SPC AC 131950

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0250 PM CDT THU OCT 13 2016

   VALID 132000Z - 141200Z

   ...THERE IS A MRGL RISK OF SVR TSTMS ACROSS PORTIONS OF THE
   ARK-LA-TEX...

   ...SUMMARY...
   ISOLATED SEVERE WIND GUSTS AND LARGE HAIL REMAIN POSSIBLE IN THE
   ARK-LA-TEX REGION THIS AFTERNOON AND EARLY EVENING.

   ...20Z UPDATE...
   OTHER THAN THE REMOVAL OF GENERAL THUNDER CHANCES ACROSS PART OF THE
   SRN HIGH PLAINS BEHIND AN EWD MOVING SHORTWAVE TROUGH...NO CHANGES
   HAVE BEEN MADE TO THE OUTLOOK WITH THIS ISSUANCE. A MARGINALLY
   SEVERE STORM OR TWO REMAIN POSSIBLE ACROSS THE ARK-LA-TEX THIS
   AFTERNOON AND EARLY EVENING...WHERE SFC HEATING HAS ALLOWED AROUND
   1000-1500 J/KG OF MLCAPE TO DEVELOP TO THE S OF A COLD FRONT. MODEST
   MID-LEVEL WINDS GENERALLY 35 KT OR LESS...RESULTANT EFFECTIVE BULK
   SHEAR OF 25-35 KT...AND POOR MID-LEVEL LAPSE RATES SHOULD LIMIT THE
   STRENGTH AND LONGEVITY OF UPDRAFTS.

   ..GLEASON/BROYLES.. 10/13/2016

   .PREV DISCUSSION... /ISSUED 1107 AM CDT THU OCT 13 2016/

   ...SYNOPSIS...
   THE MID/UPPER SYNOPTIC PATTERN WILL BE DOMINATED BY A LOW-AMPLITUDE
   TROUGH TRAVERSING THE SOUTHERN PLAINS TODAY AND TONIGHT...AND A
   POWERFUL SYSTEM APPROACHING THE PACIFIC NORTHWEST/WEST COAST.  AN
   IMPRESSIVE 150-KT UPPER LEVEL JET ASSOCIATED WITH THE NORTHWEST
   SYSTEM WILL MIGRATE INTO OREGON TONIGHT.  AT THE SURFACE...A RIDGE
   WILL DOMINATE MOST OF THE CENTRAL AND EASTERN PORTIONS OF THE LOWER
   48.  A COLD FRONT WILL EXTEND FROM THE MID-ATLANTIC SOUTHWESTWARD TO
   THE ARK-LA-TEX...WHILE BECOMING STATIONARY ACROSS PORTIONS OF
   CENTRAL TEXAS.  THIS FRONT WILL AID IN DEVELOPMENT OF A FEW STORMS
   ACROSS THIS REGION.  MEANWHILE...ELEVATED CONVECTION IS EXPECTED
   ACROSS PORTIONS OF OKLAHOMA AND NORTH/WEST TEXAS TODAY...WITH MORE
   DEVELOPMENT EXPECTED PRIMARILY ACROSS TEXAS TONIGHT.

   ...PORTIONS OF THE ARK-LA-TEX INTO NORTH TEXAS...WEST TEXAS...AND
   SOUTHERN OKLAHOMA...
   LATER THIS AFTERNOON...THE COMBINATION OF THE ADVANCING MID-LEVEL
   WAVE...SURFACE HEATING...WEAK SURFACE CONVERGENCE ALONG THE
   FRONT...AND SURFACE DEWPOINTS AROUND 70F WILL FOSTER A FEW SURFACE
   BASED THUNDERSTORMS.  SUFFICIENT DEEP SHEAR WILL EXIST FOR PRIMARILY
   OUTFLOW-DOMINANT STORMS CAPABLE OF ISOLATED WIND GUSTS AND/OR HAIL. 
   MARGINAL/5 PERCENT PROBABILITIES HAVE BEEN ADDED TO THE OUTLOOK TO
   ADDRESS THIS THREAT.

   FARTHER WEST...ELEVATED CONVECTION IS ONGOING AT THE TIME ACROSS
   PORTIONS OF THE EASTERN TEXAS PANHANDLE AND FAR WESTERN OKLAHOMA. 
   WEAK MID-LEVEL INSTABILITY SUGGESTS THESE STORMS SHOULD REMAIN
   LARGELY SUB-SEVERE...WITH SMALL HAIL POSSIBLE IN LOCALIZED AREAS
   BENEATH THE HEAVIEST THUNDERSTORM CORES.  

   ...COASTAL AREAS OF THE PACIFIC NORTHWEST...
   WIDESPREAD STRONG SURFACE WINDS ARE EXPECTED AS A POWERFUL STORM
   SYSTEM APPROACHES THE REGION OVERNIGHT.  MODELS SUGGEST THAT SOME
   WEAK /200-400 J/KG/ INSTABILITY WILL DEVELOP PRIMARILY IN COASTAL
   AREAS...SUGGESTIVE OF A LOW THREAT FOR CONVECTIVELY ENHANCED WIND
   GUSTS.  THIS THREAT APPEARS TO BE TOO LOW FOR PROBABILITIES FOR THIS
   OUTLOOK...AS MOST OF THE HIGH WIND THREAT APPEARS TO BE RELATED TO
   AMBIENT/NON-CONVECTIVE WIND GUSTS ASSOCIATED WITH THE POWERFUL STORM
   SYSTEM.

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