[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 081253
SWODY1
SPC AC 081252

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0752 AM CDT FRI SEP 08 2006

VALID 081300Z - 091200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER THE UPPER MS VALLEY AND
GREAT LAKES...

...SYNOPSIS...
HIGH AMPLITUDE SPLIT FLOW PATTERN WILL CONTINUE TODAY AS BROAD UPPER
TROUGH MOVES ESEWD ACROSS ERN CANADA AND ADJACENT PARTS OF THE UPPER
MS VALLEY/GREAT LAKES...WHILE UPSTREAM TROUGH MOVES ONSHORE INTO THE
PACIFIC NW TONIGHT.  A WEAKER TROUGH OVER THE GREAT BASIN REGION IS
FORECAST TO MOVE EWD ACROSS THE CENTRAL ROCKIES TOWARD THE CENTRAL
HIGH PLAINS.  AT THE SURFACE...A STRONG COLD FRONT FROM ERN ONTARIO
ACROSS NRN WI/SRN MN AND SD WILL CONTINUE MOVING SEWD REACHING A ST
LAWRENCE VALLEY/SRN LOWER MI/SRN IA/SRN NEB LINE BY 09/12Z. 

...UPPER MS VALLEY/GREAT LAKES...
PLUME OF STEEPER MID LEVEL LAPSE RATES EXTENDING FROM THE NRN PLAINS
ACROSS THE UPPER MS VALLEY IS FORECAST TO PERSIST INTO THIS EVENING.
THIS WILL ENHANCE INSTABILITY ALONG AND IMMEDIATELY AHEAD OF THE
ADVANCING COLD FRONT WHERE SURFACE DEW POINTS OF 55-60F WILL
CONTRIBUTE TO MLCAPE OF 1000-1500 J/KG.  

WIDELY SCATTERED CONVECTION IS LIKELY TO CONTINUE ACROSS THIS REGION
THIS MORNING...WITH MORE VIGOROUS THUNDERSTORMS EXPECTED TO DEVELOP
THIS AFTERNOON MAINLY ALONG THE FRONT AS DIURNAL HEATING CONTRIBUTES
TO DESTABILIZATION.  THE ACTIVITY MAY INITIALLY DEVELOP BY EARLY
AFTERNOON FROM ERN UPPER MI/NRN LOWER MI WSWWD INTO PARTS OF
WI...THEN GRADUALLY BUILD WWD THROUGH THE AFTERNOON ALONG THE FRONT
INTO PARTS OF IA AND POSSIBLY NRN NEB. STRONGER MID LEVEL WINDS
WILL EXTEND SWD AS FAR AS NRN/CENTRAL WI AND NRN LOWER MI WHERE DEEP
LAYER SHEAR OF 25-35 KT WILL AID IN DEVELOPMENT OF ORGANIZED STORMS.
A FEW SEVERE STORMS WILL BE POSSIBLE ACROSS PARTS OF THE UPPER GREAT
LAKES/UPPER MS VALLEY DURING THE AFTERNOON AND EVENING WITH PRIMARY
THREAT FOR LARGE HAIL AND STRONG WIND GUSTS.  

...AZ/WRN NM REGION...
MOST OF THE NOCTURNAL CONVECTION OVER WRN AZ AND EXTREME SERN CA HAS
SLOWLY WEAKENED DURING THE LAST SEVERAL HOURS ALTHOUGH SEVERAL
STRONG STORMS ARE CONTINUING NEAR YUM AND SW OF CGZ.  THESE STORMS
ARE EXPECTED TO MOVE SEWD AND GRADUALLY DIMINISH IN INTENSITY AFTER
SUNRISE. 

AMPLE MOISTURE REMAINS ACROSS THE AREA WITH PRECIPITABLE WATER
VALUES OF 1.25-1.50 INCHES INDICATED BY GPS WATER VAPOR SENSORS AND
12Z TUS/PHX SOUNDINGS...AND DRY AIR IN THE MID/UPPER LEVELS WILL
ENHANCE CONVECTIVE INSTABILITY. ADDITIONAL THUNDERSTORMS ARE
EXPECTED TO DEVELOP OVER THE HIGHER TERRAIN OF NORTH CENTRAL/ERN AZ
AND WRN NM THIS AFTERNOON AND EVENING AS THE UPPER TROUGH CONTINUES
EWD.  THIS CONVECTION IS EXPECTED TO MOVE EWD/SEWD THROUGH TONIGHT
WITH STRONGER STORMS CAPABLE OF PRODUCING STRONG WIND GUSTS AND
MARGINALLY SEVERE HAIL.

..WEISS/JEWELL.. 09/08/2006