MESOSCALE DISCUSSION 1491
NWS STORM PREDICTION CENTER NORMAN OK
0342 PM CDT WED JUL 08 2009
AREAS AFFECTED...IL...IN
CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY
VALID 082042Z - 082215Z
TSTMS APPEAR TO BE INCREASING IN COVERAGE AND ORGANIZATION ALONG A
QUASI-STATIONARY SURFACE FRONTAL ZONE SITUATED FROM WRN IL SEWD TO
THE OH RIVER/SWRN IND. LIFT ACROSS THIS BOUNDARY IS LIKELY TO BE
MAINTAINED/ENHANCED AS A WEAK MCV/SHORT WAVE TROUGH AND ASSOCIATED
SFC REFLECTION RIPPLE SEWD ALONG THE FRONTAL ZONE THROUGH THE
EVENING. MID LEVEL WIND SHIFT ASSOCIATED WITH THE MCV WAS INDICATED
IN THE WNC WIND PROFILER OVER THE PAST HOUR AND THIS FEATURE MAY
CONTRIBUTE TO A CORRIDOR OF RELATIVELY STRONGER EFFECTIVE SHEAR
ALONG THE BOUNDARY.
GIVEN THE WARM AND VERY MOIST AIRMASS /MLCAPE TO AROUND 1000 J PER
KG/ FUELING THE DEVELOPING CONVECTION...A FEW CELLS MAY BRIEFLY
ATTAIN GREATER ORGANIZATION AND POSE A THREAT FOR STRONG DOWNDRAFTS
AND/OR HAIL. HOWEVER...LIMITED DYNAMIC FORCING AND MARGINAL SHEAR ON
THE ORDER OF 25-30KT WOULD SUGGEST THAT ACTIVITY WILL BE PRIMARILY
MULTICELLULAR IN NATURE AND PROBABLY WEAKEN AS DAYTIME
HEATING/DESTABILIZATION WEAKENS TOWARD EVENING.
..CARBIN.. 07/08/2009
