Area Forecast Discussion
Issued by NWS Melbourne, FL

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403
FXUS62 KMLB 172004
AFDMLB

Area Forecast Discussion
National Weather Service Melbourne FL
403 PM EDT Thu May 17 2018

.DISCUSSION...

Currently/Tonight...

Very moist/unstable airmass overhead combined with convective
triggers in the L/M80s lead to an early start to diurnal convection
with initialization sparking by late mrng before lcl CAPE values
could reach their max potential. As a result, convection remained
largely blo svr lvl with fqnt ltg and very heavy rain as the primary
WX threats. Latest radar data shows peak convective activity north
of the I-4 Corridor and along the Treasure Coast, all of which will
consume the remaining areas of energy by late aftn.

H100-H70 analysis shows an anticyclone over the Great Lakes/Upr
Midwest combining with a cyclone over the Deep South/Lwr MS Valley
to form a classic "rex" blocking pattern. This will maintain the
deep S/SW flow that will continue to tap the tropical airmass to the
south. PWats AOA 2.00" will keep the lcl airmass sufficiently moist
to keep PoPs in the fcst overnight. However, the bulk of any
activity should be done before midnight once available energy is
depleted. Will keep chc shras/slgt chc tsras thru late evng,
diminishing to slgt chc overnight. Min temps will be near current
sfc dewpoints, L/M70s.


Fri-Fri Night...
Blocking pattern will hold the cyclone over the Deep South in place
for one more day, with its axis extending into the ern GOMex.
However, this block will will begin to break down Fri aftn/Fri night
 as the Great Lakes anticyclone drifts east into New England and the
Canadian Maritimes. S/SW flow will continue to dominate the column
with SSW winds thru the day, becoming S/SE overnight as the cyclone
drift north into the TN/OH river valleys.

Deep tropical moisture on the ascending ern flank of the cyclone
will support another day of high precip coverage with nmrs/wdsprd
shras and sct tsras...PoPs at 70pct interior and 80pct coast to
account for the SW steering flow. Convection ending by midnight over
the interior as winds shift to the S/SE, but that same flow will
require at slgt chc of shras along the coast. Deep cloud cover and
high precip coverage will keep max temps L/M80s, high dewpoints will
keep min temps in the L/M70s.

Sat-Sun...(Mod prev disc)
Bermuda ridge will lift into the Deep South as the cyclone continues
to drift N/NE. Low level flow will strengthen out of the SE on Sat,
tapping deep moisture that will continue to support 60/70 pct
shras/tsras. However, the focus will shift to the interior with the
increasing easterly steering component. On Sunday...low level
southeast flow will continue with deeper moisture beginning to work
slowly westward. Will have rain chances lower for the coastal
counties as the east east coast sea breeze becomes dominant...PoPs
decreasing to 50/60pct. Lcl heavy rainfall/fqnt CG ltg will continue
as the primary storm concerns with the recent heavy rainfall across
portions of east central Florida this week. Highs will range from
the mid 80s coast to upper 80s well inland Saturday and in the mid
80s Sunday...mins U60s/L70s.


Mon-Thu...(prev disc)
The low level Atlantic ridge axis will move northward into mid week
with a period of low level southeast flow around the ridge expected.
Moisture levels will continue to support mainly diurnal showers and
storms along the inland moving east coast sea breeze with rain
chances in the scattered range each day. Should see morning morning
sun into next week before afternoon cloudiness increases with daily
convection. Highs will be near normal in the mid 80s along the coast
to the upper 80s across the interior.

&&

.AVIATION...
Numerous showers and thunderstorms will continue across the interior
and northern areas through this evening. Have included TEMPO groups
at all terminals for this afternoon/early evening as strong storms
will be capable of producing IFR conditions of 2-3SM visibilities,
and BKN020-025 CIGs. Earlier today a strong to severe thunderstorm
produced VLIFR conditions at KLEE. High resolution models indicate
thunderstorms will end around 17/22Z-23Z for the interior terminals
and KDAB, but I did keep VCTS through 17/24Z for possible lingering
thunderstorms. Showers will continue through around 18/03Z-04Z from
KTIX-KSUA. Models are also indicating additional showers and
thunderstorms will develop later this evening after 17/24Z and
impact mainly KTIX-KMLB-KVRB, but I have lower confidence that this
will occur due to showers/storms that have already occurred. Thus,
will continue TEMPO groups as they are, with the caveat that
amendments may be needed before the 00Z TAF issuance. Forecasting
VFR conditions after 18/04Z for all terminals.

&&

.MARINE...
Tonight...Weak low pres over the Deep South will combine with the
Bermuda ridge axis over the Nrn Bahamas/FL Straits to maintain a
gentle to moderate S/SW breeze over the lcl Atlc. Seas 2-3FT
nearshore and 3-4FT offshore...up to 5FT in the Gulf Stream north of
Sebastian Inlet. Prolonged southerly fetch will place much of the
Treasure Coast waters in the Bahama shadow, resulting in rough short
pd seas AOB 5sec. Wdsprd shras/tsras with shras/tsra moving offshore
in the early evng.

Fri-Fri Night...Bermuda ridge axis will begin a slow drift to the
north as the low pres over the Deep South lifts out of the area.
Gentle to moderate S/SW breeze thru the day will shift to the S/SE
overnight. Seas 2-4FT nearshore and 3-5FT offshore. Numerous
showers/scattered storms are expected over the local Atlantic waters.

Sat-Tue...(prev disc) The Atlantic ridge will elongate north of the
waters through the weekend with winds becoming southeast up to 15
knots offshore. Seas generally in the 3-4 ft range near shore and up
to 4-6 ft well offshore. Numerous showers and storms Saturday will
become scattered across the waters into early next week.

&&

.PRELIMINARY POINT TEMPS/POPS...
DAB  70  85  70  85 /  50  60  40  60
MCO  70  88  71  88 /  50  70  40  60
MLB  71  85  72  84 /  50  70  40  70
VRB  71  86  72  84 /  50  70  50  70
LEE  71  88  71  89 /  40  60  30  60
SFB  70  88  71  87 /  50  70  40  60
ORL  71  88  71  87 /  50  70  40  60
FPR  71  86  72  84 /  50  70  50  70

&&

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

&&

$$

Short/Mid Term....Bragaw
Aviation..........Rodriguez
Radar/Impact WX...Smith



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