AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
349 PM EDT THU MAY 27 2010

.SYNOPSIS...

...INCREASING CHANCE OF SHOWERS AND THUNDERSTORMS THIS WEEKEND...

THE UPPER AIR ANALYSIS SHOWS THAT THE REX BLOCK THAT WAS IN
PLACE YESTERDAY OVER THE EASTERN U.S. HAS BROKEN DOWN. THE CLOSED
UPPER LOW OFF THE SOUTH CAROLINA COAST IS NOW MOVING EASTWARD INTO
THE OPEN ATLANTIC AND AN UPPER LEVEL RIDGE AXIS EXTENDS FROM THE
GREAT LAKES SOUTHWESTWARD TO THE GREAT PLAINS. CLOSER TO HOME...WE
ARE STILL UNDER THE INFLUENCE OF LIGHT OFFSHORE FLOW.
HOWEVER...THAT WILL BE CHANGING OVER THE NEXT FEW DAYS AS WE
TRANSITION TO A WETTER PATTERN WITH A SHORTWAVE DIVING SOUTH
AROUND THE GREAT PLAINS RIDGE AND CLOSING OFF AN UPPER LOW ACROSS
THE SOUTHEAST U.S.

&&

.SHORT TERM...
(TONIGHT THROUGH SATURDAY NIGHT) BOUNDARY LAYER MOISTURE HAS MIXED
OUT A BIT MORE TODAY VS YESTERDAY...RESULTING IN SLIGHTLY LOWER
DEWPOINTS AND LESS COVERAGE OF ISOLATED SHOWERS AND THUNDERSTORMS.
WAS TEMPTED TO PULL BACK THE EVENING POPS TO SILENT 10...BUT THE VIS
SAT DOES SHOW SOME AGITATED TOWERING CU SO WILL LEAVE IN 20 PERCENT
FOR THE EVENING HOURS FOR NOW. FOR FRIDAY...MOISTURE WILL BE
GRADUALLY INCREASING AS THE PERSISTENT OFFSHORE FLOW WEAKENS AND THE
SEABREEZE IS ALLOWED TO PUSH FURTHER INLAND. OUR LOCAL WRF IS
SHOWING GREATER COVERAGE OF CONVECTION ALONG THE SEABREEZE BOUNDARY
COMPARED TO PREVIOUS DAYS...SO WENT WITH 30 POPS INLAND. AS WE HEAD
INTO SATURDAY...THE AFOREMENTIONED SHORTWAVE CLOSES OFF AN UPPER
LEVEL LOW. GIVEN AMPLE MOISTURE WITH WEAK SOUTHERLY FLOW AND
SLIGHTLY COOLER AIR ALOFT...EXPECT FAIRLY HIGH COVERAGE OF SHOWERS
AND THUNDERSTORMS. FELT CONFIDENT ENOUGH TO BUMP UP POPS INTO THE
LIKELY (60 PERCENT) RANGE FOR SATURDAY GIVEN THE INCREASING MODEL
CONSENSUS. THE LOCALLY RUN CONFIDENCE GRIDS ALSO SHOW POPS QUITE
HIGH ON SATURDAY.

.LONG TERM...
(MODIFIED SUNDAY THROUGH THURSDAY) THE UPPER LEVEL LOW AND THE
ASSOCIATED TROUGH WILL GRADUALLY WEAKEN AND MOVE SLOWLY EAST ACROSS
THE SOUTHEAST CORNER OF THE U.S. THROUGH EARLY NEXT WEEK. A WEAK
PRESSURE PATTERN WILL PERSIST AT THE SURFACE WITH A SEA BREEZE
DEVELOPING EACH DAY. THIS ALONG WITH DAYTIME HEATING...SUFFICIENT
MOISTURE AND ABOVE MENTIONED INSTABILITY WILL GENERATE DAILY
AFTERNOON AND EVENING CONVECTION. POPS WILL BE IN THE CHANCE RANGE
FOR MOST OF THE AFTERNOON/EVENING PERIODS. THE LATEST 12Z GUIDANCE
HANGS MOISTURE AROUND A LITTLE LONGER THAN EARLIER GUIDANCE
SUGGESTED...SO INCREASED POPS TO 50 PERCENT FOR SUNDAY. TEMPS WILL
REMAIN NEAR TO ABOVE AVERAGE WITH LOWS IN THE UPPER 60S TO LOWER 70S
AND INLAND MAX TEMPS MOSTLY IN THE UPPER 80S TO LOWER 90S.

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