FXUS62 KMFL 251155
AFDMFL
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MIAMI FL
655 AM EST FRI DEC 25 2009
.AVIATION...
EXPECT VFR CONDITIONS TO PREVAIL AT ALL SOUTH FLORIDA TERMINALS
THRU THE FORECAST PERIOD...WITH INTERMITTENT PERIODS OF MVFR
CIG/VSBY IN PASSING SHRA. ISOLD SHRA ALREADY BEGINNING TO AFFECT
EAST COAST TERMINALS IN INCREASING SE FLOW REGIME...AND WILL CARRY
VCSH/CB FROM ONSET OF FORECAST AT THESE LOCATIONS...ALONG WITH
SCT/BKN STRATOCU DECK AROUND 2.5 KFT AND SE FLOW 12G20 KNOTS.
WINDS WILL VEER TO SW AND DECREASE SLIGHTLY BY MID-MORNING AS
SURFACE TROUGH APPROACHES REGION. THIS WILL ALLOW FOR SOME
IMPROVEMENT IN CIGS...BUT SHRA/CB THREAT WILL CONTINUE THRU THE
DAY. WEAKENING COLD FRONT SHOULD ARRIVE AT APF AROUND 26/00Z...PBI
02Z...FLL/FXE 03Z...AND MIA/OPF/TMB 04Z...WITH WINDS SHIFTING TO
NW AND DECREASING FURTHER. BEST CHANCE FOR SUSTAINED/WIDESPREAD
MVFR CIGS AND -RA/DZ WILL OCCUR FOLLOWING FRONTAL PASSAGE...AND
WILL INDICATE THIS WITH VCSH AND NO CB GROUP.
70/DD
&&
.PREV DISCUSSION... /ISSUED 404 AM EST FRI DEC 25 2009/
DISCUSSION...
..HIGH RISK FOR RIP CURRENTS THIS MORNING...
DEEP/STACKED CYCLONE OVER MISSOURI EARLY THIS MORNING WILL
CONTINUE TO PULL NORTH DURING THE DAY TODAY...DRAGGING A COLD
FRONT CURRENTLY ACROSS THE ERN GULF AND THEN THE SOUTHERN FL
PENINSULA DURING THE DAY. CURRENTLY...A LINE OF SHOWERS WITH
EMBEDDED TSTMS JUST EAST OF A LINE FROM BUOYS 42036 TO 42003 HAS
UNDERGONE SOME SLIGHT INTENSIFICATION OVERNIGHT...AS CAN TYPICALLY
BE EXPECTED.
AHEAD OF THE APPROACHING FRONT...BRISK SERLY WINDS EARLY THIS
MORNING SHOULD SWING TO THE S AND THEN EVENTUALLY SW THIS
AFTERNOON. MODEL GUIDANCE IS IN GOOD AGREEMENT THAT AT LEAST
ISOLATED TO SCATTERED SHOWERS ARE A GOOD BET AHEAD OF THE FRONT IN
THE MOIST AND SLIGHTLY UNSTABLE AIRMASS TODAY. HOWEVER...MOST
GUIDANCE INCLUDING LOCALLY RUN WRF-ARW SUGGEST THE LINE OF STORMS
JUST AHEAD OF THE FRONT WILL BREAK UP AS IT MOVES ONSHORE ACROSS
THE GULF COAST THIS AFTERNOON. THIS MAKES SENSE GIVEN THE BEST
DYNAMICS WITH THIS STORM SYSTEM WILL REMAIN WELL N OF THE
REGION...AND MODEL GUIDANCE INDICATES SOUTH FL WILL BE IN THE
UNFAVORABLE RIGHT EXIT REGION OF A POTENT UPPER JET ALONG THE GULF
COAST. WILL CONTINUE WITH ONLY A SLIGHT CHC OF TSTMS ONLY TODAY AS
A RESULT. THE FRONT SHOULD GRADUALLY CLEAR ERN AREAS DURING THE
EVENING HRS WITH PSBLY A FEW LINGERING SHOWERS AND THEN JUST
SLIGHT CLEARING OVERNIGHT.
THE LATEST RUNS OF THE GFS/ECMWF AGREE THAT THE FRONT WILL PUSH
JUST FAR ENOUGH S OF THE REGION TO ALLOW PARTIAL CLEARING AND
MAINLY DRY CONDITIONS ON SATURDAY...BUT THE FRONT WILL NOT MAKE IT
VERY FAR S AS IT BEGINS TO RUN INTO A STRONG MID-LEVEL RIDGE OVER
THE CARIBBEAN AND PARALLELS THE MID-LEVEL FLOW ACROSS THE REGION.
HOWEVER...MOISTURE STREAMING NE TO THE N OF THE BOUNDARY SHOULD
KEEP SKIES AT LEAST PARTLY CLOUDY AND PERHAPS MOSTLY CLOUDY AT
TIMES THROUGH THE WEEKEND. ALL GUIDANCE AGREES THAT THE SLOW
MOVING/STACKED LOW WILL MEANDER TOWARDS THE GREAT LAKES OVER THE
WEEKEND...WITH ANOTHER WEAK PIECE OF MID-LEVEL ENERGY ROTATING
ACROSS THE S SIDE ALONG THE GULF COAST BRINGING A FRONT THROUGH
THE REGION SUN EVENING OR EARLY MONDAY. MOST OF THE ENERGY WITH THE
SHORTWAVE FIZZLES OUT THOUGH...SO DO NOT EXPECT MORE THAN A FEW
SHOWERS.
STRONG SFC HIGH WILL BUILD SOUTH ACROSS THE PLAINS AND USHER IN A
QUICK SHOT OF COOLER/DRIER AIR FOR THE EARLY PART OF THE WEEK WITH
HIGHS MOSTLY IN THE 70S. TEMPS WILL BE NOTICEABLY COOLER AT NIGHT
HOWEVER...WITH MONDAY NIGHT BEING THE COOLEST AS SKIES SHOULD ONLY
BE PARTLY CLOUDY AND DECENT RADIATIONAL COOLING MAY OCCUR AS WINDS
DROP OFF ACROSS THE INTERIOR. MODEL FCSTS SHOW 1000-850MB
THICKNESSES AROUND 1345M ACROSS GLADES/HENDRY COUNTIES BY 12Z
TUESDAY...AND THIS SHOULD SUPPORT MIN TEMPS IN THE LOWER 40S
ACROSS THESE LOCATIONS...WITH MID/UPPER 40S ACROSS THE REST OF THE
INTERIOR AND 50S ALONG THE COASTAL REGIONS. TEMPS SHOULD WARM A
COUPLE OF DEGREES ACROSS ALL AREAS TUESDAY NIGHT.
FOR THE MID-LATE WEEK PERIOD...STRONG RIDGING OVER THE NRN
CARIBBEAN ALONG WITH THE DEPARTING STACKED CYCLONE OVER THE ERN
CONUS WILL LEAVE BEHIND A FAIRLY ZONAL FLOW REGIME WITH THE MAIN
JET AXIS ALONG THE GULF COAST. A BRIEF PERIOD OF MODERATE NERLY
FLOW IS PSBL TUE-WED TIMEFRAME AS THE STRONG SFC HIGH BUILDS EAST
TOWARDS THE MID ATLC. BEYOND THEN...THE ZONAL FLOW ALONG THE GULF
COAST COULD LEAD TO A MORE ENHANCED SOUTHERN STORM TRACK ACROSS
THE CONUS...AND INDEED THE GFS/ECMWF SHOW A SYSTEM MOVING ACROSS
THE NRN GULF LATE NEXT WEEK...POSSIBLY DRAGGING ANOTHER FRONT
ACROSS THE REGION TOWARDS THE NEW YEAR.
REGARDING MAX TEMPS...MET MOS GENERALLY OUTPERFORMED THE MAV
BEHIND THE LAST FRONT...SO WHERE DIFFERENCES POPPED UP BETWEEN THE
TWO HAVE STAYED CLOSER TO THE MET GUIDANCE THIS PACKAGE. FOR
NAPLES...HAVE GENERALLY GONE AT OR JUST BELOW EVEN THE COOLEST
GUIDANCE THIS PERIOD AS THE GULF COAST ALMOST NEVER GETS AS WARM
AS MODELS PREDICT BEHIND FRONTS THIS TIME OF YEAR DUE TO WINDS OFF
THE COOL MID-60S GULF WATERS.
MARINE...
EXTENDED THE SCA UNTIL 15Z THIS MORNING AS SERLY WINDS CONTINUE TO
BLOW OVER 20KTS STEADILY AT FOWEY ROCKS AND VIRGINIA KEY. WINDS
SHOULD SUBSIDE SOME LATER THIS MORNING AS THEY GRADUALLY SWING
AROUND TO THE S AND THEN SW. WINDS WILL BECOME NRLY 10-15KTS
QUICKLY BEHIND THE FRONT TOMORROW INTO SUNDAY THEN BECOME LIGHT
NERLY SUNDAY NIGHT INTO MONDAY. SEAS WILL RUN 6FT OR LESS THIS
PERIOD...THOUGH OCCASIONAL N/NERLY SWELL WILL IMPACT THE ATLC
WATERS AT TIMES THROUGH THE UPCOMING WEEK.
FIRE WEATHER...
NO CONCERNS THIS PERIOD. DRIER CONDITIONS WILL MOVE INTO THE
REGION MONDAY AND TUESDAY BUT MAX TEMPS WILL BE COOL ENOUGH TO
PREVENT RH'S FROM DROPPING MUCH BELOW 40 PERCENT.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 81 59 73 58 / 60 30 10 20
FORT LAUDERDALE 82 62 76 62 / 50 30 10 20
MIAMI 82 65 76 62 / 50 30 10 20
NAPLES 78 61 70 54 / 60 10 10 20
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...SMALL CRAFT ADVISORY UNTIL 10 AM EST THIS MORNING FOR AMZ630-
AMZ650-AMZ651-AMZ670-AMZ671.
GM...NONE.
&&
$$
LONG TERM...65/GS
SHORT TERM/AVIATION...70/DD
