Area Forecast Discussion
Issued by NWS Melbourne, FL
FXUS62 KMLB 031920
Area Forecast Discussion
National Weather Service Melbourne FL
220 PM EST Sat Dec 3 2016
Tonight...High pressure centered over the Ohio Valley will nudge
eastward overnight, causing winds to veer further as its southern
flank nudges off the Carolina coast. Available moisture will
remain low enough (PWATs between 1.0 to 1.2") to exclude
precipitation from the forecast. Most of the moisture is confined
within the mixed marine layer trapped beneath drier air above
850mb. Will maintain higher sky cover along the coast, and
especially south of Cape Canaveral, where patches of marine
stratocumulus will move in off the Atlantic. Tight gradient in low
temps along the coast as onshore flow will keep temperatures 5-10F
warmer along the barrier islands and along/east of I-95.
Sunday...Mid/upper level ridging persists over the Peninsula,
deflecting energy in association with an active southern jet
stream well away from the area. Meanwhile, surface ridge axis
shifts off the east coast and veers our local winds to out of the
southeast by late morning. While moisture will steadily increase
through the day, persistent mid/upper level ridging suggests
little more than pancaked stratocumulus moving in off the
Atlantic. Will maintain a dry forecast during the day on Sunday.
Temperatures will continue their upward trend and approach 80F
most areas save for the immediate coast, several degrees above
the climatological normal for early December.
Mon-Tue...The flow aloft will remain W/SW across the FL Peninsula
courtesy of upper-level high pressure situated to the south and low
pressure and the associated upper trough transitioning ENE out of TX.
In motion, the strongest mid-upper level energy looks to remain well
north of the forecast area as the upper trough lifts across Old
Dixie during the period. At the surface, high pressure off of the
Southeast U.S. coast early next week relocates slowly into the
Western Atlc. This feature will facilitate return flow moisture and
higher PWATS gathering over the eastern Gulf of Mexico ahead of the
evolving low pressure system reflected at the surface. This feature
is expected to move from TX/LA toward the TN Valley. Have introduced
isolated showers starting Mon afternoon (a little earlier) over land
with scattered showers over the coastal waters as setup for the
advancing system and developing rain chances for Mon night thru Tue.
Will push cold front down thru to South Florida by Wed morn with
local atmosphere progressively assuming pre-frontal SW flow posture
until then. Max temps in the L/M80s with min temps in the 60s Mon
night and U60s to near 70 Tue night. POPs 40-50 percent most places
for Tue, except 30-40 percent Treasure Coast. Shower/thunderstorm
precipitation should end from northwest to southeast during the
Wed-Fri...(modified from previous) The flow aloft continues to
remain W/SW across the region. Confidence continues to remain meager
for the extended forecast with differences in the medium range
models (GFS/ECMWF). The GFS content to slow the front across South
FL Wed/Thu before clearing and making the Straits Thu night due to a
reinforcing shot. This will promote keeping small POPs in mention
for St. Lucie, Martin, and Okeechobee counties until then. The ECMWF
remains a bit more consistent bringing the next front into the area
late Thu/early Fri along with more moisture which would signal
higher precipitation chances again ahead of it. Even so, much
cooler/drier air possible behind this stronger shot for Fri and into
at least the early part of the weekend.
Continued VFR as winds veer steadily from east northeast this
afternoon to southeast by late Sunday morning. Patches of marine
stratocumulus, with bases between FL030-FL040, will move off the
Atlantic over the next 24 hours...keeping cloud cover slightly
higher over coastal aerodromes.
Tonight...Winds will become easterly while averaging around or
slightly above 15 knots across much of the waters. Small craft
should continue to exercise caution well offshore and within the
Gulf Stream where seas will occasionally reach 6 feet overnight.
Sunday...High pressure axis shifts east of the Peninsula, veering
low level winds to the southeast by early afternoon. Wind speeds
will average 15 knots over the open Atlantic as seas subside
somewhat, 3 to 5 feet.
Sun Night-Wed...Winds will continue to veer SE Sun night, then SSE/S
on Mon/Mon night and SWRLY on Tue ahead of the front. Wind speeds
will average around 15 kts over the open Atlc over much of this
time, perhaps 15-20 kts offshore ahead of the approaching front late
Mon/Mon night. Latest model guidance suggests 20 kt winds on Tue
before winds decrease Tue evening/night.
Seas initially 3-4 ft into early Mon evening before building to 4-5
ft offshore Mon night. On Tue seas may build up to around 6 ft over
the Gulf Stream (to cautionary conditions), perhaps 7 ft well
offshore north of the Cape. Seas will begin to diminish Tue night
into Wed as the pressure gradient weakens.
.PRELIMINARY POINT TEMPS/POPS...
DAB 63 79 64 83 / 10 10 10 20
MCO 61 79 64 83 / 0 0 10 20
MLB 68 79 68 83 / 10 10 10 20
VRB 68 79 68 82 / 10 10 10 20
LEE 59 80 65 82 / 0 0 10 20
SFB 60 80 65 83 / 0 0 10 20
ORL 62 79 64 82 / 0 0 10 20
FPR 68 79 68 83 / 10 10 10 20