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180
FXUS62 KMLB 231331
AFDMLB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MELBOURNE FL
930 AM EDT WED JUL 23 2014

.DISCUSSION...

CURRENT-THIS AFTERNOON...THE CLOSED UPPER LEVEL THAT WAS OVER THE
MOBILE AND WESTERN FLORIDA PANHANDLE TUESDAY HAS RETROGRADED TO THE
MISSISSIPPI GULF COAST AND SOUTHEAST LOUISIANA AS FORECAST BY THE
MODELS. FOR FLORIDA...THE SOUTH TO SOUTHWEST FLOW AHEAD/EAST OF THE
LOW WILL CONTINUE TO FEED A WARM AND MOIST AIR MASS INTO THE FLORIDA
PANHANDLE AND NORTH FLORIDA. TO THE EAST...THE CURRENT WATER VAPOR
SATELLITE LOOP IS SHOWING A SWATH OF DRIER AIR STRETCHING FROM
CENTRAL AND SOUTH FLORIDA EAST ACROSS THE BAHAMA ISLANDS...NORTH OF
PUERTO RICO AND CONTINUING WELL INTO THE CENTRAL ATLANTIC. LOOKS TO
BE A BATTLE OF WHICH AIR MASS WILL WIN OUT THIS AFTERNOON...THE
MOIST AIR MASS FROM THE WEST OR THE DRIER AIR FROM THE EAST. THE 06Z
MODELS WERE FAVORING THE MOIST AIR MASS WINNING FOR AT LEAST THE
AFTERNOON WITH THE STRONGER LOW AND MID LEVEL SOUTHWEST FLOW PUSHING
THE MOIST AIR MASS INTO CENTRAL FLORIDA DURING THE AFTERNOON.

FOR NOW AM GOING TO GO WITH THAT SCENARIO AND LEAVE THE CURRENT
FORECAST AS IS WITH ITS HIGHER THAN MAV/MOS POP OF 30 AND 40
PERCENT. DID NOT THAT THE 06Z POP NUMBERS WERE A LITTLE HIGHER THAN
THE 00Z POP VALUES. MAYBE THE MODELS ARE STARTING TO LEAN TOWARD THE
MOIST AIR MASS WINNING OUT FOR THE AFTERNOON.

PREVIOUS ZONES DISCUSSION

CURRENT...ANOTHER WARM AND MUGGY EARLY MORNING ACROSS EAST CENTRAL
FLORIDA. SCATTERED SHOWERS AND ISOLATED LIGHTNING STORMS OVER THE
COASTAL WATERS AND DRY OVER LAND AS CLOUD DEBRIS FROM THE PREVIOUS
DAY`S CONVECTION CONTINUE TO SLOWLY DIMINISH. DUE TO THE SOUTHERLY
STEERING FLOW MUCH OF THIS ACTIVITY WILL REMAIN AWAY FROM LAND BUT A
FEW SHOWERS COULD AFFECT THE TREASURE COAST AND BARRIER ISLANDS WITH
BRIEF DOWNPOURS. WINDS ARE LIGHT AND VARIABLE TO NEAR CALM. THE
LOW-LEVEL RIDGE AXIS REMAINS SOUTH OF EAST CENTRAL FLORIDA.

TODAY-TONIGHT...AN UPPER LOW OVER THE MISSISSIPPI DELTA WILL
CONTINUE TO RETROGRADE AND WEAKEN OVER THE NEXT 24 HOURS. THIS WILL
ALLOW FOR MID-LEVEL HIGH PRESSURE TO BECOME MORE ESTABLISHED OVER
THE BAHAMAS AND FLORIDA PENINSULA. PRECIPITABLE WATER VALUES WILL
CONTINUE IN EXCESS OF 2 INCHES WITH 500 MB TEMPERATURES RELATIVELY
WARM AT AROUND -6C. THE PRESSURE GRADIENT WILL REMAIN WEAK AS
LIGHT/VARIABLE EARLY MORNING WINDS GRADUALLY BECOME SOUTHWEST AT
LESS THAN 10 MPH...EVENTUALLY BECOMING EAST-SOUTHEAST ALONG THE
COAST BY EARLY AFTERNOON WITH SEA BREEZE FORMATION. THE SEA BREEZE
WILL DEVELOP SOONER AND MOVE INLAND QUICKER OVER THE TREASURE COAST.
BOTH THE EAST/WEST COAST SEA BREEZES WILL MEET UP OVER THE INTERIOR
LATE TODAY AND ALONG WITH VARIOUS OTHER MESOSCALE BOUNDARY
COLLISIONS WE SHOULD SEE A 40 TO 50 PERCENT CHANCE FOR SHOWERS AND
STORMS AREAWIDE.

STEERING FLOW FOR STORMS REMAINS VERY LIGHT FOR THIS AFTERNOON INTO
EARLY EVENING WITH A MAIN DIRECTIONAL COMPONENT OUT OF THE
SOUTHWEST...THOUGH MANY CELLS WILL LIKELY EXHIBIT ERRATIC MOVEMENT
AT TIMES. AS SUCH...SEVERAL CELLS WILL LIKELY PUT DOWN 2 TO 3 INCH
RAINS LOCALLY IN A SHORT PERIOD OF TIME LEADING TO PONDING OF WATER
ON ROADWAYS WITH OTHER NUISANCE FLOODING OF LOW LYING AREAS
POSSIBLE. OTHER THREATS WILL CONTINUE TO BE FREQUENT LIGHTNING AND
GUSTY WINDS.

SHOWERS AND STORMS WILL DISSIPATE BY MIDNIGHT AND SKIES WILL BECOME
PARTLY CLOUDY TOWARD SUNRISE. LIGHT TO CALM WINDS AGAIN TONIGHT AS
THE LOWER LAYERS DECOUPLE. SOME SHALLOW/PATCHY GROUND FOG POSSIBLE
IN PRONE AREAS...THOUGH DOES NOT DESERVE MENTION IN GRIDS/ZONES.

AFTERNOON HIGHS IN THE UPPER 80S TO AROUND 90 DEGREES AT THE COAST
WITH LOW TO MID 90S INLAND. HEAT INDICES WILL RANGE FROM 98F-103F
THIS AFTERNOON. OVERNIGHT CONDITIONS MUGGY WITH MINIMUM TEMPERATURES
IN THE LOW TO MID 70S.

THU-FRI...RATHER AMPLIFIED PATTERN ALOFT FOR LATE JULY WILL SHUNT
DEEP LAYER RIDGE AXIS INTO THE NORTHERN BAHAMAS. THIS WILL PRODUCE
A DEEP LAYER SOUTHWEST FLOW...A PATTERN FAVORABLE FOR STORMS OVER
THE EAST SIDE OF THE PENINSULA. THE MODELS HAVE BEEN BRINGING A
LITTLE BIT OF DRIER IN FROM THE SOUTH/SOUTHEAST LATELY AND THE
00Z GFS POPS WERE 20-30 PERCENT.

WHILE SOME LOWERING OF PRECIPITABLE WATER LOOKS REASONABLE...
WHICH WOULD DELAY STORMS A BIT...VERY MOIST LOW LEVELS SHOULD KEEP
AT LEAST CLIMATOLOGICAL POPS OVER EAST CENTRAL FLORIDA. HAVE OPTED
FOR POPS MOSTLY AT 40 PERCENT ON THU. THE MODEL SHOWS COOLER TEMPS
ALOFT ON FRI AS TAIL END OF NORTHERN STREAM TROUGH APPROACHES.
THEREFORE WILL GO WITH 50 PERCENT POPS FOR MOST OF THE AREA.

WEEKEND...TROUGH ALOFT OVER THE SOUTHEAST STATES WILL WEAKEN SO
DEEP LAYER RIDGE SHOULD NUDGE BACK A LITTLE TO THE NORTH. A LIGHT
SOUTHWEST STEERING FLOW IS STILL INDICATED THOUGH. MOS POPS
CONTINUE LOW...AROUND 30 PERCENT BUT THE GFS SHOWS A RIBBON OF
HIGHER MOISTURE ACROSS THE AREA...SO WILL CONTINUE TO GO WITH POPS
CLOSE TO CLIMO...40-50 PERCENT.

MON-NEXT WED...A RETURN OF THE RATHER AMPLIFIED PATTERN ALOFT IS
INDICATED. THIS WILL SHUNT THE DEEP LAYER RIDGE BACK SOUTHWARD AND
PRODUCE A DEEP LAYER SOUTHWEST FLOW. THE GFS SUGGESTS DRIER AIR
WORKING IN MON INTO TUE...QUITE A BIT IN FACT...WITH THE 00Z RUN
KNOCKING PRECIPITABLE WATER BELOW 1.5 INCHES. THIS LOWERS MOS POPS
TO 20-30 PERCENT MON.

WHILE GETTING SOME OF THIS DRYING ALOFT...WHICH IS CLEARLY EVIDENT
ON WATER VAPOR OVER THE ATLANTIC...IS REASONABLE...WE ARE NOT SURE
THAT IT WILL NEARLY COMPLETELY OVERWHELM THE RIBBON OF HIGHER
MOISTURE THAT HAS BEEN OVER THE AREA RECENTLY. WITH AN OTHERWISE
FAVORABLE SYNOPTIC PATTERN FOR HIGHER EAST COAST STORM COVERAGE...
WILL KEEP POPS AT 30-40 PERCENT THROUGH THIS PERIOD. MOISTENING
AHEAD OF FRONTAL TROUGH OVER THE DEEP SOUTH COULD EVEN BOOST POPS
HIGHER BY WED.

&&

.AVIATION...ALL TAF SITES CURRENTLY VFR. THE COASTAL TAF SITES FROM
KSUA-KMLB SHOULD START TO SEE MVFR CEILINGS SPREADING SOUTH TO NORTH
THE NEXT TWO HOURS AS THE VISIBLE SATELLITE LOOP IS SHOWING THE
CLOUDS OVER THE COASTAL WATERS FROM CAPE CANAVERAL SOUTH MOVING
TOWARD LAND. KPBI WAS RECORDING SCT024CB AND BKN034-O47 AS THE
CLOUDS MOVE ONSHORE THE PAST COUPLE OF HOURS.

PREVIOUS AVIATION DISCUSSION

SCT TSRA SHOULD DEVELOP 15Z-17Z WITH THE EAST COAST SEA
BREEZE KMLB-KSUA. THEN STORMS DEVELOPING OVER THE INTERIOR TERMINALS
DURING THE LATE AFTN/EARLY EVE. VCTS FOR NOW IN TAFS WITH FUTURE
SHIFTS TO CONSIDER TEMPO GROUPS FOR CONVECTION. LIGHTNING...GUSTY
WINDS AND TORRENTIAL DOWNPOURS ALL CONTINUING THREATS WITH CELLS.

&&

.MARINE...

CURRENT-THIS AFTERNOON...NOAA BUOYS 009 AND 010 AT 20NM AND 120NM
OFFSHORE WERE RECORDING SOUTHWEST WINDS AT 8 TO 10 KNOTS AND SOUTH
WINDS 16 TO 19 KNOTS. THE STRONGER WINDS AT BUOY 010 MOST LIKELY
ASSOCIATED THE STORMS JUST TO THE WEST OF THE BUOY. THE BUOYS WERE
RECORDING 2 TO 4 FOOT SEAS AT 20 AND 120NM RESPECTIVELY. THE TWO
SCRIPPS BUOYS AT 4 AND 6NM OFF THE BEACHES WERE STILL RECORDING 2
FOOT SEAS.

MORNING UPDATE...A PERSISTENCE FORECAST BEST CHOICE FOR THE
AFTERNOON...NO SIGNIFICANT CHANGES PLANNED.


PREVIOUS MARINE DISCUSSION

TODAY-TONIGHT...A WEAK PRESSURE GRADIENT CONTINUES ACROSS THE AREA
WITH THE LOW-LEVEL RIDGE AXIS SUPPRESSED SOUTHWARD. THE MORNING SSW
WIND COMPONENT WILL BECOME ESE NEAR THE COAST BY EARLY AFTERNOON
WITH ECSB DEVELOPMENT. WINDS SHOULD REMAIN MAINLY SOUTHERLY
ELSEWHERE. WINDS AGAIN S/SSW TONIGHT. WIND SPEEDS MAINLY AOB 10
KTS...EXCEPT 10-12 KTS NEAR THE COAST WITH SEA BREEZE FORMATION. A
NOCTURNAL INCREASE THIS EVENING TO NEAR 15 KTS IS FORECAST AWAY FROM
THE COAST. SEAS AOB 3 FT BUT WINDS/SEAS LOCALLY HIGHER INVOF OF
STORMS.

SHOWERS AND STORMS WILL DEVELOP ALONG THE SEA BREEZE OVER
INTRACOASTAL WATERWAYS/IMMEDIATE COAST EARLY THIS AFTERNOON.
STEERING FLOW FOR CELLS IS LIGHT SOUTHWESTERLY THOUGH DIRECTIONAL
COMPONENT LIKELY ERRATIC AT BEST DUE TO LIGHT NATURE OF STEERING
WINDS. MARINERS NEAR THE COAST WILL NEED TO MONITOR DEVELOP
CONVECTION THIS AFTERNOON AS MARINE THREATS CONTINUE TO BE CLOUD TO
WATER LIGHTNING...GUSTY WINDS AND HEAVY DOWNPOURS.

THU-FRI...AXIS OF ATLANTIC SURFACE RIDGE WILL SETTLE INTO THE
NORTHERN BAHAMAS. THIS WILL PROVIDE A SOUTH/SOUTHWEST WIND FLOW.
SOME NOCTURNAL INCREASE OF WINDS TO 10-15 KNOTS IS INDICATED BUT
OVERALL WIND/WAVE CONDITIONS WILL REMAIN RATHER BENIGN. THE MAIN
MARINER HAZARD WILL BE AFTERNOON/EVENING STORMS OVER THE PENINSULA
THAT WILL SHOW AN INCREASING TREND OF PUSHING BACK ACROSS THE
COAST...ESPECIALLY FROM CANAVERAL NORTH.

WEEKEND...THE AXIS OF THE ATLANTIC SURFACE RIDGE SHOULD NUDGE BACK
TOWARDS CENTRAL FLORIDA SAT BUT THERE DOES NOT LOOK TO BE MUCH
CHANGE IN THE SOUTH/SOUTHWEST FLOW PATTERN. ENOUGH SOUTHWEST
STEERING FLOW SHOULD CONTINUE FOR AFTERNOON/EVENING STORMS TO
PUSH BACK ACROSS THE COAST.

&&

.PRELIMINARY POINT TEMPS/POPS...
DAB  91  75  92  76 /  40  30  40  30
MCO  93  75  94  75 /  50  20  40  20
MLB  90  75  91  76 /  50  20  40  20
VRB  88  74  91  75 /  50  20  30  20
LEE  93  76  94  77 /  50  20  40  30
SFB  93  76  94  77 /  50  30  40  30
ORL  93  77  94  78 /  50  20  40  20
FPR  88  74  90  74 /  50  20  30  20

&&

.MLB WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
&&

$$

IMPACT WX...MOSES
IMPACT WX...PLOTKIN
PUBLIC SERVICE...CARTWRIGHT
FORECASTS...WIMMER






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