Area Forecast Discussion
Issued by NWS Tampa Bay Area, FL

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FXUS62 KTBW 291408
AFDTBW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAMPA BAY RUSKIN FL
905 AM EST MON DEC 29 2014

.UPDATE (REST OF TODAY THROUGH TUESDAY)...
14Z WATER VAPOR AND H4 RAP ANALYSIS SHOW THAT MUCH OF THE CONUS IS
NOW UNDER BROAD LONGWAVE TROUGHING...AS THE RIDGE THAT WAS ALONG THE
EASTERN SEABOARD HAS BEEN DEAMPLIFIED BY SHORTWAVE ENERGY PASSING
OFF THE CAROLINA COAST AND PUSHED SOUTHEAST INTO THE WESTERN
ATLANTIC. THE CENTRAL/SOUTHERN FLORIDA PENINSULA IS STILL SOMEWHAT
UNDER THE SUBSIDENCE OF THIS RIDGE...BUT HEIGHTS HAVE CERTAINLY COME
DOWN ACROSS THE PENINSULA DURING THE PAST 24 HOURS. THE MOST
INTERESTING FEATURE IN THE UPPER LEVELS IS A STRONG PIECE OF
SHORTWAVE/JET ENERGY DIVING DOWN THE PACIFIC COAST. THIS ENERGY IS
PROGGED TO EVOLVE INTO A LARGE CUTOFF LOW OVER THE SOUTHWESTERN
STATES BY THE MIDDLE OF THE WEEK AND THEN SLOWLY EJECT EASTWARD
ACROSS THE SOUTHERN PLAINS.

29/12Z KTBW SOUNDING PROFILE SHOWS THAT ALTHOUGH THE RIDGE ALOFT IS
WEAKENING...IT STILL HAS SOME INFLUENCE ON THE REGION. AN ASSOCIATED
SUBSIDENCE INVERSION IS EVIDENT AROUND 850MB WITH QUITE A DRY COLUMN
ABOVE IN THE MID LAYERS OF THE ATMOSPHERE.

AT THE SURFACE...ATLANTIC HIGH PRESSURE RIDGES BACK OVER THE CENTRAL
AND SOUTHERN FL PENINSULA...WHILE AT THE SAME TIME A COLD FRONT
SLOWLY CRAWLS EASTWARD THROUGH THE FL PANHANDLE AND NORTH-CENTRAL
GULF OF MEXICO. THE FLOW BETWEEN THESE 2 FEATURES IS PROVIDING
ABUNDANT LOW LEVEL MOISTURE TO THE REGION. THESE RICH DEWPOINTS
(LOWER 70S AT BUOY 42036) ARE ADVECTING OVER THE LOWER 60S
TEMPERATURE SHELF WATERS OF EASTERN APALACHEE BAY AND RESULTING IN
AREAS OF DENSE SEA FOG. HAVE ISSUED A MARINE DENSE FOG ADVISORY FOR
THE COASTAL WATERS NORTH OF PINELLAS COUNTY. FOR NOW MOST OF THE FOG
IS UP TOWARD THE COASTS OF CITRUS/LEVY COUNTIES...BUT THERE IS A
GOOD CHANCE TO SEE AN EXPANSION OF THIS FOG SOUTHWARD LATER TODAY
AND ESPECIALLY INTO TONIGHT. THIS EXPANSION IS SHOWN BY THE SREF AND
ALSO THE ENSEMBLE LOCAL SUITE OF HIGH RESOLUTION GUIDANCE.

REST OF TODAY...
FOG OVER LAND WILL BURN OFF IN THE NEXT FEW HOURS. ONLY EXCEPTION
MAY BE AT THE IMMEDIATE COASTS OF CITRUS AND LEVY COUNTY AS THE SEA
FOG MOVES ASHORE AND IS NOT INFLUENCED BY DIURNAL MIXING. WILL CALL
IT A "MIX OF SUN AND CLOUDS" IN THE FORECAST AS WE DO HAVE SEVERAL
PATCHES OF CLOUDS AND CLEAR SKIES ACROSS THE REGION. ALL WE NEED IS
A LITTLE BIT OF SUN GIVEN THE THERMAL POTENTIAL OF THE LOW LEVEL
COLUMN TO END UP WITH AN ABOVE NORMAL DAY IN TERMS OF TEMPERATURES.
INLAND LOCATIONS...ESPECIALLY ALONG AND SOUTH OF THE I-4 CORRIDOR
SHOULD REACH THE LOWER 80S...WHILE THINGS HOLD IN THE 70S AT THE
BEACHES DUE TO A DEVELOPING ONSHORE COMPONENT TO THE WIND THIS
AFTERNOON. THE FRONT WILL BE MAKING VERY SLOW PROGRESS EASTWARD
THROUGH THE DAY BUT WILL FAIL TO REACH OUR COUNTIES TODAY. EVEN
STILL...A FEW SHOWERS AHEAD OF THE BOUNDARY MAY REACH LEVY COUNTY
AND THE NORTHERN COASTAL WATERS BY EARLY THIS EVENING. JUST HAVE A
20% CHANCE OF A SHOWER THROUGH THE EVENING FOR LEVY COUNTY AS THE
OVERALL SYNOPTIC SETUP FOR LIFT ALONG THE BOUNDARY WILL BE FADING
WITH TIME. CAN NOT RULE OUT A BRIEF SHOWER OR 2 DEVELOPING OVER THE
INTERIOR SOUTH-CENTRAL ZONES EITHER AS A RESULT OF A LATE DAY
SEA-BREEZE MERGER. A FEW OF THE LOCAL CONVECTION ALLOWING MODELS ARE
SHOWING THIS POTENTIAL AND WILL KEEP THE 20% POP AFTER 18Z OVER
HIGHLANDS COUNTY.

TONIGHT...
THE APPROACH OF ONE FINAL PIECE OF WEAK SHORTWAVE ENERGY OVER THE
NORTHERN GULF COAST WILL FINALLY GIVE THE FRONT THE PUSH IT NEEDS TO
ENTER THE FL PENINSULA. THE BOUNDARY SHOULD BE LOCATED SOMEWHERE
BETWEEN TAMPA AND CHIEFLAND BY SUNRISE ON TUESDAY. WILL HAVE TO PUT
A FEW SHOWERS IN THE FORECAST FROM TAMPA NORTHWARD IN PROXIMITY TO
THIS BOUNDARY...HOWEVER ANY RAINFALL DOES NOT LOOK TO BE A BIG
DEAL...WITH VERY LOW QPF. TEMPERATURES WILL REMAIN ABOVE NORMAL WITH
LOWS IN THE 60S FOR ALL.

TUESDAY...
COLD FRONT MAKES SLOW BUT STEADY PROGRESS SOUTHWARD THROUGH THE DAY
REACHING THE SOUTHERN FL PENINSULA TUESDAY EVENING. A FEW SHOWERS
WILL REMAIN IN THE FORECAST...ALTHOUGH THE BEST CHANCES WILL SLIP TO
THE SOUTHERN HALF OF THE REGION BY THE AFTERNOON. DO NOT ANTICIPATE
THAT TUESDAY WILL BE CONSIDERED A "WET" DAY. ONCE AGAIN...ANY
SHOWERS SHOULD BE BRIEF AND QPF IS QUITE LOW. THERE REALLY IS NOT A
WHOLE LOT OF COLD AIR BEHIND THIS COLD FRONT. WE WILL SEE SOME
DECREASE IN TEMPS INTO THE MIDDLE OF THE WEEK...BUT MAINLY IT WILL
GET DRIER AND MORE COMFORTABLE FEELING. HOWEVER...DO NOT GET USED TO
IT...AS ALL SIGNS POINT TO A QUICK MODERATING TREND IN BOTH
TEMPERATURES AND DEWPOINTS AS HEAD TOWARD THE END OF THE WEEK.

&&

.AVIATION...
CONDITIONS HAVE RETURNED TO VFR FOR ALL TERMINALS THIS MORNING.
AREAS OF BKN CLOUDS 3500-4500 FEET WILL BE AROUND...BUT DO NOT
ANTICIPATE ANY ADDITIONAL RESTRICTIONS ALONG OR SOUTH OF THE I-4
CORRIDOR THE REMAINDER OF THE DAY AND EVENING HOURS. AFTER MIDNIGHT
INTO EARLY TUESDAY MORNING IS LOOKING MORE AND MORE FAVORABLE FOR
PERIOD OF SIGNIFICANT RESTRICTIONS AT ALL TERMINALS. THE STATISTICAL
AND DETERMINISTIC GUIDANCE SOLUTIONS ARE ALL POINTING TO WIDESPREAD
DENSE FOG AND LOW CEILINGS. WILL CONTINUE TO MONITOR THE INCOMING
GUIDANCE AND BEGIN TO MAKE ADJUSTMENTS WITH THE 18Z TAF PACKAGE.

&&

.MARINE...
DENSE FOG ADVISORY REMAINS IN EFFECT FOR THE NORTHERN COASTAL WATERS
AS WARM...HUMID AIR CONTINUES TO OVERRIDE THE COOLER WATERS. PATCHY
FOG WILL BE POSSIBLE ACROSS THE REST OF THE WATERS TODAY BUT BEST
CHANCES APPEAR TO BE NORTH OF PINELLAS COUNTY.

OTHERWISE...A WEAK FRONTAL BOUNDARY WILL APPROACH THE AREA LATE
TONIGHT AND INTO TUESDAY WITH A SLIGHT CHANCE OF SHOWERS POSSIBLE.
THE WINDS WILL SHIFT TO THE NORTH AND NORTHEAST IN THE WAKE OF THIS
FRONT ON TUESDAY...AND WILL REMAIN OUT OF THE NORTHEAST THROUGH THE
REMAINDER OF THE UPCOMING WEEK AS HIGH PRESSURE SETTLES INTO THE
REGION.


&&

.PRELIMINARY POINT TEMPS/POPS...
TPA  78  67  77  61 /  10  10  30  10
FMY  82  66  81  65 /  10  10  20  10
GIF  81  65  79  61 /  10  10  30  10
SRQ  79  65  77  62 /  10  10  30  10
BKV  80  63  78  55 /  10  20  30  10
SPG  77  66  76  62 /  10  10  30  10

&&

.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...DENSE FOG ADVISORY UNTIL 1 AM EST TUESDAY FOR TARPON
     SPRINGS TO SUWANNEE RIVER OUT 20 NM-TARPON SPRINGS TO
     SUWANNEE RIVER OUT 20 TO 60 NM.

&&

$$

UPDATE/AVIATION...MROCZKA
MARINE...MCKAUGHAN




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