SWODY1
SPC AC 041241
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0741 AM CDT TUE SEP 04 2007
VALID 041300Z - 051200Z
..NO SVR TSTM AREAS FORECAST...
..NRN GREAT BASIN TODAY INTO EARLY TONIGHT...
A PRONOUNCED MID LEVEL SHORTWAVE TROUGH MOVING OVER THE PAC NW COAST
WILL CONTINUE PROGRESSING ESEWD TO NRN NV BY EARLY WEDNESDAY...WHILE
THE ACCOMPANYING BAROCLINIC ZONE DEVELOPS EWD FROM ORE/NRN CA ACROSS
NV/ID. DOWNSTREAM FROM THIS TROUGH...A LOW-MID LEVEL MOISTURE PLUME
/PW VALUES AOA 1 INCH/ WILL SPREAD NNEWD FROM ERN NV/WRN UT INTO SRN
ID. THIS MOISTURE...ALONG WITH SUFFICIENTLY STEEP LAPSE RATES AND
DAYTIME HEATING...WILL SUPPORT SCATTERED THUNDERSTORM DEVELOPMENT
TODAY FROM ERN NV/UT INTO S/SE ID. VERTICAL SHEAR WILL INCREASE
GRADUALLY DURING THE AFTERNOON OVER THIS AREA AS THE MID-UPPER
TROUGH APPROACHES FROM THE W...AND THE STRONGER STORMS MAY DEVELOP
SOME BOWING LINE SEGMENT OR SUPERCELL STRUCTURES WHICH WOULD LOCALLY
ENHANCE THE THREAT FOR DAMAGING WINDS AND MARGINALLY SEVERE HAIL.
FARTHER W...ADDITIONAL CONVECTION IS EXPECTED IN PROXIMITY TO THE
MID LEVEL TROUGH AND DEEP BAROCLINIC ZONE. THE MORE PROBABLE AREA
FOR DEVELOPMENT WILL BE ACROSS ERN ORE DURING THE LATE AFTERNOON AS
SURFACE HEATING COINCIDES WITH THE MID LEVEL THERMAL TROUGH TO
MAXIMIZE INSTABILITY. DEEP LAYER VERTICAL SHEAR MAY BE SUFFICIENT
FOR ORGANIZED STORM STRUCTURES ON THE CYCLONIC SIDE OF THE MID LEVEL
JET...THOUGH INSTABILITY WILL NOT BE PARTICULARLY STRONG AND THE
SEVERE STORM THREAT SHOULD REMAIN MARGINAL.
..UPPER MI AREA TODAY...
A BAND OF ELEVATED CONVECTION PERSISTS OVER UPPER MI AND NRN LOWER
MI THIS MORNING IN ASSOCIATION WITH LOW-LEVEL WAA/FRONTOGENESIS. A
NARROW BELT OF MOISTURE ALONG THE STALLED BAROCLINIC ZONE IS FEEDING
THIS CONVECTION...ALONG WITH THE REMNANTS OF AN ELEVATED MIXED LAYER
PLUME FROM THE NRN ROCKIES. INSTABILITY COULD BE SUFFICIENT FOR
MARGINALLY SEVERE HAIL...AND PERHAPS GUSTY OUTFLOW WINDS...WITH THE
STRONGER STORMS TODAY.
..SRN PLAINS/NW GULF COAST...
A BROAD/DEEP MOISTURE PLUME EXTENDS NWD FROM THE NW GULF COAST TO
OK/AR...TO THE E OF A MID LEVEL TROUGH OVER W TX. AN EMBEDDED
VORTICITY CENTER NEAR DRT WILL MOVE NNEWD AND HELP MAINTAIN A SWATH
OF WEAK CONVECTION/RAIN ACROSS CENTRAL TX...WHILE CLOUD BREAKS ALLOW
SUFFICIENT SURFACE HEATING FOR SCATTERED THUNDERSTORM DEVELOPMENT
FARTHER E DURING THE DAY ON THE PERIPHERY OF THE THICKER CLOUD
COVER.
.THOMPSON/GRAMS.. 09/04/2007
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