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Area Forecast Discussion (AFD)

Issued by Melbourne, FL (MLB)

                            
000
FXUS62 KMLB 250759
AFDMLB

Area Forecast Discussion
National Weather Service Melbourne FL
359 AM EDT Fri May 25 2018

.DISCUSSION...
...Locally Heavy Rainfall Expected Over This Holiday Weekend and 
Into Next week...

Today and Tonight...Increasing moisture will become evident as
showers increase in coverage during the afternoon from the south.
Most areas across south and central FL will see showers along with
isolated lightning storms by evening with rain amounts of one half
to one inch and wind gusts of 35 to 40 mph possible in heavier 
showers. A somewhat lower chc of rain exists over Volusia county
as the moisture works up into that area a little later in the day.
Showers will diminish tonight with high precipitable over 
spreading the entire region overnight with PWAT in excess of 2 
inches and considerable cloud cover. Will keep a sct mention of 
showers along with coastal and marine storms into the overnight 
hours with lows remaining in the 70s. 

Sat-Mon...Continued concern for the holiday weekend remains heavy 
rainfall and localized flooding potential to the east of low 
pressure that will lift northward from the Yucatan Peninsula into 
the central/eastern Gulf of Mexico. NHC continues a high chance (70% 
next 48 hours/90% next 5 days) for a named tropical/subtropical 
system to develop. GFS continues a weaker and more eastward track
with this system over the Gulf compared to other global model 
guidance. 

Regardless of track or development between the models, they are 
all in good agreement of a northward transport of deep tropical 
moisture, with PW values of 2+ inches across the area through the 
period. This values are well above climatological norms for this 
time of year and will make for a very wet Memorial Day weekend, 
with rain chances remaining high (60% or greater) over much of the
area each day. 

Area average rainfall totals of 2-4 inches through Sat-Mon look 
likely. However locally heavy rainfall in training rain bands or 
storms can easily exceed these amounts. The greatest threat for 
excessive rainfall and localized flooding will shift northward along 
the coast from Saturday afternoon into Saturday night where 
increasing low level E/SE flow up to 25-30 kts will maximize coastal 
convergence. This threat then expands farther inland into Sunday 
from south to northward moving bands of shower/storms, depending on 
how far east the system tracks toward Florida. Due to the more 
saturated ground conditions from the recent heavy rains, a Flood 
Watch will likely be needed for portions if not much of east central 
Florida. An isolated tornado threat can also not be ruled out 
especially Saturday night to Sunday, when model guidance shows 
greatest increase in 0-1 km helicity values across the area.  

Overall wind threat remains rather low based on latest guidance with 
this system. However, breezy S/SE winds will occur across the area 
and a few stronger storms/shower bands could produce strong gusty 
winds. 

Tue-Thu...A wet pattern persists through at least the middle of next 
week as a deep S/SW flow keeps a very moist airmass across the 
region. Scattered to numerous showers and thunderstorm expected each 
day with convective development becoming more diurnally driven, with 
greatest coverage into the afternoon hours. Localized flooding 
issues will continue to be a concern due to the rain soaked grounds 
following the holiday weekend. 

&&

.AVIATION...Expect VFR conds this morning with isold shra 
developing S of MLB-ISM FM 25/14Z-25/17z. Aft 25/17Z lcl MVFR
conds in SHRA/TS. LCL obstructions to SKY and VIS ascd with 
afternoon showers and LCL TSRA FM25/18Z-25/22Z mainly S of a line
from MCO-TTS. BECMG mainly VFR aft 25/23Z with sct shra and isold
TS producing brief obstructions through 26/03Z.

&&

.MARINE...
Today and Tonight...SE flow will continue with winds of 10 to 15 
kts enhanced somewhat by an onshore coastal breeze developing in 
the afternoon. Seas mainly 2 to 3 ft with 3 to 4 ft seas over the 
outer waters. wins and seas will be higher near showers and storms
developing and moving toward the coast. 

Sat-Sun...Low pressure is expected to strengthen as it lifts 
northward into the central/eastern Gulf of Mexico this weekend. 
NHC continues a high chance for subtropical/tropical development 
with this system. Latest guidance at least supports poor to 
hazardous boating conditions through much of the weekend as S/SE 
winds increase through the period building seas up to 6-7 feet. 
SCA headlines will likely be needed, especially into Saturday 
night through the Sunday night timeframe. 

Mon-Tue...Currently model guidance indicates a slow improvement in 
winds and seas through early next week, as southerly winds gradually 
decrease. However, poor boating conditions will likely continue for 
much of the waters through at least Memorial Day for southerly 
winds 15-20 knots and seas up to 6 feet. 

&&


.PRELIMINARY POINT TEMPS/POPS...
DAB  86  71  83  74 /  40  20  40  50 
MCO  89  71  83  72 /  60  30  60  60 
MLB  85  74  82  76 /  50  30  60  70 
VRB  85  73  82  75 /  60  40  60  70 
LEE  91  71  83  72 /  60  30  60  50 
SFB  89  70  83  72 /  50  20  50  50 
ORL  88  70  82  72 /  50  30  60  60 
FPR  84  71  82  76 /  60  40  70  70 

&&

.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...None.

&&

$$

SHORT TERM...Pendergrast
LONG TERM....Weitlich