Area Forecast Discussion
Issued by NWS Melbourne, FL

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FXUS62 KMLB 100820

Area Forecast Discussion
National Weather Service Melbourne FL
420 AM EDT Fri Aug 10 2018


Latest RAP40 analysis shows a broad, deep lyr trof over the Mid
Atlc/New England region and a deep lyr anticyclone centered over the
SE GOMex. Interaction btwn these to WX systems is generating a W/NW
flow acrs the FL peninsula thru the H100-H70 lyr. Little change in
general flow thru tonight as the east coast trof keeps the axis of
the anticyclone suppressed over south FL.

While the wrly flow component will concentrate diurnal precip over
the east central peninsula, the northerly component will tap a
relatively dry continental airmass over the Deep South with H100-H70
mean RH values btwn 70-75pct. Mid lvl moisture acrs the region is
sparse as well with H85-H50 mean dewpoint depressions btwn 7-10C.
The 10/00Z RAOBS measured PWat values btwn 1.75"-2.00", but these
are a little deceptive as much of the upstream moisture at KJAX/KTAE
is trapped abv H50, while the H100-H50 lyr has more or less uniform
moisture distribution.

The NWrly flow pattern is not climatologically favorable for
widespread diurnal precip. Given the current moisture profile acrs
the state, it appears this case will be no different. H70 temps btwn
8-9C will couple with H50 btwn -6C/-7C to produce meager lapse rates
btwn 5.5-6.0C/KM. Even so, latest sat pics show minimal cloud cover
over central FL, and with sfc dewpoints in the L/M70s areawide and a
warm wrly flow component, temps should reach their convective
triggers by (U80s/L90s) by midday. Lcl HRRR/WRF models suggesting
coverage blo 50pct, though the dry mid lyr air will enhance
downburst potential, especially in mesoscale collision zones. Will
paint the CWA with 40pct PoPs. Temps a few degs abv avg with aftn
maxes in the L/M90s, overnight mins in the L/M70s.

Sat-Sat night...
The low level ridge will remain south of the state on Sat with low
level W/WNW flow in the morning becoming W/SW in the afternoon. GFS
indicates a low level trough near the Treasure coast in the morning
with deeper moisture (PWATs to 2.0 inches) near the boundary and 1.8-
1.9 inches across nrn sections. The area will also be under the
influence of a low level trough from Carolinas into GA which will
keep fairly deep moisture across the area. Convection should develop
along a progressive west coast breeze boundary into the interior and
also near a slow moving east coast sea breeze along the Treasure
coast. Will keep POPs above climo mainly in the 50-60 percent range.
Highs will reach around 90 along the Treasure coast to the lower 90s
over the remainder of the area.

On Sunday, the surface ridge will remain across south FL with deep
moisture and low level SW flow north of the ridge axis. This will
spell high rain chances across the interior and from Brevard
northward along the coast in the likely range. On Monday, the low
level ridge begins to lift northward to Lake Okeechobee with models
indicating some drying in the H7-H5 layer. This should lower rain
chances some but still expected in the 40-50 percent range with
adequate moisture for afternoon convection with SW flow continuing
in the low levels. Highs mainly in the lower 90s.

The mid level ridge east of the state on Tuesday will drift westward
over central FL into late week. GFS indicates 596 DM heights over
the nrn peninsula by Thu evening which should suppress convective
chances into Thu/Fri. For Tuesday, low level W-SW flow is still
expected across the area with some drying aloft in the H7-H5 layer.
Will keep rain chances in the 30-40 percent range with higher
coverage into mid/late afternoon and early evening with boundary
interactions. For Wed/Thu...The low level ridge will lift toward
central FL with a drier airmass and onshore flow limiting rain
chances for the Treasure coast. Slightly higher rain chances to
around 30 percent are forecast across the interior with the inland
moving east coast sea breeze each afternoon. With the lessening rain
chances into late week, expect some high to reach the mid 90s across
the interior and lower 90s for the coastal counties.


.AVIATION...Thru 11/12Z.
Sfc Winds: Thru 10/12Z...W/SW 4-7KTS. Btwn 12/15Z...bcmg W/NW 7-
11KTS. Btwn 10/17Z-10/20Z...coastal sites bcmg E/NE 8-12KTS. Btwn
10/23Z-11/02Z...bcmg W/SW 3-6KTS.

Vsbys/WX/Cigs: Btwn 10/12Z-10/16Z...cigs AOA FL120...N of KISM-KOMN
slgt chc MVFR shras/IFR tsras. Btwn 10/16Z-10/20Z...cigs btwn FL060-
080...W of KOMN-KOBE chc MVFR shras/IFR tsras slgt chc LIFR tsras
with sfc G35KTS. Btwn 10/18Z-10/22Z...cigs btwn FL060-080...E of
KOMN-KOBE chc MVFR shras/IFR tsras slgt chc LIFR tsras with sfc
G35KTS...W of KOMN-KOBE chc MVFR shras. Btwn 10/22Z-11/02Z...cigs
btwn FL100-120...E of KOMN-KOBE chc MVFR shras.


Today-Tonight...Broad, deep lyr trof just off the ern seaboard will
keep the Bermuda ridge axis suppressed over south FL and the Nrn
Bahamas, resulting in a light to gentle W/NW breeze acrs the lcl
Atlc. Winds bcmg light and variable by mid aftn as the east coast
sea breeze dvlps, bcmg a light S/SE breeze by late aftn, then
veering to a light to gentle W/SW breeze arnd midnight as the land
breeze circulation kicks in. Seas AOB 2FT nearshore and 2-3FT
offshore thru late aftn, subsiding to AOB 2FT areawide arnd sunset.
Primary marine threat will be sct tsras moving offshore capable
of generating wind gusts in excess of 34KTS.

Sat-Sun...Westerly flow to 10 knots Sat morning will become SW/S
into the afternoon. Seas 1-2 ft near shore and around 2 ft offshore.
Winds will become S/SSW on Sunday with seas up to 2 ft offshore. The
main hazard this weekend will be scattered showers/storms moving
from the mainland toward the intracoastal/near shore waters each
afternoon into the early evening.

Mon-Tue...S/SW winds into early next week around 10 knots around the
Atlantic ridge will keep seas in the 1-2 ft range near shore and
around 2 ft offshore.


The Saint Johns River at Astor is forecast to remain close to flood
stage into the weekend.  A River Flood Warning remains in effect
there until a slow decline commences late this weekend or early next
week. Elsewhere, river levels are forecast to remain within Action
Stage over the next 5 days.

Please refer to our River Flood Warnings/Statements (FLSMLB) and
Hydrologic Statements (RVSMLB) for the most recent stage and
forecast information.


DAB  94  74  92  75 /  40  30  50  30
MCO  94  73  92  75 /  40  20  60  30
MLB  94  74  91  75 /  40  30  50  40
VRB  92  72  91  74 /  40  30  40  40
LEE  94  75  92  76 /  40  20  50  30
SFB  96  75  93  76 /  40  20  60  30
ORL  95  74  93  76 /  40  20  60  30
FPR  92  72  90  73 /  40  30  40  40





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