Amarillo, TX...Wichita Falls, TX...Altus, OK...Weatherford, OK...Memphis, TX...
Forecast Discussion
SPC AC 221728
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1228 PM CDT WED MAY 22 2013
VALID 231200Z - 241200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER NWRN TX AND WRN OK...
...SYNOPSIS...
UPPER LOW OVER THE UPPER MS VALLEY IS FORECAST TO MOVE EWD AND
WEAKEN TOMORROW AS IT SHEARS NEWD IMMEDIATELY IN ADVANCE OF A SHORT
WAVE TROUGH DIGGING SEWD ACROSS THE GREAT LAKES AND OHIO VALLEY. IN
THE WEST...AN UPPER LOW OVER THE PACIFIC NW IS EXPECTED TO REMAIN
ACROSS THE REGION WHILE AN UPPER RIDGE AMPLIFIES OVER THE PLAINS
STATES. AT THE SURFACE...A LOW IN THE ST. LAWRENCE VALLEY IS
EXPECTED TO LIFT SLOWLY NEWD...AS A TRAILING COLD FRONT MOVES SEWD
FROM THE LOWER GREAT LAKES/OH VALLEY/MID-SOUTH EARLY IN THE PERIOD
REACHING THE ATLANTIC COAST AND NRN GULF COAST BY 24/12Z. THE WRN
PORTION OF THE FRONT WILL EXTEND NWWD INTO NWRN TX AND THE ROCKIES.
...NWRN TX/WRN OK...
A FEW ELEVATED THUNDERSTORMS MAY BE ONGOING EARLY IN THE PERIOD OVER
PARTS OF OK TO THE NORTH OF THE AFOREMENTIONED FRONTAL BOUNDARY
EXTENDING ACROSS NWRN TX. ASSOCIATED CLOUDS/PRECIPITATION MAY DELAY
STRONGER DIABATIC HEATING TO THE NORTH OF THE FRONT RESULTING IN AN
ENHANCEMENT OF THE THERMAL GRADIENT ATTENDING THE FRONT DURING THE
AFTERNOON. WITH SURFACE DEW POINTS IN THE 60S ALONG AND NORTH OF
THE FRONT OVERLAID BY STEEP MID LEVEL LAPSE RATES ASSOCIATED WITH AN
ELEVATED MIXED LAYER...THE ENVIRONMENT IS LIKELY TO BECOME VERY
UNSTABLE WITH MLCAPE REACHING 3000-3500 J/KG. ALTHOUGH DYNAMIC
FORCING FOR LARGE SCALE ASCENT WILL BE MINIMAL WITHIN THE UPPER
RIDGE...LOW LEVEL CONVERGENCE/WARM ADVECTION ALONG AND NORTH OF THE
FRONT COUPLED WITH STRONG HEATING SHOULD WEAKEN THE CAP SUFFICIENTLY
FOR WIDELY SCATTERED STORMS TO DEVELOP DURING THE MID/LATE
AFTERNOON. DESPITE MODEST WINDS ALOFT /25 KT AT 500 MB/...STRONG
DIRECTIONAL SHEAR WITH HEIGHT WILL ENHANCE STORM ORGANIZATION WITH
POTENTIAL FOR A FEW SUPERCELLS TO DEVELOP. STRONGER CELLS WILL BE
CAPABLE OF PRODUCING VERY LARGE HAIL AND DAMAGING WIND GUSTS...WITH
THE LATTER THREAT INCREASING IF STORMS CAN GROW UPSCALE INTO A SMALL
MCS AND MOVE EWD/SEWD DURING THE EVENING. THERE WILL ALSO BE
POTENTIAL FOR A TORNADO OR TWO TO DEVELOP ESPECIALLY DURING THE
INITIAL PHASE OF SUPERCELL DEVELOPMENT. ACTIVITY IS EXPECTED TO
DIMINISH IN INTENSITY AFTER 03-06Z.
...NEW ENGLAND SWD INTO ERN NC...
MODEL GUIDANCE SUGGESTS THAT CLOUDS AND AREAS OF PRECIPITATION WILL
BE WIDESPREAD AHEAD OF THE COLD FRONT TOMORROW WHICH WILL LIMIT THE
MAGNITUDE OF DIABATIC HEATING AND DESTABILIZATION ACROSS MUCH OF THE
AREA...WITH MLCAPE GENERALLY AOB 1000 J/KG. THERE IS ANTICIPATION
THAT SOME BREAKS IN THE CLOUD COVER WILL PERMIT LOCALIZED REGIONS TO
UNDERGO GREATER DESTABILIZATION...BUT THESE AREAS ARE DIFFICULT TO
IDENTIFY ATTM. AS STRONGER SWLY WINDS ALOFT OVERSPREAD THE
PRE-FRONTAL ENVIRONMENT DURING THE DAY...THERE WILL BE POTENTIAL FOR
A FEW STRONGER STORMS TO DEVELOP. HOWEVER...OWING TO CONCERNS ABOUT
THE EFFECTS OF CLOUDS AND ONGOING CONVECTION ON AIR MASS
STABILITY...WILL MAINTAIN THE CURRENT 5% SEVERE PROBABILITY CORRIDOR
FROM ERN NC INTO NEW ENGLAND. IF IT BECOMES EVIDENT TOMORROW THAT
ZONES OF MORE PRONOUNCED DESTABILIZATION WILL OCCUR...PORTIONS OF
THE AREA MAY REQUIRE AN UPGRADE TO SLIGHT RISK.
..WEISS.. 05/22/2013
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NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0600Z