Area Forecast Discussion
Issued by NWS Melbourne, FL
FXUS62 KMLB 040929
Area Forecast Discussion
National Weather Service Melbourne FL
429 AM EST Sun Dec 4 2016
Today...Low level flow will veer out of the Southeast as high
pressure over the mid Atlc states pushes east and offshore.
Moisture trapped beneath a subsidence inversion around 4k ft will
produce scattered to broken stratocumulus. So there will be more
clouds around then yesterday but moisture band looks too
thin/shallow to produce measurable rainfall. A few sprinkles may
occur along the Treasure coast though.
Temperatures are noticeably milder this morning due to the
onshore flow and occasional cloudiness esp along the coast. Highs
this aftn will reach 80 for most of the interior and upper 70s
Tonight...Mild southerly flow with considerable cloudiness will
hold low temperatures in the mid to upper 60s, a good 10 degrees
above normal. South winds at 925 mb of 15 to 20 knots will
contribute to hostile environment for widespread fog but expect
considerable stratus to develop after midnight. Will keep isolated
showers offshore over the Atlc but a few may brush the Martin
coast as they lift north.
Mon-Tue...The flow aloft continues W/SW with flat upper ridging over
the area and upper troughiness to the west moving northeastward and
away from the Florida peninsula. Subtle, weak impulses will exist in
the upper flow, but more significant vorticity will remain well
north of the area. Greatest jet stream energy will also remain
northward, but speeds approaching 100 kts will clip northern FL. At
the surface high pressure located off of the southeast U.S. coast
will continue to move slowly eastward, further into the western
Atlc, during the period.
Moisture will deepen with PWAT values increasing towards 2 inches
ahead of an approaching frontal boundary that will pass through ECFL
Tue overnight into early Wed morning. The GFS continues to be slower
to push the boundary into the southern peninsula compared with the
ECMWF. Latest 00Z model guidance from the ECMWF does speed this
system up a bit as well as introduce precipitation earlier out ahead
of it. Humid conditions will return with U60s/L70s dewpoints.
Winds will become SSE/S on Mon into Mon night. Direction will
continue to veer to SW on Tue, then W/NW Tue overnight behind the
front. The pressure gradient tightens on Tue with breezy wording
Will keep a small threat for precipitation on Monday, highest
chances near/north of the I-4 corridor, as well as introduce thunder
wording by late afternoon here. Will keep highest PoPs northward Mon
night, once again, with thunder mention KMLB northward thru 06Z/1AM.
Will keep 50 percent PoPs Thu southern Osceola County/Brevard County
northward, then stagger down to 30 percent for Martin County. Will
gradually end precipitation chances Tue night from northwest toward
the southeast across ECFL.
Max temps in the L/M80s with min temps in the U60s/L70s Mon night
and generally in the 60s areawide Tue night. Will have to monitor
for near record highs at DAB for both Mon/Tue (83 in 2013/85 in
1972). Record high mins (lows) may be within reach as well for Mon
overnight/Tue morning (most sites) due to the mild/humid conditions.
Wed-Sat...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
continues to slow the frontal progress across south-central FL on
Wed that would keep small precip chances in the forecast across our
southern coverage warning area. The ECMWF remains more consistent
bringing the next front into the area Thu night/early Fri along with
more moisture which would signal higher precipitation chances again
ahead of it. Even so, much cooler/drier air becoming more likely
behind this stronger shot for Fri and into at least the early part
of the weekend.
VFR conditions expected through 03Z although ocnl ceilings
between 035-045 AGL will occur esp at coastal terminals this
morning spreading to the interior terminals this aftn. IFR
ceilings are forecast to develop after 06Z tonight at most
terminals and this will likely be advertised in the next TAF
issuance at 12Z.
Today/Tonight...High pressure over the eastern U.S. will push
east and offshore tonight resulting in a veering wind flow. The
pressure gradient will support 12-15 knots of wind from the
southeast today becoming southerly tonight. This will produce
choppy wind waves of 3 to 4 feet on the Atlantic waters. While no
headlines are in place (Caution or Advisory), boating conditions
will be less than ideal.
Mon-Thu...Surface high pressure off of the southeast U.S. coast
early in the period will continue to drift eastward further into the
west Atlc Mon-Tue. An approaching cool frontal boundary is forecast
to move across the local coastal waters Tue overnight into early
Wed. The pressure gradient will tighten ahead of the approaching
boundary on Mon night thru Tue. Weak high pressure will influence
the local weather on Wed into at least early Thu. Medium range
models differ on timing/strength on next possible weather system for
Thu night so confidence lower on Thu. Isolated lightning storm
chances increase Cape northward by late Mon afternoon-Mon night and
areawide Tue into early Tue evening.
Winds will continue to veer SSE/S on Mon/Mon night and SWRLY on
Tue/Tue evening ahead of the front. Wind direction will become W/NW
behind 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 20-25 kt winds on Tue before winds decrease Tue
evening/night and remaining rather light into at least early Thu.
Seas initially 3-4 ft thru Mon evening before building to 4-5 ft
offshore late 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
thru Thu as the pressure gradient weakens.
.PRELIMINARY POINT TEMPS/POPS...
DAB 78 66 82 70 / 10 10 30 40
MCO 80 66 83 70 / 0 10 30 30
MLB 79 69 82 72 / 10 10 20 30
VRB 79 68 82 73 / 10 10 20 20
LEE 80 66 81 70 / 0 10 30 40
SFB 79 66 81 71 / 0 10 30 30
ORL 80 66 81 70 / 0 10 30 30
FPR 79 68 81 72 / 10 10 20 20