SPC AC 160558
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1258 AM CDT TUE SEP 16 2008
VALID 171200Z - 181200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
BROAD UPR TROUGH CURRENTLY SITUATED FROM QUEBEC SWWD TO THE SPLNS
WILL MOVE SLOWLY E TO LIE FROM NEW ENGLAND TO THE SERN STATES BY
WEDNESDAY EVENING. STRONGER PART OF THIS TROUGH WILL EXIST ACROSS
SERN CANADA ASSOCD WITH A STRONG VORTEX OVER FAR NRN QUEBEC. TO THE
W...IN WAKE OF AN UPR HIGH THAT WILL MOVE INTO THE CENTER OF THE
COUNTRY...THE UPR LOW A COUPLE HUNDRED MILES W OF KSFO WILL OPEN
INTO A WAVE AND MIGRATE INTO THE INTERMOUNTAIN W/NW GRT BASIN REGION
BY WEDNESDAY NIGHT.
...N FL AND PORTIONS OF CSTL GA...
BUILDING SFC PRESSURES ACROSS THE CNTRL/ERN STATES WILL FORCE THE
BAROCLINIC ZONE OVER THE SERN STATES SLOWLY SWD INTO NEARSHORE
WATERS OF NC/SC AND CSTL GA SWWD INTO PARTS OF N FL THROUGH
WEDNESDAY. AIR MASS ALONG/S OF THE FRONT WILL REMAIN
MOIST...CHARACTERIZED BY PWAT VALUES AOA 1.75 IN AND SFC DEW POINTS
IN THE LWR-MID 70S. AS SRN PORTION OF THE UPR TROUGH SPREADS
EWD...MID-LVL TEMPERATURES WILL DECREASE INTO THE MINUS 8 TO MINUS
10C RANGE ALONG WITH AN INCREASE IN H25 SWLY WINDS AOA 40-50 KTS.
TSTMS WILL DEVELOP VCNTY THE FRONT AND SWD THROUGH THE FL PENINSULA
ALONG LAKE/SEABREEZES WEDNESDAY AFTN. GIVEN THE INCREASING HIGH LVL
WINDS...APCHG TROUGH/LIFT AND FAVORABLE THERMODYNAMICS...ISOLD TSTMS
MAY APCH OR EXCEED SVR LIMITS WITH LRG HAIL/DMGG WIND GUSTS.
...INTERMOUNTAIN W...
MODELS ARE INSISTENT ON GRADUALLY INCREASING LOW/MID-LVL MOISTURE
ACROSS THE LWR CO RVR VLY/SRN CA DURING THE NEXT COUPLE OF DAYS
/SOME SIGNS OF THIS PROCESS ALREADY ONGOING IN NRN MEXICO ATTM/.
SOME OF THIS MOISTURE WILL ADVECT NWD AHEAD OF THE NEGATIVE-TILT UPR
WAVE INTO THE GRT BASIN. STEEP LOW/MID-LVL LAPSE RATES... COURTESY
OF STRONG LOW-LVL WARMING AND H5 TEMPERATURES AOB MINUS 12 DEG
C...WILL BE FAVORABLE FOR WDLY SCT TSTMS ACROSS PRIMARILY HIGHER
TERRAIN LOCATIONS OF SRN CA/SRN SIERRA EWD INTO PARTS OF THE
AZ/NM/CO PLATEAU AND UT. FARTHER N...FCST SOUNDINGS INDICATE
PRIMARILY MID-LVL MOISTENING ASSOCD WITH ASCENT/COOLING AHEAD OF THE
AFOREMENTIONED WAVE. PWAT VALUES LESS THAN 0.75 IN WILL FOSTER
HIGH-BASED TCU/CBS OVER THE MOUNTAINS WITH GENERALLY DRY
LIGHTNING/GUSTY WINDS EXPECTED OVER NRN NV/SW ID AND PARTS OF ORE.
..RACY.. 09/16/2008
NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z
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