SPC AC 131616
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1116 AM CDT TUE MAY 13 2008
VALID 131630Z - 141200Z
...THERE IS A MDT RISK OF SVR TSTMS FROM N TX INTO CENTRAL/ERN OK
AND PARTS OF SE KS/WS MO AND WRN AR......
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE SRN PLAINS/OZARKS INTO
THE MID MS VALLEY......
...SYNOPTIC DISCUSSION...
UNSEASONABLY STRONG/COLD UPPER LOW DROPPING SEWD THRU AZ INTO SWRN
NM TONIGHT. NRN BRANCH TROUGH WILL BE HEADING E ACROSS THE PLAINS
AND UPPER MS VALLEY WITH A COLD FRONT CURRENTLY TRAILING SSWWD FROM
SURFACE LOW NRN MN TO CENTRAL KS/WRN OK THEN INTO SRN NM.
...SRN PLAINS INTO THE OZARKS...
VERY MOIST/UNSTABLE AIR MASS HAS RETURN RAPIDLY NWD OVERNIGHT FROM
TX TO LOWER MO VALLEY. ALREADY ELEVATED STORMS HAVE DEVELOPED FROM
CENTRAL TX TO MID MS VALLEY WITH POTENTIAL FOR LARGE HAIL GIVEN THE
STEEP MID LEVEL LAPSE RATES AND INCREASING LOW LEVEL MOISTURE.
PRIMARY THREAT WILL BE LARGE HAIL UNTIL LATER THIS AFTERNOON WHEN
HEATING AND LARGE SCALE ASCENT SHOULD ENABLE THE VERY UNSTABLE
BOUNDARY LAYER TO BECOME AVAILABLE FOR STORM UPDRAFTS.
WITH MLCAPES UPWARDS TO 3000 J/KG CENTRAL TX INTO SRN/ERN OK AHEAD
OF THE FRONT THE POTENTIAL FOR SURFACE BASED SEVERE STORMS WILL
INCREASE RAPIDLY THROUGH THE AFTERNOON. WITH 40-50KT OF SHEAR AND
THE STEEP MID LEVEL LAPSE RATES COUPLED WITH THE STRONG INSTABILITY
SUPERCELLS WILL BE LIKELY MOST ANYWHERE ACROSS THE MDT RISK AREA.
WITH THE STRONG UPPER SUPPORT WELL TO THE W AND LOW LEVEL SHEAR
GENERALLY 20KT OF LESS...PRIMARY THREAT WITH SUPERCELLS WILL BE VERY
LARGE HAIL AND DAMAGING WINDS. TORNADO THREAT IS MORE DIFFICULT TO
PIN DOWN GIVEN THE LIMITED LOW LEVEL SHEAR BUT IS POSSIBLE WITH ANY
SURFACE BASED SUPERCELL...PRIMARILY LATER THIS AFTERNOON/EVENING.
BY THIS EVENING SURFACE LOW DEVELOPS SWRN TX ALLOWING MOISTURE TO
WORK WWD TO N OF SURFACE FRONT ACROSS NWRN TX. HAVE EXTENDED THE
SLIGHT RISK A LITTLE FURTHER W THIS AREA AS STORMS SHOULD CONTINUE
REDEVELOPING OVERNIGHT ACROSS MUCH OF N/CENTRAL TX AS UPPER LOW AND
LARGE SCALE ASCENT APPROACH FROM SRN NM.
...MID MS VALLEY...
FURTHER N ACROSS MO INTO UPPER MS VALLEY AHEAD OF FRONT INSTABILITY
WILL BE WEAKER ALTHOUGH DEEP LAYER SHEAR ASSOCIATED WITH NRN BRANCH
TROUGH WILL SUPPORT MULTICELL STORMS. SUFFICIENT MLCAPES AND STEEP
MID LEVEL LAPSE RATES WILL SUPPORT A FEW SEVERE STORMS THIS
AFTERNOON AND EVENING AS AR N AS ERN IA/NRN IL.
..HALES/SCHNEIDER.. 05/13/2008
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z
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