Area Forecast Discussion
Issued by NWS Tampa Bay Area, FL

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000
FXUS62 KTBW 010850
AFDTBW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAMPA BAY RUSKIN FL
350 AM EST SUN FEB 1 2015

.SHORT TERM (TODAY-MONDAY)...
AMPLIFIED MID-LEVEL TROUGH WILL MOVE ACROSS THE MISSISSIPPI VALLEY
TODAY AND THROUGH THE EASTERN U.S. ON MONDAY AS A CUTOFF LOW
DRIFTS ACROSS NORTHERN MEXICO. MEANWHILE AT THE SURFACE...HIGH
PRESSURE ALONG THE SOUTHEAST U.S. COAST THIS MORNING WILL MOVE OUT
INTO THE WESTERN ATLANTIC OCEAN TODAY SETTING UP A RETURN FLOW.
LOW LEVEL WINDS WILL SHIFT TO SOUTHEASTERLY LEADING TO A GRADUAL
INCREASE IN ATLANTIC MOISTURE WITH SOME SCATTERED TO BROKEN
STRATOCUMULUS/ALTOCUMULUS EXPECTED TO MOVE NORTHWESTWARD DURING
THE DAY. THE LOW LEVEL FLOW SHOULD WEAKEN ENOUGH THIS AFTERNOON
TO ALLOW WINDS TO SHIFT TO A MORE SOUTH TO SOUTHWEST DIRECTION
NEAR THE COAST DURING THIS AFTERNOON AS THE SEA BREEZE TRIES TO
DEVELOP. SOUTHEAST TO SOUTH WINDS TONIGHT WILL SHIFT TO SOUTHWEST
EARLY MONDAY AS THE COLD FRONT ASSOCIATED WITH THE MID-LEVEL
TROUGH APPROACHES FROM THE NORTHWEST. MOISTURE WILL CONTINUE TO
DEEPEN AHEAD OF THIS BOUNDARY WITH A FEW SHOWERS POSSIBLE ACROSS
THE NORTHERN HALF OF THE AREA...GENERALLY NORTH OF THE INTERSTATE
4 CORRIDOR LATE TONIGHT. WILL ALSO SEE SOME FOG LATE TONIGHT...
ESPECIALLY SOUTH OF THE INTERSTATE 4 CORRIDOR WHERE LESS CLOUDS
ARE EXPECTED OVERNIGHT AND WINDS WILL NOT BE AS STRONG. DURING
MONDAY THE COLD FRONT WILL SWEEP ACROSS THE REGION...BUT THERE ARE
SOME TIMING DIFFERENCES BETWEEN THE MODELS WITH THE OUTLIER BEING
THE NAM WHICH IS ABOUT 4 TO 6 HOURS SLOWER THAN THE OTHER MODELS.
HAVE DECIDED TO GO MORE WITH THE CONSENSUS OF THE
GFS/ECMWF/CANADIAN FOR THIS FORECAST WHICH BRING THE BOUNDARY
INTO THE NATURE COAST DURING THE MID TO LATE MORNING...THE TAMPA
BAY AREA DURING EARLY AFTERNOON AND INTO THE FORT MYERS AREA AND
SOUTHERN INTERIOR TOWARD EVENING. PLENTY OF MOISTURE WILL HAVE
OVERSPREAD THE AREA AHEAD OF THE FRONT SO EXPECT SCATTERED TO
NUMEROUS SHOWERS...AND POSSIBLY AN ISOLATED THUNDERSTORM OR
TWO...AHEAD OF IT AND HAVE THEREFORE RAISED POPS TO LIKELY FROM
AROUND TAMPA BAY AND THE INTERSTATE 4 CORRIDOR NORTHWARD WITH
CHANCE POPS FURTHER SOUTH. HIGH TEMPERATURES TODAY WILL BE A FEW
DEGREES ABOVE NORMAL AND MAINLY IN THE 70S. LOWS TONIGHT WILL BE
ABOVE NORMAL THANKS TO THE SOUTHERLY FLOW OF MOIST AIR WITH LOWS
IN THE UPPER 50S TO LOWER 60S. HIGHS ON MONDAY WILL RANGE FROM
NEAR NORMAL IN THE UPPER 60S TO LOWER 70S NORTHERN HALF TO A FEW
DEGREES ABOVE NORMAL IN THE MID TO UPPER 70S SOUTH AND SOUTHERN
INTERIOR WHERE THE CLOUDS AND RAIN WILL BE LAST TO AFFECT.

.MID/LONG TERM (MONDAY NIGHT-SATURDAY)...
COLD FRONT SHOULD BE THROUGH OUR ENTIRE REGION BY MIDNIGHT MONDAY
NIGHT WITH ANY LINGERING EVENING SHOWERS COMING TO AN END. FAIRLY
ROBUST COLD AIR ADVECTION WILL BE OCCURRING OVERNIGHT...BUT MODELS
SHOW QUITE A BIT OF SPREAD IN LOW TEMPERATURE FORECASTS. THE
WARMEST GUIDANCE IS FROM THE NAM/MET WHERE 925 MB TEMPERATURES
STAY SEVERAL DEGREES WARMER THAN THE COOLER ECMWF AND COLDEST GFS.
FOR NOW DECIDED A BLEND WAS BEST...BUT WITHOUT TOO MUCH EMPHASIS
FROM THE WARM MET GUIDANCE. THIS BRINGS LOWER TO MIDDLE 30S DOWN
THROUGH THE NATURE COAST AND MID 40S TO AROUND 50 OR SO FROM TAMPA
BAY SOUTH.

WE WILL REMAIN COOLER THAN NORMAL ON TUESDAY...BUT THE BULK OF THE
COLD AIR PASSES BY TO OUR NORTH LEAVING OUR AREA WITH HIGHS FROM
THE LOWER 60S NORTH TO LOWER 70S SOUTH.

THE FORECAST CHALLENGE FOR THE EXTENDED FORECAST LIES IN THE
EVENTUAL EVOLUTION OF A CUT-OFF UPPER-LEVEL LOW OVER NORTHERN
MEXICO. THIS ENERGY INITIALLY SHIFTS SOUTHWARD BEFORE BEGINNING
TO OPEN UP AND MOVE EASTWARD TOWARD TEXAS. MODELS BEGIN TO
STRUGGLE WITH THIS FEATURE BY WEDNESDAY WHICH LENDS TO A VERY
LOW-CONFIDENCE FORECAST FOR THURSDAY AND FRIDAY. WE ARE DEALING
WITH DIFFERENCES BETWEEN INDIVIDUAL MODELS AS WELL AS RUN-TO-RUN
VARIATIONS WITHIN EACH MODEL. THE ECMWF IS THE CLOSEST TO OUR
PREVIOUS FORECAST AND HAS WEAK LOW PRESSURE MOVING ACROSS THE
PENINSULA ON THURSDAY. THE CANADIAN IS NOT FAR OFF TIMING WISE
ALTHOUGH IT SHOWS A DEEPER LOW PASSING A LITTLE FARTHER NORTH. THE
GFS IS THE SLOWEST OF THE GUIDANCE...ABOUT 12 TO 18 HOURS BEHIND
THE ECMWF. IN THE END...CHOSE TO MAINTAIN CONTINUITY WITH THE
PREVIOUS FORECAST AND SHOW THE HIGHEST RAIN CHANCES ON THURSDAY
AS BOTH THE UPPER-SYSTEM AND ASSOCIATED SURFACE REFLECTION MOVE
ACROSS THE STATE. THIS COULD BE A DECENT RAIN MAKER AND DOES HAVE
THE POTENTIAL TO PRODUCE STRONG TO SEVERE THUNDERSTORMS OVER THE
AREA. IT IS STILL WAY TOO EARLY TO KNOW IF...WHEN...OR WHERE A
SEVERE THREAT WILL MATERIALIZE...BUT WILL BEGIN TO MENTION THE
POSSIBILITY IN THIS MORNINGS HAZARDOUS WEATHER OUTLOOK.

ANOTHER COOL AIRMASS SHOULD MOVE IN BEHIND THIS SYSTEM AND BE WITH
US FOR THE END OF THE WEEK.

&&

.AVIATION...
VFR CONDITIONS WILL PREVAIL THROUGH THIS EVENING.

&&

.MARINE...
BREEZY EAST TO SOUTHEAST WINDS WILL GRADUALLY DIMINISH TODAY AND
SHIFT TO A MORE SOUTHERLY DIRECTION. THE NEXT COLD FRONT WILL
MOVE ACROSS THE WATERS MONDAY SHIFTING WINDS TO NORTHERLY AND
INCREASING SPEEDS BACK TO EXERCISE CAUTION LEVELS INTO MONDAY
NIGHT. WINDS AND SEAS WILL THEN SUBSIDE FOR TUESDAY AND WEDNESDAY
THEN INCREASE ONCE AGAIN THURSDAY INTO FRIDAY AS ANOTHER COLD
FRONT MOVES ACROSS THE WATERS.

&&

.FIRE WEATHER...
NO FIRE WEATHER CONCERNS FOR THE NEXT FEW DAYS AS RELATIVE
HUMIDITY VALUES REMAIN ABOVE 35 PERCENT WITH ERC AND WINDS BELOW
CRITICAL THRESHOLDS. SOME AREAS OF FOG WILL BE POSSIBLE LATE
TONIGHT INTO MONDAY MORNING AS LOW LEVEL MOISTURE INCREASES AHEAD
OF THE COLD FRONT.

&&

.PRELIMINARY POINT TEMPS/POPS...
TPA  74  62  71  45 /   0  20  70  10
FMY  78  61  78  52 /   0  10  40  20
GIF  75  59  74  45 /   0  10  50  10
SRQ  76  61  73  48 /   0  10  60  10
BKV  75  59  70  36 /   0  20  70  10
SPG  72  62  70  51 /   0  20  60  10

&&

.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...SMALL CRAFT ADVISORY UNTIL 10 AM EST THIS MORNING
     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.

&&

$$

SHORT TERM/AVIATION/MARINE/FIRE WEATHER...69/CLOSE
MID/LONG TERM/DECISION SUPPORT...63/JILLSON




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