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fxus62 kmlb 201959 

Area forecast discussion
National Weather Service Melbourne Florida
255 PM EST Mon Nov 20 2017


..higher rain chances are on tap from tomorrow through Friday...

Tonight-Tuesday...broad short wave trough will drop southeast into the
western Gomex before turning eastward overnight and east-northeast Tuesday,
with its axis reaching to longitude of Nola by 12z, then, and then
extending from North Florida into the eastern Gomex early Tuesday
evening. A broad area of increasing forced ascent will begin to
overspread the peninsula starting late tonight and continuing
through the day. This will induce formation of a weak low pressure
trough over the northeast Gomex tomorrow. This feature will move NE
into the Florida Panhandle by early evening, dragging the diffuse
remnant front along with its moisture band back northward through
the state during the day.

Even with limited diurnal heating, presence of aforementioned
synoptic scale features will be more than sufficient to generate
numerous showers across ecfl. Activity should begin late tonight
along the Treasure Coast, then increase and spread north/inland
throughout the day. H50 temps between -11 and -13c could support
isolated thunderstorms, mainly during the afternoon. Guidance pops
remain pretty consistent at around 70 percent and were accepted for
this forecast package. Min temps tonight much warmer...l60s inland
and u60s along the coast. Maxes Tuesday in the M-u70s, a little on
the low side of climo owing to clouds/precip.

Wednesday-Thursday...mid and upper-level troughing pattern persists
over the southeastern Continental U.S. Extending through the central Gulf of
Mexico. Lower level winds are forecast to veer northerly to
northeasterly on Wednesday ushering in slightly drier air compared
to Tuesday. Both the GFS and European model (ecmwf) continue to show a few ripples in
the mid-level flow moving across the area. With the lingering
frontal boundary in place, these disturbances should be sufficient
enough to provide enough lift to generate showers and perhaps a few
thunderstorms as temperatures aloft remain quite cool. GFS seems
too aggressive on precip chances and have sided more with the European model (ecmwf)
and local WRF as the drier air in place should limit overall
coverage. Pops have been kept generally around 30% most areas with
the exceptions being 40% over the far interior and 20% for the
Treasure Coast. Rain chances increase in late evening and overnight
especially along and north of I-4 with a large area of upward
vertical motion forecast to across east central Florida. Haven't
gone quite as high as the mav guidance is suggesting for pops but
included 50-60% from Kissimmee to the cape northward and 40% farther

Weak surface low/inverted trough develops on Thursday along the
pseudo-stationary boundary over the eastern Gulf of Mexico in
response to a more vigorous shortwave aloft. This low/inverted
trough will move across the area on keeping high rain chances (60%)
and a few thunderstorms in the forecast for Thanksgiving day. unsettled weather pattern continues through the
end of the work week as broad mid and upper level troughing over the
Gulf gets reinforced by another shortwave digging down through
Arkansas and Louisiana. With the trough's axis remaining west of the
state, surface pressure will remain lower over the eastern Gulf of
Mexico for at least one more day. Both the GFS and European model (ecmwf) now shift a
weak low over the peninsula late Friday as the mid/upper trough gets
absorbed within a larger scale trough over the eastern Continental U.S.. a
blend of model guidance keeps higher rain chances into Friday
(capped at 50% for now given the continued uncertainties) before
drier air shifts down the backside of the low and removes rain
chances over the weekend. Temps start off near to below normal given
the ample cloud cover with a reinforcing (dry) front expected to
move through on Sunday, leading to even cooler temperatures by the
end of the period.


Aviation...VFR through 12z. Prevailing scattered-bkn045-050, becoming
multilayered broken-overcast cigs from 050 thru 120 after 06z. After 12z,
will see increasing coverage of MVFR vsbys in precip, with cigs
bkn030-050 ovc050-080. Slight chance for ts mainly after 16z.


Marine...tonight-Tuesday...high pressure north of central Florida
will gradually weaken as a weak inverted trough develops over the
local waters, winds/seas have continued to ease a bit through early
afternoon, and model/wave guidance has trended a bit lower for the
next 24 hours. This forces US to shave back the Small Craft Advisory to the 0-60nm
waters south of sipf1, and the 20-60nm Brevard Waters. Peak winds/
seas for this event remain the same, but shifted just a bit south;
20kt/6-7ft in the advisory area and 15-20kt/4-6ft elsewhere. Scec
will replace the Small Craft Advisory for near shore Brevard/offshore Volusia legs.

Wednesday...a chance of showers a few storms will stick around on
with northeasterly winds of 10-15 kt with seas of 3-5 ft nearshore
and 4-5 ft for the offshore waters.

Thursday-Saturday...low pressure is forecast to develop over the
eastern Gulf and shift over the peninsula late this week. Confidence
in the wind forecast, especially direction, remains lower than usual
given the uncertainties in the system's strength and track. Variable
winds will become more northerly and will likely increase on the
backside of the low, leading to deteriorating seas over the weekend.


Preliminary point temps/pops...
dab 64 75 64 74 / 10 70 50 30
mco 63 76 64 77 / 10 70 30 30
mlb 68 78 67 78 / 20 70 30 30
vrb 68 78 66 78 / 30 70 30 20
Lee 61 76 63 77 / 10 70 20 40
sfb 62 76 63 76 / 10 70 40 30
orl 62 75 64 76 / 10 70 30 30
fpr 68 78 66 78 / 30 70 30 20


Mlb watches/warnings/advisories...
Am...Small Craft Advisory until 4 PM EST Tuesday for Sebastian Inlet
to Jupiter Inlet 20-60 nm-Volusia-Brevard County line to
Sebastian Inlet 20-60 nm.

Small Craft Advisory until 10 am EST Tuesday for Sebastian Inlet
to Jupiter Inlet 0-20 nm.


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