FXUS62 KTBW 251843
AFDTBW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAMPA BAY RUSKIN FL
143 PM EST FRI DEC 25 2009
.SYNOPSIS...A MID AND UPPER LOW SPINNING OVER THE CENTRAL PLAINS
AND MID MISSISSIPPI VALLEY IS EMBEDDED IN LARGE SCALE TROUGHINESS
OVER MUCH OF THE NATION. THE SURFACE REFLECTION OF THE MID/UPPER
SYSTEM IN NEAR IA AND HAS A COLD FRONT ARCING ACROSS THE OHIO
VALLEY...MID-ATLANTIC COAST...CENTRAL FL...TO WESTERN CUBA.
&&
.SHORT TERM (TONIGHT -SUNDAY)...THE MID AND UPPER LOW WILL
CONTINUE TO SPIN OVER THE UPPER MIDWEST AND GREAT LAKES REGION
THROUGH THE PERIOD WITH TROUGHINESS OVER MUCH OF THE
NATION...PROVIDING SW FLOW ALOFT THE GULF AND FL. THIS MORNINGS
COLD FRONT IS EXPECTED TO REACH SOUTH FL TONIGHT AND THEN PUSH
EAST AND SOUTH OF THE STATE SAT...AS HIGH PRESSURE SLIDES ALONG
THE GULF COAST FROM TX TO NEAR AL/GA/FL. BY SUN THE HIGH WEAKENS
WHILE THE SW FLOW ALOFT CONTINUES - WITH SOME UPPER LEVEL
DISTURBANCES TRACKING ACROSS THE REGION - WHICH RESULTS IN THE OLD
FRONT SLOWLY LIFTING BACK NORTH ACROSS THE AREA.
ONLY SHOWERS...IN A NORTH-SOUTH LINE DOWN THE CENTER OF THE AREA...
ARE PUSHING EAST WHILE MOSTLY CLOUDY SKIES BUT WITH A FEW BREAKS
PERSIST. THE ZONES HANDLE THIS PRETTY GOOD BUT HAVE UPDATED THIS
AFTERNOONS GRIDS SO THE POINT AND CLICK FORECASTS ARE A LITTLE
MORE TIMELY.
CLOUDS CONTINUE OVER NIGHT AND THEN BEGIN TO CLEAR SOME SAT AS THE
HIGH BUILDS IN WITH A DRY AND COOL NORTHERLY FLOW. HIGHS WILL BE
IN THE 60S...PERHAPS NEAR 70 FAR SOUTH. THEN SAT NIGHT AND SUN...
THE SW FLOW ALOFT ALONG WITH THE BOUNDARY WORKING NORTH WILL SUPPLY
ENOUGH ENERGY AND MOISTURE FOR SOME SLIGHT CHANCE RAIN. HIGHS SUN
WARM SOME BUT STAY BELOW NORMAL.
.LONG TERM (SUNDAY NIGHT - FRIDAY)...POTENT CYCLONE IN THE MID-UPPER
LEVELS OF THE ATMOSPHERE THAT HAS BEEN SITUATED OVER THE CENTRAL
U.S. WILL PROGRESS EASTWARD ACROSS THE GREAT LAKES REGION AT THE
START OF THE LONG TERM PERIOD...WEAKEN AND EJECT OFF THE NORTHEAST
U.S. COAST DURING THE MON-TUE TIME FRAME AS LOW AMPLITUDE RIDGING
TAKES A BRIEF PERIOD OF REAL ESTATE AHEAD OF THE NEXT STORM SYSTEM.
ACTIVE SOUTHERN JET STREAM WILL KEEP A PROGRESSIVE FLOW ACROSS THE
GULF OF MEXICO TOWARD FLORIDA THROUGH MUCH OF THE PERIOD WITH
SUFFICIENT MOISTURE DEPTH FOR LOW RAIN CHANCES LATE SUNDAY...HOWEVER
THE NEXT SYSTEM WILL BEGIN TO EVOLVE AND DELIVER A GREATER POTENTIAL
FOR INCREASING CLOUDS AND RAINFALL POTENTIAL DURING THE MID-LATE
WEEK PERIOD AND AS WE ENTER THE NEXT DECADE. OVERALL THE ONGOING
FORECAST REMAINS IN GREAT SHAPE WITH FEW CHANGES ANTICIPATED.
&&
.AVIATION...MVFR CONDITIONS WILL LINGER AROUND TPA/PIE TERMINALS
UNTIL MID AFTERNOON AS A LINE OF CONVECTION CONTINUES TO DETERIORATE
AND MOVE EAST ACROSS THE EASTERN GULF AND FLORIDA PENINSULA. BEHIND
THE COLD FRONT...MVFR CONDITIONS WILL GIVE WAY TO VFR...AS CLOUDS
DECREASE AND CEILINGS RISE THROUGHOUT THE EVENING AND EARLY MORNING
HOURS. SOUTHWESTERLY AND WESTERLY FLOW WILL CONTINUE TO VEER TO THE
NORTH BY SATURDAY MORNING.
&&
.MARINE...WINDS HAVE OR SOON WILL SHIFT TO WESTERLY AND SUBSIDE...
ALONG WITH THE SEAS...AS THE FRONT MOVES THROUGH. WILL SET THE
AFTERNOON FORECAST TO EXPIRE THE ADVISORY AT 4 PM BUT CARRY
EXERCISE CAUTION THROUGH THE EVENING. HIGH PRESSURE BUILDS IN FOR
MUCH OF THE WEEKEND WITH NORTHERLY WINDS ALTHOUGH THE HIGH WEAKENS
SOME SUN NIGHT BEFORE BEING REINFORCED DURING THE EARLY PART OF
NEXT WEEK.
&&
.FIRE WEATHER...SOME DRIER AIR ADVECTS IN SAT MAINLY OVER THE
NORTH. LEVY AND NORTH CITRUS/SUMTER WILL SEE SOME BRIEF BELOW 35
PERCENT READING. WHILE OFFICES TO THE NORTH HAVE GONE WITH A
WATCH WILL REFRAIN AND JUST HEADLINE THE FIRE WEATHER FORECAST.
HUMIDITY WILL START TO RECOVER SUN.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 52 65 51 70 / 10 10 20 20
FMY 57 70 53 72 / 10 10 20 20
GIF 50 67 47 70 / 10 10 20 20
SRQ 51 66 51 71 / 10 10 20 20
BKV 43 63 38 66 / 10 10 20 20
SPG 55 65 53 68 / 10 10 20 20
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...SMALL CRAFT ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR BONITA
BEACH TO ENGLEWOOD OUT 20 TO 60 NM-ENGLEWOOD TO TARPON
SPRINGS OUT 20 TO 60 NM-TARPON SPRINGS TO SUWANNEE RIVER
OUT 20 TO 60 NM.
&&
$$
SHORT TERM/MARINE/FIRE WEATHER...09/RUDE
LONG TERM...10/LAMARRE
AVIATION...18/FLEMING
