OK & KS Under High Risk for Severe Weather Today
Posted by JAC on 5/24/2011, 5:44 am




DAY 1 CONVECTIVE OUTLOOK  
  NWS STORM PREDICTION CENTER NORMAN OK
  1259 AM CDT TUE MAY 24 2011
 
  VALID 241200Z - 251200Z
 
  ...THERE IS A HIGH RISK OF SVR TSTMS ACROSS PARTS OF SOUTH CENTRAL
  AND SOUTHEAST KANSAS SWD INTO PARTS OF CENTRAL AND EASTERN
  OKLAHOMA...
 
  ...THERE IS A MDT RISK OF SVR TSTMS ACROSS CENTRAL AND SOUTHEAST
  KANSAS...CENTRAL AND EASTERN OKLAHOMA...AND INTO WESTERN ARKANSAS...
 
  ...THERE IS A SLGT RISK OF SVR TSTMS FROM NEW ENGLAND SWD TO THE
  MID-ATLANTIC REGION...AND WWD INTO THE PLAINS...
 
  ...SYNOPSIS...
  WITH CYCLONIC FLOW ALOFT TO PERSIST ACROSS THE NORTHEAST U.S. AND
  ERN CANADA...A STRENGTHENING MID-LEVEL SYSTEM -- ACCOMPANIED BY
  70-PLUS KT MID-LEVEL JET -- IS FORECAST TO EMERGE INTO THE CENTRAL
  AND SRN PLAINS.  BY THE END OF THE PERIOD...A DEEPENING UPPER LOW IS
  FORECAST ACROSS THE KS VICINITY -- WITH A 75 KT MID-LEVEL JET AROUND
  THE SRN PERIPHERY OF THIS SYSTEM.
 
  AT THE SURFACE...A COLD FRONT WILL CONTINUE ADVANCING ACROSS ERN
  CANADA...MOVING EWD INTO NEW ENGLAND THROUGH THE AFTERNOON BUT
  BECOMING MORE WASHED OUT ACROSS THE MIDWEST/OH VALLEY WITH TIME.
  FARTHER W...A LEE LOW IS FORECAST TO MOVE VERY SLOWLY EWD/NEWD
  ACROSS KS/OK...BUT SHOULD STRENGTHEN THROUGH THE AFTERNOON AS THE
  UPPER LOW DEEPENS.  BY LATE AFTERNOON...A DRYLINE WILL EXTEND SWD
  ACROSS CENTRAL OK/CENTRAL TX AND A COMPOSITE WARM FRONT/OUTFLOW
  BOUNDARY SHOULD EXTEND SEWD ACROSS SRN KS/ERN OK AND INTO AR.  THIS
  SURFACE SYSTEM WILL BECOME A FOCUS FOR THE DEVELOPMENT OF A
  POTENTIALLY SIGNIFICANT SEVERE WEATHER OUTBREAK FOCUSED ON KS/OK/WRN
  AR THROUGH THE AFTERNOON AND EVENING HOURS.
 
  ...CENTRAL AND SRN PLAINS...
  A REGIONAL OUTBREAK OF SEVERE STORMS -- INCLUDING THE POTENTIAL FOR
  VERY LARGE HAIL...DAMAGING WINDS...AND SEVERAL LARGE/STRONG
  TORNADOES IS EXPECTED THIS AFTERNOON AND EVENING AS THE POWERFUL
  UPPER JET EMERGES INTO THE PLAINS DRIVING SURFACE CYCLOGENESIS.
 
  ELEVATED STORMS MAY BE ONGOING ACROSS PARTS OF NRN KS AND NEB AT THE
  START OF THE PERIOD...WHILE A CAPPED WARM SECTOR HINDERS STORM
  DEVELOPMENT INTO THE AFTERNOON HOURS.  BY MID AFTERNOON...SURFACE
  DEWPOINTS IN THE 60S TO NEAR 70 COMBINED WITH DAYTIME HEATING AND AN
  EWD SPREAD OF VERY STEEP MID-LEVEL LAPSE RATES ATOP THE WARM SECTOR
  WILL RESULT IN A VERY UNSTABLE ENVIRONMENT...WITH 100 MB MIXED-LAYER
  CAPE VALUES EXCEEDING 3000 TO 4000 J/KG ACROSS PARTS OF OK/KS AND
  INTO WRN AR E OF THE LOW/DRYLINE.  
 
  AS THE UPPER JET AND ASSOCIATED/DEEPENING UPPER SYSTEM EMERGE...A
  SLOWLY WEAKENING CAP SHOULD RESULT IN STORM INITIATION BY LATE
  AFTERNOON...FROM CENTRAL KS SWD INTO CENTRAL TX NEAR THE SURFACE LOW
  AND SWD ALONG THE DRYLINE.  WITH MODERATE/BACKED LOW-LEVEL FLOW
  AHEAD OF THE SURFACE LOW VEERING AND INCREASING RAPIDLY THROUGH THE
  LOWER TROPOSPHERE TO SWLY AT 50 TO 60 KT AT MID LEVELS...SHEAR VERY
  SUPPORTIVE OF BOTH MID-LEVEL AND LOW-LEVEL ROTATION WILL ALLOW
  STORMS TO RAPIDLY BECOME SUPERCELLULAR.  VERY LARGE HAIL...DAMAGING
  WINDS...AND SEVERAL POTENTIALLY SIGNIFICANT TORNADOES APPEAR LIKELY
  AS THE STORMS INCREASE AND SPREAD ACROSS KS/OK INTO WRN AR AND THEN
  LATER INTO WRN MO.  
 
  WHILE STORMS DEVELOPING SWD ACROSS CENTRAL TX ALONG THE DRYLINE
  SHOULD EVENTUALLY BEGIN DIMINISHING DURING THE EVENING AS BOUNDARY
  LAYER STABILIZATION/CAPPING BECOME REESTABLISHED...WIDESPREAD STORMS
  AND ASSOCIATED SEVERE POTENTIAL WILL CONTINUE INTO THE OVERNIGHT
  HOURS ACROSS KS/ERN OK/MO/AR.  SLIGHTLY ELEVATED STORMS SHOULD ALSO
  INCREASE INTO NEB/IA AND VICINITY...ALONG WITH SOME ACCOMPANYING
  SEVERE THREAT.  
 
  ...NEW ENGLAND SWD TO THE MID-ATLANTIC AND WWD INTO THE OH/TN/MID MS
  VALLEYS...
  SHOWERS AND SCATTERED THUNDERSTORMS MAY BE ONGOING AT THE START OF
  THE PERIOD...AND AS AIRMASS DESTABILIZES AHEAD OF THE SURFACE COLD
  FRONT AWAY FROM LINGERING CLOUDS/PRECIPITATION...EXPECT CONVECTION
  TO REDEVELOP/INTENSIFY THROUGH THE AFTERNOON.  
 
  THE BELT OF STRONGEST FLOW ALOFT IS FORECAST TO REMAIN S OF THE OH
  RIVER...BUT INSTABILITY MAY BE MORE LIMITED ACROSS PARTS OF THIS
  REGION DEPENDING UPON THE EVOLUTION OF AN ONGOING BOW APPROACHING
  THE MID MS VALLEY REGION ATTM.  OVERALL...EXPECT BROAD/WIDESPREAD
  ZONE OF SEVERE POTENTIAL NEAR AND SE OF THE COLD FRONT...WITH
  STRONGEST STORMS WITHIN MULTIPLE BANDS OF CONVECTION CAPABLE OF
  PRODUCING HAIL AND DAMAGING WINDS.
 
  ..GOSS.. 05/24/2011
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OK & KS Under High Risk for Severe Weather Today - JAC, 5/24/2011, 5:44 am
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