Area Forecast Discussion
Issued by NWS Melbourne, FL

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FXUS62 KMLB 201952
AFDMLB

Area Forecast Discussion
National Weather Service Melbourne FL
352 PM EDT Thu Jul 20 2017

.DISCUSSION...

Currently/Tonight...
Another round of high PoPs, sparked by high moisture/sfc heating and
minimal convective inhibition allowed diurnal convection to dvlp
over the Treasure Coast/Lake-O region before noon, and over the
Space Coast/I-4 Corridor by early aftn. W/SW flow aloft was pinning
the east coast sea breeze over the coastal counties, while making
much further inland progress. Outflow boundaries generated by
coastal convection will work their way inland and eventually merge
with the west coast sea breeze. This will result in nmrs shras/tsras
dvlpg btwn the FL Turnpike and I-95 through late aftn/early evng.

The early start to convection will allow sufficient time for dvlpg
convection to consume the available energy by sunset. Given the
persistent westerly steering flow, anticipate lingering areas of
debris rain with isold embedded tsras well into the evng. The 6KM
WRF model clears east central FL from precip by 00Z, the while the
HRRR anticipates an area of debris rain lingering over the Treasure
Coast/Lake-O region through 03Z. Will split the difference and
continue likely shras/slgt chc tsras thru 02Z. Bcmg mostly clear to
partly cloudy overnight min temps in the L/M70s.

Fri-Fri Night...
An H85-H50 anticyclone centered over the midsouth will push acrs the
OH/TN river valleys, forcing a mid lvl cut-off low over the Carolina
Coast to retrograde around its SE flank and into the Deep South
where it will weaken and gradually fill in. The Bermuda Ridge axis
will remain suppressed over south FL/nrn Bahamas as this takes
place. As a result, a light to moderate W/SW flow will continue to
dominate the column, maintaining a favorable pattern for diurnal
convection across the east central peninsula.

Slightly lower PWat values along and north of I-4 will push PoPs
down to 40pct, but high moisture over the Treasure Coast/Lake-O
region will keep likely PoPs (60-70pct) in the fcst. Max temps near
avg along the coast (U80s/L90s) and slightly abv avg interior
(L/M90s). Min temps abv avg in the M70s.

Sat-Sun...
Mid-level low will continue to retrograde further into the Gulf of
Mexico over the weekend allowing the low-level Atlantic ridge to
shift back a bit to the north. On Saturday, a fairly deep layer
(although light) southwest to westerly flow should delay the
Atlantic sea breeze and also not allow it to move quite as far
inland. Plenty of moisture over the area along with forecast
soundings progging 500-mb temps of approximately -8 C will support
the usual round of afternoon showers and storms. Have chance PoPs
everywhere but slightly higher chances for the southern half of the
area where higher PWATs are forecast to be.

Not much change in the pattern for Sunday. More than sufficient
moisture remains over the area but have the higher (40-50%)
shower/storm chances slightly farther north than on Saturday where
better lift is forecast to be. This looks roughly to be from central
Okeechobee to Vero Beach northward at this point. 30-40% chances
south of this line.

Highs will be low 90s with lows in the lower to mid 70s.

Extended...(prev disc)
The Bermuda Ridge is shown shifting back to the N during the weekend
and remaining in place well into next week over the forecast area as
it stretches WWD across most of the Gulf of Mex. An east coast
trough stretching NWD along the Mid Atlc coast wl keep upstream
conditions somewhat unsettled through at least the middle of next
week. Seasonal moisture values with PWAT 1.6 to 1.8" and numerous
afternoon boundary interactions justify a typical range of sct pcpn
chcs in the forecast each aftn. Seasonal temps in the M70s with
highs in the L90s are expected.

&&

.AVIATION...Thru 21/18Z.
Sfc winds: Coastal sites...thru 21/02Z E/SE 8-12KTS...btwn 21/02Z-
21/05Z bcmg S/SW AOB 3KTS. Interior sites...thru 21/24Z N/NE 3-6KTS
bcmg E/NE 5-8KTS...btwn 21/00Z-21/03Z bcmg S/SE 3-6KTS...btwn 21/03Z-
21/06Z...bcmg vrbl BLO 3KTS.

Vsbys/WX/Cigs: Thru 21/00Z...nmrs MVFR shras/IFR tsras...slgt chc
LIFR +tsras with sfc G35KTS. Btwn 21/00Z-21/02Z...E of KMLB-KOBE
nmrs MVFR shras/chc IFR tsras...W of KMLB-KOBE chc MVFR shras/slgt
chc IFR tsras. Aft 21/16Z...E of KMLB-KOBE MVFR shras/IFR tsras
lkly...W of KMLB-KOBE chc MVFR shras/IFR tsras.

&&

.MARINE...
Tonight-Fri...Bermuda ridge axis will remain surpressed over south
FL and the north Bahamas as a weak sfc/low lvl trough over north FL
and the SE coast weakens and fills in. A light to gentle southerly
wind component will prevail...shifting btwn E/SE and W/SW as per the
sea breeze/land breeze circulation. Favorable boating conditions
will continue with seas AOB 2FT nearshore and 2-3FT offshore. High
moisture and SW flow aloft will continue to support scattered late
night/early morning showers and storms, mainly over the Gulf Stream.

&&

.PRELIMINARY POINT TEMPS/POPS...
DAB  74  92  74  92 /  30  40  20  50
MCO  72  94  75  93 /  40  40  20  50
MLB  75  91  74  90 /  60  50  30  50
VRB  75  91  74  90 /  60  60  30  50
LEE  75  95  77  93 /  30  40  20  50
SFB  74  95  76  93 /  30  40  20  50
ORL  74  94  76  93 /  40  40  20  50
FPR  75  91  73  90 /  60  60  30  50

&&

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

&&

$$

Short Term...........Bragaw
Mid Term.............Combs
Aviation/Impact WX...Glitto


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