Area Forecast Discussion
Issued by NWS Melbourne, FL

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FXUS62 KMLB 221923
AFDMLB

Area Forecast Discussion
National Weather Service Melbourne FL
323 PM EDT Tue Aug 22 2017

.DISCUSSION...

Current-Tonight...The 15Z KXMR sounding shows only gradual
moistening from this morning`s atmospheric profile with a PWAT of
1.45 inches as temperatures aloft at 700/500mb (+9.7C/-5.1C) remain
warm. Water vapor imagery continues to show drier air in the
mid/upper levels over the area. As a result local Nexrad 88D has not
shown much action over land in favor of convection. The local HRRR
model does not produce much convection across ECFL over the
remainder of the afternoon and early evening. Deeper moisture does
remain forecast to push slowly northward tonight across the
Treasure/Space coasts and Okeechobee County as well. Greatest
chances for precipitation tonight will be from near Melbourne
southward along the coast and potentially west into Okeechobee and
southern Osceola counties. Will keep areas further north dry for
now. Lows will mainly be in the mid to upper 70s.

...Previous Extended Forecast Discussion...

Wed-Thu...Expect deep tropical moisture over the south half of the
peninsula with a moistening trend working northward during the
forecast period. The easterly wave will have transitioned
effectively to the Gulf side of the peninsula on Wed allowing for
invigorated onshore flow on the Atlantic side and leaving the door
fully open to the southeasterlies in the presence of the back of the
wave. The Treasure Coast will again realize the best rain chances in
this tropically disturbed pattern, but with high chances stretching
all the way across to the Gulf to include Okeechobee County. Expect
a lowering of surface pressure just offshore northwest of the Lower
Keys Wed into Thu as the wave tries to close off per GFS. Any
organization will be slow, but in the interim tropical Pwats will
have overspread the remainder of the peninsula boosting PoPs
everywhere for Thu. Max temps L/M90s Wed, then L90s Thu. Min temps
in the M/U70s.

Fri-Mon...Appreciable uncertainty continues within the extended
forecast with an attempt to glean as much information as possible
from multi-model tendencies. This uncertainty expands across the
Gulf from South Texas to South Florida with question marks over each
of the tropically suspect areas/features. Focusing closer to home, a
general meandering of lower surface pressure finds model bite just
east of the peninsula going into this weekend. The GFS shows a
developing low a little earlier and a little more south than the
ECMWF, but both currently liking the trend. The ECMWF favoring
organization over the northeast Florida waters while the GFS
offshore of the Cape. A swooping mid-latitude trough over the
Eastern CONUS in the mid-levels heading into the weekend will have
some bearing regarding ejection of any low toward the northeast as
surface pressures fall. Slightly higher than normal PoPs Fri-Sat in
the presence of plenty of tropical moisture. Max temps in the L90s,
and min temps in the M/U70s. Wind direction will be tricky and
highly dependent on the exact outcome of the developing low.

&&

.AVIATION...Generally a bust for precip today as drier air has held
its ground to the deeper moisture southward that has been unable to
erode it. Cannot rule out an isolated convective threat mainly south
of Orlando thru late afternoon, greatest chances Treasure Coast as
well as into this evening where moisture convergence is deepest.
Still mainly VFR flying weather. Deeper moisture does slowly move
northward again on Wed with gradually increasing shower/storm
chances, especially south of Orlando.

&&

.MARINE...Afternoon-Tonight...An easterly wave will continue to
traverse the southern FL peninsula this evening and move westward
overnight. With plenty of moisture in its wake, greatest precip
chances will remain over the southern waters. Generally ERLY winds
(ENE-ESE) veering more SE/S in the late evening and overnight. Seas
building to 3-5 ft near shore and 4-5 ft offshore in an east swell.

Wed-Thu...A recent tropical wave will leave plenty of moisture
around for increased shower/storm chances. The surface flow is
forecast to be mainly SE/S with speeds AOB 15 kts. Seas 2-3 ft near
shore and 3-4 ft offshore.

...Previous Extended Marine Forecast Discussion Slightly Modified...

Fri-Sat...Meandering low pressure and lingering tropical moisture
will team to keep plenty of showers and storms in the forecast. Wind
direction and wind speed will be tricky as there is some potential
for a surface low to form over or near the ECFL/NEFL coastal waters.
Seas generally 2-3 ft, perhaps 4 ft well offshore.

&&

.Climate...Potential warm minimum temperature records for 22-Aug-17.

Melbourne...82 which would tie the record from 2007.
Vero Beach..80 which would break the record of 78 set in 1944.

&&

.PRELIMINARY POINT TEMPS/POPS...
DAB  75  92  75  92 /  10  30  30  40
MCO  76  95  76  93 /  10  30  30  60
MLB  78  91  77  91 /  20  60  40  60
VRB  76  90  75  90 /  30  70  50  60
LEE  77  96  78  95 /  10  30  20  40
SFB  76  96  77  95 /  10  30  30  50
ORL  78  96  78  94 /  10  30  30  60
FPR  76  90  76  90 /  40  70  50  60

&&

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

$$

Sedlock/Pendergrast/Smith



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