Area Forecast Discussion
Issued by NWS Melbourne, FL

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FXUS62 KMLB 232002

Area Forecast Discussion
National Weather Service Melbourne FL
402 PM EDT Mon Oct 23 2017


Tonight...There will be an increase in coverage of showers/storms
into this evening as increasingly moist south southwest flow
combines with upper divergence ahead of an upper level trough. The
assocd cold front is currently located from central GA southward
across TLH and into the Gulf. Considerable cirrostratus continues
to overspread northern sections which has limited heating today
but developing convection on the FL west coast will push east and
interact with the east coast sea breeze over interior sections
toward evening. Additional storms should develop over southern
sections where more heating has taken place. So have drawn 50 PoPs
all areas. Convection will likely persist well into the night
supported by forcing aloft. The cold front is forecast to reach
Lake/Volusia counties by sunrise then push more slowly across EC
FL during Tue.

Tuesday-Wednesday (previous)...Strong upper low pressure with
associated deep troughing over the central CONUS will move slowly
east and weaken gradually with a mid-level trough axis finally
sliding across the central FL peninsula Wed overnight. This upper
system will help drive a significant cold front into north-central
FL by sunrise Tue morning, then across ECFL during the day on Tue
and Tue night. A tight pressure gradient will remain as weak high
pressure builds into the area behind the front late Tue overnight
into Wed. An above normal chance of showers and thunderstorms
will precede the boundary on Tue with much drier air filtering
into the area from the north on Wed. The showers and storms will
feed off of PWATs between 1.70-1.90 inches and some modest surface
heating. The best dynamics, however, will remain north of the
area. A few strong storms may be possible but currently are not
anticipating any severe weather.

Rain chances will range from 30 to 40 percent north of I-4 to 60
percent south of Orlando Tue. Rain chances will diminish from north
to south over the area Tue night. Have precip slowly ending on Wed
over the Treasure Coast/Okeechobee County as the ECMWF is a bit
slower to scour out moisture.

Max temps in the L80s Tue, perhaps M80s should enough surface
heating occur, and L-M70s on Wed. Mins falling back into M-U50s
north/L-M60s south behind the front Tue overnight, with L50s for
most of the area Wed night, even some U40s north of I-4 or normally
cooler areas of ECFL.

Thursday-Sunday (previous)...Aloft upper troughing continues to
push eastward away from the peninsula as brief shortwave ridging
moves across the state and northerly winds quickly back to
southwesterly ahead of an approaching upper trough to the west for
Fri into the weekend. At the surface weak high pressure builds
across the region on Thu, then off of the Atlantic Seaboard late
Fri into Sat with the approach of a tropical low from the south.
Presently, the ECMWF lifts this feature into the FL Straits by
late Sat, northeast across southeast FL Sat night, and further
northeastward away from the peninsula on Sun, swept away by an
approaching front/upper trough combo. Model consistence and timing
of surface/upper features will play a key role going forward with
exact track/strength of this system.

After cooler than normal conditions again on Thu, temps should
rebound closer to climo Thu night-Fri with the onset of
return/onshore flow, then remain near climo next weekend. For now
have kept land areas dry thru Fri night, then introduce a small
threat for showers on Sat/Sun (moisture gradient could be tight from
north to south).


Scattered SHRA/TSRA will move in from the west into this evening
ahead of a strong cold front. Will likely need to add TEMPO
groups for many terminals for MVFR CIGs and VSBYs due to
convection through 04Z. Lingering showers possible overnight
mainly south of MCO. Cold front will slowly push southeast across
the area on Tue with sct TSRA developing aft 15Z mainly MCO south.


Tonight...S/SE pressure gradient will veer out of the S/SW
supporting wind speeds of 13-18 knots and seas 4 to 5 feet with up
to 6 feet well offshore. Will maintain Caution headline for the
offshore waters of Volusia and Brevard. There will be an increase
in coverage of storms pushing offshore this evening and overnight.

Tuesday-Friday (Previous)...A rather significant cold frontal
boundary will press southward across the coastal waters Tue-Tue
night with weak high pressure building in from the west for the
remainder of the extended. S/SSW winds around 10 kts and up to 15
kts well offshore on Tue will gradually veer (toward NW/N) during
the day/evening as the front slowly moves southward across the
area. During the late evening/overnight Tue wind speeds will
gradually increase to around 20 kts over much of the area due to a
tighter pressure gradient. The gradient will be slow to decrease
into late Wed afternoon/night as the wind direction remains NW/N.
Wind speeds will continue to decrease Thu into Fri as the
northerly wind component veers to easterly by Thu overnight into

Offshore moving showers and thunderstorms will accompany the frontal
boundary Tue/Tue night, finally clearing the southern coastal marine
legs by late Wed morning or early afternoon with mostly dry
conditions prevailing into late work-week. Lightning, gusty winds,
and torrential downpours appear to be the main storm threats.

Seas will build 3-5 ft on Tue with some 2 ft seas possible very near
shore and far southern marine legs. Seas are forecast to build to
around 6-7 ft again on Wed/Wed night offshore/Gulf Stream, then
subside again Thu-Fri.


DAB  72  83  58  73 /  50  40  20  10
MCO  71  84  60  75 /  50  50  20   0
MLB  74  85  63  76 /  50  60  40  20
VRB  74  85  66  76 /  50  60  50  30
LEE  70  83  57  74 /  50  20  10   0
SFB  71  84  59  74 /  50  40  20  10
ORL  71  84  62  75 /  50  40  20   0
FPR  74  85  67  76 /  50  60  60  30





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