Area Forecast Discussion
Issued by NWS Tampa Bay Area, FL

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000
FXUS62 KTBW 301928
AFDTBW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAMPA BAY RUSKIN FL
228 PM EST FRI JAN 30 2015

.SHORT TERM (TONIGHT-SATURDAY)...
STRONG REX BLOCK DEVELOPING IN THE EASTERN PACIFIC WITH
SPLIT FLOW PATTERN ALONG THE WEST COAST OF THE U.S. WITH MAIN
NORTHERN STREAM U/L FLOW OVERRIDING THE BLOCK ACROSS NORTHERN ALASKA
TO WESTERN CANADA...AND ACROSS THE UPPER MISSISSIPPI VALLEY TO THE MID
ATLANTIC COAST.  STRONG U/L DISTURBANCE HAS CUTOFF OVER THE DESERT
SOUTHWEST AND BAJA CA IN SOUTHERN STREAM FLOW UNDERCUTTING THE BLOCK
WITH QUASI ZONAL FLOW ACROSS THE SOUTHERN TIER OF THE U.S.  AN U/L
DISTURBANCE WILL MOVE OFF THE MID ATLANTIC COAST TONIGHT WITH A
DEEPENING AREA OF LOW PRESSURE OFF THE NEW ENGLAND COAST.  COLD
FRONT ASSOCIATED WITH THE LOW PRESSURE SYSTEM WELL TO THE NORTH IS
MOVING ACROSS THE FLORIDA PENINSULA ATTM...AND WILL BE SOUTH OF THE
FORECAST AREA BY THIS EVENING.  WITH LIMITED MOISTURE AND U/L
DYNAMICS WELL TO THE NORTH...DRY FRONTAL PASSAGE WITH WINDS SHIFTING
TO THE NORTH AND NORTHEAST TONIGHT BEHIND THE FRONT.  SURFACE HIGH
PRESSURE WILL BUILD OVER THE SOUTHEAST U.S. AND FLORIDA TONIGHT AND
SATURDAY WITH CLEARING SKIES AND DRIER COOLER AIR ADVECTING ACROSS
THE REGION.  TEMPERATURES TONIGHT WILL DROP INTO THE MID TO UPPER
30S ACROSS THE NATURE COAST...LOWER TO MID 40S CENTRAL...AND UPPER
40S TO AROUND 50 SOUTH.  HIGHS ON SATURDAY WILL RANGE FROM THE MID
60S NORTH TO THE LOWER 70S SOUTH.

.LONG TERM (SATURDAY NIGHT-FRIDAY)...
HIGH PRESSURE OVER THE AREA ON SATURDAY NIGHT INTO SUNDAY MORNING
WILL BE SHORT-LIVED AS THE NEXT SYSTEM APPROACHES THE AREA FROM
THE WEST. BY SUNDAY NIGHT...THE FRONTAL SYSTEM WILL HAVE
PROGRESSED HALFWAY ACROSS THE GULF OF MEXICO. THE LOW PRESSURE
CENTER WILL PUSH OFF THE MID- ATLANTIC COAST AND THE TRAILING
FRONT WILL MOVE ACROSS THE PENINSULA OF FLORIDA ON MONDAY.

THE BOUNDARY WILL STALL OVER SOUTHERN FLORIDA ON MONDAY NIGHT INTO
TUESDAY MORNING. THE NEXT SYSTEM BEGINS TO EMERGE OVER THE WESTERN
GULF OF MEXICO AND PROGRESS EAST. THERE IS SIGNIFICANT DIFFERENCES
IN TIMING AND TRACK FOR THIS SYSTEM BETWEEN THE 12Z GFS AND ECMWF.
EITHER WAY...IT APPEARS THIS LAST SYSTEM WILL IMPACT THE AREA
BETWEEN WEDNESDAY AND THURSDAY. THE GFS IS A BIT FASTER THAN THE
ECMWF. THE ECMWF ALSO KEEPS THE LOW TRACK MORE ZONAL COMPARED TO THE
GFS LIFTING THE SYSTEM NORTHEASTWARD FROM MEXICO THROUGH THE BIG
BEND OF FLORIDA TOWARDS THE ATLANTIC.

EVEN WITH THE DIFFERENCES IN GUIDANCE...IT APPEARS RAIN CHANCES WILL
BE HIGH ENOUGH TO MENTION. HAVE ALSO INCLUDED A SLIGHT CHANCE OF
THUNDERSTORMS WITH EACH OF THESE FRONTAL PASSAGES. WE WILL HAVE TO
MONITOR DYNAMICS OVER SEVERAL MODEL RUNS TO SEE WHAT SEVERE WEATHER
POTENTIAL THERE MAY BE.

&&

.AVIATION...
AREAS OF MVFR CIGS 025-030 WILL BE ASSOCIATED WITH A COLD FRONT
PUSHING ACROSS WEST CENTRAL AND SOUTHWEST FLORIDA THIS AFTERNOON AND
WILL MAINLY AFFECT TPA/PIE/SRQ/LAL FOR 1 TO 2 HOURS.  OTHERWISE VFR
CONDITIONS WILL PREVAIL THROUGH SATURDAY.

&&

.MARINE...
WINDS AND SEAS WILL INCREASE BEHIND A COLD FRONT THIS AFTERNOON AND
EVENING WITH SMALL CRAFT ADVISORY CONDITIONS TONIGHT OVER THE
COASTAL WATERS WITH THE EXCEPTION OF TAMPA BAY AND CHARLOTTE
HARBOR.  GRADIENT WILL WEAKEN ON SATURDAY WITH WINDS VEERING TO
THE EAST AT AROUND 15 KNOTS. WINDS MAY APPROACH ADVISORY CRITERIA
SATURDAY NIGHT INTO SUNDAY AS AN AREA OF LOW PRESSURE DEVELOPS
OVER THE LOWER MISSISSIPPI VALLEY. THE ASSOCIATED COLD FRONT WILL
PUSH ACROSS THE WATERS MONDAY NIGHT WITH NORTH WINDS BEHIND THE
FRONT ALSO AROUND ADVISORY LEVELS. WINDS AND SEAS WILL SUBSIDE
MONDAY NIGHT AND TUESDAY AS HIGH PRESSURE BUILDS OVER THE WATERS.

&&

.FIRE WEATHER...
NO FIRE WEATHER HAZARDS EXPECTED. RELATIVE HUMIDITY VALUES WILL
REMAIN ABOVE CRITICAL LEVELS THROUGH THE PERIOD.

&&

.PRELIMINARY POINT TEMPS/POPS...
TPA  46  70  52  74 /   0   0   0   0
FMY  51  73  53  77 /   0   0   0   0
GIF  46  68  50  76 /   0   0   0   0
SRQ  48  71  52  74 /   0   0   0   0
BKV  38  68  44  75 /   0   0   0   0
SPG  54  68  56  73 /   0   0   0   0

&&

.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...SMALL CRAFT ADVISORY FROM 9 PM THIS EVENING TO 4 AM EST
     SATURDAY FOR BONITA BEACH TO ENGLEWOOD OUT 20 NM-
     BONITA BEACH TO ENGLEWOOD OUT 20 TO 60 NM-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.

&&

$$

SHORT TERM/AVIATION/FIRE WEATHER...13/OGLESBY
LONG TERM...02/GARCIA
MARINE...13/OGLESBY
DECISION SUPPORT...02/GARCIA




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