FXUS62 KMLB 230842
AFDMLB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MELBOURNE FL
342 AM EST WED DEC 23 2009
.DISCUSSION...
TODAY/TONIGHT...WARMING TREND DUE TO VEERING WIND AND LOWER CLOUD
COVER. AREA TEMPS WILL RISE TO THE 70S. SCATTERED AFTERNOON CLOUDS
WL DEVELOP DUE TO HEATING AND GRADUAL INCREASES IN LL MOISTURE.
TONIGHT...SUBTLE INCREASE IN PRESSURE GRADIENT SHOULD KEEP
IMMEDIATE COAST FROM DE-COUPLING WITH WINDS AVERAGING AROUND 5 TO
10 MPH WITH SOME GUSTS ALONG THE TREASURE COAST. INLAND SPOTS WILL
BE A LITTLE COOLER...HOWEVER MINS WILL BE MILDER THAN PREV NIGHTS
WITH ONLY MID 50S EXPECTED.
THU-THU NIGHT...SURFACE LOW PRESSURE NEAR THE ARKLATEX REGION WILL
LIFT NORTH TOWARDS THE UPPER MIDWEST DURING THIS PERIOD. A SURFACE
COLD FRONT WILL MOVE EAST TOWARD THE WESTERN FLORIDA PANHANDLE BY
LATE IN THE DAY AND TOWARD NORTH-CENTRAL FLORIDA OVERNIGHT. THE
PRESSURE GRADIENT WILL TIGHTEN AS EAST/SOUTHEAST WINDS INCREASE TO
15-20 MPH OVER LAND WITH BREEZY WORDING NECESSARY IN THE ZONES. THIS
IN TURN WILL ALLOW DEEPER MOISTURE TO FILTER INTO THE REGION AHEAD
OF THE APPROACHING SYSTEM. SKIES WILL SEE AN INCREASE IN CLOUD COVER
THROUGH THE DAY AND DURING THE EVENING AS THE BOUNDARY APPROACHES
FROM THE WEST. WILL CONTINUE TO CARRY 20% POPS DURING THE AFTERNOON.
WINDS WILL CONTINUE TO VEER TO THE SOUTH/SOUTHEAST DURING THE
EVENING & OVERNIGHT. A SLIGHT INCREASE IN LOW-LEVEL CONVERGENCE
COUPLED WITH IMPULSES ALOFT WILL INCREASE OUR POP CHANCES 40%-50%
OVERNIGHT. A SMALL CHANCE OF THUNDER WILL ALSO BE POSSIBLE OVERNIGHT
ACROSS NORTH LAKE AND NORTH VOLUSIA COUNTIES. WILL ONLY MAKE A SMALL
MENTION OF THIS IN PASSING FOR NOW...BUT LOCAL WIND PROFILES NORTH
AND WEST OF THE I-4 CORRIDOR ARE FAVORABLE FOR ROTATING CELLS THU
EVENING IF ACTIVITY CAN GET ORGANIZED. HIGHS WILL BE A FEW TO
SEVERAL DEGREES ABOVE CLIMO ACROSS EAST CENTRAL FLORIDA WITH MAX
TEMPS IN THE MIDDLE TO UPPER 70S. LOWS OVERNIGHT THU MILD AND WELL
ABOVE SEASONAL AND WILL AVERAGE IN THE LOW/MID 60S EXCEPT UPPER 60S
ALONG THE TREASURE COAST.
CHRISTMAS DAY...A WEAK AREA OF LOW PRESSURE IS FORECAST BY THE GFS
TO DEVELOP OVER GEORGIA DURING THE PERIOD AND PUSH THE BOUNDARY
SOUTHEASTWARD. THE COLD FRONT WILL MOVE INTO EAST CENTRAL FLORIDA
DURING THE DAY WITH A CHANCE FOR SHOWERS (40%). WILL KEEP THUNDER
MENTION ABSENT FROM THE ZONES/GRIDS FOR NOW AS INSTABILITY LOOKS
MINIMAL AT PRESENT. THE BOUNDARY WILL PUSH EAST OF THE PENINSULA
DURING THE EVENING AND OVERNIGHT. WILL CONTINUE A SMALL THREAT FOR
PRECIPITATION DURING THE EVENING. THIS DAY WILL FEEL VERY WARM AND
MUGGY WITH HIGHS IN THE UPPER 70S TO NEAR 80 DEGREES. DEWPOINT
VALUES WILL BE IN THE MIDDLE TO UPPER 60S. COOLER AND DRIER AIR WILL
FILTER SOUTHWARD BEHIND THE SYSTEM WITH LOWS MAINLY IN THE 50S
EXCEPT A FEW MINS AROUND 60 DEGREES ALONG THE TREASURE COAST.
SAT...LATEST GFS RUN TRIES TO OVERRUN SOME MOISTURE ALONG WITH SOME
MID-LEVEL IMPULSES AND UPPER LEVEL JET SUPPORT ACROSS THE OLD 850 MB
FRONT ON SAT AND PUSH OUT 30%-60% POPS ALIGNED NORTH-SOUTH ACROSS OUR
COVERAGE WARNING AREA. AT PRESENT WILL CONTINUE TO KEEP AN EYE ON
THIS SCENARIO BUT WILL LEAVE ONLY A 20% MENTION FOR SHOWERS
AREAWIDE. THE ECMWF MOVES THE AFOREMENTIONED SYSTEM THROUGH THE AREA
ON FRI LEAVING US DRY ON SAT. SO WILL NOT MAKE ANY FURTHER CHANGES
TO THIS PERIOD WITHOUT FURTHER MEDIUM RANGE MODEL CONSISTENCY.
SUN-TUE...WITH HIGHER PRESSURES GRADUALLY BUILDING INTO THE REGION
DURING THIS TIME AND WITH A LIGHT NORTHERLY COMPONENT OF WIND AT THE
SURFACE EXPECT A MAINLY DRY EXTENDED. HOWEVER...THERE WILL BE A
STRONGER UPPER JET OVERHEAD THROUGH THIS TIME AND ANY RESIDUAL
MOISTURE ALONG WITH A PASSING SHORTWAVE IMPULSE OVERHEAD COULD TOUCH
OFF AN ISOLATED SHOWER. WITH MID-HIGH LEVEL MOISTURE DURING THIS
TIME THERE WILL LIKELY BE PERIODS OF PREVAILING HIGH OVERCAST. HIGHS
MAINLY IN THE LOW-UPPER 60S FROM KISM-KTTS NORTHWARD WITH A SURGE OF
COOLER AIR AGAIN BY TUE. UPPER 60S TO LOWER 70S FOR HIGHS FURTHER
SOUTH TOWARD MARTIN COUNTY AND NEAR LAKE OKEECHOBEE. LOWS IN GENERAL
WILL AVERAGE A FEW TO SEVERAL DEGREES BELOW CLIMO.
&&
.AVIATION...
NO WEATHER ISSUES NEXT 24 HOURS WITH VFR AND SCT CLOUDS NEAR 4K FT
MAINLY IN THE AFTERNOON.
&&
.MARINE...
WAVE PERIODS WILL SHORTEN UP DUE TO GRADUAL INCREASE IN ONSHORE
FLOW THROUGH TONIGHT. OTHERWISE NO ISSUES EXPECTED OVER THE MARINE
AREA AS LONGER PERIOD SWELL GRADUALLY ABATES.
THU...THE PGRAD WILL TIGHTEN DURING THE DAY WITH E/ESE WINDS
INCREASING TO 20 KTS (POSSIBLY 20-25 KTS) THRU THU NIGHT. WINDS
CONTINUE TO VEER TO THE SE THU NIGHT WITH THE APPROACH OF THE NEXT
WEATHER SYSTEM. A SMALL CRAFT ADVISORY OF SOME KIND WILL EVENTUALLY
BE NEEDED FOR AT LEAST THE OFFSHORE LEGS AS MARINE CONDITIONS
DETERIORATE. SEAS 4-5 FT OFFSHORE WILL BEGIN TO RESPOND TO THE WINDS
AND GRADUALLY BUILD TO 6 FT OFFSHORE DURING THE DAY AND 7-9 FT
OVERNIGHT...ESPECIALLY NORTH. AN INCREASE IN SHRA ACTIVITY IS
EXPECTED THU OVERNIGHT.
FRI...THE FRONT WILL MOVE INTO EAST CENTRAL FL DURING THE DAY AND
OUT ACROSS THE COASTAL WATERS AND FURTHER EASTWARD DURING THE
EVENING AND OVERNIGHT PERIODS. WINDS WILL VEER TO THE SW AHEAD OF
THE SYSTEM AND EVENTUALLY W-WNW BEHIND THE BOUNDARY. SPEEDS WILL
GENERALLY DECREASE DURING THE DAY THOUGH REMAIN NEAR 15 KTS AWAY
FROM THE COAST. SEAS WILL CONTINUE TO BE ELEVATED 6-8 FT OFFSHORE.
SCATTERED SHOWER CHANCES WILL ACCOMPANY THE FRONT WITH LOCALLY
STRONGER & GUSTY WINDS WITHIN HEAVIER CELLS.
SAT-SUN...THERE WILL BE A GRADUAL DECREASE IN SEAS THROUGH THIS
PERIOD BUT STILL EXPECT 6 FT SEAS IN THE GULF STREAM. PERIODS OF
MODERATE NORTHWEST WINDS WILL OPPOSE THE GULF STREAM THRU THIS TIME.
&&
.FIRE WEATHER...
NO ISSUES TODAY DUE TO INCREASING ONSHORE FLOW. INLAND RH MINS
ONLY EXPECTED TO FALL INTO THE MID-UPR 40S.
ON THU...BREEZY EAST-SOUTHEAST SFC WINDS ARE
EXPECTED AS THE PRESSURE GRADIENT TIGHTENS AHEAD OF AN APPROACHING
COLD FRONT. DISPERSION VALUES WILL BE GENERALLY GOOD TO VERY GOOD ON
THIS DAY. AMOUNT OF DRYING BEHIND THE LATE WEEK COLD FRONT IS STILL
IN QUESTION. AT THE MOMENT IT APPEARS RH VALUES ACROSS ECFL WILL
STAY ABOVE CRITICAL INTO MON...BUT ANOTHER SHOT OF DRIER AIR ON TUE
MAY CREATE FIRE SENSITIVITY FOR LOW DURATION RH.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 71 54 77 65 / 0 10 20 50
MCO 72 55 77 63 / 0 10 20 40
MLB 73 59 77 67 / 10 10 20 40
VRB 75 60 78 68 / 10 10 20 40
LEE 71 54 76 62 / 0 10 20 50
SFB 73 54 77 64 / 0 10 20 50
ORL 72 55 77 63 / 0 10 20 40
FPR 75 60 78 68 / 10 10 20 40
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
&&
$$
SHORT TERM...PENDERGRAST
LONG TERM....SEDLOCK
