SWODY1
SPC AC 142000
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0300 PM CDT FRI MAR 14 2008
VALID 142000Z - 151200Z
..THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE SRN
PLAINS...OZARK PLATEAU AND TN VALLEY...
..SRN PLAINS...
WATER VAPOR IMAGERY CURRENTLY SHOWS A SHORTWAVE TROUGH OVER THE SRN
ROCKIES AND THIS FEATURE WILL MOVE INTO THE SRN PLAINS LATE THIS
AFTERNOON. AT THE SFC...A 998 MB LOW IS LOCATED ACROSS THE TX
PANHANDLE WITH SOUTH TO SELY FLOW IN PLACE ACROSS MUCH OF THE ERN
PORTION OF THE SRN PLAINS. AN EAST TO WEST THERMAL GRADIENT EXISTS
ON SFC ANALYSIS ACROSS SRN KS WITH A SFC TROUGH LOCATED FROM THE SFC
LOW NEWD INTO SCNTRL KS. AS LARGE-SCALE ASCENT INCREASES DUE TO THE
APPROACH OF THE SHORTWAVE TROUGH LATE THIS AFTERNOON...CONVECTION
APPEARS LIKELY TO INITIATE NEAR THE WRN EDGE OF THE SLIGHT RISK
AREA. THIS IS CONFIRMED BY THE RUC MODEL WHICH DEVELOPS A CONVECTIVE
CLUSTER IN SRN KS BY EARLY EVENING. SHORT-TERM MODEL FORECASTS AGREE
WITH THIS SCENARIO AND EXPAND CONVECTION SEWD ACROSS NE OK INTO AR
BY LATE THIS EVENING.
CONCERNING THE SEVERE POTENTIAL...MODERATE TO STRONG VERTICAL SHEAR
IS ALREADY IN PLACE ACROSS THE SRN PLAINS DUE TO A BROAD AXIS OF
STRONGER MID-LEVEL FLOW. THIS WILL SUPPORT SUPERCELL DEVELOPMENT AS
STORMS INITIATE IN SRN KS AND MOVE SEWD ACROSS NE OK THIS EVENING.
STEEP MID-LEVEL LAPSE RATES ALONG THIS CORRIDOR CURRENTLY EXCEED 7.5
C/KM ACCORDING TO RUC ANALYSIS AND THIS SHOULD BE FAVORABLE FOR
LARGE HAIL. SUPERCELLS MAY ALSO HAVE AN ISOLATED TORNADO/WIND DAMAGE
THREAT THIS EVENING. SFC DEWPOINTS IN SRN KS AND NRN OK ARE ONLY
AROUND 40 F BUT LOW-LEVEL MOISTURE WILL GRADUALLY RETURN NWD INTO
THE REGION. THE RELATIVELY DRY BOUNDARY LAYER MAKES THE SEVERE
WEATHER THREAT COVERAGE ACROSS THE SRN PLAINS MORE UNCERTAIN ATTM.
..OZARK PLATEAU/TN VALLEY...
A SFC LOW IS FORECAST TO MOVE EWD ACROSS THE SRN PLAINS AS A
LOW-AMPLITUDE SHORTWAVE TROUGH APPROACHES THE REGION TONIGHT. MODEL
FORECASTS ORGANIZE A WARM FRONT FROM SE OK EXTENDING EWD ACROSS SRN
AR INTO NCNTRL MS DEVELOPING CONVECTION ALONG AND NORTH OF THE
BOUNDARY AROUND MIDNIGHT. IT APPEARS THAT SEVERAL MCS/S MAY ORGANIZE
AND MOVE EWD ACROSS AR...MS..WRN TN AND NRN AL BY LATE IN THE
PERIOD.
CONCERNING THE SEVERE POTENTIAL...MODERATE TO STRONG VERTICAL SHEAR
IS ALREADY IN PLACE ACROSS THE REGION AND VERTICAL SHEAR SHOULD
CONTINUE TO INCREASE AS THE EXIT REGION OF A 75 TO 85 KT MID-LEVEL
JET APPROACHES FROM THE WEST. THIS SHOULD SUPPORT SUPERCELL
DEVELOPMENT AS STORMS INITIATE LATE THIS EVENING WITH THE MOST
LIKELY AREA ALONG AND JUST TO THE NORTH OF A WARM FRONT IN SRN AR
AND NCNTRL MS. LOW-LEVEL SHEAR WILL RAPIDLY STRENGTHEN LATE THIS
EVENING ACROSS SRN AR AND NW MS AS A LOW-LEVEL JET STRENGTHENS.
SUPERCELLS THAT TRACK EWD ALONG AND JUST NORTH OF THE WARM FRONT MAY
PRODUCE A FEW TORNADOES. IN ADDITION...STEEP MID-LEVEL LAPSE RATES
ARE ALREADY IN PLACE AND 500 MB TEMPS ARE BELOW -20C ACROSS CNTRL
AND NRN AR SUGGESTING THERMODYNAMICS ARE FAVORABLE FOR LARGE HAIL.
THE STRONG LOW-LEVEL FLOW WILL ALSO SUPPORT A THREAT FOR WIND DAMAGE
AND THE GREATEST POTENTIAL SHOULD BE ASSOCIATED WITH BOWING LINE
SEGMENTS OVERNIGHT.
.BROYLES.. 03/14/2008
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