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Area Forecast Discussion (AFD)

Issued by Melbourne, FL (MLB)

                            
000
FXUS62 KMLB 221959
AFDMLB

Area Forecast Discussion
National Weather Service Melbourne FL
359 PM EDT Thu Aug 22 2019

.DISCUSSION...

Through Tonight...Drier air mass over much of the areas has 
limited showers and storms so far today. Expect that trend to 
continue and will keep only a slight chance of showers and storms 
through sunset across interior sections with dry conditions 
prevailing tonight. 

The exception has been across the Treasure Coast where deeper 
moisture and stronger onshore flow has kept a steady stream of 
showers pushing in from the Atlantic through most of the day 
today. Expect this trend to keep going as well so will keep 
mention of a chance of showers and slight thunder chance through 
sunset.

As we get into late this evening into tonight, deeper moisture 
associated with an approaching inverted trough of low pressure 
will continue to spread north and westward across east central 
Florida. The onshore flow is expected to increase slightly, and 
with the deeper moisture remaining in place, isolated to coastal 
showers are expected to continue to move onshore, especially along
the Treasure Coast. Will keep 30% for Martin and St. Lucie 
counties and then a 20% as far north as Melbourne. Overnight lows 
will generally be in the mid 70s, but areas beachside may stay in 
the upper 70s. 

Friday-Sunday (modified previous)... A wet weekend is in store 
for most of us in east central Florida. A surge of deep moisture 
moves up and across the Florida peninsula starting early Friday 
due to the passage of an inverted surface trough/weak low. This 
will promote the development of scattered to numerous showers and 
storms each day, and some of these storms will continue through 
the overnight hours along the coast. The highest rain chances will
be confined across the southern portions of the area on Friday, 
but should overspread to the rest of central Florida by Saturday 
and Sunday. Easterly flow on Friday will veer southeast on 
Saturday, then south on Sunday. The onshore flow will keep shower 
chances along the coastal areas in the morning and possibly into 
the afternoon before a diffused sea breeze develops Friday 
bringing the higher shower and storm coverage toward the interior.
However, as winds begin to veer, a more pronounced sea breeze 
should develop, especially on Sunday where guidance indicates 
areas of heavy rainfall due to sea breeze and outflow boundary 
collisions.

The greatest threat from any storm is going to be dangerous cloud
to ground lightning strikes, and locally heavy rainfall leading 
to minor flooding of low lying and poor drainage areas. Afternoon 
temperatures are forecast in the low 90s, while overnight temps 
drop into the low to mid 70s. 

Monday-Wednesday (previous)... The low level flow veers 
southwesterly as a diffused and messy mid/upper trough the 
Southeastern states and the influence of the Atlantic ridge wanes.
The trough of low pressure gets pushed northeast and out into the
western Atlantic. The southwest flow will favor afternoon showers
and storms on the eastern side of the FL peninsula, thus high 
rain chances (50-60 percent) are likely to continue through the 
first half of next week. Temperatures will be near normal values, 
afternoon highs are forecast in the low 90s, and overnight lows in
the low to mid 70s. Locally heavy rainfall might lead to minor 
flooding in some spots.

&&

.AVIATION...

Overall lower coverage of showers and storms will continue across
the area through this afternoon and tonight. Tempo IFR/MVFR 
conditions in isolated showers and storms still possible for KISM-
KMCO-KSFB through 21Z and KLEE through 00Z. However, slightly 
greater potential for cig/vis reductions from KVRB through KSUA as
an elevated easterly flow and increasing moisture will continue 
onshore moving showers and possibly a few storms. Subsidence 
behind this sea breeze will help to weaken this activity as it 
approaches the Treasure Coast through late afternoon, but should 
pick up overnight. For now, have only included VCSH as rain 
chances remain lower than normal, but may need to add some tempo 
groups as needed. 


&&

.MARINE...

Tonight-Friday...Increasing shower and storm coverage expected as
an inverted trough of low pressure approaches the waters. East to
east-southeast winds around 10-15 kt will continue tonight and 
Friday south of Sebastian Inlet and around 10 kt to the north. 
Seas remain around 2 ft nearshore and 2-3 ft offshore. 

Friday night-Tuesday...Some uncertainty among the models on how 
to handle the inverted trough/surface low pressure, but there 
could be a period of deteriorating boating conditions Friday night
into Saturday. Southeasterly winds may approach 20 kt during this
period but confidence is low. 

Scattered to numerous showers and storms are forecast to develop 
each day through Tuesday as the inverted trough/surface low moves 
through the coastal waters through Sunday before pushing northeast
away from the area early next week. Winds are forecast to be 
southerly Sunday before veering southwesterly by early next week.

&&

.PRELIMINARY POINT TEMPS/POPS...
DAB  76  90  76  89 /  10  30  30  30 
MCO  77  92  76  92 /  10  40  10  50 
MLB  79  90  77  88 /  20  60  30  60 
VRB  77  89  76  88 /  20  60  40  60 
LEE  77  94  77  93 /  10  30  10  30 
SFB  77  93  75  92 /  10  40  20  40 
ORL  77  93  77  92 /  10  40  10  40 
FPR  77  89  75  88 /  30  60  40  60 

&&

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

$$

Combs/Spratt/Weitlich