Area Forecast Discussion
Issued by NWS Melbourne, FL
FXUS62 KMLB 310127
Area Forecast Discussion
National Weather Service Melbourne FL
928 PM EDT TUE AUG 30 2016
...High Rain Chances will Persist into Late Week...
Overnight...Surface winds will turn more SE-S through the overnight
hours. Shower activity has become isolated over interior sections
and latest HRRR model run keeps coverage limited over land areas
over the next several hours. Some increase in coverage toward
sunrise will favor the southern sections of EC FL. Making minor PoP
tweaks for the rest of tonight based on this. Rest of forecast
package still on track.
Previous discussion... Wed-Thu (modified)...TD9 is forecast to be a
Tropical Storm and making a northward turn early Wed, then will
start accelerating to the northeast through Thu. The models have
been in good agreement with the track and the 00z GFS/ECMWF
continued that trend. The system will be well to our west on Wed but
a large moisture plume will extend across the local area. The GFS
showed precipitable water values 2.2-2.4 inches so with just a
little surface heating, widespread showers and isolated storms are
expected. Didn`t change our previous 70 PoPs for Wed.
The low center is forecast to move towards Apalachee Bay on Thu
with increasing low level southerly flow maintaining high moisture
especially across the north. Have drawn 80 PoPs Orlando north
decreasing to 60 PoPs Treasure coast. There will be a continued
heavy rain threat and expect a Flood Watch will be necessary. But
there does not appear to be any focusing mechanism to anchor heavy
rains on Wed, though locally heavy rain will occur. Widespread
heavy rain should accompany the closest approach of the tropical
cyclone on Thu north of Orlando but models are showing a trend
toward a leftward shift in the track which would keep the heaviest
rains north of Lake/Volusia.
With increasing low level winds/shear late Wednesday night
through Thursday, an isolated tornado threat may also materialize.
Fri-next Tue (previous)...The tropical system will move off
toward the northeast away from the area early in the period. The
00z GFS showed a weak trailing surface trough into the peninsula
through Friday, with high moisture continuing into Sat. The model
then builds northeast winds slowly down the peninsula into early
next week with gradual drying. PoPs look above normal 50-60
percent on Fri-Sat, then should taper back to 30-40 percent for
the start of next week.
.AVIATION...Isolated cig/vsby reductions in shra through late
evening...shra coverage picking up toward sunrise S to N. On
Wed...expect prolonged passing showers/storms with tempo ifr/mvfr
cigs/vsbys with gusty winds 25-35 knots. This will require VCSH/VCTS
to remain in the TAFs.
Previous CWF still on track...no sig changes planned for late eve.
Previous discussion...Tonight...Increasing southerly flow around
developing tropical cyclone in the southern Gulf of Mexico is
forecast to increase near 20 knots this evening and overnight. Seas
do not respond very quickly in such a flow regime but combined seas
and long period swell will produce 7 ft seas offshore. So have
raised Small Craft Advisory for most of the coastal waters except
coastal Volusia waters where a caution headline is in place.
Wed-Fri...Poor to hazardous boating conditions will exist through
this period as the tropical system lifts north/northeast over the
eastern Gulf of Mexico then crosses the northern peninsula Thu
night. The latest track would place the tightest pressure
gradient across the waters from about Canaveral north Thu night.
The less then favorable boating conditions will be accompanied by
an increasing coverage of rain/storms and attendant threat for
locally higher winds and seas in gusty storms/squalls.
Sat...The latest GFS and ECMWF show a weak surface trough trailing
from the tropical system and extending into the local waters. This
will lead to diminishing winds, but high moisture and westerly
steering winds will continue the threat for storms affecting the
AM...Small Craft Advisory until 11 AM EDT Wednesday for 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.