Significant Severe Weather for OKC area this evening and thru DFW area overnight
Posted by JAC on 5/19/2010, 6:37 am





DAY 1 CONVECTIVE OUTLOOK CORR 1
  NWS STORM PREDICTION CENTER NORMAN OK
  0106 AM CDT WED MAY 19 2010
 
  VALID 191200Z - 201200Z
 
  ...THERE IS A MDT RISK OF SVR TSTMS ACROSS MUCH OF OKLAHOMA AND
  ADJACENT PARTS OF NORTH TEXAS AND WESTERN ARKANSAS...
 
  ...THERE IS A SLGT RISK OF SVR TSTMS FROM SOUTHWEST KANSAS TO
  NORTHERN TEXAS...PARTS OF SOUTHWEST ARKANSAS AND NORTHERN
  LOUISIANA...
 
  ADDED APPROXIMATE INITIATION TIME IN 4TH PARAGRAPH.
 
  ...SYNOPSIS...
  A POTENTIALLY SIGNIFICANT SEVERE WEATHER OUTBREAK APPEARS
  INCREASINGLY LIKELY ACROSS PARTS OF OKLAHOMA...SOUTHERN KANSAS...AND
  NORTHERN TEXAS LATER TODAY. STRONG TO SEVERE STORMS WILL ALSO BE
  POSSIBLE SOUTH AND EAST FROM THESE AREAS...FROM ARKANSAS TO
  LOUISIANA.
 
  ...SRN PLAINS INTO ARKLATEX...
  A LARGE DEEP-LAYER CYCLONE WILL EVOLVE ACROSS CO/WY EARLY TODAY AND
  THEN DRIFT EAST ACROSS THE CENTRAL PLAINS STATES THROUGH TONIGHT.
  WIDESPREAD THUNDERSTORMS WERE ALREADY OCCURRING AHEAD OF THIS
  DEVELOPING LOW AS WARM ADVECTION AND LARGE SCALE ASCENT ACT ON A
  MOIST AND MODERATELY UNSTABLE AIR MASS FROM TX TO KS. PRECIPITATION
  AND RESIDUAL CLOUDINESS FROM THE STORMS NOW DEVELOPING ACROSS NRN OK
  AND KS WILL ACT TO ESTABLISH A NW-SE ORIENTED WARM FRONT ACROSS OK
  LATER THIS MORNING.
 
  AS THE UPPER LOW EMERGES OVER WRN KS LATER THIS AFTERNOON... TRIPLE
  POINT SURFACE LOW IS FORECAST TO STRENGTHEN INVOF OK PANHANDLE AS
  DRYLINE SHARPENS AND SPREADS EAST FROM ERN TX PANHANDLE. BELT OF
  40-50KT WLY CYCLONIC MID LEVEL FLOW ATOP SLY/SELY LOW LEVEL FLOW
  ACROSS THE WARM SECTOR WILL CONTRIBUTE TO STRONG EFFECTIVE SHEAR AOA
  40KT. DIURNAL HEATING AND GRADUAL MOISTENING OF THE BOUNDARY LAYER
  SHOULD RESULT IN AN INCREASINGLY UNSTABLE WARM SECTOR WITH WEAKLY
  CAPPED MLCAPE OF 1500-2000 J PER KG BY AFTERNOON.
 
  GIVEN WEAK INHIBITION AND PERSISTENT MODEST FORCING FOR ASCENT
  EXPECT WARM SECTOR STORM INITIATION BY 21Z. DISCRETE SUPERCELLS
  SHOULD EVOLVE QUICKLY AHEAD OF THE DRY LINE IN WRN OK...WITH
  ADDITIONAL STORMS POSSIBLE NEAR/ALONG RESIDUAL OUTFLOWS AND NEAR
  SURFACE WARM FRONT...FROM NRN/CNTRL OK TO NRN TX/AR/LA. EFFECTIVE
  HELICITY IN THE RANGE OF 200-300 M2/S2...AND RELATIVELY HIGH
  BOUNDARY LAYER RH/LOW LFC ACROSS CNTRL OK...SHOULD RESULT IN AN
  ENHANCED STRONG TORNADO POTENTIAL ACROSS THIS AREA FROM LATE
  AFTERNOON INTO EARLY EVENING.
 
  UNLIKE MAY 10...WEAKER FLOW REGIME RESULTS IN SLOWER STORM/BUNKERS
  CELL MOTION OF ENE AROUND 25 KT...AS OPPOSED TO ENE AT 50KT.
  FURTHERMORE...INSTABILITY APPEARS A BIT WEAKER. NONETHELESS...A
  POTENTIALLY VOLATILE STRONG TORNADO SITUATION MAY EVOLVE ACROSS
  PORTIONS OF CNTRL OK DURING THE AFTERNOON...POSSIBLY MOVING TOWARD
  ERN OK INTO THE EVENING. THIS IS A RELATIVELY LIMITED GEOGRAPHIC
  AREA OF GREATER TORNADO POTENTIAL. COMBINED WITH THE POSSIBILITY
  THAT FORECAST CERTAINTY CAN INCREASE WITH THE LIGHT OF DAY...GREATER
  TORNADO PROBABILITIES...AND AN UPGRADE TO HIGH RISK...MAY OCCUR IN
  SUBSEQUENT OUTLOOKS.
 
  IN ADDITION TO THE TORNADO POTENTIAL...VERY LARGE HAIL AND LOCALLY
  DAMAGING DOWNBURST/OUTFLOW WINDS WILL ACCOMPANY STORM DEVELOPMENT
  ACROSS A LARGER AREA FROM SRN KS EXTENDING INTO TX...AR AND LA FROM
  AFTERNOON THROUGH THE EVENING.
 
  AS CONVECTION CONGEALS OVER ERN OK THROUGH THE EVENING...LIFT AND
  SUSTAINED INSTABILITY ACROSS THE WARM FRONT...AND UPSCALE EVOLUTION
  IN STRONGLY SHEARED FLOW...WILL CONTRIBUTE TO FORWARD PROPAGATING
  MCS/SQUALL LINE WITH DAMAGING WINDS SPREADING SEWD TOWARD AR AND THE
  ARKLATEX THROUGH THURSDAY MORNING.
 
  ...ERN NC...
  GREATER LOW LEVEL MOISTURE ALONG A RESIDUAL FRONTAL SEGMENT ACROSS
  SERN NC...COUPLED WITH DIURNAL HEATING...SHOULD CONTRIBUTE TO
  MODERATE INSTABILITY LATER TODAY. STRENGTHENING MID LEVEL WLY FLOW
  AROUND 40KT AND DPVA ASSOCIATED WITH PASSAGE OF SHORT WAVE TROUGH TO
  THE NORTH MAY BE SUFFICIENT FOR A FEW VIGOROUS STORMS ACROSS THE
  IMMEDIATE COASTAL ZONE. A COUPLE HAIL/WIND EVENTS APPEAR POSSIBLE
  WITH THIS ACTIVITY.
 
  ..CARBIN.. 05/19/2010
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Significant Severe Weather for OKC area this evening and thru DFW area overnight - JAC, 5/19/2010, 6:37 am
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