Area Forecast Discussion
Issued by NWS Melbourne, FL

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FXUS62 KMLB 181324

Area Forecast Discussion
National Weather Service Melbourne FL
924 AM EDT Wed Jul 18 2018


Current-Today...915 MHZ Cape wind profilers show deep SWRLY flow
averaging 15 kts above the surface. KXMR 10Z sounding shows a PWAT
of 2.05 inches with 700/500mb temperatures of +9.0C/-7.0C
respectively. A weak mid-level trough extending across north Florida
and the north Gulf will continue to gradually weaken during the day.
The low-level surface ridge axis remains situated south of the area.
Apparently enough lift and moisture early this morning to get
convection initiated already across the western FL peninsula. The 15
kt steering flow should bring convection into ECFL, if it holds
together, by late morning/early afternoon north of I-4. Otherwise,
expected surface heating and seasonal afternoon boundary collisions
will again get SCT-NMRS showers/storms going through late day.
Activity will again pile up across the eastern peninsula, given the
deep westerly flow, late today/evening. Given the flow the east
coast sea breeze either will not develop or likely will be pinned
along the immediate east coast. Should this occur, brief pulsing of
storms may occur at the immediate coast and across the intracoastal
and near shore Atlc waters. Mariners and beach-goers will need to
keep an eye to the sky westward today.

Storm threats today will include frequent cloud to ground/water
lightning in a few storms, torrential downpours leading to brief
nuisance flooding, gusty winds up to around 50 mph, and perhaps some
small hail.

High temps should reach the lower 90s inland, and lower-mid 90s
along the coast, before convection initiated on the west coast sea
breeze moves/propagates across the area.  Heat indices continue in
the 100-105F range areawide in the afternoon.

Tonight...Previous...The GFS shows most precip shifting into the
Atlantic during the evening, so will only have a small PoP along the
coast for that. Low-mid level southwest flow may push some showers
well inland from the Gulf of Mexico late in the night, mainly west
of I-4, so will have a small PoP for that too.


.AVIATION...Continued mainly VFR this morning. The west coast sea
breeze will be more active today with the deep SWRLY flow across the
area. Movement of scattered showers/isolated early afternoon storms
will be toward the NE, higher threat along the I-4 corridor early.
Activity will increase in coverage through late day and push towards
the coast late in the day/evening where the ECSB, if able to develop
at all, likely will be pinned along the coast. A few strong pulse
storms at the coast are possible. Timing based on higher resolution
models continue to show a little quicker progression of convection
across the peninsula today. A few pockets of instability should
linger behind the initial band of showers/storms. Gusty winds 35
knots or greater could occur with a few of the storms.


.MARINE...Today-Tonight...Surface ridge axis remains shunted south
of the area. Deep SWRLY flow generally around 10 kts near shore and
10-15 kts offshore through the period. Seas 1-2 ft near shore and up
to 3 ft well offshore, perhaps up to 4 ft offshore tonight. Winds
and seas locally higher later this afternoon/evening surrounding
offshore moving showers/storms. Torrential downpours, frequent cloud
to water lightning, and wind gusts in excess of 35 kts all in play
later today.


.HYDROLOGY...Previous modified...The Saint Johns River is either
above Action Stage or just above Flood Stage between Geneva and
Astor. Little change is expected through late week.

Near Geneva, just south of Lake Harney, the most recent stage was
8.15 feet, which is above Flood Stage (8.0 feet). The river is
forecast to fall slightly but remain near Flood Stage into late
week. A River Flood Warning remains in effect for this area.

At Sanford, the most recent stage was 5.09 feet, which is above
Action Stage (4.2 feet). The river is forecast to remain nearly
steady, staying below Flood Stage (5.5 feet) into late week.

Near Deland, the most recent stage was 3.53 feet, which is just
above Action Stage (3.5 feet). The river is forecast to remain
nearly steady into late week.

At Astor, the most recent stage was 2.29 feet, which is right around
Flood Stage (2.3 feet). The river is forecast to remain nearly
steady into late week. A River Flood Warning remains in effect for
this area.




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