Area Forecast Discussion
Issued by NWS Melbourne, FL

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000
FXUS62 KMLB 170835
AFDMLB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MELBOURNE FL
435 AM EDT SUN AUG 17 2014

.DISCUSSION...

...TURNING HOTTER WITH BELOW NORMAL RAIN CHANCES THIS WEEK...

CURRENTLY...
WEAK JET PATTERN ACRS THE CONUS THIS MORNING...ASIDE FROM A 60-80KT
H30-H20 STREAK OVER THE MID ATLC/SRN NEW ENGLAND STATES...WINDS ARE
BLO 50KTS. BROAD TROFFING PATTERN OVER THE NE CONUS IS KEEPING THE
ATLC RIDGE AXIS SUPPRESSED OVER S FL...RESULTING IN A DEEP WRLY FLOW
ACRS THE CENTRAL PENINSULA.

MOST NOTABLE FEATURE OF THE LCL AIRMASS IS THE LACK OF DEEP
MOISTURE. H100-H70 MEAN RH VALUES ARE BLO 70PCT...A TONGUE OF MID
LVL MOISTURE OVER S FL IS KEEPING H85-H50 MEAN RH VALUES BTWN
60-80PCT...THOUGH MUCH DRIER AIR IS FLANKING IT TO THE S AND W.
MID LVL VORT FIELDS WITHIN THE PERIPHERY OF THE ATLC RIDGE ARE QUITE
WEAK...AS ARE UPR LVL DIV FIELDS ACRS THE GOMEX/SW ATLC. NARROW
THERMAL RIDGE OVERHEAD WITH H70 TEMPS ARND 10C...THOUGH COOLER TEMPS
PREVAIL UPSTREAM WITH READINGS BLO 8C OVER THE NE GOMEX. MID LVL
TEMPS ARND -6C...RESULTING IN MID LVL LAPSE RATES BTWN 5.5-6.0C/KM
THRU THE H85-H50 LYR.

TODAY-TONIGHT...
THE JET STREAK OVER THE NE CONUS WILL LIFT INTO THE CANADIAN
MARITIMES...PULLING THE DEEP TROF ALONG WITH IT. THIS WILL ALLOW THE
WRN PERIPHERY OF THE ATLC RIDGE TO DRIFT N INTO THE LAKE OKEECHOBEE
REGION...ALBEIT QUITE SLOWLY. WEAK DRY AIR ADVECTION WILL OCCUR AS
W/SW FLOW ON THE N SIDE OF THE RIDGE PUSHES THE LINGERING MID LVL
MOISTURE INTO THE ATLC. BY 18Z...MODEL SOUNDINGS INDICATE PWAT
VALUES DROPPING TO ARND 1.8" ACRS CENTRAL FL WITH DEWPOINT
DEPRESSIONS LARGELY AOA 5C...EXCEPT THROUGH THE H90-H80 LYR.  MID
LVL SUPPRESSION WILL OCCUR AS WELL TODAY AS RIDGE AXIS LIFTS N AND
PULLS THE LOW VORT ENERGY WITH IT.

LOW LVL WRLY FLOW WILL DIMINISH AS THE RIDGE DRIFTS N...ALLOWING THE
EAST COAST SEA BREEZE TO DLVP BY EARLY AFTN. BNDRY SHOULD BE WELL
DEFINED AS WRLY FLOW PREVAILS ALOFT AND PREVENTS IT FROM PUSHING
MUCH FURTHER INLAND THAN THE I-95 CORRIDOR. DRIER AND SLIGHTLY
SUPPRESSED AIR WILL KEEP RAIN CHANCES BLO 50PCT...WEAK COOL AIR
ADVECTION THRU THE H70-H50 LYR MAY SUPPORT SOME STRONG DOWNBURST
WINDS...BUT LITTLE MORE THAN THAT.

THE 00Z GFS MOS GUIDANCE CAME IN WITH POPS BLO 20PCT...A BIT LOW IT
SEEMS GIVEN SFC DEWPOINTS IN THE L/M70S...A WELL DEFINED SEA
BREEZE... AND THE POTENTIAL FOR SOME COOL AIR ADVECTION. WILL KEEP
30/40 POPS ALONG THE COAST AND AROUND THE LAKE OKEECHOBEE REGION...
20 POPS OVER THE INTERIOR N OF LAKE MARIAN/LAKE KISSIMMEE. MAX TEMPS
WILL BE A TOUCH WARMER TODAY DUE TO THE WRLY FLOW AND THE LOWER
PRECIP COVERAGE...EXPECT L90S ALONG THE COAST BEFORE THE SEA BREEZE
KICKS...M90S OVER THE INTERIOR.

WITH THE LOSS OF DAYTIME HEATING AND THE LACK OF MID/UPR LVL DYNAMIC
SUPPORT...CONVECTION SHOULD DISSIPATE AROUND SUNSET OR SHORTLY
THEREAFTER. WILL KEEP THE FCST DRY AFT 00Z WITH MIN TEMPS FALLING TO
WITHIN 2-3F OF CURRENT SFC DEWPOINTS OVERNIGHT.

MON...LOW LEVEL RIDGE AXIS WILL REMAIN DRAPED ACROSS LAKE
OKEECHOBEE WITH A LIGHT TO MODERATE OFFSHORE FLOW...TURNING
ONSHORE IN A SEA BREEZE FIRST ALONG THE TREASURE COAST THEN ZIPPER
UP THE COAST TO THE CAPE. OFFSHORE FLOW LOOKS STRONG ENOUGH TO
PIN THE SEA BREEZE TO THE COAST NORTH OF THE CAPE. MOISTURE
CONVERGENCE ON THE NORTH SIDE OF THE RIDGE AXIS SHOULD PRODUCE
ISOLATED STORMS ACROSS SOUTHERN SECTIONS EARLY IN THE AFTN
(OKEECHOBEE TO THE TREASURE COAST). THEN BOUNDARY COLLISIONS LATER IN
THE AFTN SHOULD PRODUCE THE BEST CHANCE FOR SCATTERED STORMS ALONG
OR JUST INLAND FROM THE COAST. DRIER AIR ALOFT WILL LIMIT COVERAGE
BUT THE BEST CHANCE APPEARS TO BE IN VOLUSIA COUNTY (30 TO 40
PERCENT). A FEW STORMS WILL BE CAPABLE OF STRONG DOWNBURST WINDS
GIVEN THE DRIER AIR ALOFT.

TUE-SAT...BOTH THE GFS AND ECMWF MODELS SHOW RISING HEIGHTS ALOFT
AS UPPER RIDGING BUILDS OVER THE AREA TUE-THU. THIS WILL CAUSE A
MORE SUPPRESSED ATMOSPHERE WITH DECREASING MOISTURE IN THE H8-H5
LAYER. THIS WILL PRODUCE MUCH BELOW NORMAL RAIN CHANCES MID WEEK.
WITH LITTLE MEANINGFUL CLOUD COVER...STRONG SURFACE HEATING WILL
PRODUCE HOT TEMPERATURES SOLIDLY IN THE MID 90S OVER THE
INTERIOR...WITH SOME UPPER 90S EXPECTED. THE SEA BREEZE WILL
DEVELOP SOUTH OF THE CAPE EACH AFTN BUT HIGHS WILL REACH THE LOWER
90S EVEN AT THE IMMEDIATE COAST. A STRONGER OFFSHORE FLOW WILL PIN
THE SEA BREEZE ALONG THE VOLUSIA COAST ALLOWING TEMPS TO REACH THE
MID TO UPPER 90S IN COASTAL VOLUSIA. THERE IS A CHANCE DAYTONA
BEACH COULD TIE ITS RECORD HIGH ON ONE OR MORE DAYS.

RAIN CHANCES LOOK LOWEST ON WEDNESDAY WHERE A TOKEN 20 POP IS
DRAWN ONLY AROUND LAKE OKEECHOBEE WITH A SILENT 10 POP ELSEWHERE.
HAVE DRAWN A 20 POP AREAWIDE TUE AND THU WITH ONLY SLIGHTLY BETTER
STORM CHANCE AROUND LAKE OKEECHOBEE DUE TO INTERACTION WITH THE
EAST COAST SEA BREEZE AND LAKE BREEZE BOUNDARIES.

LATE IN THE WEEK...THE UPPER HIGH IS FORECAST TO PULL WEST TO THE
LOWER MS VALLEY. THIS SHOULD ALLOW HEIGHTS OVER FL TO LOWER AND
THE SUPPRESSION TO RELAX SOMEWHAT. AS A RESULT...HAVE STARTED A
TREND OF SLIGHTLY HIGHER RAIN CHANCES...30 PERCENT INTERIOR
FRI...WHICH IS STILL BELOW NORMAL FOR THIS TIME OF YEAR. HAVE
TRENDED BACK TOWARD CLIMATOLOGY FOR SAT BUT A VERY
UN-CLIMATOLOGICAL BACKDOOR FRONT IS SHOWN BY THE GFS TO REACH GA BY
LATE SAT. THE ECMWF IS MUCH SLOWER PUSHING THE FRONT DOWN THE
EASTERN SEABOARD SO THERE IS LOWER FORECAST CONFIDENCE AT THE
MOMENT FOR DAY 7 (SAT).

&&

.AVIATION...
THRU 17/13Z...PREVAILING VFR ALL SITES...S/SW SFC WND AOB 5KTS...LCL
IFR/LIFR VSBYS IN BR/FG BTWN KDAB-KFPR. BTWN 17/13Z-17/16Z...VFR ALL
SITES...W/SW SFC WND 5-10KTS. BTWN 17/16Z-17/18Z...KDAB-KSUA SFC WND
BCMG E/SE 5-10KTS WITH TEMPO MVFR CIGS...INTERIOR SITES VFR. BTWN
17/18Z-17/24Z...CHC MVFR SHRAS/IFR TSRAS ALL SITES.

&&

.MARINE...
TODAY-TONIGHT...SUBTROPICAL RIDGE AXIS OVER S FL WILL DRIFT SLOWLY
NWD TOWARD LAKE OKEECHOBEE...MAINTAINING A LIGHT TO GENTLE S/SW
BREEZE ACRS THE LCL ATLC AS IT DOES. WINDS NEAR THE COAST WILL SHIFT
TO THE E/SE ARND MIDDAY AS THE EAST COAST SEA BREEZE DVLPS...CONTG
THRU EARLY EVNG. SEAS AOB 2FT WITH DOMINANT PDS AOA 8SEC. SCT
AFTN/EVNG TSTMS MVG OFFSHORE WILL BE THE PRIMARY BOATING THREAT.

MON-WED...SOUTH TO SOUTHWEST FLOW WILL TURN SE NEAR THE COAST IN A
SEA BREEZE EACH AFTN. DRIER AIR WILL LIMIT COVERAGE OF STORMS
OVER THE PENINSULA WITH LESS OF A CONCERN FOR OFFSHORE MOVING
STORMS TUE-WED.

&&

.PRELIMINARY POINT TEMPS/POPS...
DAB  91  73  94  76 /  30  10  40  20
MCO  94  75  95  75 /  20  10  30  20
MLB  91  75  92  75 /  30  10  30  20
VRB  91  72  93  75 /  30  10  30  10
LEE  92  75  96  77 /  20  10  30  10
SFB  94  75  96  77 /  20  10  40  20
ORL  94  76  96  78 /  20  10  30  20
FPR  91  72  92  74 /  30  10  30  10

&&

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

&&

$$

SHORT TERM...BRAGAW
LONG TERM....KELLY







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