUN 21 2009

AREAS AFFECTED...CNTRL IL INTO SWRN IND

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 211923Z - 212100Z

THE THREAT FOR A FEW SEVERE STORMS CAPABLE OF HAIL...LOCALLY
DAMAGING WIND GUSTS AND PERHAPS A BRIEF TORNADO OR TWO WILL BE
POSSIBLE ACROSS DISCUSSION AREA THIS AFTERNOON INTO EVENING. WHILE
A WW IS NOT CURRENTLY ANTICIPATED...CONVECTIVE TRENDS WILL BE
MONITORED FOR MORE ORGANIZED TSTM DEVELOPMENT WHICH WOULD
POTENTIALLY WARRANT A WATCH.

A STORM EXHIBITING SOME SUPERCELL CHARACTERISTICS HAS RECENTLY
DEVELOPED OVER CNTRL IL /JUST E OF SPI/ INVOF A STATIONARY BOUNDARY
EXTENDING NW-SE FROM NEAR BRL THROUGH SPI TO NEAR EVV. WHILE
MIDLEVEL LAPSE RATES REMAIN QUITE WEAK OWING TO PROXIMITY TO RIDGE
AXIS...AMBIENT BOUNDARY LAYER IS HOT AND QUITE MOIST WHICH IS
SUPPORTING MLCAPE OF 1000-1500 J/KG. THE ABSENCE OF ANY APPRECIABLE
CAPPING COMBINED WITH THE INFLUENCE OF A WEAK MCV MOVING THROUGH THE
AREA MAY CONTRIBUTE TO ADDITIONAL TSTM DEVELOPMENT SEWD ALONG
BOUNDARY INTO THIS EVENING.

CURRENT ILX VWP INDICATES MODEST MIDLEVEL FLOW /AROUND 30 KT ABOVE 3
KM/ WHICH IS RESULTING IN MARGINALLY SUFFICIENT DEEP-LAYER SHEAR FOR
STORM ORGANIZATION/ROTATION. AS SUCH...SETUP IS FAVORABLE FOR AT
LEAST ISOLATED SEVERE STORMS CAPABLE OF MAINLY HAIL AND LOCALLY
STRONG WIND GUSTS. A BRIEF TORNADO OR TWO IS POSSIBLE WITH ANY
SUPERCELL STRUCTURES THAT CAN PROPAGATE SEWD ALONG SURFACE BOUNDARY
WHERE LOW-LEVEL SHEAR IS LOCALLY ENHANCED.

..MEAD.. 06/21/2009

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

ATTN...WFO...LMK...IND...PAH...LOT...ILX...LSX...

LAT...LON 39598994 40278981 40688909 40278771 39108598 38508597
38138659 38148720 39018900 39598994

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