FXUS62 KTBW 271854
AFDTBW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAMPA BAY RUSKIN FL
154 PM EST FRI NOV 27 2009
.SHORT TERM (TONIGHT - SUNDAY)...WE WILL SEE A CHILLY START TO
THE WEEKEND AS HIGH PRESSURE BUILDS OVERHEAD FROM THE WEST
RESULTING IN LIGHT WINDS AND MAINLY CLEAR SKIES. SOME CIRRUS WILL
BE TRAVERSING THE SKIES OVERNIGHT...AND MAY HAVE SOME IMPACT ON
THE LOW TEMPERATURES. FOR NOW I HAVE CHOSEN TO IGNORE THE CIRRUS
AS IT WILL LIKELY BE MAINLY THIN WITH JUST PATCHES OF DENSE
CIRRUS AT TIMES. BOTH THE NAM AND GFS HAVE BACKED OFF ON BRINGING
IN THE DENSE CIRRUS.
WILL ALSO BRING TEMPERATURES TO A DEGREE OR SO BELOW MAV GUIDANCE.
LAST NIGHTS OVERNIGHT TEMPERATURES WERE UP TO 3 DEGREES
COLDER...WITH BROOKSVILLE DROPPING TO 35 DEGREES JUST AFTER 7 AM
AND VANDENBURG DOWN TO AT LEAST 39 DEGREES. WITH THIS IN
MIND...HAVE EXTENDED PATCHY FROST DOWN INTO THE NORMALLY COLDER
LOCATIONS OF THE INTERIOR ALL THE WAY DOWN TO CHARLOTTE COUNTY.
MOST OF THE MORE POPULATED CENTERS SOUTH OF HILLSBOROUGH COUNTY
WILL NOT SEE FROST.
AFTER A COLD START...TEMPERATURES WILL REBOUND NICELY ON SATURDAY
WITH HIGHS GETTING CLOSER TO 70 DEGREES FROM TAMPA BAY SOUTHWARD
BUT REMAINING IN THE MID TO UPPER 60S FOR THE NATURE COAST.
ANOTHER CHILLY NIGHT ON TAP FOR SATURDAY NIGHT BUT NOT AS COLD AS
TONIGHT. LOWS WILL STILL REACH THE MID 30S FOR THE NATURE COAST
BUT WILL LIKELY STAY IN THE 40S FOR THE REST OF THE INTERIOR
CENTRAL AND SOUTH.
SUNDAY WILL BE A PERFECT DAY FOR ANY OUTDOOR PLANS YOU MAY HAVE
WITH TEMPERATURES CLIMBING QUICKLY INTO THE 70S UNDER LOTS OF
SUNSHINE. SOME CIRRUS WILL DIM THE SUN AT TIMES...BUT WINDS WILL
BE LIGHT AND HUMIDITIES WILL REMAIN LOW.
.LONG TERM (SUNDAY NIGHT - FRIDAY)...PROGRESSIVE AMPLIFIED SPLIT
FLOW PATTERN WILL CONTINUE OVER THE CONTINENTAL U.S. DURING THE
LONG TERM PERIOD. SURFACE HIGH PRESSURE OVER THE PENINSULA AT THE
START OF THE LONG TERM WILL SHIFT EASTWARD INTO THE WESTERN
ATLANTIC ON MONDAY AS A SHORT WAVE TROUGH MOVING FROM THE PLAINS
INTO THE MS VALLEY PUSHES A COLD FRONT INTO THE PANHANDLE LATE ON
MONDAY...THEN INTO THE NORTHERN PENINSULA MONDAY NIGHT...BEFORE IT
STALLS OUT ACROSS THE NORTH CENTRAL PENINSULA ON TUESDAY. A SLOW
MOISTENING OF THE AIR MASS ACROSS THE REGION VIA MODEL CROSS-
SECTIONS WILL SUPPORT INCREASING CHANCES FOR SHOWERS WITH THIS
FRONT...SO WILL MAINTAIN 20 PERCENT POP COVERAGE IN THE GRIDS FOR
MONDAY NIGHT. DURING TUESDAY LATEST MEX POP GUIDANCE LOOKS A BIT
AGGRESSIVE GIVEN A SLOW MOISTURE RECOVERY...SO WILL UNDERCUT
SLIGHTLY FOR NOW AND ADVERTISE POPS IN THE 30 TO 40 RANGE FROM
SOUTH TO NORTH.
DURING TUESDAY NIGHT INTO WEDNESDAY THE STALLED FRONTAL BOUNDARY
WILL BEGIN TO LIFT BACK TO THE NORTH AS A WARM FRONT AS SURFACE
LOW PRESSURE DEVELOPS ALONG THE FRONT OVER THE NORTHWEST GULF IN
RESPONSE TO UPSTREAM SHORT WAVE ENERGY OVER TEXAS. THE GFS IS THE
FASTEST IN EJECTING THIS DEVELOPING LOW NORTHEAST ACROSS THE
NORTHERN GULF AND SOUTHEASTERN STATES...AND THEN UP ALONG THE MID
ATLANTIC WEDNESDAY NIGHT INTO THURSDAY WHILE THE ECMWF IS SLOWER
AND A BIT FURTHER TO THE WEST WITH ITS TRACK. GIVEN THE SUBTLE
DIFFERENCES WILL USE A BLEND FOR NOW AND SEE IF BETTER CONTINUITY
DEVELOPS AMONG THE MODELS OVER THE COMING DAYS.
AS THE LOW LIFTS OUT TO THE NORTHEAST INCREASING MOISTURE AND LIFT
ASSOCIATED WITH IT WILL LEAD TO INCREASING CHANCES FOR SHOWERS AND
THUNDERSTORMS (POPS INCREASING INTO THE 50-60 PERCENT RANGE)
ACROSS THE FORECAST AREA WEDNESDAY THROUGH EARLY THURSDAY. IN
ADDITION TO THE RAIN CHANCES WILL NEED TO MONITOR FOR THE
POSSIBILITY FOR SOME STRONG TO SEVERE STORMS AS WELL ALONG THE
TRAILING COLD FRONT AS A LOW LEVEL JET (IN THE 45-55 KNOT RANGE)
ASSOCIATED WITH THIS SYSTEM WILL BE MOVING OVER THE REGION. ANY
LINGERING SHOWERS/STORMS EARLY ON THURSDAY WILL END FROM NORTH TO
SOUTH DURING THE DAY WITH THE FRONTAL PASSAGE WITH COOLER/DRIER
WEATHER EXPECTED ACROSS THE REGION FOR THURSDAY NIGHT AND FRIDAY.
TEMPERATURES WILL RUN ABOVE NORMAL THROUGH MID WEEK THEN FALL BACK
TO WELL BELOW NORMAL BY WEEKS END AS THE FRONT MOVES THROUGH.
&&
.AVIATION...VFR CONDITIONS ARE EXPECTED AT ALL TERMINAL SITES
THROUGH SATURDAY.
&&
.MARINE...WINDS HAVE TURNED A BIT MORE NORTHWESTERLY THIS
AFTERNOON AND REMAIN IN THE 10 TO 15 KNOT RANGE. SEAS ARE ON THE
BORDER NOW OF SMALL CRAFT EXERCISE CAUTION...OR 5 FEET AT 42036
AND 6 FEET WAY OUT AT BUOY 42099. THIS FORECAST WILL ASSUME SEAS
ARE AT MOST 5 FEET INSIDE OUR 60 NM WATERS SO NO HEADLINES WILL BE
USED. TRANQUIL CONDITIONS ARE EXPECTED THROUGH THE WEEKEND AND
INTO EARLY NEXT WEEK...BUT THE NEXT SYSTEM WILL BRING INCREASING
WINDS AND SEAS LATE TUESDAY AND DURING WEDNESDAY WITH SMALL CRAFT
CONDITIONS AGAIN POSSIBLE.
&&
.FIRE WEATHER...WESTERLY WINDS AND COOLER TEMPERATURES ARE KEEPING
THE NATURE COAST FROM FLAGGING SO FAR. OTHERWISE...INLAND AREAS
FROM HILLSBOROUGH AND POLK COUNTIES ON SOUTH ARE WELL ON THEIR WAY
TO LONG DURATIONS OF CRITICAL RELATIVE HUMIDITIES. PREFER NOT TO
CHANGE ANY OF THE WATCHES AND WARNINGS IN PLACE AT THIS TIME.
DRY CONDITIONS MAY PERSIST INTO SUNDAY AS WELL...AND A WATCH MAY BE
NEEDED FOR PORTIONS OF THE NATURE COAST. WILL ALLOW FUTURE SHIFTS
TO EVALUATE THIS FURTHER.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 41 70 51 76 / 0 0 0 0
FMY 43 71 52 80 / 0 0 0 0
GIF 41 69 50 77 / 0 0 0 0
SRQ 43 69 47 76 / 0 0 0 0
BKV 31 68 35 75 / 0 0 0 0
SPG 50 67 55 75 / 0 0 0 0
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...RED FLAG WARNING UNTIL 6 PM EST THIS EVENING FOR CHARLOTTE-
CITRUS-DE SOTO-HARDEE-HERNANDO-HIGHLANDS-HILLSBOROUGH-LEE-
LEVY-MANATEE-PASCO-POLK-SARASOTA-SUMTER.
FIRE WEATHER WATCH FROM SATURDAY MORNING THROUGH SATURDAY
AFTERNOON FOR CHARLOTTE-CITRUS-DE SOTO-HARDEE-HERNANDO-
HIGHLANDS-HILLSBOROUGH-LEE-LEVY-MANATEE-PASCO-POLK-SARASOTA-
SUMTER.
GULF WATERS...NONE.
&&
$$
SHORT TERM/MARINE/FIRE WEATHER...JILLSON
LONG TERM/AVIATION...MCMICHAEL
