FXUS62 KTBW 241826
AFDTBW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAMPA BAY RUSKIN FL
126 PM EST THU DEC 24 2009
.SYNOPSIS...LARGE SCALE UPPER TROUGHINESS...WITH AN EMBEDDED LOW
NEAR MT/ND AND A SECOND OVER TX... REACHES FROM THE CANADIAN PRAIRIES
TO THE MEXICAN BORDER WHILE WEAK RIDGING EXTENDS FROM FL TO THE
SE U.S. MEANWHILE AT THE SURFACE...A LOW NEAR THE LOWER MID-
MISSISSIPPI VALLEY HAS A COLD FRONT EXTENDING SOUTH WITH A WARM
FRONT ARCING SE AND THEN EAST...TO THE GA/FL LINE. HIGH PRESSURE
OVER JAMES BAY RIDGES SOUTH ACROSS THE MID-ATLANTIC COAST TO FL
ATLANTIC WATERS.
&&
.SHORT TERM (TONIGHT - SATURDAY)...THE UPPER TROUGHINESS WILL
PERSIST WEST OF THE AREA THROUGH THE PERIOD AS THE EMBEDDED LOWS
ROTATE THROUGH IT TONIGHT AND THEN MERGE FRI OVER THE UPPER MIDWEST.
AS THE SOUTHERN UPPER LOW LIFTS N-NE TONIGHT AND EARLY FRI IT
DRAGS THE SURFACE REFLATION ALONG WITH IT...AS A TRAILING COLD
FRONT SWEEPING ACROSS THE CENTRAL/EAST GULF TONIGHT AND MOST OF FL
FRI.
ON SAT...THE BY NOW CONSOLIDATED SYSTEM OVER THE MIDWEST MEANDERS
INTO THE UPPER GREAT LAKES WITH THE TROUGHING KEEPING SW FLOW ALOFT
THE REGION AND...AS IN RECENT FRONTAL PASSAGES...ALLOWING THE FRONT
TO STALL OUT EAST-SOUTH OF THE AREA. MEANWHILE WEAK HIGH PRESSURE
BUILDS IN OVER THE WESTERN GULF COAST AND MOVES EAST.
THE GFS/NAM/ECMWF/UKMET ARE ALL VERY SIMILAR WITH THE UPPER
FEATURES. THEY ALSO GENERALLY AGREE WITH A FRONT MOVING THROUGH
FRI AND THEN HANGING UP TO THE EAST AND SOUTH OF THE AREA AS HIGH
PRESSURE MOVES ALONG THE GULF COAST. THE BIGGEST DISAGREEMENT IS
TIMING AND EVEN THAT IS RATHER MINOR. THE LATEST GFS/ECMWF/UKMET
BRING THE FRONT INTO THE NORTH END OF THE CWA SHORTLY AFTER
MIDNIGHT...THE TAMPA BAY AREA AROUND SUNRISE...THEN THE SOUTH CWA
IN THE AFTERNOON. THE NAM IS SLOWER WITH THE FRONT...SLIGHTLY...
WHICH RESULT IN LOWER POPS TONIGHT. WITH CONSISTENCY BETWEEN THE
MODELS AND THE PREVIOUS FORECASTS HAVE KEEP THE CURRENT TREND OF
LIKELY POPS SPREADING ACROSS THE NORTH TONIGHT AND THEN OVER THE REST
OF THE AREA DURING THE DAY FRI. PRECIPITATION WILL PREDOMINATELY
BE SHOWERS ALTHOUGH WEAK DISTURBANCES MOVING THROUGH THE SW FLOW
ALOFT WILL BRING SOME ISOLATED THUNDERSTORMS. THE BEST ENERGY
APPEARS TO GO BY TO THE NORTH...SO ONLY THE EXTREME NORTH CWA
COULD SEE A STRONG STORMS OR TWO. HOWEVER...ANY THREAT OF SEVERE
WEATHER WILL CONTINUE TO BE EXAMINED. TEMPERATURES BEGIN FRI NEAR
NORMAL THEN GRADUALLY DECREASE.
.LONG TERM (SATURDAY NIGHT-THURSDAY)...THE BOUNDARY WILL BE SLOWLY
PUSHING SOUTH OF THE AREA SATURDAY NIGHT INTO SUNDAY MORNING WITH A
FEW ISOLATED SHOWERS POSSIBLY LINGERING OVER THE AREA. CLEARING WILL
THEN OCCUR MONDAY WITH COOLER AND DRIER AIR MOVING INTO THE AREA
UNDER HIGH PRESSURE. THE COLDEST MORNING SHOULD BE TUESDAY MORNING
WITH NEAR-FREEZING TEMPERATURES POSSIBLE IN THE NORMALLY COOLER
LOCATIONS ACROSS THE NATURE COAST. HIGH PRESSURE WILL REMAIN IN
PLACE ACROSS THE AREA THROUGH WEDNESDAY WITH TEMPERATURES AND
MOISTURE MODERATING. LOW PRESSURE WILL THEN APPROACH FROM THE GULF
OF MEXICO AND MOVE ACROSS THE AREA THURSDAY BRINGING SCATTERED RAIN
CHANCES. TEMPERATURES WILL GENERALLY REMAIN BELOW NORMALS THROUGH
THE PERIOD.
&&
.AVIATION...GENERALLY VFR CONDITIONS WILL CONTINUE THROUGH THE REST
OF THE DAY...WITH SCT-BKN MID AND HIGH CLOUDS AND GUSTY WINDS. THEN
AROUND 08-10Z...A COLD FRONT WILL MOVE INTO THE AREA BRINGING SOME
SHOWERS AND MVFR/LOCALLY IFR CEILINGS AND VISIBILITIES TO THE
TERMINALS. THESE SHOULD LINGER INTO THE AFTERNOON FRIDAY AS THE
FRONT GRADUALLY MOVES THROUGH THE AREA.
&&
.MARINE...TIGHT GRADIENT MAINTAIN SMALL CRAFT ADVISORY OFFSHORE
WITH EXERCISE CAUTION OVER NEAR SHORE WATERS OVERNIGHT AND INTO
EARLY FRI. A FRONT MOVING INTO THE WATERS FRI WILL ALLOW THE
GRADIENT TO RELAX AND WINDS TO SHIFT TO NW. HIGH PRESSURE BUILDING
IN OVER THE WEST COAST COAST AND THEN MOVING EAST WILL KEEP
NORTHERLY WINDS THROUGH THE WEEKEND AND EARLY NEXT WEEK.
&&
.FIRE WEATHER...NO LOW HUMIDITY CONCERNS FOR NEXT COUPLE OF DAYS
ALTHOUGH COOLER AND DRIER AIR BEGINS TO FILTER OVER THE AREA STARTING
SUNDAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 66 75 52 65 / 50 60 20 20
FMY 65 78 56 70 / 40 60 20 30
GIF 64 75 50 66 / 50 60 20 20
SRQ 65 75 51 66 / 50 60 20 20
BKV 64 72 44 65 / 60 60 10 20
SPG 66 73 52 65 / 50 60 20 20
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...SMALL CRAFT ADVISORY UNTIL 10 AM EST FRIDAY 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/AVIATION...24/COLSON
