[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 130046
SWODY1
SPC AC 130044

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0744 PM CDT TUE SEP 12 2006

VALID 130100Z - 131200Z

...NO SVR TSTM AREAS FORECAST...

...SRN GREAT LAKES REGION/LOWER OH VALLEY SWD INTO MS VALLEY...
WATER VAPOR IMAGERY SHOWED A POSITIVELY TILTED MID/UPPER LEVEL
TROUGH EXTENDING FROM THE WRN GREAT LAKES TO THE SRN HIGH PLAINS. 
THIS LARGE SCALE TROUGH WILL REMAIN PROGRESSIVE WITH AMPLIFICATION
EXPECTED OVERNIGHT AS EMBEDDED SHORT WAVE TROUGH...NOW LOCATED OVER
ERN IA...TRACKS SEWD INTO THE LOWER OH VALLEY. EARLY EVENING
SURFACE ANALYSIS SHOWED AN AREA OF LOW PRESSURE JUST EAST OF ORD...
WITH A COLD FRONT TRAILING SWWD TO NRN LA AND CENTRAL TX.  SURFACE
LOW WILL TRACK ENEWD REACHING LOWER GREAT LAKES REGION BY 12Z
WEDNESDAY...WHILE THE FRONT MOVES SLOWLY EWD INTO OH/TN VALLEYS AND
LOWER MS VALLEY.

45-50 KT WNWLY MID LEVEL JET OVER LOWER MO VALLEY WILL TRANSLATE
ESEWD MAINTAINING STRONG DEEP LAYER SHEAR SUPPORTIVE OF ORGANIZED
STORMS.  HOWEVER...THE COMBINATION OF WEAK MID LEVEL LAPSE RATES AND
DECREASING SURFACE BASED INSTABILITY ALONG AND AHEAD OF THE COLD
FRONT ARE EXPECTED TO MINIMIZE ANY ADDITIONAL SEVERE THREAT FROM THE
LOWER OH INTO LOWER MS VALLEYS.

...SWRN NM WWD TO LOWER CO RIVER VALLEY...
UPPER LOW OVER FAR NRN BAJA REGION WILL MOVE SLOWLY EWD REACHING
SOUTH CENTRAL AZ...ALONG THE MEXICAN BORDER BY 12Z WEDNESDAY. 
ASCENT DOWNSTREAM OF UPPER LOW CENTER COMBINED WITH A CONTINUED
INFLUX OF LOW LEVEL MOISTURE INTO AZ/SWRN NM AND STEEP MID LEVEL
LAPSE RATES SHOULD SUPPORT ADDITIONAL THUNDERSTORM DEVELOPMENT THIS
FORECAST PERIOD.  DEEP LAYER SHEAR IS SUPPORTIVE OF ORGANIZED STORMS
PER LATEST WSR-88D VADS.  HOWEVER...EXTENSIVE AREA OF CLOUDINESS
ACROSS MUCH OF THIS REGION AND EVENTUAL LOSS OF DAYTIME HEATING WILL
FURTHER LIMIT AVAILABLE CONVECTIVE INSTABILITY FOR ADDITIONAL STRONG
TO SEVERE STORMS.

THE EXCEPTION MAY BE ACROSS LOWER CO RIVER VALLEY WHERE STRONG
SURFACE HEATING HAS RESULTED IN LARGE TEMPERATURE/DEWPOINT SPREADS
EXCEEDING 50+ DEGREES...WITH DCAPE VALUES RANGING FROM 1300-1600
J/KG.  CONVECTIVE OUTFLOW SPREADING WWD FROM STORMS NOW LOCATED IN
WRN YAVAPAI COUNTY TO WRN PIMA COUNTY SHOULD HAVE THE GREATEST
POTENTIAL TO PRODUCE A FEW STRONG WIND GUSTS...POTENTIALLY EXCEEDING
SEVERE LEVELS INTO THIS EVENING...BEFORE THE BOUNDARY LAYER
STABILIZES.

..PETERS.. 09/13/2006