Area Forecast Discussion
Issued by NWS Tampa Bay Area, FL

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FXUS62 KTBW 041017
AFDTBW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAMPA BAY RUSKIN FL
517 AM EST WED MAR 4 2015

...AREAS OF VERY LOW VISIBILITY ACROSS PARTS OF WEST-CENTRAL
FLORIDA THIS MORNING...

.UPDATE...
PATCHY FOG MAINLY ACROSS WEST CENTRAL FLORIDA HAS BECOME LOCALLY
DENSE WITH A DENSE FOG ADVISORY FOR A FEW LOCATIONS EAST AND
NORTH OF TAMPA BAY.

&&

.PREV DISCUSSION... /ISSUED 351 AM EST WED MAR 4 2015/

SYNOPSIS...
ALOFT - LONG WAVE TROUGH STRETCHED SOUTHWESTWARD ACROSS THE CONUS
FROM HUDSON BAY TO NORTHERN BAJA CALIFORNIA. AN UPPER RIDGE...
CENTERED NEAR THE YUCATAN CHANNEL SPRAWLED NORTHWARD TO THE GULF
COAST REGION. SURFACE - HIGH PRESSURE OVER THE CANADIAN PRAIRIES
SPREAD SOUTH AND SOUTHEAST...UP AGAINST A COLD FRONT THAT ARCED
FROM THE NORTHERN U.S. ROCKIES THROUGH THE SOUTH-CENTRAL U.S.
PLAINS THEN UP ACROSS THE LOWER GREAT LAKES. HIGH PRESSURE IN THE
OPEN ATLANTIC RIDGED ACROSS FL AND THE GULF OF MEXICO.

SHORT TERM (TODAY - THURSDAY)...
THE LONG WAVE TROUGH MOVES EAST AND STRETCHES OUT...FROM THE SAINT
LAWRENCE VALLEY TO THE SOUTHERN HIGH PLAINS. THE COLD FRONT OVER THE
PLAINS SHIFTS EAST AND SOUTHEAST...TO THE MID-ATLANTIC COAST THEN
THROUGH THE CENTRAL GULF COAST TO THE WESTERN GULF. THE CANADIAN
HIGH PRESSURE MOVES INTO THE MID-MISSISSIPPI VALLEY. BOTH THE
RIDGE ALOFT THE YUCATAN CHANNEL AND THE SURFACE HIGH IN THE
ATLANTIC TRACK EAST-NORTHEASTWARD...WITH DEEP LAYER RIDGING
HANGING BACK ACROSS FL AND THE EASTERN GULF.

THE UPPER RIDGE MAINTAINS A WARM AND STABLE AIRMASS ACROSS THE AREA
AS IT SLIDES BY WHILE THE SURFACE RIDGE PROVIDES SOUTHEAST TO
SOUTHERLY LOW LEVEL FLOW WITH INCREASING MOISTURE. THIS WILL
CONTINUE THE PATTERN OF LATE NIGHT-EARLY MORNING PATCHY TO AREAS OF
FOG ON LAND. CURRENTLY THERE ARE ONLY A COUPLE OF LOCATIONS WITH
LOWER VISIBILITY BUT WILL CLOSELY MONITOR FOR ANY DENSE FOG. THE
POTENTIAL FOR SEA FOG REMAINS HIGH BUT SEA SURFACE TEMPERATURES HAVE
WARMED SLIGHTLY FROM TAMPA BAY SOUTH...LOWERING THE THREAT THERE.
HOWEVER SEA SURFACE TEMPERATURES OFF THE NATURE COAST REMAIN COOL
WITH SEA FOG MORE LIKELY.

BY THU AFTERNOON THE APPROACHING UPPER TROUGH AND COLD FRONT WILL
BE NEAR ENOUGH TO PROVIDE A FEW SHOWERS BUT ONLY FOR THE FAR
NORTH...IN LEVY COUNTY. AS NOTED ABOVE THE UPPER RIDGE KEEPS A
WARM ATMOSPHERE WITH TEMPERATURES RUNNING ABOVE NORMAL. HIGHS WILL
BE SOME 3 TO 5 DEGREES ABOVE WITH LOWS EVEN A BIT HIGHER.

MID/LONG TERM (FRIDAY THROUGH NEXT TUESDAY)...
MID/UPPER LEVEL RIDGING EAST OF THE BAHAMAS EXTENDS WEST SOUTHWEST
OVER CUBA  AND SOUTHERN FLORIDA. THIS RIDGING WILL WEAKEN AND SLIP
SOUTHEASTWARD AS TROUGHING FROM THE GREAT LAKES TO TEXAS MOVES
EASTWARD. SURFACE HIGH PRESSURE THAT HAS BEEN RIDGING OVER FLORIDA
FOR THE PAST SEVERAL DAYS WILL MOVE EASTWARD AS A FRONTAL BOUNDARY
DRIFTS SOUTHWARD OVER NORTHERN FLORIDA ON FRIDAY. THIS FRONT WILL
STALL OUT ACROSS THE PENINSULA THROUGH THE WEEKEND AS IT IS PINNED
BETWEEN HIGH PRESSURE TO THE NORTH AND HIGH PRESSURE EAST OF THE
BAHAMAS. CLOUD COVER WILL INCREASE WITH THIS FRONT BUT ONLY A SLIGHT
CHANCE OF SHOWERS IS EXPECTED THROUGH SUNDAY.

GFS/ECMWF/CMC ARE IN GOOD AGREEMENT WITH THE PLACEMENT OF THE HIGH
PRESSURE CENTERS AND FRONTAL BOUNDARY THROUGH MONDAY MORNING AND THEN
THEY START TO DIVERGE. GFS/CMC KEEPS STRONG HIGH PRESSURE TO THE
NORTH AS THE DOMINANT FACTOR...WHERE THE ECMWF SLIDES THE HIGH
OFF INTO THE WESTERN ATLANTIC. THE ECMWF IS MORE AGGRESSIVE IN
DEVELOPING AN AREA OF LOW PRESSURE OVER THE NORTHERN GULF COAST.
THEY TAKE THIS LOW OVER THE PANHANDLE AND INTO GEORGIA ON TUESDAY.
THE ECMWF IS THE OUTLIER ON THIS LOW...SO WILL GO WITH THE CONSENSUS
OF THE GFS/CMC AND KEEP MORE BENIGN WEATHER ASSOCIATED WITH HIGH
PRESSURE TO THE NORTH. WINDS THROUGH THE WEEKEND AND INTO EARLY NEXT
WEEK WILL REMAIN OUT OF THE NORTHEAST THROUGH EAST AS THE HIGH TO
THE NORTH RIDGES WEST OVER NORTHERN FLORIDA.

AVIATION...
THROUGH 05/06Z. CURRENTLY VFR BUT ANTICIPATE MVFR 04/08Z-04/13Z...
WITH IFR POSSIBLE. VFR FROM MID MORNING INTO TONIGHT...WITH BR OR
FG BEYOND 05/06Z. LIGHT AND VARIABLE TO CALM WINDS PICK UP AND
BECOME SOUTHERLY FOR THE AFTERNOON.

MARINE...
A STABLE AIRMASS WITH A MOIST LOW LEVEL SOUTHEASTERLY TO SOUTHERLY
FLOW WILL CONTINUE TO RESULT IN PATCHY TO AREAS OF SEA FOG THROUGH
THU. COOLER SEA SURFACE TEMPERATURES NORTH OF TAMPA BAY MAKE DENSE
SEA FOG MORE LIKELY THERE. A COLD FRONT MOVES IN THU NIGHT AND EARLY
FRI WITH A FEW SHOWERS AND NORTHERLY WINDS...REDUCING IF NOT
ELIMINATING ANY SEA FOG CONCERNS IN THE MID TERM. THE FRONT STALLS
OVER THE STATE THROUGH THE WEEKEND AS HIGH PRESSURE SETTLES ALONG
THE GULF COAST WITH WINDS BECOMING NORTHEASTERLY...AND SOMEWHAT
ROBUST AT TIMES...THEN SHIFTING TO EASTERLY AND DIMINISHING WITH
TIME.

FIRE WEATHER...
NO CONCERNS OVER THE NEXT FEW DAYS WITH RELATIVE HUMIDITIES ABOVE
35 PERCENT WITH WINDS AND ERC VALUES BELOW CRITICAL THRESHOLDS.
HOWEVER SOME LATE NIGHT-EARLY MORNING FOG IS EXPECTED OVER THE NEXT
COUPLE OF DAYS.

&&

.PRELIMINARY POINT TEMPS/POPS...
TPA  81  66  81  64 /   0   0   0  10
FMY  85  66  86  66 /   0   0   0  20
GIF  86  66  86  64 /   0   0  10  10
SRQ  82  65  80  64 /   0   0   0  10
BKV  84  59  82  59 /   0   0  10  20
SPG  80  67  80  65 /   0   0   0  20

&&

.TBW WATCHES/WARNINGS/ADVISORIES...
FL...DENSE FOG ADVISORY UNTIL 9 AM EST THIS MORNING FOR INLAND
     CITRUS-INLAND HERNANDO-INLAND PASCO-POLK-SUMTER.

GULF WATERS...NONE.
&&

$$

UPDATE...09/RUDE
SYNOPSIS/SHORT TERM/AVIATION/MARINE/FIRE WEATHER...09/RUDE
LONG TERM/DECISION SUPPORT SERVICES...74/WYNN






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