SWODY1
SPC AC 051226
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0726 AM CDT SUN AUG 05 2007
VALID 051300Z - 061200Z
..THERE IS A SLGT RISK OF SVR TSTMS PORTIONS OF THE OHIO VALLEY...
..THERE IS A SLGT RISK OF SVR TSTMS LARGE PORTION OF WESTERN WY AND
ADJACENT AREAS OF ID AND MT...
..SYNOPSIS...
OVERALL LARGE SCALE PATTERN CHANGING LITTLE WITH BROAD RIDGE
EXTENDING FROM SWRN U.S. EWD ACROSS THE U.S. PRIMARY UPPER TROUGH
REMAINS VICINITY NWRN COAST WITH IMPULSES TRACKING OUT OF TROUGH
ACROSS NRN INTERMOUNTAIN REGION THEN EWD TO GREAT LAKES.
AT THE SURFACE FRONTAL BOUNDARY HAS STALLED ACROSS DELMARVA AND
EXTENDS WWD THRU OH VALLEY TO A WEAK LOW WRN IA. FRONTAL ZONE
SEPARATES VERY MOIST WARM SECTOR FROM DRIER MORE STABLE AIR.
MONSOONAL MOISTURE REMAINS OVER AZ AND TO A LESSOR DEGREE NWD THRU
UT INTO WRN WY.
..WRN WY AND ADJACENT PORTIONS OF ID/MT...
W/V IMAGERY SUPPORTS PARTICULARLY THE GFS...PLACING A WELL DEFINED
S/WV TROUGH NRN CA MOVING NEWD OUT OF MAIN TROUGH POSITION.
UNSEASONABLY STRONG WIND MAX OF 80-90KT AT 300MB AND 50KT AT 500MB
TRACKS ACROSS SRN ID LATER THIS AFTERNOON AND INTO WRN WY/SRN MT
THIS EVENING. IN ADDITION MID LEVEL COLD ADVECTION WITH THE TROUGH
ALONG WITH THE LARGE SCALE ASCENT SUPPORT POTENTIAL FOR DEVELOPMENT
OF ORGANIZED CONVECTION THIS AFTERNOON. AIR MASS IN ADVANCE OF THIS
SYSTEM IS DRY IN LOW LEVELS ACROSS NRN NV AND SWRN ID...BUT WILL
ENCOUNTER INCREASING MONSOONAL MOISTURE SPREADING NEWD THRU UT INTO
WRN WY LATER THIS AFTERNOON.
GIVEN THE STRENGTH OF SYSTEM HIGH BASED STORMS EXPECTED TO DEVELOP
BY EARLY AFTERNOON FROM ERN NV/UT BORDER NWD INTO SRN ID. STRONGER
THUNDERSTORMS...LIKELY EVOLVING INTO A LINEAR MODE IS EXPECTED TO
OCCUR AS ACTIVITY APPROACHES THE ID/WY BORDER WHERE MUCAPES EXPECTED
TO BE AOA 500 J/KG GIVEN THE MOISTURE AVAILABILITY.
IN ADDITION TO THE POTENTIAL OF STRONG/DAMAGING WINDS...MODEL
SOUNDINGS SUPPORT A HAIL THREAT PARTICULARLY NWRN WY WHERE STEEP
LAPSE RATES AND TERRAIN ENHANCEMENT WILL OCCUR IN ADVANCE OF
STRONGER FLOW AND ASCENT WITH APPROACHING TROUGH.
..OH VALLEY...
SHARP MOISTURE/INSTABILITY GRADIENT EXISTS ACROSS FRONTAL ZONE FROM
SRN OH TO NRN IL. BOUNDARY WILL SHIFT A LITTLE NORTH AHEAD OF IA
SURFACE LOW...HOWEVER WITH PREDOMINANT WESTERLY COMPONENT ABOVE
ABOUT 1KM...THE PRIMARY FOCUS FOR ANY SURFACE STORM INITIATION
SHOULD REMAIN ACROSS NRN OH VALLEY TODAY. WITH DEWPOINTS RISING
INTO THE LOW/MID 70S AND TEMPERATURES TO NEAR 90F...MLCAPES FROM
2500-3000 J/KG WILL BE COMMON IN WARM SECTOR THIS AFTERNOON. HOWEVER
THE FRONTAL BOUNDARY LIES UNDER THE SRN FRINGE OF STRONGER WNWLYS TO
THE N...WITH BULK SHEAR GENERALLY 20KT OR LESS.
THUNDERSTORMS EXPECTED TO DEVELOP VICINITY AND SOUTH OF FRONTAL ZONE
BY MID AFTERNOON WHEN CINH WILL WEAKEN SUFFICIENTLY. THE LIMITED
SHEAR COUPLED WITH WARM MID LEVEL TEMPERATURES AND LAPSE RATES OF
6C/KM OR LESS...SUGGESTS THE SEVERE THREAT WILL BE LIMITED TO MOSTLY
WET DOWNBURSTS. ENHANCED DIRECTIONAL SHEAR VICINITY FRONTAL ZONE
DOES SUPPORT POTENTIAL FOR SUPERCELLS...WHICH COULD ENHANCE
PRIMARILY THE WIND THREAT.
..DELMARVA...
E/W FRONTAL ZONE STALLED CLOSE TO DCA THIS AM. S OF FRONT AIRMASS
IS WARM AND MOIST AND WITH AFTERNOON HEATING MLCAPES SHOULD CLIMB TO
AROUND 2000 J/KG. WHILE DEEP LAYER SHEAR IS GENERALLY LESS THAN
20KT...WET MICRO BURSTS ARE POSSIBLE GIVEN THE STEEP LOW LEVEL LAPSE
RATES THIS AFTERNOON AND AVAILABLE INSTABILITY.
.HALES/JEWELL.. 08/05/2007
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