Area Forecast Discussion
Issued by NWS Tampa Bay Area, FL

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FXUS62 KTBW 182008
AFDTBW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAMPA BAY RUSKIN FL
308 PM EST THU DEC 18 2014

...INCREASING RAIN CHANCES LATE IN THE WEEKEND AND EARLY NEXT
WEEK...

.SHORT TERM (TONIGHT - FRIDAY)...
ZONAL FLOW ALOFT AND SURFACE HIGH PRESSURE OVER THE REGION WILL
SUPPORT PLEASANT DRY WEATHER ACROSS THE ENTIRE FORECAST AREA
TONIGHT WITH A STRONG UPPER LEVEL JET ACROSS THE DEEP SOUTH
PRODUCING INTERVALS OF HIGH CLOUDS OVERNIGHT. LIGHT WINDS COMBINED
WITH LOW TEMPERATURE DEW POINT SPREADS WILL FAVOR SOME PATCHY FOG
DEVELOPMENT AFTER MIDNIGHT WITH SOME OF THE FOG POSSIBLY BECOMING
LOCALLY DENSE IN SOME LOCATIONS EARLY FRIDAY MORNING.

ON FRIDAY THE SURFACE HIGH WILL BEGIN TO SHIFT EASTWARD AS A SHORT
WAVE TROUGH AND WEAK WAVE OF LOW PRESSURE MOVES SLOWLY EAST ALONG
THE TX/LA COASTS. AS THE HIGH SHIFTS EAST THE LOW LEVEL FLOW WILL
VEER INTO THE NORTHEAST AND EAST. DRY AND PLEASANT WEATHER WILL
CONTINUE WITH HIGH LEVEL MOISTURE FROM THE AFOREMENTIONED JET
CONTINUING TO SUPPORT INTERVALS OF HIGH CLOUDS. TEMPERATURES
TONIGHT WILL BE TRICKY DUE TO THE HIGH CLOUDS...BUT OVERALL MODEL
CONSENSUS DEPICTS LOWS FALLING TO AROUND 40 ACROSS THE NATURE
COAST...LOWER TO MID 40S CENTRAL INTERIOR ZONES...AND UPPER 40S TO
LOWER 50S SOUTH. HIGH TEMPERATURES ON FRIDAY WILL REMAIN SLIGHTLY
BELOW NORMAL WITH HIGHS AROUND 70 OVER THE NATURE COAST...AND
LOWER TO MID 70S CENTRAL AND SOUTH.

.LONG TERM (FRIDAY NIGHT - THURSDAY)...
THE MODELS ARE IN FAIRLY GOOD AGREEMENT FOR THIS SCENARIO...
ZONAL FLOW CONTINUES FOR SATURDAY WITH GREAT LAKES HIGH PRESSURE
RIDGING SOUTH OVER FLORIDA. SOUTHERLY WINDS DEVELOP AND MAY LEAD
TO SEA FOG AND A CHANCE FOR SHOWERS OVER THE NORTHERN FORECAST
AREA. BY SUNDAY A LONGWAVE TROUGH MOVES OVER THE MISSISSIPPI
VALLEY AND LOW PRESSURE THAT BEGINS TO DEVELOP OVER THE GULF AND
WILL MOVE ASHORE OVER THE FLORIDA PANHANDLE CONTINUING A CHANCE
FOR THUNDERSTORMS. BY MONDAY THE GULF LOW AND RESULTING LOW LEVEL
FLOW STRENGTHENS AND PUMPS UP MORE MOISTURE FROM THE SOUTH AS THE
LONG WAVE TROUGH DEEPENS IN PLACE. THIS WILL BRING A GREATER
CHANCE FOR RAIN. DURING THIS TIME FRAME THE MODELS ARE DEPICTING
SOME WIND SHEAR THAT COULD LEAD TO ORGANIZED CONVECTION. AFTER THE
ACTIVITY TUESDAY THE MOISTURE DECREASES SOME TUESDAY AND RAIN
CHANCES DECREASE SOME BUT ANOTHER SURGE OF MOISTURE COMES TUESDAY
NIGHT INTO WEDNESDAY AS THE LONGWAVE TROUGH DEEPENS FURTHER AND
LOW PRESSURE AREAS INTENSIFY OVER THE GREAT LAKES AND ATLANTIC. A
COLD FRONT PASSES WEDNESDAY AND SKIES BEGIN TO CLEAR FOR THURSDAY.

&&

.AVIATION...
BRIEF MVFR VISIBILITIES FROM PATCHY FOG MAY IMPACT THE TERMINAL
SITES BETWEEN 09-12Z FRIDAY MORNING OTHERWISE VFR CONDITIONS WITH
INTERVALS OF HIGH CIRRUS CLOUDS AOA 200 WILL BE THE RULE. NORTHWEST
WINDS IN THE 6 TO 8 KNOT RANGE THIS AFTERNOON WILL BECOME VARIABLE
5 KNOTS OR LESS AFTER 01Z TONIGHT...BECOMING NORTHEAST TO EAST AT
5 TO 7 KNOTS AFTER 14Z ON FRIDAY.

&&

.MARINE...
WEAK RIDGING WILL BE IN PLACE ACROSS THE WATERS AS WEAK LOW PRESSURE
DEVELOPS OVER THE NORTHERN GULF WATERS THROUGH SATURDAY. THIS TROUGH
WILL THEN LINGER OVER THE EASTERN GULF AND THE LOCAL COASTAL WATERS
THROUGH MONDAY BEFORE FINALLY SHIFTING OFF TO THE NE AND CROSSING
THE PENINSULA. THE FRONTAL BOUNDARY WITH IT WILL LINGER ACROSS THE
SOUTHERN HALF OF THE PENINSULA AS ANOTHER SYSTEM PUSHES INTO THE
REGION TUESDAY NIGHT. WINDS MAY START TO INCREASE EARLY MONDAY AS
THE LOW DEEPENS A BIT OVER THE NORTHERN COASTAL WATERS...AND THEN
AGAIN APPROACH CAUTIONARY LEVELS LATE TUESDAY AS THE NEXT SYSTEM
MOVES INTO THE REGION. OTHERWISE NO HIGHLIGHTS ARE EXPECTED.

&&

.FIRE WEATHER...
DRY AIR OVER THE REGION WILL SUPPORT 2 TO 4 HOURS OF CRITICALLY
LOW HUMIDITY VALUES BELOW 35 PERCENT ACROSS INTERIOR PORTIONS OF
THE NATURE COAST AND INTO CENTRAL INTERIOR SECTIONS OF POLK AND
HILLSBOROUGH COUNTIES DURING FRIDAY AFTERNOON. DESPITE THESE LOW
VALUES THOUGH LOW ERCS AND LIGHT WINDS WILL PRECLUDE RED FLAG
CONDITIONS. IN ADDITION TO THE LOW HUMIDITY LIGHT 20 FOOT WINDS
AND TRANSPORT WINDS WILL YIELD LOW DISPERSION INDICES ACROSS THE
REGION ON FRIDAY AND AGAIN SATURDAY. DURING THE UPCOMING WEEKEND
A SLOW INCREASE IN MOISTURE AND RAIN CHANCES WILL KEEP HUMIDITY
VALUES ABOVE CRITICAL LEVELS WITH NO OTHER FIRE WEATHER ISSUES
EXPECTED AT THIS TIME.

&&

.PRELIMINARY POINT TEMPS/POPS...
TPA  50  72  56  75 /   0   0   0   0
FMY  52  76  58  79 /   0   0   0   0
GIF  48  72  54  76 /   0   0   0   0
SRQ  49  72  55  75 /   0   0   0   0
BKV  40  73  46  75 /   0   0   0  10
SPG  54  71  59  74 /   0   0   0   0

&&

.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&

$$

SHORT TERM/AVIATION/FIRE WEATHER...57/MCMICHAEL
LONG TERM/DECISION SUPPORT...03/PAXTON
MARINE...24/HUBBARD



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