Dallas could be under the gun Thursday morning
Posted by JAC on 10/28/2009, 9:55 am





DAY 2 CONVECTIVE OUTLOOK  
  NWS STORM PREDICTION CENTER NORMAN OK
  1232 AM CDT WED OCT 28 2009
 
  VALID 291200Z - 301200Z
 
  ...THERE IS A SLGT RISK OF SVR TSTMS FROM TX/LA...NWD TO SRN MO...
 
  ...TX/LA...NWD TO SRN MO...
 
  NRN PIECE OF BIFURCATING UPPER TROUGH WILL EJECT ACROSS CO INTO THE
  NRN RED RIVER REGION OF NWRN MN BY THE END OF THE PERIOD WHILE A
  SLOWER OPEN SHORTWAVE BEGINS TO SHIFT EWD ACROSS NM INTO FAR WEST
  TX.  A VERY STRONG JET CORE WILL DEVELOP ON FORWARD SIDE OF LONGWAVE
  AND EXTEND FROM THE TX SOUTH PLAINS...NEWD INTO THE UPPER MS
  VALLEY...DISPLACED A FEW HUNDRED MILES TO THE COOL SIDE OF FRONTAL
  ZONE.  EVEN SO...STRONG MID LEVEL FLOW WILL OVERSPREAD ADVANCING
  COLD FRONT SUCH THAT ANY STORMS THAT MANAGE TO ROOT INTO MOISTENING
  WARM SECTOR BOUNDARY LAYER WILL HAVE A PROPENSITY TO ROTATE.  MODELS
  CONTINUE TO SUGGEST MARITIME AIRMASS WILL INDEED RETURN ACROSS TX
  LATE DAY1 INTO EARLY DAY2 WITH MID 60S SFC DEW POINTS EXPECTED AS
  FAR NORTH AS CNTRL OK AHEAD OF COLD FRONT.  MOISTURE PLUME WILL
  GRADUALLY EXPAND AND SPREAD NWD ACROSS THE LOWER MS VALLEY AND
  IMMEDIATE GULF COAST BY THE END OF THE PERIOD WITH 70+ DEW POINTS
  LIKELY INTO SRN AR/MS.  ALTHOUGH PRIMARY FORCING WILL SPREAD
  INITIALLY TO THE NORTH OF THE CURRENT DAY2 OUTLOOK...IT APPEARS A
  SQUALL LINE SHOULD DEVELOP ALONG FRONTAL ZONE AS IT INTERACTS WITH
  INCREASINGLY MOIST...BUT ONLY MODESTLY UNSTABLE...ENVIRONMENT ACROSS
  OK/TX.  A CONSIDERABLE AMOUNT OF CONVECTION MAY ALSO TRAIL THE
  LEADING WIND SHIFT AS FRONTAL ASCENT MAY BE REQUIRED FOR CONVECTIVE
  INITIATION/MAINTENANCE OF LIKELY LINEAR MCS.  IT/S NOT ENTIRELY
  CLEAR HOW MUCH PRE-FRONTAL ACTIVITY WILL DEVELOP WITHIN STRONGLY
  SHEARED AND MOIST WARM SECTOR.  CURRENT THINKING IS THE MOST LIKELY
  STORM MODE WILL BE A SQUALL LINE WITH EMBEDDED BOW-TYPE STRUCTURES
  AND POSSIBLE SUPERCELLS.  FORECAST SOUNDINGS EVEN AT 29/12Z ARE
  QUITE IMPRESSIVE...SHEAR WISE...ACROSS PARTS OF NCNTRL TX INTO
  SCNTRL OK...THOUGH INSTABILITY IS A BIT MEAGER.  DAMAGING WINDS
  APPEAR TO BE THE GREATEST RISK WITH THIS CONVECTIVE EVENT...ALONG
  WITH ISOLATED TORNADOES...ESPECIALLY IF DISCRETE SUPERCELLS CAN
  DEVELOP AHEAD OF MCS.  ACTIVITY SHOULD PROGRESS ACROSS OK/TX INTO
  THE LOWER/MID MS VALLEY DURING THE AFTERNOON/EVENING HOURS WITH
  FRONTAL ZONE/MCS EXPECTED TO EXTEND FROM THE MOUTH OF THE SABINE
  RIVER IN SERN TX/SWRN LA INTO WRN TN BY THE END OF THE PERIOD.
 
  ..DARROW.. 10/28/2009
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Possible Severe System for MS-Valley/Midwest around the Weekend - JAC, 10/26/2009, 3:53 pm
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