Area Forecast Discussion
Issued by NWS Melbourne, FL

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FXUS62 KMLB 281958
AFDMLB

Area Forecast Discussion
National Weather Service Melbourne FL
358 PM EDT Fri Apr 28 2017

.DISCUSSION...

...HOT AND DRY...

Current-Tonight...Another hot afternoon with Heat Indices
approaching U90s across the interior. The ECSB is venturing slowly
inland this afternoon and will continue to move inland into this
evening toward the WCFL peninsula. The warm atmosphere remains
convectively suppressed. Surface high pressure ridging will move
north of ECFL tonight. Mid/upper level ridging remains forecast to
move northward to just off of the southeast U.S. coast. Warm and
humid again overnight with a sultry SE flow keeping mins in the L70s
inland, and M70s along the coast.

Sat...The east-west oriented surface ridge axis will lie north of
ECFL. This will provide the area with near breezy/breezy SERLY
winds. The center of mid-level high pressure continues to advance
northward to just off of the coast of the mid Atlc. We still
maintain relatively warm mid-level (700-500mb) temperatures and
relative stability. This will continue to convectively suppress
precipitation potential across the area. Unseasonably warm
conditions continue with highs in M-U80s along the coast and L90s,
perhaps a few M90s, further inland.

Sun...(modified slightly from previous) the H100-H70 high pres
ridge centered near Bermuda and extending WSW into the GOMex will
be the primary WX feature for central FL thru the upcoming
weekend. Position of the ridge will generate a brisk SE flow thru
10KFT while maintaining a stout low to mid lvl subsidence
inversion that will keep the local airmass well capped.

The onshore flow will promote the formation of a diffuse east coast
sea breeze as well as rapid inland penetration...collision with the
west coast sea breeze most likely will occur over west of the CWA.
Fcst PWat values btwn 1.00"-1.25", though much of this will be in
the form of upr lvl cirrus as the srn branch of the H30-H20 jet
pushes a 60-80KT streak acrs the FL peninsula. While the strength
and depth of the SE flow may generate a few low-topped nocturnal
showers along the Treasure Coast thru the weekend, impact would be
negligible with QPF well blo 0.10". Will keep PoPs in the silent
10pct range.

Temps will remain above avg as the southerly wind component
maintains a warm air advection pattern: aftn maxes in the M/U80s
along the coast and U80s/L90s inland. Overnight mins generally in
the L/M70s, though a few interior spots may dip into the U60s.

Mon-Thu...(from previous) Highly amplified jet pattern over the
central Pacific will push a strong H30-H20 jet core from the Pac
NW into the desert SW, where if will feed a dvlpg storm system
over the TX plains. Both GFS/ECMWF models indicate a deep and well
organized low pressure system over the Upr Midwest by daybreak
Mon that will lift acrs the Great Lakes on Tue, then into ern
Canada on Wed. The result will be a broad troughing pattern the
eastern half of the CONUS that will erode the wrn flank of the
Atlc ridge and shunt its center east of Bermuda, allowing the
opportunity for the system to crank a frontal boundary into
central FL on Mon night into Tue. Front is fcst to stall Tue night
into Wed over the Treasure Coast/Lake-O region as the parent low
lifts into ern Canada and begins to weaken.

Moisture band associated with the trof will reach central FL Mon
night into Tue. Increasing moisture and warm srly flow may
generate isold tsras over the interior as local mesoscale lake/sea
breeze boundaries interact. Front will washout over central FL on
Tue as the Atlc ridge tries to rebuild acrs the FL Peninsula.
However, global models indicate a secondary mid lvl short wave
pushing acrs the central plains and into the Deep South by the end
of the fcst pd...a reflection of the strong and active jet
pattern over the central Pacific. GFS is a bit more aggressive
than ECMWF wrt its more organized sfc low and more amplified mid
lvl trof, but either pattern would allow a new frontal boundary
and its associated moisture band to work its way into central FL.
Extended numerical guidance agrees that moisture will be
sufficient to support isold/sct PoPs thru midweek.

&&

.AVIATION...
ESE-SE winds approaching 15 kts over the interior remainder of
this afternoon and 15-20 kts and gusty along the Space/Treasure
coasts. Will not rule out some patchy low stratus around for an
hour or two early Sat morning. Otherwise, breezy ESE-SE winds once
again during the day.

&&

.MARINE...
Afternoon-tonight...East-west oriented high pressure ridging
moving north of ECFL. SE winds 10-15 kts near shore and 16- 19 kts
over the Gulf Stream south of Sebastian Inlet where small craft
should exercise caution. Seas continue mainly 3-4 ft, but could
approach 5 ft toward daybreak away from the coast where winds are
stronger.

Sat...High pressure remains north of the local coastal waters. SERLY
winds around 15 kts near shore and 17-18 kts offshore with marginal
conds in terms of cautionary statements for small craft. Seas 3-4 ft
very near shore and building to 4-5 ft over the open Atlc.

Sun-Mon...(modified slightly from previous) Deep high pres ridge
over the W Atlc extending into the GOMex/Deep South will dominate
the lcl WX pattern, generating a moderate to fresh SE breeze acrs
the area into early next week. Seas 3-5FT Sat, building to 4-6FT
on Sun, then 5-7FT on Mon. The persistent SE flow will place the
waters south of Sebastian Inlet in the shadow of the nrn Bahamas,
resulting in rough, short pd chop. Isold shras on Mon, chc of
tsras late Mon night as a frontal boundary approaches the area.

Tue...Weak frontal boundary will push into central FL and
washout. Winds diminishing and briefly veering to S/SW before
shifting back to the S/SE by late aftn. Seas 3-5FT nearshore and
4- 6FT offshore at daybreak, subsiding to 2-3FT nearshore and
3-4FT offshore by sunset.

&&

.FIRE WEATHER...Remainder of afternoon...Previous...Afternoon RH
values will reach the mid-upper 30s west of the SJR this afternoon,
with a few hours in the L30s likely across Lake County. County-
averaged ERC values are generally between 30-40, while the K-B
drought index map shows just about all of the CWA AOA 500, and most
of that between 600-700. Only two areas below this range - north
Lake/Volusia (which had a rain event on 4/4), and coastal Saint
Lucie/Martin (locally very heavy rain fell there 4/23).

The Fire Danger will remain in the "high" to "very high" range thru
this afternoon even though critical RH values (35 pct)/durations (4-
hours), and average ERC values (37) in some counties, fall a few
clicks short of RFW criteria.

This weekend...Deep SE flow continues areawide and should push
sufficient Atlc humidity across east central FL to keep min RH
values abv critical levels. Even so, the local Fire Danger will
remain High as a fresh transport breeze and aftn temps in the L-M90s
generate very good to excellent dispersion. The dry
ground/vegetation combined with the hot and breezy conditions, and
increasing sun angle will continue to add to the severe/near
critical fire sensitivity.

&&

.PRELIMINARY POINT TEMPS/POPS...
DAB  72  85  73  86 /  10   0  10  10
MCO  71  92  71  90 /   0   0  10  10
MLB  76  85  73  87 /  10   0  10  10
VRB  73  86  73  87 /  10  10  10  10
LEE  73  94  72  91 /  10   0  10  10
SFB  72  91  71  90 /   0   0  10  10
ORL  73  91  71  90 /   0   0  10  10
FPR  73  86  74  87 /  10  10  10  10

&&

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

$$

SHORT TERM...TS
LONG TERM/DSS....DS/JC
AVIATION...JC


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