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NOAA Forecast Discussion

000
FXUS62 KTBW 061816
AFDTBW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAMPA BAY RUSKIN FL
116 PM EST TUE JAN 6 2009

.SHORT TERM (TONIGHT - THURSDAY)...A SLOW INCREASE IN CLOUDS IS EXPECTED
ACROSS THE FORECAST AREA LATER TONIGHT AS A MID/UPPER LEVEL TROUGH AND
ATTENDANT COLD FRONT MOVES INTO THE LOWER MS VALLEY WITH A PRE-FRONTAL
LINE OF SHOWERS AND STORMS MOVING INTO THE FL PANHANDLE. MODEL GUIDANCE
STILL SUGGESTS A 20% CHANCE FOR A FEW SHOWERS TOWARDS MORNING ACROSS
LEVY COUNTY AND THE NORTHERN MOST COASTAL WATERS...SO WILL RETAIN A
MENTION IN THESE LOCATIONS WITH DRY CONDITIONS (POPS ~10%) CONTINUING
ELSEWHERE. IT WILL BE ANOTHER VERY MILD NIGHT WITH OVERNIGHT LOWS IN
THE LOWER/MID 60S WITH AN INCREASE IN SURFACE WINDS LIKELY TO FAVOR
LATE NIGHT LOW STRATUS AND KEEP FOG DEVELOPMENT AND COVERAGE (PATCHY
IN NATURE) MUCH LOWER THAN THIS MORNING.

ON WEDNESDAY THE AFOREMENTIONED COLD FRONT IS FORECAST TO MOVE THROUGH
WEST CENTRAL AND SOUTHWEST FLORIDA AS THE STRONG MID/UPPER LEVEL TROUGH
ADVANCES EASTWARD WITH THE TROUGH BECOMING NEGATIVELY TILTED AS IT MOVES
OFF THE U.S. EAST COAST EARLY ON THURSDAY. ONGOING PRE-FRONTAL BAND OF
CONVECTION ALONG AND AHEAD OF THE COLD FRONT WILL MOVE INTO THE NATURE
COAST BY MID MORNING...THEN SPREAD SOUTHEAST THROUGH THE REMAINDER OF
THE FORECAST AREA DURING THE AFTERNOON AND EARLY EVENING HOURS. STRONG
JET DYNAMICS COMBINED WITH DEEP LAYERED SHEAR...AND A LOW LEVEL JET
(IN THE 45-50 KNOT RANGE) MAY BE SUPPORTIVE OF A FEW STRONG STORMS WITH
DAMAGING WIND GUSTS A POSSIBILITY...BUT SIMILAR TO YESTERDAY LIMITED
INSTABILITY AND WEAK LAPSE RATES VIA MODEL SOUNDING DATA SHOULD KEEP
STORM DEVELOPMENT AND OVERALL SEVERE THREAT TO A MINIMUM AS THE FRONT
MOVES THROUGH. STRONG AMBIENT WINDS WILL YIELD BREEZY TO WINDY CONDITIONS
ACROSS THE FORECAST AREA AND MAY NEED TO ISSUE A LAKE WIND ADVISORY
EARLY ON WEDNESDAY. GFS/NAM TIMING OF THE FROPA AND POPS DIFFER SOME
SO WILL USE AN BLEND FOR TIMING AND KEEP POP VALUES AS IS IN THE
40-60% RANGE FROM SOUTH TO NORTH. CLOUD COVER AND RAIN CHANCES WILL
RESULT IN COOLER TEMPERATURES WITH HIGHS IN THE UPPER 60S TO ~70 FAR
NORTH...LOWER/MID 70S CENTRAL AND UPPER 70S FAR SOUTH.

COOLER AND DRIER AIR WILL OVERSPREAD THE REGION WITH CLEARING SKIES
EXPECTED FROM NORTH TO SOUTH WEDNESDAY NIGHT IN THE WAKE OF THE FRONT
WITH TEMPERATURES FALLING INTO THE 40S OVER THE NATURE COAST...LOWER
TO MID 50S CENTRAL...AND UPPER 50S FAR SOUTH. DRY NORTHWEST FLOW ALOFT
AND SURFACE HIGH PRESSURE BUILDING IN OVER THE EASTERN GULF WILL PROVIDE
PLEASANT DRY WEATHER WITH AMPLE SUNSHINE AND SLIGHTLY BELOW NORMAL
TEMPERATURES ON THURSDAY WITH HIGH TEMPERATURES IN THE UPPER 60S TO
~70 NORTH INTO CENTRAL ZONES...AND LOWER 70S FAR SOUTH.

&&

.LONG TERM (THURSDAY NIGHT - TUESDAY)...THE PERIOD WILL START OFF
WITH SURFACE HIGH PRESSURE PROVIDING DRY AND BELOW NORMAL TEMPERATURES
FRIDAY THEN COMING TO NORMAL FOR SATURDAY. ON SATURDAY THE HIGH BE
IN THE ATLANTIC AND WILL RIDGE ACROSS THE REGION AS A COLD FRONT
MOVES INTO THE SOUTHEAST U.S. MODELS CONTINUE THEIR ROLLER COASTER
RIDE WITH THE TIMING OF THIS FRONT. 06Z GFS HAD PUSHED IT'S PASSAGE
INTO TUESDAY...BUT 12Z VERSION IS CLOSER TO PREVIOUS FORECAST AS
WELL AS TIMING OF ECMWF AND DGEX. GIVEN THE UNCERTAINTY STILL THOUGH
WOULD PREFER TO KEEP POPS AT 20 PERCENT UNTIL THIS FRONT MOVES INTO
THE DAYS 2-4 TIME FRAME. WE MAY ALSO HAVE TO DEAL WITH A LINGERING
BOUNDARY THAT DOES NOT CLEAR THROUGH THE CWA...SO WILL KEEP A 10-20
POP MONDAY AND TUESDAY. FOR TEMPERATURES...00Z ENSEMBLE MEANS ARE
RUNNING SEVERAL DEGREES BELOW THE OPERATIONAL GUIDANCE AND WILL LEAN
IN THAT DIRECTION.

&&

.AVIATION...FEW TO SCATTERED CLOUDS AT 2000-3500 FEET THIS AFTERNOON.
A COLD FRONT WILL APPROACH TONIGHT AND KEEP WINDS UP SOMEWHAT...ESPECIALLY
OVER KTPA...WHERE WINDS COMING OFF THE BAY COULD BE GUSTY. THEN LOW
LEVEL MOISTURE WILL PROVIDE IFR TO MVFR STRATUS AFTER MIDNIGHT. SHOULD
BE ENOUGH WIND TO KEEP OUT FOG...BUT MAY SEE SOME OVER SOUTHWEST
FLORIDA. WEDNESDAY MORNING WINDS WILL PICK UP WITH GUSTS UP TO 25
KNOTS AND CONTINUED MVFR CEILINGS. SHOWERS AND STORMS ARE POSSIBLE
LATE IN THE TAF PERIOD...BUT HAVE KEPT THEM OUT FOR NOW TO FOCUS
ON EARLIER EVENTS.

&&

.MARINE...SOUTH TO SOUTHWEST WIND FLOW WILL INCREASE OVER THE WATERS
TONIGHT AHEAD OF AN APPROACHING COLD FRONT. CURRENT MODEL DATA SUGGEST
SMALL CRAFT CONDITIONS DEVELOPING OVER THE NEAR AND OFFSHORE WATERS
WITH EXERCISE CAUTION OVER THE TAMPA BAY LATE TONIGHT THROUGH WEDNESDAY
AND WILL RAISE THESE FLAGS LATER THIS AFTERNOON. STRONG AND GUSTY
SOUTHWEST WINDS AHEAD OF THE FRONT WILL SHIFT INTO THE WEST AND NORTHWEST
WEDNESDAY AFTERNOON AND EVENING AS THE FRONT MOVES THROUGH. IN ADDITION
TO BUILDING SEAS...THE STRONG ONSHORE FLOW MAY ELEVATE TIDE LEVELS BY
A FOOT OR TWO DURING WEDNESDAY. MUCH LIGHTER WINDS AND DECREASING SEAS
WILL RETURN ON THURSDAY AS SURFACE HIGH PRESSURE BUILDS IN OVER THE
EASTERN GULF WITH A WEST NORTHWEST FLOW EXPECTED. ANOTHER WEAKER FRONT
WILL PASS THROUGH THE WATERS EARLY ON FRIDAY WITH LITTLE IMPACT...FOLLOWED
BY HIGH PRESSURE BUILDING IN OVER THE SOUTHEASTERN STATES FRIDAY
AFTERNOON...THEN SHIFTING EAST INTO THE WESTERN ATLANTIC FRIDAY NIGHT
THROUGH SUNDAY WITH THE RIDGE AXIS EXTENDING BACK TO THE WEST ACROSS
THE CENTRAL PENINSULA WITH A LIGHT EASTERLY WIND FLOW WITH A SEA
BREEZE COMPONENT DEVELOPING NEAR SHORE EACH AFTERNOON.

&&

.FIRE WEATHER...AMPLE LOW LEVEL MOISTURE WILL KEEP HUMIDITY VALUES
ABOVE CRITICAL LEVEL THROUGH WEDNESDAY...BUT INCREASING 20 FOOT WINDS
AND TRANSPORT WINDS WILL YIELD HIGH DISPERSION INDICES. DRIER AIR IN
THE WAKE OF THE COLD FRONT WILL LOWER HUMIDITIES TO NEAR CRITICAL
LEVELS OVER INTERIOR LOCATIONS BOTH THURSDAY AND FRIDAY AFTERNOONS
BUT LIMITED DURATIONS (2-3 HRS) SHOULD PRECLUDE RED FLAG CONDITIONS
AT THIS TIME...BUT WILL MAKE OF NOTE OF THE POSSIBLE LOW RH'S AND
HIGH DISPERSION IN THE FIRE WEATHER PACKAGE LATER THIS AFTERNOON.

&&

.PRELIMINARY POINT TEMPS/POPS...
TPA 65 73 50 70 / 10 60 10 0
FMY 64 77 52 72 / 10 40 10 0
GIF 63 75 49 70 / 10 60 10 0
SRQ 66 72 50 70 / 10 50 10 0
BKV 60 74 43 69 / 10 60 5 0
SPG 65 72 53 69 / 10 60 10 0

&&

.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...SMALL CRAFT ADVISORY FROM 1 AM TO 10 PM EST WEDNESDAY FOR
ENGLEWOOD TO TARPON SPRINGS OUT 20 NM-ENGLEWOOD TO TARPON
SPRINGS OUT 20 TO 60 NM-TARPON SPRINGS TO SUWANNEE RIVER
OUT 20 NM-TARPON SPRINGS TO SUWANNEE RIVER OUT 20 TO 60 NM.

SMALL CRAFT ADVISORY FROM 10 AM TO 10 PM EST WEDNESDAY FOR
BONITA BEACH TO ENGLEWOOD OUT 20 NM-BONITA BEACH TO
ENGLEWOOD OUT 20 TO 60 NM.

SMALL CRAFT EXERCISE CAUTION FROM WEDNESDAY MORNING THROUGH
WEDNESDAY EVENING FOR TAMPA BAY WATERS.

&&

$$

SHORT TERM/MARINE/FIRE WEATHER...57/MCMICHAEL
LONG TERM/AVIATION...55/SHARP

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