[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 211641
SWODY1
SPC AC 211639

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1139 AM CDT THU SEP 21 2006

VALID 211630Z - 221200Z

...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTN AND EARLY TNGT ACROSS
PARTS OF THE CENTRAL AND SRN PLAINS....

...SYNOPSIS...
VIGOROUS MID/UPR LEVEL LOW OVER THE OK/TX PANHANDLE THIS MORNING IS
FORECAST TO MOVE NEWD INTO THE MIDDLE MO VALLEY DRAGGING A NEUTRALLY
THEN NEGATIVELY TILTED TROF THRU THE SRN PLAINS INTO THE MID MS
VALLEY.  MEANWHILE...NEXT MID/UPR LEVEL TROUGH WILL DIVE SWD THRU
THE NRN PLATEAU CARVING OUT A BROAD MID/UPR LVL TROUGH OVER THE
CENTRAL U.S. BY THE END OF THE PERIOD.

...CENTRAL AND SRN PLAINS...

SURFACE ANALYSIS THIS MORNING SHOWS 986 LOW OVER SERN CO WITH A COLD
FRONT EXTENDING SWWD/WWD ACROSS NRN NM.  PRONOUNCED SFC
DRYLINE/TROUGH EXTENDS FROM W CENTRAL KS SWD ALONG THE WRN OK/TX
PANHANDLE BORDER THEN WSWWD THRU EXTREME W TX. A WARM FRONT REACHES
FROM NW AREAS OF TX SEWD THRU THE SERN TX GULF COAST.  THE NAM/NAMKF
AND HI RES WRF MODELS ARE CLOSE IN AGREEMENT TO HOW FAR LOW LEVEL
MOISTURE WILL ADVECT NWD LATER THIS AFTN.  BUT...THE GENERAL
CONCENSUS BRINGS MID 60S TO 70 DEG DEWPOINTS INTO NERN PARTS OF NERN
TX.  MEANWHILE...AS MID/UPR LVL TROUGH MOVES EWD ACROSS THE
CENTRAL/SRN PLAINS...THIS WILL PUSH THE DRYLINE EWD INTO S CENTRAL
KS SWD THRU CENTRAL OK AND N CENTRAL TX BY 21Z.  STRONG LOW/MID LVL
DRY INTRUSION WILL PROVIDE SUFFICIENT FORCING FOR LINE OF STG/SVR
TSTMS AS THERE WILL BE HEATING/DESTABILIZATION MOSTLY ACROSS CENTRAL
TX INTO EXTREME S CENTRAL OK.

AIR MASS JUST AHEAD OF THE DRYLINE IS FORECAST TO ACHIEVE 1000-2000
J/KG OF SBCAPE BETWEEN 21-00Z NWD TO THE ERN RED RIVER VALLEY OF
OK/TX AS PER LATEST RUC FORECAST.  FEEL THIS IS MORE REALISTIC THAN
THE NAM WHICH TAKES THIS INSTABILITY NWD ALONG THE I35 CORRIDOR TO
THE KS/OK BORDER.  WOULD EXPECT THEN THAT 1500-2000 J/KG SBCAPE WILL
MAKE IT INTO SERN OK BETWEEN 00-03Z PLACING GRADIENT OF INSTABILITY
ALONG NERN TX/SERN OK REGION COUPLED WITH DEEP LAYER SHEAR OF 50-55
KT.  THUS...EXPECT DISCRETE SUPERCELLS TO DEVELOP BETWEEN 21-03Z IN
THE VICINITY OF THE RED RIVER VALLEY OF OK/TX E OF THE I35 CORRIDOR
WHERE SUFFICIENT INSTABILITY AND ENHANCED STREAMWISE VORTICITY COULD
SUPPORT A FEW TORNADOES.  ADDED SIGNIFICANT TORNADO PROBABILITIES TO
THE FORECAST AS ANALYSIS OF NAM/RUC MODEL SNDGS INDICATE LFC/LCL
VALUES BETWEEN 1000/2000M AND 0-1KM SHEAR OF 30-35 KT. AS SQUALL
LINE DEVELOPS ALONG/JUST E OF SFC DRYLINE...WOULD EXPECT MAIN
THREATS ASSOCIATED WITH THIS TO BE HAIL AND DAMAGING WINDS.

..MCCARTHY/GUYER.. 09/21/2006