Saturday, May 8, 2010

Day 1 outlooks






SPC AC 080559

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1259 AM CDT SAT MAY 08 2010

VALID 081200Z - 091200Z

...NO SVR TSTM AREAS FORECAST...

...SERN U.S...

WLY FLOW WILL GRADUALLY INCREASE ACROSS THE SERN U.S. WITHIN BASE OF
EJECTING GREAT LAKES UPPER TROUGH. INTERIOR SFC RIDGING WILL BUILD
ACROSS THE MIDDLE OF THE CONUS FORCING A FAIRLY WELL DEFINED COLD
FRONT AND PRE-FRONTAL WIND SHIFT EAST OF THE APPALACHIANS EARLY IN
THE PERIOD. ALTHOUGH WINDS WILL VEER CONSIDERABLY ACROSS GA AND SC
IT APPEARS SFC DEW POINTS SHOULD HOLD IN THE 60S AHEAD OF THE FRONT.
PRIOR TO LOW LEVEL MOISTURE BEING SCOURED OFFSHORE...STRONG HEATING
SHOULD FORCE SFC PARCELS TO REACH THEIR CONVECTIVE TEMPERATURES.
IT/S NOT ENTIRELY CLEAR HOW CONVERGENT THIS BOUNDARY WILL BE ACROSS
GA/SC...BUT EARLY MORNING WV IMAGERY SUGGESTS A WEAK
IMPULSE/SHORTWAVE TROUGH MAY BE EMBEDDED WITHIN THE BASE OF THE
BROADER TROUGH OVER LA/MS. SUBSEQUENT EWD MOVEMENT OF THIS FEATURE
WOULD INTERACT WITH TRAILING FRONTAL ZONE ACROSS GA/CAROLINAS DURING
PEAK HEATING. ALTHOUGH SUBTLE...A FEW STRONG OR ISOLATED SEVERE
THUNDERSTORMS COULD DEVELOP DURING THE AFTERNOON HOURS.
HOWEVER...COVERAGE WILL LIKELY BE INSUFFICIENT TO WARRANT A SLIGHT
RISK...THOUGH LARGE HAIL AND LOCALLY DAMAGING WINDS WOULD BE THE
PRIMARY RISKS WITH STRONGER UPDRAFTS.

...NERN U.S...

IMPRESSIVE HEIGHT FALLS WILL OVERSPREAD THE NERN U.S. AHEAD OF
STRONG UPPER TROUGH EARLY IN THE PERIOD. ASSOCIATED SFC COLD FRONT
WILL SURGE INTO THE HUDSON VALLEY BY 16Z WITH A SMALL WARM SECTOR
EXPECTED TO BECOME WEAKLY UNSTABLE ACROSS PORTIONS OF SRN NEW
ENGLAND INTO THE HUDSON VALLEY BY MID DAY. FORECAST SOUNDINGS
SUGGEST A NARROW WINDOW OF OPPORTUNITY WILL EXIST FOR SFC-BASED
CONVECTION ALONG ADVANCING COLD FRONT IF DEW POINTS CAN RISE INTO
THE UPPER 50S WHERE SFC TEMPERATURES WARM INTO THE 60S. ALTHOUGH
DEEP LAYER SHEAR IS QUITE STRONG...INSTABILITY WILL LIKELY PROVE TOO
WEAK TO WARRANT MORE THAN A FEW ROBUST UPDRAFTS CAPABLE OF PRODUCING
GUSTY WINDS.

...ELSEWHERE...

A FEW POCKETS OF THUNDERSTORMS WILL DEVELOP ACROSS HIGHER ELEVATIONS
OF THE CNTRL AND NRN ROCKIES...AS WELL AS THE MOUNTAINS OF NRN CA.
ANOTHER REGION WHERE THUNDERSTORMS MAY DEVELOP WILL BE ACROSS NRN TX
INTO SRN OK AS STRONG WARM ADVECTION DEVELOPS ACROSS THE SRN PLAINS
LATE IN THE PERIOD. MOIST ISENTROPIC ASCENT ATOP A VERY COOL
RETREATING ANTICYCLONE SHOULD ENCOURAGE ELEVATED CONVECTION TOWARD
09/12Z. THIS ACTIVITY WILL LIKELY BE ROOTED NEAR 700MB AND SEVERE
HAIL IS NOT ANTICIPATED.

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