000
FXUS62 KMFL 222325
AFDMFL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MIAMI FL
725 PM EDT MON SEP 22 2008

.AVIATION...MOSTLY VFR CONDITIONS WILL REMAIN OVERNIGHT...EXCEPT
FOR KAPF WHERE A FEW TSTMS COULD PASS CLOSE TO THE TERMINAL WITH
CONDITIONS GOING MVFR BRIEFLY. STILL, BELIEVE IT WOULD BE OF SHORT
DURATION AND SO ONLY INDICATED VCTS FOR KAPF. SIMILAR CONDITIONS
EXPECTED TUESDAY WITH NE WNDS AROUND 8 KTS AND VCSH IN THE
MORNING FOR EAST COAST TERMINALS AND VCTS IN THE AFTERNOON FOR KAPF.


&&

.PREV DISCUSSION... /ISSUED 238 PM EDT MON SEP 22 2008/

DISCUSSION...
WATER VAPOR IMAGERY SHOWS MID/UPPER LEVEL TROUGH AXIS ACROSS THE
SPINE OF THE APPALACHIANS INTO THE NORTHERN GULF OF MEXICO. A DEEP
MOISTURE PLUME LIES AHEAD OF IT ROUGHLY ALONG OR JUST OFF THE EAST
COAST OF THE CONUS...STRETCHING SW INTO THE NE GULF.
LOCALLY...SCATTERED SHOWERS WERE HAVING A TOUGH TIME GETTING GOING
ACROSS THE INTERIOR AND WEST COAST THIS AFTERNOON BUT A GRADUAL
INCREASE WITH SOME THUNDER IS EXPECTED THROUGH EARLY THIS EVENING.

MODEL GUIDANCE AGREES THAT THE UPPER TROUGH AXIS WILL DRIFT SE
TONIGHT AND EARLY TUESDAY FORMING A CLOSED/CUTOFF LOW SOMEWHERE IN
THE VICINITY OF THE CAROLINA COAST...WITH WEAK SFC LOW DEVELOPMENT
ALONG THE WEAK/DIFFUSE BAROCLINIC BOUNDARY JUST OFFSHORE. THE
TROUGH AXIS WILL SWING THROUGH DURING THE DAY ON TUESDAY AS A
LARGE RESERVOIR OF DRY AIR OVER NORTH GA/AL SURGES SOUTH DOWN THE
FL PENINSULA. MEANWHILE...NNE/NE FLOW WILL GRADUALLY INCREASE
THROUGH TUESDAY EVENING WITH A SLIGHT INCREASE IN THE PRESSURE
GRADIENT ACROSS THE REGION. AS THE TROUGH/MOISTURE AXIS SAG
THROUGH...EXPECT MORE WIDESPREAD SHOWER AND THUNDERSTORM CHANCES
TOMORROW. THINGS SHOULD GET GOING FAIRLY EARLY ACROSS THE NORTHERN
THIRD OF THE CWA AND THEN SAG SOUTH AS THE DAY PROGRESSES DUE TO
INCREASING NORTHERLY COMPONENT OF THE LOW/MID LEVEL FLOW OVER A
DEEP LAYER. NE LOW LEVEL WINDS HOWEVER COMBINED WITH INSTABILITY
WILL FAVOR REGENERATION OF SHOWERS FURTHER NORTH EVEN INTO THE
AFTERNOON AS THE TROUGH AXIS DOES NOT CLEAR UNTIL EVENING.

FOR THE TUESDAY NIGHT THROUGH FRIDAY PERIOD...MOST MODEL GUIDANCE
AGREES THE CLOSED UPPER LOW AND ANY WEAK SURFACE LOW DEVELOPMENT
BENEATH IT OFF THE CAROLINA COAST WILL RETROGRADE WEST BACK INLAND
ACROSS THE SOUTHEAST STATES AND STALL LATE IN THE WEEK. AS THIS
HAPPENS...IT WOULD LIKELY PULL ANY TROPICAL ENTITY CURRENTLY NEAR
THE NORTH COAST OF HISPANIOLA NORTHWARD INTO THE WESTERN ATLANTIC
WELL EAST OF THE FL PENINSULA. THE STALLED UPPER LOW WILL CONTINUE
A WNW MID-LEVEL FLOW OF DRY AIR AND SUBSIDENCE INTO SOUTH
FL...WITH SEVERAL DAYS OF ISOLATED SHOWERS POSSIBLE AT BEST DUE TO
INCREASING MID-LEVEL SUBSIDENCE INVERSION AND PWATS DROPPING BELOW
1.3 INCHES. DEWPOINTS MAY ALSO DROP INTO THE 60S ACROSS THE NW
INTERIOR FOR A TIME AS WELL ALONG WITH LIGHT AND VARIABLE SURFACE
WINDS. HOWEVER THIS TIME PERIOD IS OPEN TO A LOT OF CHANGES
BECAUSE THE INTERACTION BETWEEN THE CUTOFF LOW...ASSOCIATED WEAK
SURFACE LOW...AND ANY POSSIBLE TROPICAL ENTITY GETTING INTERTWINED
WITH IT IS LIKELY TO BE A COMPLEX PROCESS WHICH THE MODELS MAY NOT
HAVE A GOOD HANDLE ON.

BEYOND FRIDAY...MODELS SUGGEST THAT THE DEEP LAYERED MOISTURE
PLUME THAT GETS SUPPRESSED TO OUR SOUTH BY THE UPPER LOW WILL
SLOWLY MIGRATE BACK NORTH ACROSS THE CWA...WITH INCREASING POPS IF
THIS VERIFIES.

MARINE...
DIFFICULT MARINE FORECAST THIS PERIOD. GFS AND THUS WAVEWATCH
CONTINUES TO SUGGEST IDEAL FETCH FOR MODERATE LONG-PERIOD SWELLS
TO IMPACT MUCH OF THE ATLANTIC WATERS BEGINNING WEDNESDAY AND
PEAKING THURSDAY. ECMWF/CANADIAN/UKMET MODELS SUGGEST UPPER SYSTEM
AND ASSOCIATED WEAK SURFACE REFLECTION WILL DEVELOP CLOSER TO THE
COAST AND MOVE INLAND FASTER...LEADING TO LITTLE OR NO SWELL DUE
TO UNFAVORABLE FETCH. WILL TAKE AN IN-BETWEEN APPROACH AT THIS
POINT WITH 4-6 FT SWELLS ACROSS THE NORTHERN ATLANTIC LEG...BUT
AFTER WEDNESDAY NIGHT ACTUAL WIND WAVES MAY BE NEGLIGIBLE DUE TO
LIGHT OFFSHORE FLOW LESS THAN 10 KTS INTO FRIDAY. MARINERS SHOULD
CHECK THE LATEST THE NEXT FEW DAYS AS THIS IS A HIGHLY UNCERTAIN
SITUATION.

FIRE WEATHER...
NO CONCERNS THIS PERIOD EVEN AS DEWPOINTS FALL A FEW DEGREES
MID TO LATE WEEK.

&&

.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH  77  86  73  86 / 30 60 30 30
FORT LAUDERDALE  79  87  74  86 / 30 60 40 30
MIAMI            78  89  74  86 / 30 60 40 30
NAPLES           74  88  71  87 / 30 60 20 20

&&

.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&

$$

LONG TERM...54/BNB
SHORT TERM/AVIATION...47/RHG