Categorical Graphic
Probabilistic Tornado Graphic
Probabilistic Damaging Wind Graphic
Probabilistic Large Hail Graphic

   SPC AC 180612
   
   DAY 1 CONVECTIVE OUTLOOK CORR 1
   NWS STORM PREDICTION CENTER NORMAN OK
   0112 AM CDT TUE MAR 18 2008
   
   VALID 181200Z - 191200Z
   
   ...THERE IS A MDT RISK OF SVR TSTMS FROM ERN TX...SRN AR AND NRN
   THROUGH WRN LA...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM ERN TX INTO THE LOWER
   MS...TN AND SRN OH VALLEYS...
   
   CORRECTED FOR WORDING IN 1ST AND 3RD PARAGRAPHS
   
   ...SYNOPSIS...
   
   SPLIT FLOW PROGRESSIVE PATTERN WILL REMAIN THROUGH TUESDAY. NRN
   STREAM UPPER TROUGH WILL MOVE EWD THROUGH THE UPPER MS VALLEY AND
   INTO THE GREAT LAKES REGION...WHILE SRN STREAM CUTOFF LOW EJECTS
   NEWD THROUGH ERN TX AND THE LOWER MS VALLEY. SW-NE ORIENTED
   BAROCLINIC ZONE FROM SWRN TX NEWD INTO SRN MO AND THE OH VALLEY
   EARLY TUESDAY WILL SHIFT SLOWLY SEWD DURING THE DAY...WHILE FRONT
   ACCOMPANYING THE SRN STREAM UPPER LOW WILL ADVANCE THROUGH SERN
   TX...REACHING THE LOWER MS VALLEY TUESDAY NIGHT.
   
   
   ...ERN TX THROUGH THE LOWER MS VALLEY REGION...
   
   WIDESPREAD CONVECTION WILL LIKELY BE ONGOING AT THE START OF THE
   PERIOD FROM PARTS OF W CNTRL TX NEWD THROUGH OK AND THE MID MS
   VALLEY REGION. SOME HAIL WILL REMAIN POSSIBLE...MAINLY WITH ACTIVITY
   OVER TX WHERE STEEPER LAPSE RATES AND STRONGER INSTABILITY WILL
   EXIST. RICH LOW LEVEL MOISTURE RESIDES IN WARM SECTOR ACROSS ERN TX
   AND THE LOWER MS VALLEY WITH DEWPOINTS IN THE UPPER 60S TO AROUND
   70. AS THE BOUNDARY LAYER WARMS THE ATMOSPHERE WILL BECOME
   MODERATELY UNSTABLE. SLY MID LEVEL TRAJECTORIES 500 MB LEVEL THERMAL
   RIDGE DOWNSTREAM FROM UPPER TROUGH WILL RESULT IN ONLY MODEST
   700-500 MB LAPSE RATES. HOWEVER...WARMING OF THE BOUNDARY LAYER WILL
   CONTRIBUTE TO 1500 J/KG MLCAPE DURING THE DAY. STORMS ARE EXPECTED
   TO REDEVELOP ACROSS PARTS OF SERN AND ERN TX IN VICINITY OF EWD
   ADVANCING FRONT AND WITHIN DIVERGENT EXIT REGION OF UPPER JET.
   FORECAST VERTICAL WIND PROFILES SHOW STRONG LOW LEVEL SHEAR ALONG
   THE 50+ KT LOW LEVEL JET AXIS...BUT EXHIBIT A VEER-BACK PATTERN IN
   THE 850-700 MB LAYER. THIS PROFILE WILL LIKELY SUPPORT AN EVOLUTION
   TO MIXED STORM MODES INCLUDING LINES WITH EMBEDDED SUPERCELLS THAT
   WILL MOVE THROUGH ERN TX AND THE LOWER MS VALLEY REGION. DAMAGING
   WIND AND A FEW TORNADOES WILL BE POSSIBLE WITH GREATEST THREAT
   EXPECTED IN MODERATE RISK AREA. DESPITE WEAKENING
   INSTABILITY...STRONG LINEAR FORCING WILL LIKELY MAINTAIN LINES OF
   STORMS THROUGH THE LOWER MS VALLEY AND INTO A PORTION OF THE SERN
   STATES OVERNIGHT.
   
   
   
   ...MID MS AND TN VALLEY THROUGH SRN PARTS OF THE OH VALLEY...
   
   DESPITE AN AXIS OF LOWER 60S DEWPOINTS ADVECTING NEWD ALONG THE
   SW-NE BAROCLINIC ZONE...INSTABILITY WILL REMAIN WEAK IN THIS REGION
   OWING TO EXPECTED WIDESPREAD CLOUDS AND MODEST MID LEVEL LAPSE
   RATES. HOWEVER...POTENTIAL WILL EXIST FOR ORGANIZED STORM STRUCTURES
   ALONG THE SW-NE ORIENTED BOUNDARY WITHIN ZONE OF FORCING ASSOCIATED
   WITH NEWD MIGRATING LOW LEVEL JET AND SURFACE LOW. VERTICAL WIND
   PROFILES WILL SUPPORT ORGANIZED STORM STRUCTURES INCLUDING POTENTIAL
   FOR SUPERCELLS AND BOW ECHOES. ISOLATED DAMAGING WIND AND TORNADOES
   WILL BE POSSIBLE. THE THREAT APPEARS SOMEWHAT MORE MARGINAL TOWARD
   THE TN AND OH VALLEY WHERE INSTABILITY WILL BE MORE LIMITED.
   
   ..SELECT A FORECASTER.. 03/18/2008
   
   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z