MESOSCALE DISCUSSION 0231
NWS STORM PREDICTION CENTER NORMAN OK
0135 AM CST THU MAR 13 2003
AREAS AFFECTED...SRN IL...WRN KY...WRN TN...NRN AR
CONCERNING...SEVERE THUNDERSTORM POTENTIAL
VALID 130735Z - 130930Z
NEW WWS ARE NOT CURRENTLY ANTICIPATED.
MID/UPPER TROUGH AXIS CONTINUES TO SHIFT EASTWARD THROUGH THE
MIDDLE MISSISSIPPI VALLEY ACCOMPANIED BY WEAK COLD FRONT. IN
LOW-LEVEL WARM ADVECTION ZONE AHEAD OF FRONT...VIGOROUS
CONVECTIVE SYSTEM IS ONGOING FROM PARTS OF CENTRAL/SOUTHERN
ILLINOIS INTO NORTHWEST ARKANSAS/SOUTHWEST MISSOURI. ACTIVITY IS
NOW MOSTLY ROOTED ABOVE RELATIVELY COOL/STABLE BOUNDARY
LAYER...WHICH APPEARS LIKELY TO INHIBIT STRONG DOWNDRAFTS. GUSTY
WINDS TO 30 KTS OR SO...ASSOCIATED WITH DOWNWARD MOMENTUM
TRANSFER...MAY ACCOMPANY STRONGEST CELLS NEXT FEW HOURS...BUT
LARGE HAIL SHOULD REMAIN PRIMARY SEVERE THREAT THROUGH THE
REMAINDER OF THE NIGHT...AND EVEN THIS IS EXPECTED TO BECOME
RATHER ISOLATED/SPORADIC.
MUCH OF ACTIVITY ACROSS CENTRAL/SOUTHERN ILLINOIS IS EXPECTED TO
WEAKEN IN PROGRESSIVELY MORE STABLE ENVIRONMENT ACROSS THE LOWER
OHIO VALLEY. STEEPER MID-LEVEL LAPSE RATES ARE PRESENT ON
NORTHERN PERIPHERY OF ERODING LOW-LEVEL THERMAL RIDGE ACROSS
WESTERN ARKANSAS ...AND THIS MAY HELP MAINTAIN STRONGER
CONVECTION WHICH WILL APPROACH THE MEMPHIS TN/LITTLE ROCK AR
AREAS TOWARD 12Z.
..KERR.. 03/13/2003
ATTN...WFO...PAH...MEG...LSX...LZK...SGF...
35889314 36379197 37369020 38318941 38368864 37398823
36438814 35098950 34849111 34759304
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