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Area Forecast Discussion (AFD)

Issued by Melbourne, FL (MLB)

                            
000
FXUS62 KMLB 261858
AFDMLB

Area Forecast Discussion
National Weather Service Melbourne FL
258 PM EDT Sat May 26 2018

...Flood Watch Remains in Effect for East Central Florida Over 
the Holiday Weekend...

.DISCUSSION...
Moisture in association with Alberto is gradually building
northward, primarily in the mid and upper levels as south to 
southwest flow aloft transports convective debris over the area. 
An east component to the wind beneath 650mb continues to advect 
drier air in the low levels and is keeping surface-based activity
to a minimum. We will still need to wait for those low-level winds
to shift more southerly before significantly deeper moisture advects
into the area. That will take place after sunset as Alberto continues
lifting over the eastern Gulf of Mexico, veering winds and tapping
an airmass with precipitable water in excess of 2 inches. 

Will maintain a south-north gradient in PoPs through this evening,
with better chances across the Treasure Coast and Okeechobee County.
Thereafter, increased PoPs overnight, particularly after midnight
as low-level flow veers and moisture increases. Coastal convergence
should provide greater coverage south of Cape Canaveral. Additionally,
there is a window of opportunity for rotating storms Sunday morning
into the afternoon hours. 

Sun-Mon...Rain chances ramp up considerably Sunday (up to 80%) 
and remain high Monday (70-80%) as deep southerly flow to the east
of Alberto transport a very moist tropical airmass with PW values
of 2+ inches northward across the area. 

Heavy rainfall and localized flooding remain the main concerns from 
this system, with the potential for training bands of showers and
storms moving northward across the area. Rainfall totals of 2-3 
inches are generally expected through Sun- Mon across much of the 
area, with locally higher totals possible. A Flood Watch remains 
in effect for all of east central Florida during this timeframe. 
An isolated tornado threat will also exist across the region, 
mainly into Sunday, when low level helicity values are maximized 
to the east of Alberto. While wind threat continues to remain low 
for the area with Alberto's forecast track, breezy S/SE winds will
still be expected into Sunday, with stronger showers and storms 
having the potential to produce strong wind gusts. 

Cloudy to mostly cloudy skies will persist through the holiday 
weekend, keeping highs limited to the low 80s on Sunday and mid 80s 
on Memorial Day. Overnight lows will remain above normal with values 
in the low to mid 70s.  

Tue-Fri...Even as Alberto weakens after landfall along the northern 
Gulf coast, a moist plume of 2+ inch PW values will persist in a 
deep S/SW flow over the area. This will continue a wet pattern 
through at least Wednesday, with likely rain chances (60-70%) 
forecast across much of the region. Showers and storms will likely 
transition to becoming more diurnally driven, with greatest coverage 
in the afternoon each day. Into late week, models indicating a 
slight decrease in rain chances as deeper moisture shifts south and 
east. However, scattered shower and thunderstorm coverage will
remain in the forecast each afternoon. Highs will range from the 
mid- upper 80s, with low 90s possible across portions of the area 
on Friday.

&&

.AVIATION...
Multilayered clouds will gradually lower and thicken as "Alberto" 
lifts north over the eastern Gulf of Mexico through Sunday. Have 
kept VFR CIGs in place through 08Z except tempo MVFR in SHRA mainly 
over the interior this afternoon. Moisture will increase from the 
south aft 06Z with an increase in shower coverage with prevailing RA 
with embedded TSRA on Sunday. SE winds 10-15 knots this afternoon 
will increase near 15 knots and gusty on Sunday interior and 20 
knots and gusty at coastal terminals.

&&

.MARINE...
Tonight...Pressure gradient increases locally between Subtropical
Storm Alberto as it lifts north over the Gulf of Mexico and high 
pressure over the western Atlantic. SE flow around 15 kts will 
increase steadily to 15 to 20 knots this evening. Seas 3-5 feet 
will increase to 4-6 feet in the developing wind gradient into 
tonight. Small Craft Advisory will go into effect at 4:00 PM for 
Treasure Coast waters and offshore Brevard waters due to sustained
winds near 20 knots. Seas building up to 6 feet offshore 
overnight.

Sun...Hazardous boating conditions expected over the waters Sunday 
into Sunday night, as S/SE winds increase up to 20-25 knots well to 
the east of Alberto. These winds will build seas up to 7 feet, 
mainly offshore, with seas nearshore up to 5 to 6 feet. SCA
remains in effect for the entire coastal waters for Sunday, which
will continue for most of the adjacent Atlantic into Sunday 
night.

Mon-Wed...Poor boating conditions will likely continue into 
Memorial Day as model guidance only shows a slow decrease in winds
and seas into early next week. S/SE winds are still forecast up 
to 15-20 knots Monday with seas up to 6 feet offshore.

Winds and seas will then continue to gradually improve through mid 
week, with southerly winds decreasing to 10-15 knots and seas 
falling to 5 feet or less. 


&&

.PRELIMINARY POINT TEMPS/POPS...
DAB  75  82  74  84 /  60  80  40  70 
MCO  73  82  74  85 /  50  80  40  70 
MLB  75  83  75  85 /  60  80  50  70 
VRB  75  84  75  85 /  60  80  50  70 
LEE  73  82  74  85 /  50  80  40  70 
SFB  73  82  74  85 /  50  80  40  70 
ORL  73  82  74  85 /  50  80  40  70 
FPR  75  84  75  85 /  60  80  50  70 

&&

.MLB WATCHES/WARNINGS/ADVISORIES...
FL...Flood Watch through Monday evening for Coastal Volusia County-
     Indian River-Inland Volusia County-Martin-Northern Brevard 
     County-Northern Lake County-Okeechobee-Orange-Osceola-
     Seminole-Southern Brevard County-Southern Lake County-St. 
     Lucie.

AM...Small Craft Advisory from 8 AM to 10 PM EDT Sunday for Flagler 
     Beach to Volusia-Brevard County Line 0-20 nm.

     Small Craft Advisory from 8 AM Sunday to 8 AM EDT Monday for 
     Flagler Beach to Volusia-Brevard County Line 20-60 nm-
     Volusia-Brevard County Line to Sebastian Inlet 0-20 nm.

     Small Craft Advisory until 8 AM EDT Monday for Sebastian Inlet 
     to Jupiter Inlet 0-20 nm-Sebastian Inlet to Jupiter Inlet 
     20-60 nm-Volusia-Brevard County Line to Sebastian Inlet 20-
     60 nm.

&&

$$

Ulrich/Kelly/Combs/Smith