FXUS62 KTBW 151817
AFDTBW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAMPA BAY RUSKIN FL
117 PM EST TUE DEC 15 2009
.SHORT TERM (TONIGHT-THURSDAY)...PATTERN CHANGE ON THE WAY. UPPER
RIDGE TO WEAKEN AND BECOME SUPPRESSED BACK INTO THE CARIBBEAN AS
SHORTWAVE TROUGH DEEPENS AND MOVES INTO THE NW GULF BY THURSDAY.
FRONTAL BOUNDARY OVER THE DEEP SOUTH THIS AFTERNOON EXPECTED TO
SAG FURTHER SOUTH AS LARGE DOME OF HIGH PRESSURE MOVES THROUGH
THE SOUTHERN GREAT LAKES REGION BRIDGING FRONT AND VEERING OUR LOW
LEVEL WINDS MORE NORTHERLY BY MORNING. DEEPER MEAN LAYER MOISTURE
AND INSTABILITY TO REMAIN OVER N FL CLOSE TO FRONT AND ALSO SW AND
S FL CLOSE TO SE TROPICAL FLOW. WILL KEEP SLIGHT CHANCE POPS THOSE
AREA ONLY TONIGHT. LOW LEVEL FLOW EXPECTED TO BE LIGHT OVERNIGHT
WITH PARTLY CLOUDY SKIES...HIGH DEWPOINTS...AND WARM TEMPERATURES
MAY AGAIN SEE PATCHY TO AREAS OF FOG OVERNIGHT.
ON WEDNESDAY MEAN LAYER MOISTURE INCREASES FURTHER AS UPPER
VORTICITY MAXIMUM MOVES OFF THE E GULF OVER THE AREA WITH MID TO
UPPER SW FLOW. SURFACE HIGH PRESSURE N OF THE REGION AND LOWER
PRESSURE TO THE S TO PRODUCE TIGHTER GRADIENT AND NE LOW LEVEL
FLOW. THIS IS ANOTHER PRIME SET UP FOR AN OVERRUNNING RAIN EVENT
WITH MOSTLY CLOUDY TO CLOUDY SKIES...COOL BUT NEAR NORMAL SURFACE
TEMPERATURES AND CHANCES FOR RAIN. BY THURSDAY RAIN CHANCES
INCREASE FURTHER AS MEAN LAYER MOISTURE CONTINUES TO INCREASE AND
SERIES OF UPPER LEVEL DISTURBANCES MOVE OVER THE REGION AND HAVE
BUMPED UP POPS ALL AREAS.
.LONG TERM (THURSDAY NIGHT THROUGH MONDAY)...MAIN FOCUS FOR THE LONG
TERM REMAINS THE POTENTIAL IMPACTS FROM A LOW PRESSURE SYSTEM MOVING
INTO OUR REGION FROM THE WESTERN GULF. GFS AND ECMWF REMAIN IN
GOOD AGREEMENT ABOUT THE TIMING AND PLACEMENT OF THIS SYSTEM. BOTH
REMAIN CONSISTENT SHOWING STRONG ZONAL FLOW OVER THE SE US COAST
WHICH WILL HELP PUSH THIS SYSTEM QUICKLY THROUGH THE REGION BY
SATURDAY MORNING. NOT EXPECTING MUCH IN THE WAY STRONG THUNDERSTORMS
AS THIS SYSTEM BEGINS TO AFFECT THE AREA ON FRIDAY MORNING. UPPER
LEVEL SUPPORT DOES NOT REMAIN FAVORABLE FOR MUCH THUNDERSTORM
DEVELOPMENT SHOWING ONLY A WEAK UPPER LEVEL SHORTWAVE TRAVERSING THE
REGION. ALTHOUGH...FORECASTED THERMODYNAMICS DO INDICATE SOME
POTENTIAL FOR SOME STORMS SO WILL CARRY A CHANCE OF THUNDERSTORMS
FOR FRIDAY MORNING. MAIN IMPACT WILL BE HEAVY RAINFALL ALONG THE
FRONT.
AS THE SYSTEM QUICKLY MOVES THROUGH THE REGION BY EARLY
SATURDAY...HIGH PRESSURE BUILDS FROM THE NORTH. ALONG WITH THE
SURFACE RIDGE BUILDING IN...COLD AIR ADVECTION WILL START TO FILTER
IN SOME BRISK DECEMBER TEMPS. MORNING LOWS FOR MONDAY COULD DIP INTO
THE LOW TO MID 30S FURTHER NORTH AWAY FROM THE COAST TO THE MID 40S
FURTHER SOUTH. AFTERNOON HIGHS ARE CURRENTLY FORECAST TO FALL ABOUT
5-10 DEGREES BELOW NORMAL FOR THE BRINGING OF THE WEEK WITH TEMPS
RANGING FROM THE UPPER 50S UP NORTH TO THE LOW TO MID 60S SOUTH.
$$
AVIATION...VFR CONDITIONS EXPECTED THROUGH EARLY TOMORROW FOR ALL
TERMINALS. BY THE MORNING...FOG IS EXPECTED TO SET IN ONCE AGAIN
WHICH WILL CAUSE PERIODS OF IFR/LIFR CONDITIONS. A WEAK FRONT IS
FORECAST TO PUSH THROUGH THE REGION BEGINNING TOMORROW MORNING SO
FOG MAY NOT BE AS THICK AROUND THE TAMPA BAY AREA. REGARDLESS...WILL
CARRY A TEMPO GROUP FOR A COUPLE HOURS RIGHT AROUND SUNRISE TO
HIGHLIGHT FOG DEVELOPMENT.
&&
.MARINE...WARM AND HUMID AIRMASS TO HOLD OVER THE E GULF REST OF
THIS AFTERNOON INTO THIS EVENING TO CONTINUE TO PRODUCE AREAS OF
SEA FOG WITH LOCALLY DENSE PATCHES OF VIS LESS THAT 1 NM. SO WILL
CONTINUE DENSE FOG ADVISORY FOR MARINE ZONE FROM ENGLEWOOD TO
SUWANNEE RIVER OUT TO 60MN UNTIL 10 PM.
COLD FRONT OVER THE N CENTRAL GULF REGION THIS AFTERNOON TO PUSH
INTO THE NE GULF LATE THIS EVENING AND THE E GULF OVERNIGHT TO BRING
WINDS AROUND TO A NORTHERLY DIRECTION. THIS WILL BRING LOWER
DEWPOINTS TO THE WATERS AND REDUCE SEA FOG POTENTIAL OVERNIGHT. BY
WEDNESDAY MORNING THE GRADIENT OVER THE E GULF TO TIGHTEN...INCREASING
NE WINDS AND SEAS LASTING THROUGH THURSDAY BETWEEN HIGH PRESSURE
OVER THE CAROLINAS AND THE STALLED FRONT IN THE SOUTHERN GULF. LOW
PRESSURE CENTER EXPECTED TO FORM ALONG THE GULF FRONT AND MOVE
INTO THE NE-E GULF FRIDAY WITH BREEZY CONDITIONS AND HIGH RAIN
CHANCES. ANOTHER RIDGE OF HIGH PRESSURE TO BUILD OVER REGION WITH
BREEZY NW-NORTHERLY WINDS AND SEAS FOR THE WEEKEND.
&&
.FIRE WEATHER...LOW LEVEL MOISTURE TO REMAIN OVER THE AREA REST OF
THE WEEK INTO THE WEEKEND. COOLER AND DRIER CONDITIONS ARE EXPECTED
BY EARLY NEXT WEEK.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 65 76 60 74 / 10 30 20 40
FMY 66 81 62 78 / 20 30 20 50
GIF 63 76 57 74 / 10 30 20 40
SRQ 63 78 60 76 / 10 30 20 40
BKV 59 74 56 73 / 10 30 10 30
SPG 66 75 62 73 / 10 30 20 40
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...DENSE FOG ADVISORY UNTIL 10 PM EST THIS EVENING FOR
ENGLEWOOD TO SUWANNEE RIVER OUT TO 60 NM.
&&
$$
SHORT TERM/MARINE/FIRE WEATHER...25/DAVIS
LONG TERM/AVIATION...20/BARRON
