Area Forecast Discussion
Issued by NWS Melbourne, FL
FXUS62 KMLB 110921
Area Forecast Discussion
National Weather Service Melbourne FL
421 AM EST Sun Dec 11 2016
Today and Tonight...Sfc troughing along the FL E cst responsible
for considerable cloudiness and some light pcpn over the past 24H
will lift Nwd around periphery of a large high pressure center
off the E US coast. LL winds will veer to a SE component late today
and into tonight while decreasing in speed. Incrsg moisture justifies
continuation of iso/sct pcpn chcs mainly along the coast and marine
areas today and into tonight with light accumulating rain in affected
locations. A noticeable decrease in gradient winds will occur at
nightfall as the coastal trough pulls away from the area.
MOS guid suggests a good setup for development of fog areawide
overnight and there may be some locations which experiences dense
fog inland by daybreak Mon, depending on the lighter winds as
advertised. Milder temps this aftn in the M-U 70s with lows
tonight in the L-M60s can be expected.
Warm and dry fcst to start the workweek as a high pres ridge over
the W Atlc pushes east, allowing the lcl pgrad to weaken. Storm
system dvlpg over the Central Plains will ride up over the backside
of the retreating ridge, driven by an almost perfect zonal flow
pattern that will dominate the column abv H85.
The storm system will pull a cold front into the Deep South on Mon
as it lifts acrs the Great Lakes/New England region. However, given
the absence of anything that resembles meridional flow, the front
will stall north of the FL Panhandle no later than Mon evng. While
the front will not have a direct impact on central FL thru Tue
night, it will suppress the ridge axis trailing Atlc high into the
south FL peninsula. The resulting S/SW flow that will dominate the
H100-H70 lyr, generating a warm air advection pattern that will keep
temp well abv avg. Max temps in the L/M80s, min temps in the L/M60s.
With the front stalled to the north and the zonal flow carrying the
bulk of any mid/upr lvl synoptic forcing into the Atlc, precip
chances are going to be on the low side at best. Models do hint at
some low lvl moisture advection occurring as a frontal boundary
stalled over the FL Straits works its way north in the dvlpg
southerly flow. However, much of this will lift out of the area by
late Mon, leaving the lcl airmass somewhat starved of moisture. Fcst
PWat values generally in the 1.00"-1.25" range do not inspire
confidence in PoPs any higher than 20pct. Furthermore, the fcst temp
profile reveals multiple subsidence inversions thru the H90-H60
lyr that will effectively quash any chances of deep convection.
Little change from previous forecast philosophy as extended models
show little sign that the zonal will break down before the weekend,
especially with regard to the H30-H20 jet pattern acrs the CONUS.
GFS/ECMWF models continue to hint that the front stalled over the
Deep South will get a secondary push from an arctic airmass expected
to spill out of W Canada by midweek. Higher confidence that the
front will push thru central FL on Thu and into the FL Straits by
daybreak Fri...about 12-24hrs slower than the 10/00Z run.
However, by the time the front pushes central FL, it will have spent
two to three days over the Mid and Deep South. Post frontal airmass
will modify significantly so as to minimize any cool down. Given
that the warm air advection preceding the fropa will push temps 10-
15F abv avg, any cooling will only return temps to near avg Thu/Fri.
Neither ECE/MEX MOS guidance indicate more than a 10F temp drop
behind the front with max temps in the L70s/U70s...min temps in the
L/M50s along and north of I-4...L/M60s along the Treasure Coast.
MOS PoPs remain unimpressive as the zonal flow to the north carries
the bulk of any short wave energy into the Atlc well north of
central FL. Central FL will be left with a of broad, low amplitude
short wave to support what remains of the sfc frontal bndry. Neither
GFS/ECMWF manages to squeeze out more than 20 PoPs on Thu/Fri,
either with the fropa or the return flow that dvlps on Fri behind
the front. Will bookmark with a token 20pct areawide on Thu, then
20pct along the coast on Fri.
Considerable cloudiness with higher decks prevalent most areas
into this Aftn. Expect sct to ocnly bkn clouds invof FL040 along
with sct -shra along cst fm SUA-FPR this AM spreading N to nr MLB
aft 10/16Z, then iso/sct further N to DAB/OMD aft 10/20Z.
Today and Tonight...The transition in gradient winds to highest
onshore values occurs south of the Volusia and Brevard Co line
attm. The Air Force profiler network is indicating 20 kts at Cape
Canaveral with coastal sites supporting advisory conds generally
south of Mosquito lagoon to the Treasure Coast. Have extended the
SCA for the Brevard coast until 10 AM. Points south will remain in
SCA through 4 PM until higher gradient winds lift north ofthe
marine area later today. Winds and seas will steadily diminish
Mon-Mon Night...Lcl pgrad will weaken as a high pres ridge retreats
into the Atlc. Gentle to moderate S/SW breeze at daybreak
diminishing to a light to gentle S breeze by mid aftn, then bcmg
light/vrbl overnight. Seas 3-4FT nearshore and 4-5FT offshore thru
the day, subsiding to 2-3FT nearshore and 3-4FT offshore overnight.
Tue-Tue Night...Vrbl winds as a frontal trof stalls over the Deep
South and keeps the lcl pgrad disrupted. From Sebastian Inlet
northward...light N breeze bcmg E/NE thru the day, SE by sunset,
then light to gentle W/SW overnight. South of Sebastian Inlet,
light/vrbl bcmg E/SE by midday, SE by sunset, then S/SW overnight.
Seas 2-3FT over most of the area...up to 4FT in the Gulf Stream.
Wed-Wed Night...Low pres dvlpg off the Carolina Coast will pull the
stalled front into central FL, allowing the lcl wind field to become
better defined. Light to gentle W/SW breeze thru the day, freshening
aft sunset to a gentle to moderate W breeze by midnight, then a
gentle to moderate NW breeze by daybreak. Seas generally 2-3FT...up
to 4FT in the Gulf Stream.
Thu-Thu Night...Conditions expected to deteriorate as a cold front
pushes down the FL Peninsula and into the FL Straits. Moderate to
fresh N/NW breeze thru the day, bcmg gentle to moderate NE breeze
overnight. From Sebastian Inlet northward, seas 3-5FT thru the day,
building to 4-6FT by sunset...south of the Inlet seas 2-4FT thru
the day, building to 4-6FT by sunset.
.PRELIMINARY POINT TEMPS/POPS...
DAB 74 62 78 63 / 20 20 20 10
MCO 76 63 83 64 / 20 10 20 10
MLB 76 65 82 67 / 30 20 20 10
VRB 78 65 82 65 / 30 20 20 10
LEE 75 62 81 62 / 10 10 20 10
SFB 75 62 82 64 / 20 20 20 10
ORL 75 63 82 64 / 20 10 20 10
FPR 76 64 81 65 / 30 20 20 10
AM...Small Craft Advisory until 10 AM EST this morning for
Volusia-Brevard County Line to Sebastian Inlet 0-20 nm-
Volusia-Brevard County Line to Sebastian Inlet 20-60 nm.
Small Craft Advisory until 4 PM EST this afternoon for Sebastian
Inlet to Jupiter Inlet 0-20 nm-Sebastian Inlet to Jupiter
Inlet 20-60 nm.