[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 060556
SWODY1
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