SWODY1
SPC AC 191239
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0739 AM CDT SAT MAR 19 2011
VALID 191300Z - 201200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE TX AND OK PANHANDLES
ACROSS SRN KS AND NRN OK...
...SYNOPSIS...
WATER VAPOR IMAGERY SHOWS THE UPPER LOW OFF THE PACIFIC NW COAST
REDEVELOPING SLIGHTLY WWD AS A NEW VORTICITY CENTER ROTATES SWD NEAR
45N/133W. A STRONG SHORT WAVE TROUGH HAS MOVED INLAND ACROSS
NRN/CENTRAL CA...AND THIS FEATURE IS FORECAST TO LOSE AMPLITUDE AS
IT MOVES NEWD INTO THE DOWNSTREAM UPPER RIDGE BEFORE REACHING THE
NRN ROCKIES TONIGHT.
A WEAK SHORT WAVE TROUGH IS EVIDENT IN WATER VAPOR IMAGERY EXTENDING
FROM ERN AZ SEWD INTO NRN MEX. THIS TROUGH IS FORECAST TO MOVE NEWD
ACROSS NM AND SWRN TX THIS AFTERNOON AND THE SRN HIGH PLAINS
TONIGHT.
AT THE SURFACE...A COLD FRONT EXTENDS FROM NERN NC ACROSS NRN AL AND
SRN AR INTO SWRN TX. THE WRN PART OF THE FRONT WILL GRADUALLY
RETURN NWD AS A WARM FRONT AS SOUTHERLY SURFACE WINDS DEVELOP OVER
THE PLAINS IN RESPONSE TO INCREASING PRESSURE FALLS OVER THE
NRN/CENTRAL HIGH PLAINS. AS THIS OCCURS...A DRY LINE WILL DEVELOP
NEAR THE TX/NM BORDER.
...TX PANHANDLE ENEWD INTO THE OZARKS AND ERN KS...
ELEVATED THUNDERSTORMS ARE CONTINUING NORTH OF THE SURFACE FRONT
OVER THE TX PANHANDLE AND WRN OK...AND OVER NERN OK/SERN KS AND
EXTREME SWRN MO. THESE STORMS ARE SUPPORTED BY LOW LEVEL WARM
ADVECTION/ISENTROPIC ASCENT ASSOCIATED WITH A BROAD LOW LEVEL JET
OVER THE SRN PLAINS. THE WRN CLUSTER OF STORMS IS IN ADVANCE OF THE
SHORT WAVE TROUGH MOVING NEWD INTO NM/NRN MEXICO...AND THIS MAY BE
ENHANCING LARGE SCALE ASCENT OVER NM AND PARTS OF WRN TX.
REGIONAL SOUNDINGS INDICATE STEEP MID LEVEL LAPSE RATES ABOVE AN
INVERSION BASED IN THE 800-700 MB LAYER...COINCIDENT WITH THE NRN
EDGE OF MOISTURE EVIDENT IN THE BLENDED TPW DATA THAT HAS BEEN
SPREADING NWD TOWARD THE CENTRAL PLAINS. THIS IS RESULTING IN
MUCAPE OF 1000-2000 J/KG INDICATING POTENTIAL FOR STRONGER UPDRAFTS
TO DEVELOP. VEERING WIND PROFILES THROUGH THE LOWER HALF OF THE
STORM LAYER ARE ALSO CONTRIBUTING TO EFFECTIVE SHEAR OF 30-35 KT
WHICH IS SUFFICIENT TO ENHANCE STORM ORGANIZATION WITH POTENTIAL FOR
A FEW STRONGER CELLS TO EXHIBIT MARGINAL SUPERCELL CHARACTERISTICS.
THE PRIMARY SEVERE THREAT FROM THE ELEVATED STORMS WILL BE
HAIL...ALTHOUGH LOCALIZED STRONG WINDS GUSTS MAY BE POSSIBLE THIS
AFTERNOON IF STORMS ALONG THE SRN EDGE OF THE CONVECTIVE CLUSTERS
ARE ABLE TO BECOME NEAR SURFACE-BASED AS THE WARM FRONT LIFTS NWD.
ADDITIONAL ELEVATED STORMS ARE EXPECTED TO DEVELOP TONIGHT OVER
PARTS OF THE LOWER MO VALLEY IN THE WAKE OF THE INITIAL CONVECTIVE
ACTIVITY AS THE LOW LEVEL JET INTENSIFIES FROM THE CENTRAL
PLAINS/LOWER MO VALLEY INTO THE UPPER MS VALLEY. ISOLATED STRONGER
STORMS MAY PRODUCE MAINLY SMALL HAIL.
...EXTREME EAST CENTRAL/SERN NM AND WRN TX...
A DRY LINE IS FORECAST TO DEVELOP NEAR THE NM/TX BORDER AS THE WARM
FRONT LIFTS NWD AND DRY AIR OVER SOUTH CENTRAL NM GRADUALLY MIXES
EWD TODAY. STRONG DIURNAL HEATING COUPLED WITH EXISTING STEEP MID
LEVEL LAPSE RATES WILL DESTABILIZE THE ENVIRONMENT WITH MLCAPE
AROUND 1000-1500 J/KG THIS AFTERNOON AND EVENING. MESOSCALE FORCING
FOR ASCENT APPEARS TO BE LIMITED...WITH UPSTREAM NM/NRN MEXICO SHORT
WAVE TROUGH POSSIBLY PROVIDING WEAK UPWARD MOTION OVER THE AREA.
THIS IS CONSISTENT WITH MODEL GUIDANCE WHICH INDICATE ISOLATED
STORMS MAY DEVELOP LATER THIS AFTERNOON INTO THE EVENING. WINDS ARE
EXPECTED TO GRADUALLY VEER AND INCREASE WITH HEIGHT INDICATING A
THREAT FOR SUPERCELLS WITH ANY SUSTAINED UPDRAFTS THAT FORM...WITH
STRONGER CELLS CAPABLE OF PRODUCING HAIL AND STRONG WIND GUSTS.
..WEISS/GRAMS.. 03/19/2011
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