FXUS62 KTBW 290736
AFDTBW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAMPA BAY RUSKIN FL
236 AM EST SUN NOV 29 2009
.SHORT TERM (TODAY THROUGH TUESDAY)...THE SHORT TERM FORECAST
PERIOD WILL REMAIN RATHER QUIET FOR THE FIRST TWO DAYS WITH ONLY
SOME MINOR TWEAKS. HAVE ADJUSTED SKY COVER UP A BIT FOR THE FIRST
PART OF TODAY. IR SAT CONTINUES TO SHOW LARGE AREA OF CIRRUS
FLOWING ACROSS THE AREA...REPRESENTED BY H5 RH IN THE MODEL
FIELDS...AND THIS SHOULD BE LARGELY THROUGH THE AREA BY THE 15 TO
18Z TIME FRAME. THIS IS DUE TO A WEAK SHORTWAVE WHICH IS CROSSING
THE AREA AND WILL EXIT AFTER 18Z...ALLOWING FOR SUBSIDENCE AND
CLEARING IN ITS WAKE THIS AFTERNOON. TEMPS WILL WARM FROM THE PAST
FEW DAYS AS THE AIRMASS MODERATES AND WINDS TURN SOUTHWESTERLY.
ANOTHER COOL NIGHT TONIGHT BUT NOT AS COOL AS THE PREVIOUS NIGHTS
DUE TO A MODERATED AIRMASS. SOME LOWER 40S POSSIBLE IN THE NORTH
BUT IN THE SOUTH LOWS SHOULD REMAIN MORE IN THE 50S. MONDAY SEES
THE AREA EXPERIENCE THE APPROACH OF A WEAKENING COLD FRONT INTO
THE NORTHERN PANHANDLE. THIS WILL KEEP A LOW LEVEL WARM ADVECTION
PATTERN AND TEMPS WILL REMAIN IN THE MIDDLE TO UPPER 70S.
BY TUESDAY THE TRAILING END OF THE FRONT OVER THE NORTHWEST GULF
WILL ALLOW A LOW PRESSURE SYSTEM TO SPIN UP TO OUR WEST AS A
STRONG H5 TROUGH SLOWLY MEANDERS EAST OUT OF NORTHERN MEXICO. THIS
WILL INCREASE LOW LEVEL WARM ADVECTION IN THE AREA AND PUSH TEMPS
TO NEAR 80. HOWEVER IT WILL SLOW BRING AN INCREASE OF MID LEVEL
MOISTURE AND THIS WILL MEAN MORE CLOUDINESS AND A CHANCE OF
SHOWERS IN THE NORTH CLOSER TO THE STATIONARY FRONTAL BOUNDARY.
HOWEVER WILL JUST KEEP THE LOW CHANCES IN THE FORECAST GIVEN THAT
THE SYSTEM CONTINUES TO LOOK SLOWER EACH RUN.
.LONG TERM...(TUESDAY NIGHT THROUGH SATURDAY)...POTENTIAL FOR
SIGNIFICANT WEATHER EVENT TO MOVE THROUGH THE AREA LATE WEDNESDAY
INTO EARLY THURSDAY. CONTINUE TO EXPECT CLOSED UPPER LOW OVER S
TEXAS TO MOVE EASTWARD TUESDAY NIGHT AND BECOME OPEN WEDNESDAY IN
THE LOWER MISSISSIPPI RIVER VALLEY COMING IN PHASE WITH LONGWAVE
TROUGH FROM THE GREAT LAKES REGION. WARM FRONT TO LIFT INTO NORTH
FLORIDA TUESDAY NIGHT WITH CHANCE POPS OVER NORTHERN AREAS CLOSEST
TO THE FRONT WITH SLIGHT CHANCE POPS FROM THE BAY AREA SOUTHWARD.
SIGNIFICANT DYNAMICS TO MOVE THROUGH THE DEEP SOUTH WEDNESDAY
PUSHING SURFACE STORM SYSTEM THROUGH THE DEEP SOUTH WITH ATTENDANT
COLD FRONT AND PRE FRONTAL LINE OF CONVECTION OVER THE
NORTHEASTERN GULF THEN EASTERN GULF. HAVE KEPT LIKELY POPS OVER
THE NATURE COAST AND ADJACENT COASTAL WATERS LATE WEDNESDAY WITH
CHANCE POPS FROM THE BAY AREA SOUTHWARD. BY WEDNESDAY NIGHT UPPER
TROUGH TO BECOME SLIGHTLY NEGATIVELY TILTED ENHANCING UPPER
SUPPORT WHILE UPPER JET STREAK AND LOW LEVEL JET MOVE OVER THE
AREA TO GENERATE LIKELY THUNDERSTORMS AREA WIDE. EXPECT STRONG TO
POSSIBLY SEVERE STORMS WITH THE PRE FRONTAL LINE WITH STRONG GUSTY
WINDS AND HEAVY RAIN THE MAIN THREATS. ALL LONG RANGE MODELS HAVE
THIS SCENARIO BUT EXACT TIMING AND PLACEMENT OF MOST SIGNIFICANT
FEATURES VARY SLIGHTLY WITH THE GFS ABOUT 6 HOURS FASTER THAN
OTHERS. WILL CONTINUE TO CLOSELY MONITOR MODEL OUTPUT AND ADJUST
TIMING AS NEEDED. ACTUAL COLD FRONT TO MOVE OVER THE AREA THURSDAY
WITH COOLER AND DRIER CONDITIONS FILTERING INTO THE AREA AS HIGH
PRESSURE BUILDS INTO THE REGION TO END THE WEEK. UPPER FLOW TO
REMAIN SW WITH SEVERAL VORTICITY MAXES ROTATING OVERHEAD SO WILL
KEEP 10 TO 20 POPS TO END THE WEEK AND INTO THE WEEKEND.
TEMPERATURES TO RUN SLIGHTLY ABOVE NORMAL AHEAD OF THE FRONT THROUGH
MID WEEK THEN FALL 5 TO 10+ DEGREES BELOW NORMAL BEHIND THE FRONT TO
END THE WEEK.
&&
.AVIATION...VFR CONDITIONS TO CONTINUE TODAY AND TONIGHT WITH
CIRRUS CLOUDS OVERHEAD.
&&
.MARINE...NO MARINE CONCERNS FOR THE NEXT SEVERAL DAYS WITH HIGH
PRESSURE OVER THE EASTERN GULF CONTINUING TO PROVIDE LIGHT WINDS
AND SEAS. A LOW PRESSURE SYSTEM DEVELOPING OVER THE NORTHWEST GULF
OF MEXICO BY TUESDAY AND MOVING EAST BY WEDNESDAY AND THURSDAY
WILL BRING SOME MARINE CONCERNS IN THE FORM OF HAZARDOUS BOATING
CONDITIONS DURING THE LATE WEEK TIME. MARINERS SHOULD CONTINUE TO
MONITOR THIS DEVELOPING SITUATION.
&&
.FIRE WEATHER...LOW RH VALUES OF 35 PERCENT OR LOWER ARE POSSIBLE
FOR AN HOUR OR TWO IN AREAS FROM TAMPA BAY TO THE NORTH. ELSEWHERE
THE RH WILL BE 40 PERCENT OR LESS BUT NOT QUITE LOW ENOUGH TO
CREATE CRITICAL FIRE WEATHER CONDITIONS. THIS WILL BE DUE TOT HE
INCREASING LOW LEVEL MOISTURE AS WINDS TURN MORE WESTERLY TODAY.
THIS TREND WILL CONTINUE FOR THE NEXT FEW DAYS AS MORE LOW LEVEL
RH RETURNS AND DIMINISHES FIRE WEATHER CONCERNS.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 74 56 77 60 / 0 5 5 10
FMY 78 57 82 61 / 0 5 5 10
GIF 73 54 78 59 / 0 5 5 10
SRQ 73 53 78 59 / 0 5 5 10
BKV 73 39 76 52 / 0 5 5 10
SPG 70 59 75 62 / 0 5 5 10
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
SHORT TERM/MARINE/FIRE WEATHER...35/JOHNSON
LONG TERM/AVIATION...25/DAVIS
