Feb 10, 2009 1300 UTC Day 1 Convective Outlook
Updated: Tue Feb 10 12:46:12 UTC 2009
Probabilistic to Categorical Outlook Conversion Table (Effective Feb 14, 2006).
Public Severe Weather Outlook

The SPC is forecasting ...severe weather outbreak expected over the arklatex later this afternoon and tonight....   Please read the latest public statement about this event.

Categorical Graphic
20090210 1300 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20090210 1300 UTC Day 1 Tornado Probabilities Graphic
Torndao Legend Image
Probabilistic Damaging Wind Graphic
20090210 1300 UTC Day 1 Damaging Wind Probabilities Graphic
Wind Legend Image
Probabilistic Large Hail Graphic
20090210 1300 UTC Day 1 Large Hail Probabilities Graphic
Hail Legend Image
   SPC AC 101242
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0642 AM CST TUE FEB 10 2009
   
   VALID 101300Z - 111200Z
   
   ...THERE IS A MDT RISK OF SVR TSTMS THIS AFTERNOON INTO TONIGHT FOR
   NE TX...SE OK...WRN AND CENTRAL AR...AND NW LA...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK AREA
   FROM CENTRAL AND ERN TX/OK/KS EWD TO THE MS RIVER...
   
   ...A SIGNIFICANT SEVERE WEATHER OUTBREAK -- INCLUDING SUPERCELLS
   WITH STRONG TORNADOES -- IS EXPECTED THIS AFTERNOON INTO TONIGHT FOR
   ERN OK/NE TX...INTO WRN/CENTRAL AR AND NW LA...
   
   ...ERN OK/ARKLATEX REGION THIS AFTERNOON THROUGH TONIGHT...
   AN INTENSE MID LEVEL SHORTWAVE TROUGH OVER AZ THIS MORNING WILL
   EJECT EWD ACROSS NM INTO W TX BY THIS EVENING...AND THEN PROGRESS
   ENEWD OVER TX/OK OVERNIGHT AND DEVELOP A NEGATIVE TILT.  THE SHORT
   RANGE MODELS ARE IN GOOD AGREEMENT WITH THIS SYNOPTIC EVOLUTION...
   INCLUDING INITIAL LEE CYCLOGENESIS TODAY INVOF OF EKA AND THE
   FORMATION OF A DRYLINE FROM CENTRAL TX NWD INTO OK...FOLLOWED BY AN
   ENEWD ACCELERATION OF THE SURFACE LOW INTO MO OVERNIGHT.  AN EWD
   SURGING PACIFIC COLD FRONT ACCOMPANYING THE MID LEVEL WAVE AND
   OVERTAKE THE DRYLINE NEAR I-35 JUST AFTER 00Z...AND THEN ACCELERATE
   EWD ACROSS LA/AR TO NEAR THE MS RIVER AT THE END OF THE PERIOD.  
   
   BOUNDARY LAYER DEWPOINTS IN THE LOW-MID 60S CONTINUE TO SPREAD NWD
   ACROSS E TX/LA TOWARD AR AND ERN OK.  THIS MOISTURE RETURN WILL
   INCLUDE WIDESPREAD LOW CLOUDS INTO AT LEAST EARLY AFTERNOON ACROSS
   THE ARKLATEX.  GREATER SURFACE HEATING IS EXPECTED FARTHER W NEAR
   I-35 FROM CENTRAL TX INTO SRN/CENTRAL OK...AFTER A BAND OF THICK
   MID-HIGH CLOUDS /ASSOCIATED WITH AN EJECTING SPEED MAX OVER THE TX
   BIG BEND/ MOVES E OF THE DEVELOPING DRYLINE BY ABOUT 18Z.  MODIFIED
   OBSERVED SOUNDINGS AND MODEL FORECAST SOUNDINGS ALL AGREE ON THE
   POTENTIAL FOR MLCAPE TO REACH ROUGHLY 1500 J/KG ALONG THE DRYLINE
   THIS AFTERNOON ACROSS CENTRAL/N TX...WITH VALUES DECREASING TO THE
   500-1000 J/KG RANGE FARTHER E/NE AS A RESULT OF LINGERING CLOUDS AND
   COOLER SURFACE TEMPERATURES.
   
   SOME CONVECTION IS EXPECTED BY MIDDAY-EARLY AFTERNOON OVER SE OK/NE
   TX IN CONJUNCTION WITH THE LEAD EJECTING SPEED MAX AND LOW-LEVEL
   WAA...BUT THE MAJORITY OF ANY SUCH CONVECTION WILL LIKELY MOVE E OF
   NE TX/SE OK BY MID-LATE AFTERNOON.  THE GREATER RISK FOR
   SURFACE-BASED STORM INITIATION WILL BE FARTHER W ALONG THE DRYLINE
   CLOSE TO I-35.  HERE...THE N-S BOUNDARY WILL LIKELY REMAIN
   QUASI-STATIONARY THROUGH THE AFTERNOON AS THE SURFACE CYCLONE FORMS
   WELL TO THE NW...THUS ALLOWING THE INITIAL STORMS TO MOVE OFF THE
   DRYLINE AND NEWD INTO THE WARM SECTOR.  MEANWHILE...VERTICAL SHEAR
   IS FORECAST TO STRENGTHEN THROUGH LATE AFTERNOON INTO EARLY TONIGHT
   ACROSS NE TX/SE OK AS THE LLJ INTENSIFIES...WHERE 0-1 KM SRH AND 0-6
   KM BULK SHEAR WILL EXCEED 300 M2/S2 AND 60 KT...RESPECTIVELY.  THE
   COMBINATION OF INSTABILITY AND VERTICAL SHEAR WILL FAVOR DISCRETE
   SUPERCELLS WITH THE INITIAL DEVELOPMENT...WHILE THE STRONG LOW-LEVEL
   SHEAR AND MOIST LOW LEVELS WILL SUPPORT THE POSSIBILITY OF A FEW
   LONG-TRACK SUPERCELLS WITH STRONG TORNADOES LATE THIS AFTERNOON INTO
   EARLY TONIGHT ACROSS THE MDT RISK AREA.  THE MAGNITUDE AND SPATIAL
   EXTENT OF THE UNSTABLE WARM SECTOR APPEARS TO BE THE PRIMARY
   POTENTIAL LIMITING FACTOR WITH RESPECT TO STORM INTENSITY AND
   CONVECTIVE MODE...THOUGH OBSERVATIONAL TRENDS COULD STILL
   NECESSITATE A HIGH RISK UPGRADE FOR A PORTION OF THE NE TX/SE OK/WRN
   AR AREA IN THE 1630Z OR 20Z OUTLOOK UPDATES.
   
   OVERNIGHT...SQUALL LINE DEVELOPMENT APPEARS LIKELY AS THE COLD FRONT
   OVERTAKES THE DRYLINE AND THE MID LEVEL WAVE EJECTS ENEWD OVER TX. 
   THIS SQUALL LINE WILL THEN RACE EWD FROM TX/OK INTO AR/LA...REACHING
   THE MS RIVER NEAR THE END OF THE PERIOD.  LOW-LEVEL SHEAR WILL
   REMAIN QUITE STRONG IN ADVANCE OF THE LINE...AND A FEW TORNADOES MAY
   OCCUR WITH EMBEDDED CIRCULATIONS.  HOWEVER...DAMAGING WINDS SHOULD
   BE THE MOST COMMON THREAT OVERNIGHT SINCE THE CONVECTION WILL BE
   STRONGLY FORCED AND INSTABILITY WILL BE WEAKER OVERNIGHT IN AR/LA
   COMPARED TO TX/OK DURING THE AFTERNOON/EVENING. 
   
   ...NRN OK/SRN KS THIS AFTERNOON/EVENING...
   SLOW MOVEMENT OF THE INITIAL LEE CYCLONE INVOF SW KS/OK PANHANDLE
   WILL ALLOW BOUNDARY LAYER DEWPOINTS IN THE 50S TO SPREAD FARTHER NW
   INTO OK/KS THAN PREVIOUSLY EXPECTED.  FORECAST SOUNDINGS JUST E OF
   THE TRIPLE POINT IN NW OK/KS ARE SUPPORTIVE OF SOME SUPERCELL
   THREAT...INCLUDING A COUPLE OF TORNADOES AND LARGE HAIL THIS
   EVENING.
   
   ..THOMPSON.. 02/10/2009
   
   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z