FXUS62 KTBW 120223
AFDTBW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAMPA BAY RUSKIN FL
923 PM EST FRI DEC 11 2009
.UPDATE...PREVIOUS FORECAST WAS BASICALLY IN GOOD SHAPE TONIGHT.
ONLY SOME MINOR ADJUSTMENTS MADE TO LOWER POPS ACROSS THE NORTH A
BIT...AND ADJUST TEMPERATURE AND DEW POINT GRIDS TO REALITY.
FRONTAL BOUNDARY REMAINS ACROSS THE FAR SOUTHERN FORECAST AREA
AND NAM FORECAST INDICATES WARM ADVECTION WILL COMMENCE OVERNIGHT
AS THE SURFACE HIGH SHIFTS TOWARDS THE CAROLINA COAST AND ALLOWS
RETURN FLOW...ESPECIALLY AT H8 LEVEL WHERE H8 TEMPS WILL REACT TO
AN LLJ OVER THE EASTERN GULF THAT WILL BRING +18C TOWARDS THE
SOUTHERN FORECAST AREA...SETTING THE STAGE FOR A WARMER SATURDAY.
RAIN CHANCES MAY BE LIMITED TO AREAS ALONG AND NORTH OF THE NOSE
OF THE LLJ...WHICH COULD CONFINE MOST RAIN TO THE FAR NORTH.
&&
.AVIATION...WILL MAINTAIN VCSH FOR SRQ NORTHWARD AS RADAR STILL SHOWS
SOME WEAK PULSES PUSHING ONSHORE FROM THE GULF. BKN TO OVC DECKS
AROUND 3-4KFT WILL PERSIST THROUGH TOMORROW MORNING BEFORE GIVING
WAY TO SCT DECKS BY TOMORROW EVENING.
&&
.PREV DISCUSSION... /ISSUED 111 PM EST FRI DEC 11 2009/
SHORT TERM (TONIGHT-SUNDAY)...MID TO UPPER SW FLOW TO CONTINUE
OVER THE REGION TONIGHT THROUGH SUNDAY WHILE COOL SURFACE HIGH
PRESSURE OVER THE CAROLINAS TONIGHT MOVES INTO THE WESTERN
ATLANTIC THIS WEEKEND. STALLED FRONT OVER EXTREME SOUTHERN FL TO
SLOWLY MOVE NWARD AS WARM FRONT DURING THE DAY SATURDAY WITH
INCREASING LOW LEVEL MOISTURE AND TEMPERATURES S OF THE FRONT.
MODELS DIFFER ON EXACT TIMING OF THIS...WITH THE GFS SLIGHTLY
FASTER THAN THE NAM. THE FASTER MOVEMENT WOULD INCREASE MAX TEMPS
SATURDAY IN THE WAKE OF THE FRONT WHILE THE SLOWER MOVEMENT WOULD
KEEP MOST OF THE AREA COOLER. BUT WILL CONTINUE OVERCAST SKIES
WITH ISENTROPIC LIFT OVER THE FRONT AND CHANCES FOR LIGHT TO
MODERATE RAIN AREAWIDE WITH THE BEST CHANCES OVER NORTHERN AREAS
WITH BEST LIFT TONIGHT THROUGH SATURDAY. ON SUNDAY LOW PRESSURE
AREA ON THE FRONT OVER N FLORIDA TO PUSH EAST WITH TRAILING FRONT
DRAPED OVER THE DEEP SOUTH. SLIGHTLY DRIER MID TO UPPER CONDITIONS
FOR THE CENTRAL AND SOUTHERN AREAS AND HAVE DROPPED POPS IN THE
SLIGHT CHANCE CATEGORY WITH WARMING TEMPERATURES THERE.
LONG TERM (SUNDAY NIGHT THROUGH FRIDAY)...BEGINS WITH AN UPPER
TROUGH OVER THE WESTERN U.S. AS RIDGING...CENTERED OVER THE
GREATER ANTILLES...EXTENDS NORTH TO THE SOUTHEASTERN STATES. AT
THE SURFACE...A LOW OVER THE PLAINS TRAILS A FRONT SOUTH OVER TX TO
NORTHERN MEXICO WHILE HIGH PRESSURE OVER THE ATLANTIC RIDGES WEST
ACROSS FL TO THE GULF. WITH TIME THE WESTERN TROUGH AND ASSOCIATED
SURFACE FEATURES SLIDE EAST AS THE RIDGE...BOTH SURFACE AND
ALOFT...OVER THE AREA EXITS. THE TIMING OF THE FRONT MOVING OVER THE
GULF AND FL IS ABOUT MID-WEEK...TUE THROUGH WED. THEN A SURFACE HIGH
DROPS SOUTHEASTWARD OUT OF THE CANADIAN PRAIRIES AS UPPER RIDGING
BUILDS NORTH OVER THE WESTERN STATES FOR THE END OF THE WEEK.
THE RIDGING EARLY IN THE WEEK WILL KEEP TEMPERATURES WARM AND
PROVIDE ENOUGH STABILITY TO PRECLUDE ANY SIGNIFICANT PRECIPITATION.
THEN THE FRONT MID-WEEK BRINGS A CHANCE TO SLIGHT CHANCE OF SHOWERS
AND ISOLATED THUNDERSTORMS...ALONG WITH SOME RATHER ROBUST WINDS -
ESPECIALLY ON THE GULF - IN ITS WAKE. THE CANADIAN HIGH SETTLES IN
OVER THE SE U.S. BY THU AND FRI...PUSHING THE FRONT DOWN ACROSS THE
STRAITS...WITH COOLER TEMPERATURES GENERALLY BELOW NORMAL AND SOME
DRIER AIR CREATING POSSIBLE FIRE WEATHER CONCERNS IN THE FAR NORTH.
MARINE...4-6MB GRADIENT TO REMAIN OVER THE E GULF THIS AFTERNOON
INTO SATURDAY MORNING AND COMBINE WITH EASTERLY SURGE THIS EVENING
THEN FUNNELING OF WINDS UNDER THE OVERNIGHT INVERSION TO KEEP
SMALL CRAFT ADVISORIES IN PLACE ALL ZONES UNTIL AT LEAST 10 PM
TONIGHT THEN OFFSHORE WATERS OVERNIGHT. GRADIENT OT RELAX SATURDAY
AS WARM FRONT MOVES OVER THE E GULF WITH EASTERLY WINDS AND SEAS
SUBSIDING TO END THE WEEKEND. WEAK GRADIENT OVER THE E GULF TO
START NEXT WEEK AHEAD OF ANOTHER FRONT MID WEEK.
FIRE WEATHER...LOW LEVEL MOISTURE TO HOLD OVER THE KEEPING RHS UP
INTO NEXT WEEK.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 65 58 77 67 / 30 40 50 40
FMY 78 62 81 67 / 30 40 40 30
GIF 66 57 77 65 / 30 40 50 40
SRQ 69 59 78 66 / 30 40 50 30
BKV 58 54 77 63 / 30 40 60 40
SPG 65 58 75 67 / 30 40 50 40
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...SMALL CRAFT ADVISORY UNTIL 10 AM EST SATURDAY FOR BONITA BEACH
TO ENGLEWOOD OUT 20 NM-BONITA BEACH TO ENGLEWOOD OUT 20 TO
60 NM-ENGLEWOOD TO TARPON SPRINGS OUT 20 NM-ENGLEWOOD TO
TARPON SPRINGS OUT 20 TO 60 NM-TARPON SPRINGS TO SUWANNEE
RIVER OUT 20 TO 60 NM.
SMALL CRAFT ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR TAMPA BAY
WATERS-TARPON SPRINGS TO SUWANNEE RIVER OUT 20 NM.
&&
$$
SHORT TERM/MARINE/FIRE WEATHER...35/JOHNSON
LONG TERM/AVIATION...20/BARRON
