Scientific Forecaster Discussion
fxus62 kmlb 200816
Area forecast discussion
National Weather Service Melbourne Florida
416 am EDT Fri Sep 20 2019
today-tonight...broad low-level high pressure centered over the mid-
Atlantic states will gradually sag southward to become centered near
or just offshore the North Carolina coast by this evening. This and
the pressure gradient remaining tight across the area will give US
another day of breezy onshore flow. Winds are already breezy along
the coast, but the east-northeasterly winds will also increase
inland to around 20 mph with frequent gusts of 25 to 30 mph by late
morning/early afternoon as higher winds mix down from aloft. A lake
Wind Advisory has been issued for all of east central Florida
through 8 PM this evening.
Most recent 00z sounding from xmr shows warm and very dry air above
700 mb (approx. 10,000 ft) due to the subsidence from the mid-level
ridge, but as can be seen on latest radar imagery from kmlb, enough
moisture in the low-levels is sufficient enough for showers to
develop over the Atlantic and move onshore. Forecast soundings show
this airmass sticking around, so still expect the isolated to
scattered showers to continue for a good part of the day. Areas from
Melbourne southward have 30% shower chances with slightly higher low-
level moisture, and areas to the north have a 20% for the day.
Showers will be moving west or west-southwest at 25 mph and could
produce wind gusts of 35 to 40 mph in addition to a brief heavy
downpour. High temperatures will be in the mid 80s along the coast
and mid-upper 80s inland.
Large, long-period swells from Humberto will again keep beach
conditions hazardous with dangerous rip currents and rough surf. A
high surf advisory and a high risk of rip currents is in effect.
By later this afternoon into this evening, models are showing some
additional dry air moving into the area, and expecting the vast
majority of the area to stay dry this evening and tonight. However,
some higher moisture is forecast to advect into the Treasure Coast
region from the south overnight, so will carry 20-30% shower chances
for the overnight period south of Vero Beach. Breezy conditions
look to continue along the space and Treasure coasts as well, which
may keep temperatures along the immediate coast in the upper 70s.
Winds are not forecast to be as strong along the Volusia coast so
temperatures may drop into the low to mid 70s. Across the interior,
low temperatures will be cooler and generally low 70s, but some
spots that see winds drop off could fall into the upper 60s.
Weekend...blocking high pressure anchored over Georgia will remain in
place into early next week. Stout easterly winds (breezy in the
afternoons) underneath the ridge will provide continued winds off
the Atlc ocean, with subsidence ascd with the dominant high
bringing an end to mentionable rain chcs across most of the area
Sunday and ending areawide Sun night. Under mostly sunny skies highs
will remain in the M-u80s Sat-sun with lows in the u60s-l70s.
Extended...avbl medium range guid agrees the dominant ridge over
the southeast will flatten Monday in response to a shortwave transiting
the Ohio Valley. As this wave amplifies swd along the mid Atlc coast
on Tue, modest high pressure both at the sfc and aloft should try
to establish over the Florida Peninsula. A gentle onshore flow will
keep temperatures restricted, especially near the coast with rain
chcs in the absence of any notable moisture return remaining to
silent to very low chcs through the middle of next week. Expect
highs in the u80s to l90s.
VFR conditions outside of shower activity. Isolated to scattered
fast-moving showers will continue to move in from the Atlantic
today. Coverage only enough to include vcsh for the coastal
terminals with no mention for interior sites. Showers will be
moving mainly to the west around 20 to 25 knots and could produce
wind gusts to around 30 knots along with brief MVFR restrictions.
Drier conditions this evening and tonight but may need to include
vcsh at sua and fpr for overnight tonight.
today-tonight...no change in the short-term as the solid Small Craft
Advisory conditions remain with the large, long-period swells from
Humberto and easterly winds between 20 and 25 knots. Seas continue
to run 9 to 11 feet nearshore and 10 to 12 ft offshore.
Weekend...advisory headlines will continue as significant swell
event ascd with tropical activity over the basin keeps seas well
within criteria. By Sunday, guidance suggests headlines may begin
to be trimmed over a portion of the waters depending on expected
decay of swell and the underlying wind forecast. Navigation near
inlets will also remain a concern due to primary swell component
to wave height.
Extended...WV heights begin to slip to 6 ft or less during Mon and
if forecast holds all headlines should finally be lowered
incrementally over the waters early in the week. Decaying swell
should continue to make up the primary wave component into at
least Wed of next week.
a river Flood Warning remains in effect for the St Johns River at
Astor. River levels on the St Johns River are forecast to slowly
decline, but still remain in minor flood stage near Astor over
the next several days. The St Johns River above Lake Harney
remains in action stage. River levels are forecast to slowly
decline over the next several days, falling below action stage
Preliminary point temps/pops...
dab 85 73 83 68 / 20 10 10 0
mco 88 71 86 68 / 20 10 10 0
mlb 87 77 84 72 / 30 10 20 10
vrb 86 76 84 71 / 30 20 30 20
Lee 88 70 89 68 / 20 10 10 0
sfb 87 71 86 68 / 20 10 10 0
orl 87 71 87 69 / 20 10 10 0
fpr 86 76 84 71 / 30 20 40 20
Florida...Lake Wind Advisory from 10 am this morning to 8 PM EDT this
evening for coastal Volusia-Indian River-inland Volusia-
Martin-northern Brevard-Northern Lake-Okeechobee-Orange-
Osceola-Seminole-southern Brevard-Southern Lake-St. Lucie.
High surf advisory until 4 PM EDT Saturday for coastal Volusia-
Indian River-Martin-northern Brevard-southern Brevard-St.
Am...Small Craft Advisory until 10 am EDT Sunday for Flagler Beach to
Volusia-Brevard County line 0-20 nm-Flagler Beach to
Volusia-Brevard County line 20-60 nm-Sebastian Inlet to
Jupiter Inlet 0-20 nm-Sebastian Inlet to Jupiter Inlet 20-
60 nm-Volusia-Brevard County line to Sebastian Inlet 0-20
nm-Volusia-Brevard County line to Sebastian Inlet 20-60 nm.