SPC AC 210041
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0641 PM CST SAT NOV 20 2004
   
   VALID 210100Z - 211200Z
   
   THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 45 S
   VCT 25 N NIR 55 ESE AUS 25 NW HOU 25 S BPT.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 15 SSE P07 15 NW FST
   45 E ROW 25 SE AMA 15 W LBL DDC P28 25 W OKC ADM PRX 10 SW ELD GWO
   BHM ATL 40 ENE MCN AYS VLD 30 SE TLH.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 80 NNW SVC 55 WNW SAD
   GBN 50 NW GBN 10 SE IGM 35 SW BCE 25 SSW CNY 30 SW MTJ 35 E DRO 35
   ENE 4SL 15 S SAF 40 WNW ONM 80 NNW SVC.
   
   ...THERE IS A SLGT RISK OF SVR TSTMS THIS EVENING ALONG THE
   MID/UPPER TEXAS COAST....
   
   STRONG MID/UPPER JET...DIGGING AROUND NORTHEASTERN PACIFIC RIDGE
   INTO BROAD WESTERN/CENTRAL U.S. TROUGH...WILL CONTINUE SOUTHWARD
   FROM THE LEE OF THE CASCADES THROUGH THE VICINITY OF THE SIERRA
   NEVADA TONIGHT.  AS THIS OCCURS...CLOSED LOW...NOW EVOLVING OVER THE
   GREAT BASIN...WILL GRADUALLY DEVELOP SOUTH/SOUTHWESTWARD THROUGH THE
   REMAINDER OF THE FORECAST PERIOD.  MEANWHILE..AS SIGNIFICANT
   NORTHERN BRANCH SHORT WAVE PROGRESSES SLOWLY EASTWARD ACROSS THE
   UPPER MISSISSIPPI VALLEY/UPPER GREAT LAKES REGION...WEST
   SOUTHWESTERLY MID/UPPER FLOW REGIME WILL CONTINUE TO STRENGTHEN IN
   BROAD SWATH ACROSS THE SOUTHEASTERN TWO-THIRDS OF THE NATION.
   
   ....SOUTHERN PLAINS/GULF COASTAL AREAS...
   WHILE LOW-LEVEL FRONTAL ZONE ASSOCIATED WITH LEAD UPPER SYSTEM
   ADVANCES SOUTHEASTWARD THROUGH THE OHIO VALLEY...FRONT WILL STALL
   ACROSS THE RED RIVER VALLEY AND TEXAS SOUTH PLAINS.  PRIOR COOL
   SURGE WILL CONTINUE TO WEAKEN OVER THE SOUTHEAST STATES...WITH AIR
   MASS CONTINUING TO MOISTEN/WARM OVER THE MUCH OF THE GULF OF MEXICO
   AND GULF COASTAL AREAS.  EVAPORATIVE COOLING OF CONVECTIVE
   PRECIPITATION IN DRY BOUNDARY LAYER HAS SLOWED INLAND PROGRESSION OF
   COASTAL FRONT ACROSS SOUTH CENTRAL TEXAS/THE UPPER TEXAS AND
   LOUISIANA COASTS AND THE FLORIDA PANHANDLE.  HOWEVER...WEAK SURFACE
   BASED DESTABILIZATION IS EXPECTED OVERNIGHT FARTHER INLAND ACROSS
   THE CENTRAL GULF COAST STATES...IN ASSOCIATION WITH CONTINUED WEAK
   SOUTHERLY LOW-LEVEL FLOW.  THIS WILL OCCUR AS DE-AMPLIFYING IMPULSE
   EMBEDDED WITHIN WEST SOUTHWESTERLY UPPER FLOW REGIME PROGRESSES OUT
   OF TEXAS.
   
   UPPER FEATURE APPEARS TO BE PROVIDING FORCING FOR ONGOING CONVECTIVE
   DEVELOPMENT FROM WESTERN OKLAHOMA INTO EASTERN/SOUTHEAST TEXAS. 
   WHILE SOME MARGINALLY SEVERE HAIL WILL REMAIN POSSIBLE INTO THE
   EVENING ACROSS PARTS OF WESTERN OKLAHOMA AND NORTHWEST/NORTH CENTRAL
   TEXAS...NORTH OF CYCLONIC UPPER JET AXIS...PRIMARY SEVERE THREAT
   SHOULD REMAIN FOCUSED ON COASTAL FRONT NEAR THE MID/UPPER TEXAS
   COAST.
   
   DESPITE WEAK MID-LEVEL LAPSE RATES BENEATH SUBTROPICAL MOIST
   PLUME...BOUNDARY LAYER DEW POINTS AROUND 70F ALONG TEXAS COASTAL
   AREAS ARE CONTRIBUTING TO MIXED LAYER CAPE TO 2000 J/KG.  THIS IS
   SUPPORTING VIGOROUS UPDRAFTS IN FAVORABLY SHEARED ENVIRONMENT FOR
   SUPERCELLS...AND ONGOING ACTIVITY NORTH OF VICTORIA WILL PERSIST AT
   LEAST ANOTHER FEW HOURS...SPREADING ALONG FRONT INTO AREAS
   NEAR/SOUTH OF HOUSTON LATER THIS EVENING.  WITH SOUTHERLY LOW-LEVEL
   JET ONLY ON THE ORDER OF 25 KT...LOW-LEVEL SHEAR PROFILES ARE
   SOMEWHAT MARGINAL...BUT STILL MAY BE SUFFICIENT FOR AN ISOLATED
   TORNADO OR DAMAGING WIND GUST.
   
   LOW-LEVEL JET IS NOT PROGGED TO STRENGTHEN SIGNIFICANTLY AS IT VEERS
   AND SHIFTS NORTHEASTWARD INTO THE CENTRAL GULF STATES OVERNIGHT. 
   THUS...WHILE STRONGER CONVECTION WILL TEND TO DEVELOP INTO THIS
   REGION...SEVERE THREAT APPEARS EVEN MORE MARGINAL THAN ALONG THE
   TEXAS COAST.
   
   ...SOUTHERN PLATEAU...
   STRONG FORCING FOR UPWARD VERTICAL MOTION/MID-LEVEL COOLING WILL
   CONTRIBUTE TO SUFFICIENT DESTABILIZATION TO MAINTAIN SCATTERED
   THUNDERSTORM ACTIVITY OVERNIGHT ACROSS MUCH OF NORTHERN ARIZONA AND
   THE FOUR CORNERS REGION.
   
   ..KERR.. 11/21/2004
   
   ...NOTICE...
   FOR USERS DECODING THE POINTS PARAGRAPH HEREIN...LATITUDE AND
   LONGITUDE POINTS FOR THE CATEGORICAL AND PROBABILISTIC OUTLOOK
   GRAPHICS ALSO ARE LOCATED IN A SEPARATE PRODUCT UNDER THE WMO
   HEADINGS WUUS01 PTSDY1...WUUS02 PTSDY2...AND WUUS03 PTSDY3.  THE
   INCLUSION OF POINTS IN THIS PRODUCT WILL EVENTUALLY BE DISCONTINUED.
   
   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0600Z