Area Forecast Discussion
Issued by NWS Tampa Bay Area, FL

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS62 KTBW 280212
AFDTBW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAMPA BAY RUSKIN FL
910 PM EST TUE JAN 27 2015

.DISCUSSION...
THIS EVENINGS SOUNDING SHOWS THE SUBSIDENCE INVERSION WITHIN
NORTHWESTERLY FLOW WITH THE BASE ABOUT 900 MB. SKIES ARE MOSTLY
CLEAR AND TEMPERATURES IN THE 40S OVER NORTHERN ZONES TO 50SS
CENTRAL AND SOME 60S SOUTH. THE SURFACE WINDS ARE NORTHWEST WITHIN A
FAIRLY TIGHT PRESSURE GRADIENT. THE FORECAST IS ON TRACK AND NO
CHANGES ARE NEEDED.

.PREVIOUS LONG TERM (WEDNESDAY NIGHT-TUESDAY)...
WEAK U/L SPLIT FLOW ALONG THE WEST COAST OF THE U.S. WILL BEGIN THE
PERIOD WITH PREDOMINATE NORTHERN STREAM FLOW FROM THE NORTHERN
PLAINS ACROSS THE GREAT LAKES AND MID ATLANTIC REGION. WEAK SOUTHERN
STREAM FLOW WILL OCCUR FROM BAJA CA ACROSS THE SOUTHERN PLAINS AND
SOUTHEAST U.S.  U/L PATTERN WILL TRANSITION THIS WEEKEND INTO EARLY
NEXT WEEK AS A REX BLOCK TAKES SHAPE OVER ALASKA AND THE NORTH
CENTRAL PACIFIC...WITH ZONAL FLOW UNDERCUTTING THE BLOCK AND
ENTERING THE WEST COAST OF THE U.S. WHILE NORTHERN STREAM FLOW RIDES
OVER THE BLOCK ACROSS WESTERN CANADA AND THE NORTHERN PLAINS.
NORTHERN AND SOUTHERN STREAM FLOWS WILL MERGE AROUND THE MID
MISSISSIPPI VALLEY NEAR THE BASE OF THE L/W TROUGH EXTENDING FROM
HUDSON BAY.

SOME SOUTHERN STREAM ENERGY WILL BE PINCHED OFF WITH AN U/L LOW
FORMING VICINITY OF BAJA CA.  EURO AND GFS NOT IN GOOD AGREEMENT IN
THE LONG RANGE WITH THIS FEATURE AS THE EURO OPENS THIS LOW
RATHER QUICKLY AND EJECTS IT THROUGH THE SOUTHERN STREAM EARLY NEXT
WEEK.  GFS HOLDS THIS FEATURE BACK SEVERAL DAYS BEFORE BEING
CAPTURED BY THE MAIN WESTERLIES.  THIS CREATES A SIGNIFICANT
DIFFERENCE REGARDING POSSIBLE SURFACE LOW DEVELOPMENT OVER THE GULF
OF MEXICO NEXT WEEK IN BOTH TIMING AND STRENGTH.  WHEN THIS FEATURE
DOES EJECT...IT WILL PRESENT THE NEXT BEST CHANCE FOR SIGNIFICANT
RAIN ACROSS WEST CENTRAL FLORIDA.

IN THE MEANTIME...GRADUAL MODERATING TEMPERATURES EACH DAY THROUGH
THE WEEKEND.  SURFACE HIGH PRESSURE WILL BE OVER THE CAROLINAS
WEDNESDAY NIGHT SINKING SOUTH OVER FLORIDA ON THURSDAY.  AN U/L
DISTURBANCE WILL DIG OVER THE OHIO AND TENNESSEE RIVER VALLEYS
THURSDAY...MOVING TO THE MID ATLANTIC COAST THURSDAY NIGHT. AN
ASSOCIATED COLD FRONT WILL APPROACH NORTH FLORIDA LATE THURSDAY
NIGHT STALLING AND WASHING OUT OVER THE CENTRAL FLORIDA PENINSULA
FRIDAY AS THE FRONT BECOMES PARALLEL TO THE U/L FLOW.  U/L SUPPORT
WILL REMAIN WELL NORTH OF THE FORECAST AREA...AND MOISTURE WILL BE
EXTREMELY LIMITED SO NO POPS MENTIONED ATTM WITH THE FRONT.  SURFACE
HIGH PRESSURE WILL BUILD OVER THE MID ATLANTIC COAST SATURDAY AND
WILL BRIDGE SOUTH OVER WEST CENTRAL AND SOUTHWEST FLORIDA.  A MUCH
MORE EXTENSIVE L/W TROUGH WILL DEVELOP FROM THE UPPER MISSISSIPPI
VALLEY TO BAJA CA WITH GOOD INFLOW OF DEEP LAYER MOISTURE FROM THE
EASTERN PACIFIC ACROSS THE GULF OF MEXICO.  A NORTHERN STREAM S/W
WILL DIG ACROSS THE MIDWEST U.S. SUNDAY WITH AN ASSOCIATED COLD
FRONT MOVING ACROSS THE LOWER MISSISSIPPI VALLEY AND WESTERN FLORIDA
PANHANDLE WITH AN AREA OF SHOWERS AND THUNDERSTORMS.  THE FRONT WILL
APPROACH NORTH CENTRAL FLORIDA LATE SUNDAY NIGHT...HOWEVER U/L
SUPPORT WILL BE LIFTING OUT RAPIDLY AND L/L CONVERGENCE ALONG THE
BOUNDARY WILL BE WEAKENING.  THIS WILL CAUSE THE AREA OF SHOWERS AND
THUNDERSTORMS TO GRADUALLY WEAKEN AND DECREASE IN AREAL COVERAGE AS
THE PRECIPITATION APPROACHES THE FORECAST AREA...WITH ONLY A CHANCE
OF SHOWERS SUNDAY NIGHT AND MONDAY. THE FRONT MAY STALL ACROSS THE
CENTRAL FLORIDA PENINSULA ON TUESDAY...WITH A SLIGHT CHANCE OF
SHOWERS PERSISTING AND SLIGHTLY COOLER AIR ADVECTING OVER THE
REGION.


&&

.AVIATION...
VFR CONDITIONS WILL CONTINUE.

&&

.MARINE...
THE WINDS HAVE INCREASED TONIGHT BEHIND A REINFORCING COLD FRONT
THREFORE A SMALL CRAFT ADVISORY WAS ISSUED WITH SCEC CONDITIONS FOR
THE NEARSHORE WATERS. WINDS WILL BECOME MORE NORTHERLY OVERNIGHT AND
SUBSIDE WEDNESDAY AS HIGH PRESSURE SETTLES ACROSS THE AREA.

&&

.TBW WATCHES/WARNINGS/ADVISORIES...
FL...RIP CURRENT RISK UNTIL 10 PM EST THIS EVENING FOR COASTAL
     CHARLOTTE-COASTAL HILLSBOROUGH-COASTAL LEE-COASTAL
     MANATEE-COASTAL SARASOTA-PINELLAS.

GULF WATERS...SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 4 AM
EST      WEDNESDAY FOR BONITA BEACH TO ENGLEWOOD OUT 20 TO 60
NM-ENGLEWOOD TO TARPON SPRINGS OUT 20 TO 60 NM-TARPON      SPRINGS
TO SUWANNEE RIVER OUT 20 TO 60 NM.

&&

$$

CP/PC/AM









USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.