Scientific Forecaster Discussion
fxus62 kmlb 201946
Area forecast discussion
National Weather Service Melbourne Florida
346 PM EDT Sat Oct 20 2018
Current-tonight...latest radar trends show the West Coast sea breeze
associated convection moving thru west-central Florida this afternoon. This
activity will make its way into the Central Peninsula into the
evening with local hrrr showing some of this activity hanging on
into mid-evening, likely from future boundary collisions with the
limited moisture/instability, so have adjusted grids to account for
Weak high pressure ridging will slide south and east of the area
with the approach of a cool front. This latest boundary will move
into North Florida early this evening and continue to traverse the
peninsula overnight and should lie across the Central Peninsula by
sunrise Sun morning. Deep moisture and energy aloft will be minimal
by the time the front swings into/through the area so not expecting
much and will keep pops below 20pct for this. Light west-northwest/northwest winds
this evening will increase a bit (5-10 mph) after midnight with the
approach/passage of the front late. Min temps in the u60s/l70s.
Sun...the cool front will continue to move into the southern
peninsula early in the period. Still just a small threat for showers
from near the cape southward into Okeechobee County with most of the
interior north of here remaining dry. Early morning northwest/north winds will
quickly veer NE through the morning and afternoon with breezy/gusty
(15-20 mph) conditions at times. High temperatures will be
noticeably cooler with highs in the m70s in Volusia and near 80
Orlando Metro. L80s around Lake Okeechobee with some m80s possible
St. Lucie/Martin counties. Lower dewpoint readings, especially
northward, will make this day feel pleasant.
Sun night-Monday...surface high pressure to the north weakens and
pushes quickly out into the Atlantic. This will veer the winds out
of the east and it will remain breezy along the coast, perhaps
becoming breezy for some interior areas as well. Airmass will be
quite dry in the mid levels, but moisture streams in across the h30-
20 layer. Meaning cirrus, and a thin layer of stratocu will produce
a partly cloudy day. Temps Monday will be very seasonal, near climo
in the low/mid 80s.
Tue-Wed...both GFS and European model (ecmwf) show the subtropical jet stream ride
atop the ridge from Baja California through the deep south in
largely zonal flow. Both models show a moistening trend with the GFS
more rapid and the European model (ecmwf) more gradual. The GFS develops an inverted
surface trough along/just offshore the Florida East Coast which focuses
much higher rain chances along the coast. While the official
forecast shows higher rain chances near the coast (30-40 percent),
have not gone as high as GFS MOS. Forecast model soundings do show
the sky condition will be mostly cloudy to overcast during mid week
predominantly due to mid and upper cloudiness across the area. This
should have an impact on high temps as indicated by the slightly
cooler European model (ecmwf) MOS, lower 80s north and mid 80s south.
Thu-Sat...aforementioned conditions will play out into the extended
long-range. By Thursday the GFS and European model (ecmwf) show a weak frontal
boundary stalling just north of the area. Both models also show a
developing surface low moving from the northern Gomex and across the
Florida Peninsula. Still, a lot of uncertainty with the pops and inherent
thunder chances, GFS mos: 30-40 percent, nbm: 40-50 percent,
GFS/ECMWF/others 50-70+ percent...so, I cut the difference and
capped pops at 40 percent at night, and 50 percent during the day.
Aviation...the East Coast sea breeze was pushing slowly inland
while light westerly flow was pushing the West Coast sea breeze
inland a little farther. There's been a few small showers
developing over the interior and figure that with Max temps around
90 and dew points still around 70, additional showers should form
through late afternoon and linger until around sunset, mainly kism-
A cool front will drop down out of North Florida late tonight and
should reach kdab-klee by 12z sun. The main affect with this
boundary will be increasing winds behind it as low level convergence
looks too weak for showers. Breezy conditions will overspread most
of the terminals by Sun afternoon, with gusts possibly reaching 20-
25 knots along the coast, especially kdab-ktix-kmlb.
Marine...afternoon-tonight...will monitor late day/early evening
trends north of Melbourne near the coast in case late day fireworks
from boundary collisions over land push isolated convection toward the
intracoastal and near shore waters.
Weak high pressure again moves south and east of the area as a cool
front slides down the Florida Peninsula overnight. Only a small threat
for showers will exist with the boundary. Already light/variable
winds will respond through the evening by becoming westerly, then
northwesterly after midnight. Speeds will increase behind the front
in upwards of around 20 kts from the cape northward by daybreak Sun
morning. Seas near 3 ft near shore and south of Sebastian Inlet
(offshore). The remainder of the offshore legs north of Sebastian
Inlet will build to around 4 ft, perhaps as high as 5 ft north of
the cape depending on timing of front.
A Small Craft Advisory will go into effect at 4am/08z north of
Sebastian Inlet with the start of the Sun morning forecast package.
Sun...conditions continue to deteriorate across the local coastal
waters with hazardous conditions spreading areawide with a Small Craft Advisory for
all marine legs by 10am/14z. Winds will build to 20 kts, perhaps 20-
25 kts with frequent higher gusts during the day. Seas will build
quickly from the north to south. Sea heights will build 6-8 ft
offshore, perhaps up to 9 ft at times in the Gulf Stream. Near shore
seas will build 5-7 ft away from the coast.
Mon...Small Craft Advisory will continue through late Monday as
hazardous conditions are expected due to gusty winds and high seas.
Winds of 15-20 knots will quickly shift from northeast to east early
on Monday as a surface high pressure pushes quickly into the western
Atlantic. Seas will build to 5-6 feet in the nearshore, and up to 8
feet in the Gulf Stream.
Tue-Thu...pressure gradient should relax on Tue resulting in east
winds 10-15 knots, but seas remain 3-5 feet nearshore and 5 feet
offshore. On Wednesday, seas are expected to drop below 5 feet
offshore as onshore flow decreases to 10 knots or less. A frontal
boundary approaches the area on Thursday, increasing the winds and
seas along the northern Volusia waters.
Preliminary point temps/pops...
dab 68 75 62 79 / 20 10 0 10
mco 70 82 61 79 / 20 10 0 10
mlb 72 81 67 82 / 20 20 10 10
vrb 70 83 69 81 / 10 20 10 10
Lee 70 79 58 81 / 10 10 0 10
sfb 69 78 60 82 / 20 10 0 10
orl 71 80 61 82 / 20 10 0 10
fpr 69 84 70 81 / 10 20 10 10
Am...Small Craft Advisory from 4 am to 11 PM EDT Sunday for Flagler
Beach to Volusia-Brevard County line 0-20 nm.
Small Craft Advisory from 4 am Sunday to 4 am EDT Monday for
Volusia-Brevard County line to Sebastian Inlet 0-20 nm.
Small Craft Advisory from 10 am Sunday to 11 PM EDT Monday for
Sebastian Inlet to Jupiter Inlet 0-20 nm-Sebastian Inlet to
Jupiter Inlet 20-60 nm.
Small Craft Advisory from 4 am Sunday to 11 PM EDT Monday for
Flagler Beach to Volusia-Brevard County line 20-60 nm-
Volusia-Brevard County line to Sebastian Inlet 20-60 nm.