Area Forecast Discussion
Issued by NWS Melbourne, FL

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FXUS62 KMLB 120832

Area Forecast Discussion
National Weather Service Melbourne FL
430 AM EDT Sun Aug 12 2018


FL is currently sandwiched btwn two areas of high pres...a closed
H100-H70 anticyclone over the GOMEX, and the wrn flank of the
Bermuda ridge over the Bahama Bank. Btwn the two, as weak trof/col
runs down the spine of the FL Peninsula. This trof extend north to
merge with a weak frontal trof over the Carolinas. Resulting H100-
H70 mean flow is SW btwn 10-15KTS. Evng RAOBs measured PWat values
arnd 2.00" acrs central and south FL...latest RAP40 analysis
confirming this with values approaching 2.25" over the SW peninsula.
H100-H70 mean RH values btwn 70-80pct, and H85-H50 dewpoint
depressions arnd 5C.

An H85-H50 col over the SW peninsula points to a convergence zone
extending from Ft. Myers to Cape Canaveral. Dynamic instability is
on the moderate side:  Mid lvl omega/upr lvl divergence is lacking,
but lcl pockets of vorticity over the Nature Coast and over the Lake-
O region will make up for this.  Thermodynamic support is moderate
as well: H70 temps arnd 9C and H50 temps arnd -7C will yield lapse
rates arnd 6.0C/KM.

With low pres straddling the peninsula the lcl airmass is primed for
convection. Furthermore, the moisture profile suggests precip likely
areawide. H70 temps suggest a weak thermal cap that will delay
convective initiation until early aftn, while the steering flow
suggests convection peaking in the late aftn along the coast. Lcl
HRRR/WRF models support this. Given the SW steering flow, will go
with 60pct over the interior and 70pct along the coast today, precip
lingering thru 02Z with 20pct interior and 30pct alng the coast.
Temps near avg with aftn maxes in the U80s/L90s, overnight mins in
the L/M70s.

Mon-Mon Night...
Low to mid level SSW/SW flow is expected Mon around the Atlantic
ridge and south of the large mid level closed low near the Ohio
valley and mid Atlantic. The low level ridge will be across south FL
with deeper moisture with PWATs to 1.9 to 2.0 inches across nrn
sections and lower PWATs around 1.6 inches around Lake Okeechobee.
Will have highest shower/storm chances to 50 percent across the
north in the area of deeper moisture with a progressive west coast
sea breeze likely moving all the way to Volusia county. Across
southern sections, lower coverage of afternoon showers and storms is
expected though slightly higher rain chances are expected for Martin
county as some storms from Palm Beach may advect NNE into the late
afternoon hours. Highs mainly in the lower 90s.

On Tuesday the low level ridge will makes it way northward to near
Lake Okeechobee with deeper moisture across srn sections and lower
PWAT air across the north with continued low level SW flow north of
the ridge. Will keep rain chances in the scattered range around 30
percent from Orlando northward to 40-50 percent across srn sections.
The low level ridge will move northward up the central peninsula on
Wed allowing low level flow to veer to the ESE/SE. Should see lower
rain chances overall with 20 percent along the coast to 30 percent
over much of the interior. High temps 90-91 along the coast to 92-94
across the interior.

Low level southeast flow around the Atlantic ridge will be the
dominant weather pattern for late week and the upcoming weekend.
Will have POPs in the 30-40 percent range most days with highest
rain chances across the interior each afternoon as the east coast
sea breeze boundary moves inland each day with low level SE winds.
The lowest rain chances looks to be Friday for this period in the 20-
30 percent range as the mid level ridge builds closer and some lower
PWAT air works into the area from the east. Highs will be in the
lower 90s coast to mid 90s interior and lows in the mid 70s inland
to upper 70s near and along the east coast.


.AVIATION...Thru 13/12Z.
Sfc Winds: Thru 12/12Z...SW 3-6KTS. Btwn 12/12Z-12/15Z...bcmg S/SW 6-
9 KTS. Btwn 12/15Z-12/18Z...coastal sites bcmg SE 7-11KTS. Btwn
12/23Z-13/02Z...bcmg S/SW 3-6KTS.

Vsbys/WX/Cigs: Btwn 12/12Z-11/16Z...slgt chc MVFR shras/IFR tsras.
Btwn 12/16Z-12/20Z...cigs btwn FL060-080...N of KISM-KTIX nmrs MVFR
shras/IFR tsras slgt chc LIFR tsras with sfc G35KTS...S of KISM-KTIX
sct MVFR shras/IFR tsras. Btwn 12/19Z-12/23Z...cigs btwn FL060-
080...S of KISM-KTIX nmrs MVFR shras/IFR tsras slgt chc LIFR tsras
with sfc G35KTS...N of KISM-KTIX chc MVFR shras/IFR tsras. Btwn
12/23Z-13/02Z...cigs btwn FL100-120...coastal sites chc of MVFR
shras/IFR tsras...interior sites slgt chc MVFR shras/IFR tsras.


Today-Tonight...Weak trof over the spine of the FL Peninsula will
combine with the wrn flank of the Bermuda Ridge over the Bahama Bank
to generate a light to gentle S/SW breeze acrs the lcl Atlc. Winds
shifting to S/SE over the nearshore waters by early aftn as the east
coast sea breeze dvlps. Seas AOB 2FT, though the offshore wind
component will generate choppy wind waves with dominant pds AOB
4sec. Primary boating hazard will be sct/nmrs shras/tsras moving
offshore btwn midday and early evng.

Mon...S/SW winds expected in the morning becoming S/SE by late
afternoon. Seas 1-2 ft srn waters to around 2 ft from Sebastian
Inlet northward.

Tue-Thu...Southerly winds Tue will become SE into mid week. Seas
around 2 ft will gradually build to 2-3 ft offshore Tue afternoon
into mid week with winds up 10-15 knots around the Atlantic ridge at


No sites along the Saint Johns river are at or above Flood Stage,
however most locations remain within Action Stage except Deland.
Refer to the latest Hydrologic Statements (RVSMLB) for the latest
stage and forecast information.


DAB  90  75  92  73 /  70  30  50  30
MCO  94  74  92  74 /  60  20  50  20
MLB  89  75  91  74 /  70  30  30  20
VRB  88  73  92  75 /  70  30  30  20
LEE  93  75  92  76 /  60  20  50  20
SFB  94  74  93  75 /  60  20  50  20
ORL  94  75  93  76 /  60  20  50  20
FPR  88  74  92  73 /  70  30  30  20





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