Monday, May 21, 2007

MESO: Mesoscale Discussion 0847

ACUS11 KWNS 211822
SWOMCD
SPC MCD 211822
NDZ000-211945-

MESOSCALE DISCUSSION 0847
NWS STORM PREDICTION CENTER NORMAN OK
0122 PM CDT MON MAY 21 2007

AREAS AFFECTED...CNTRL/WRN ND

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 211822Z - 211945Z

TSTMS WILL LIKELY DEVELOP BY MID-AFTN ACROSS PORTIONS OF WRN ND WITH
RISKS FOR LARGE HAIL...DAMAGING WINDS AND ISOLD TORNADOES.

EARLY AFTN VSBL SATL SHOWS AN INCREASING SFC-BASED CU FIELD ACROSS
SWRN ND...JUST AHEAD OF A COLD FRONT/SFC LOW. 17Z BIS SOUNDING
EXHIBITED A CAPPING INVERSION...BUT WITH CONTINUED WARMING AND
INCREASING AFTN HEIGHT FALLS...LARGE SCALE WILL BECOME FAVORABLE FOR
TSTM DEVELOPMENT.

TSTMS SHOULD INITIATE BETWEEN 20-22Z OVER AREAS BETWEEN KBIS-KDIK IN
A ZONE OF INCREASING MASS CONVERGENCE. VERTICAL SHEAR WAS SOMEWHAT
WEAK OVER THE WARM SECTOR CURRENTLY...BUT SOME INCREASE IS EXPECTED
LATER THIS AFTN AS UPSTREAM TROUGH EDGES EWD. THIS COMBINED WITH THE
STEEP LAPSE RATES ALOFT WILL ENCOURAGE STRONG UPDRAFT GROWTH.

ORIENTATION OF THE FLOW PARALLEL TO THE BOUNDARY SUGGESTS THAT
ACTIVITY MAY GROW INTO LINEAR MULTICELLULAR BANDS WITH WEAK EMBEDDED
SUPERCELL STRUCTURES POSSIBLE. LARGE HAIL WILL BE THE PRIMARY
RISK...BUT POTENTIAL FOR DAMAGING WINDS WILL ALSO EXIST AS ACTIVITY
GAINS STRONGER COLD POOLS BY LATE AFTN/EARLY EVE. BOUNDARY
INTERACTIONS AND BACKING NEAR SFC FLOW AHEAD OF THE SFC LOW MAY
BOOST ISOLD TORNADO RISKS AS WELL.

.RACY.. 05/21/2007

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

ATTN...WFO...FGF...BIS...

46100354 48960209 48979903 46089946

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