SPC AC 060554
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1254 AM CDT SAT MAY 06 2006
   
   VALID 061200Z - 071200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS TODAY ACROSS PARTS OF THE SRN
   PLAINS INTO THE WRN/CNTRL GULF COAST....
   
   STRONG ZONAL NORTH PACIFIC JET CONTINUES TO PROPAGATE TOWARD THE
   PACIFIC NORTHWEST COAST.  ASSOCIATED SHORT WAVE TROUGH ON NOSE OF
   THIS FEATURE IS SPLITTING IN DISTINCT NORTHERN/SOUTHERN BRANCHES OF
   STRONGER FLOW EXTENDING INLAND DOWNSTREAM...WITH STRONGER NORTHERN
   IMPULSE PROGGED EAST OF THE CANADIAN/NORTHERN U.S. ROCKIES BY 12Z
   SUNDAY.  WEAKER SOUTHERN IMPULSE IS FORECAST TO DIG INTO THE LOWER
   COLORADO VALLEY/NORTHERN BAJA...AND LAST IN SERIES OF SHORT
   WAVES...ASSOCIATED WITH WHAT IS LEFT OF LARGER SCALE SOUTHERN BRANCH
   TROUGH...IS PROGGED TO ACCELERATE EAST NORTHEAST OF THE SOUTHERN
   HIGH PLAINS AND RED RIVER VALLEY.  FARTHER EAST...AS MOST
   SIGNIFICANT SHORT WAVE EMBEDDED WITHIN NORTHERN BRANCH TROUGH LIFTS
   FROM THE LOWER LAKES THROUGH THE CANADIAN MARITIMES/NORTH ATLANTIC
   COAST...WEAK TROUGH IN THE SOUTHERN BRANCH WILL FINALLY PROGRESS
   EAST OF SOUTH ATLANTIC COASTAL AREAS.
   
   FORCING ASSOCIATED WITH VARIOUS SHORT WAVE TROUGHS AND SEASONABLE
   INSTABILITY WILL SUPPORT SCATTERED THUNDERSTORM ACTIVITY ACROSS THE
   NATION TODAY.  HOWEVER...LOW-LEVEL COOLING/DRYING EAST OF THE
   ROCKIES...PRIMARILY IN ASSOCIATION WITH AMPLIFIED NORTHERN BRANCH
   TROUGH...BUT ALSO IN PART DUE TO EXTENSIVE CONVECTIVE DEVELOPMENT
   ASSOCIATED WITH THE SOUTHERN STREAM...HAS NOW SUPPRESSED SIGNIFICANT
   MOISTURE TO SOUTHERN/EASTERN TEXAS AND THE CENTRAL GULF COAST.
   
   ...SOUTHERN PLAINS/LOWER MISSISSIPPI VALLEY...
   ONE OR MORE CLUSTERS OF STORMS IS EXPECTED TO BE ONGOING AT THE
   BEGINNING OF THE FORECAST PERIOD ACROSS PARTS OF SOUTHEAST TEXAS/
   LOUISIANA.  IT SEEMS MOST PROBABLE THAT CONVECTION NEAR/EAST OF
   CONVECTIVELY INDUCED/ENHANCED CYCLONIC VORTICITY CENTER WILL BE
   WEAKENING NEAR THE SABINE RIVER.  HOWEVER...VIGOROUS STORMS MAY
   PERSIST IN ASSOCIATION WITH LOW-LEVEL CONVERGENCE/WARM ADVECTION
   ALONG OUTFLOW BOUNDARY PROGRESSING TOWARD MID/UPPER TEXAS COASTAL
   AREAS. THIS MAY PROVIDE THE PRIMARY SEVERE THREAT THIS FORECAST
   PERIOD AS IT PROGRESSES ACROSS HOUSTON AND ADJACENT AREAS BY MID
   DAY.
   
   REDEVELOPMENT IN WAKE OF THIS ACTIVITY IS UNCERTAIN.  SIGNIFICANT
   STABILIZATION OF LOWER LEVELS MAY OCCUR ACROSS A LARGE PORTION OF
   CENTRAL/EASTERN TEXAS. ADDITIONALLY...MID-LEVEL SUBSIDENCE/WARMING
   SOUTH OF 50 KT CYCLONIC 500 MB JET PROGGED ACROSS NORTHERN TEXAS
   DURING THE DAY WILL BE INHIBITIVE.
   
   HOWEVER...BOUNDARY LAYER WILL REMAIN MOIST AND POTENTIALLY
   MODERATELY UNSTABLE NEAR INTERSECTION OF STALLING OUTFLOW BOUNDARY
   AND DRY LINE...NEAR/NORTH OF SAN ANTONIO BY LATE AFTERNOON.  THIS
   COULD SERVE AS THE FOCUS FOR AT LEAST ISOLATED NEW CONVECTIVE
   DEVELOPMENT. IF THIS OCCURS...GENERALLY LIGHT BUT VEERING WINDS WITH
   HEIGHT BENEATH MODERATE WESTERLY MID-LEVEL FLOW WILL BE SUFFICIENT
   FOR SUPERCELLS...PRIMARILY WITH LARGE HAIL/GUSTY WINDS.  OTHER
   STORMS COULD DEVELOP OFF THE HIGHER TERRAIN OF MEXICO THROUGH THE
   LOWER RIO GRANDE VALLEY BY EARLY EVENING.
   
   THE GFS...MORE SO THAN THE NAM...SUGGESTS THAT FORCING ASSOCIATED
   WITH THE SOUTHERN STREAM IMPULSE COULD SUPPORT ADDITIONAL
   SIGNIFICANT CONVECTIVE DEVELOPMENT NEAR LINGERING SYNOPTIC FRONTAL
   ZONE ACROSS NORTH CENTRAL/NORTHEAST TEXAS LATE THIS AFTERNOON. 
   BOUNDARY LAYER RECOVERY NORTH OF COMPOSITE CONVECTIVE OUTFLOW IS
   UNCERTAIN...BUT THIS ACTIVITY COULD AT LEAST POSE A RISK FOR LARGE
   HAIL BEFORE WEAKENING ACROSS THE LOWER MISSISSIPPI VALLEY THIS
   EVENING.
   
   ..KERR/JEWELL.. 05/06/2006
   
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   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z