SPC AC 010648

   DAY 2 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1248 AM CST THU JAN 01 2015

   VALID 021200Z - 031200Z

   ...THERE IS A MRGL RISK OF SVR TSTMS FROM SOUTHEAST TX EAST TO SRN
   MS/LA...

   ...SUMMARY...
   THUNDERSTORMS MAY AFFECT A BROAD SWATH FROM CENTRAL AND SOUTHERN
   TEXAS TO ALABAMA.  A FEW OF THESE MAY REACH SEVERE LEVELS FROM
   EXTREME SOUTHEAST TEXAS EAST ACROSS SOUTHERN SECTIONS OF LOUISIANA
   AND MISSISSIPPI.

   ...SYNOPSIS...
   A SPLIT-FLOW REGIME IN THE MID-UPPER LEVELS WILL REMAIN IN PLACE
   FRIDAY AND FRIDAY NIGHT. A SRN-BRANCH TROUGH/CLOSED UPPER LOW
   INITIALLY NEAR THE FOUR-CORNERS REGION WILL LIFT NE AND WEAKEN
   FRIDAY NIGHT AS A STRONG /140 KTS AT 250 MB/ SPEED MAX DIVES
   SOUTHEAST ACROSS THE PACIFIC NORTHWEST. DIFFERENCES PERSIST
   REGARDING THE LOCATION/MOVEMENT OF THE UPPER TROUGH AND LARGE-SCALE
   FORCING FOR ASCENT...ESPECIALLY DURING THE 00Z-12Z TIME FRAME
   SATURDAY. THE LATEST ECMWF REMAINS SLOWER/STRONGER AND MAINTAINS A
   CLOSED UPPER LOW THROUGH 03/12Z WHILE THE 00Z NAM IS FASTER AND WITH
   AN OPEN UPPER TROUGH LIFTING ACROSS THE SOUTHERN/CENTRAL PLAINS LATE
   IN THE DAY 2 PERIOD. THE 00Z GFS SOLUTION REMAINS IN BETWEEN THESE
   SCENARIOS. 

   AN EAST-WEST SFC FRONT FROM NEAR THE LA COAST EAST ACROSS NORTHERN
   FL FRIDAY MORNING WILL LIFT NORTHWARD AS A WARM FRONT ACROSS
   SOUTHERN LA/MS BY 12Z SAT. A WEAK SFC LOW DEVELOPING OVER THE WRN
   GULF WILL MOVE TO NEAR THE LA/TX BORDER BY 12Z SATURDAY WITH A COLD
   FRONT EXTENDING SWD INTO THE WRN GULF. AFOREMENTIONED DIFFERENCES IN
   THE EVOLUTION OF UPPER LEVEL FEATURES LEADS TO DIFFERENCES IN THE
   NWD MOVEMENT OF THE SFC LOW/WARM FRONT AND DEGREE OF SFC-BASED
   DESTABILIZATION IN THE 00Z-12Z SAT TIME FRAME. 

   ...WRN/CENTRAL GULF REGION AND LOWER MS VALLEY...
   MOIST/THERMAL ADVECTION NORTH OF THE EAST-WEST FRONTAL BOUNDARY AND
   RESULTANT MODEST ELEVATED INSTABILITY MAY RESULT IN A FEW TSTMS
   DURING THE DAY FROM THE ARKLATEX REGION EAST ACROSS THE LOWER MS
   VALLEY. SMALL HAIL WILL BE POSSIBLE WITH THE STRONGEST STORMS...BUT
   OVERALL SVR THREAT SHOULD REMAIN LOW GIVEN MUCAPE AOB 300 J/KG AND
   EFFECTIVE BULK SHEAR GENERALLY BELOW 30 KTS.

   PRIMARY CONCERN REMAINS DURING THE LATTER HALF OF THE PERIOD AS THE
   WARM FRONT LIFTS NWD ACROSS PORTIONS OF LA/MS AND THE SFC LOW MOVES
   INLAND ALONG THE TX/LA BORDER WITH A TRAILING COLD FRONT INTO THE
   WRN GULF. STRENGTHENING LOW-LEVEL WIND FIELDS WILL ALLOW LOWER 60S
   SFC DEW POINTS TO LIFT NORTHWARD IN CONCERT WITH THE WARM FRONT.
   NORTHWARD EXTENT OF WARM FRONTAL MOVEMENT MAY BE LIMITED BY
   EXTENSIVE PRECIPITATION NORTH OF THE FRONT...BUT GUIDANCE SUGGESTS
   SFC-BASED INSTABILITY OF BETWEEN 750 AND 1000 J/KG WILL EXIST ACROSS
   SRN PORTIONS OF LA/MS BY 12Z SAT. DEEP-LAYER SHEAR WILL BE
   SUPPORTIVE OF SUPERCELLS WITH ANY WARM SECTOR STORM THAT DEVELOPS.
   CURVED LOW-LEVEL HODOGRAPHS WILL BE SUFFICIENT FOR A
   TORNADO/DAMAGING WIND THREAT. ADDITIONALLY...TSTMS SHOULD EXPAND IN
   COVERAGE ALONG THE EWD-MOVING COLD FRONT ACROSS SOUTHEAST TX WITH A
   RISK OF STRONG WINDS. PRIMARY UNCERTAINTY REMAINS WITH THE EXTENT OF
   TSTM DEVELOPMENT PRIOR TO 12Z SAT AS THE STRONGEST HEIGHT FALLS
   REMAIN NORTH/WEST OF THE WRN/CENTRAL GULF COAST. THE GREATER SVR
   THREAT WILL LIKELY EXIST INTO THE DAY 3 TIME FRAME...AND THUS WILL
   MAINTAIN CATEGORICAL MARGINAL RISK WITH THIS OUTLOOK.

   ..BUNTING.. 01/01/2015

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   NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z