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Area Forecast Discussion (AFD)

Issued by Melbourne, FL (MLB)

                            
033 
FXUS62 KMLB 211945
AFDMLB

Area Forecast Discussion
National Weather Service Melbourne FL
245 PM EST Wed Feb 21 2018

.DISCUSSION...

Tonight-Thursday...
Highly amplified mid/upr lvl pattern prevails over the CONUS with 
troffing over the mountain west and ridging over the eastern 
seaboard.  Little change anticipated as the western trof is 
reinforced by a 120KT meridional jet streak digging into the PacNW, 
while a 100KT zonal jet over the Baja Peninsula lifts into the Rio 
Grande Valley/Srn Plains. Large scale mid/upr lvl SW flow acrs the 
GOMEX/SE CONUS will continue, generating a warm air advection pattern 
thru the H85-H50 lyr, that in turn, will reinforce the deep lyr 
ridge axis over the W Atlc. 

No sig change to the current mild/dry WX pattern as the Atlc ridge 
axis maintains a steady E/SE flow thru the H100-H70 lyr acrs the FL 
Peninsula. Upstream analysis shows sparse low/mid lvl moisture with 
H100-H70 mean RH btwn 50-60pct and H85-H50 dewpoint depressions btwn 
25-30C. Convergent wake eddys forming downwind of the nrn Bahamas 
may allow a few, brief low-topped shras to form over the Gulf 
Stream, but such precip generally does not survive for long once 
they push into the cooler shelf waters. Those that do survive their 
trek onshore have minimal impact with QPF blo 0.10". 

Onshore component will keep sfc dewpoints in the M/U60s...suggesting 
min temps half a cat higher (arnd 15F abv avg). Thu max temps 
similar to today's with L80s east of I-95...M80s to the west. 

Thu Night-Sat...
Dominant high pressure over the central Atlantic remains stationary 
through the period,  as ridge axis positioned over north FL 
maintains a SE flow regime. Relatively dry conditions persist, with 
highest rainfall chances on Thu night mainly for marine and coastal 
areas, and slight chance Fri thru Sat. Warmer than normal 
temperatures continue, with most areas seeing highs nearly 10 
degrees above normal. Along the coast, highs in the low 80s to the 
mid 80s for the interior. Mild overnight lows in the mid 60s.

Sun-Wed(modified previous)...
Mid/upper level ridge across Florida remains through the weekend 
into early next week. However, this feature is compressed by cutoff 
low moving through the upper Great Lakes early Sunday, and deeper 
trough moving through the Midwest into Sunday night/Monday. Surface 
ridge axis north of the area gradually settles southward across 
Florida into Sunday and Monday. Enough moisture may be present on 
Sunday and Monday to generate some low-topped showers during the 
afternoon along the sea breezes but a lot of dry air aloft will keep 
coverage isolated.  A cold front moves into the southeast and 
weakens/decelerates into early next week and may slowly cross 
central Florida into Tuesday with onshore flow behind this system. 
This will increase moisture and rain chances toward the middle of 
next week.  Warmer than normal conditions will continue through the 
period.

&&

.AVIATION...Thru 22/18Z.
Sfc Winds: Thru 22/00Z...coastal sites E/SE 9-13KTS with ocnl G18-
22KTS...interior sites E/SE 7-11KTS. Btwn 22/00Z-22/03Z...coastal 
sites bcmg E/SE 8-12KTS...interior sites bcmg E/SE 5-8KTS. Btwn 
22/03Z-22/06Z...coastal sites bcmg E/SE 4-7KTS...interior sites bcmg 
E/SE AOB 3KTS. Btwn 22/12Z-22-15Z...bcmg E/SE 8-12KTS...E of KVRB-
KOBE ocnl G18-22KTS. 

Vsbys/WX/Cigs: Thru 22/02Z...lcl cigs btwn FL035-050. Btwn 
22/08Z-22/14Z...N of KISM-KTIX areas MVFR/lcl IFR vsbys in BR. 

&&

.MARINE...
Tonight-Thu...Marginal boating conds high pres ridge over the W Atlc 
maintains a gentle to moderate E/SE acrs the region. Data buoys/C-
MAN stations slow winds have diminished to 10-15KTS, gusting higher 
near the coast due to the east coast sea breeze. Seas measuring 3-
5FT seas with dominant arnd 7sec...suggesting seas up to 6FT psbl in 
the Gulf Stream. Tighter pgrad over south FL will generate slightly 
stronger winds south of Sebastian Inlet, while the E/SE component 
places the Treasure Coast waters in the shadow of the nrn Bahamas, 
resulting in lclly rough conditions south of Ft. Pierce. Small craft 
operators should exercise caution when operating in the Gulf Stream. 

Fri-Sat...The axis of the Atlc high pres ridge will remain draped 
over north FL from mid to late week, generating a gentle to moderate 
E/SE breeze. Pressure gradient will be support 10-14 knots across 
the north and 15-19 knots across the southern waters.
So small craft will frequently need to exercise caution south of 
Sebastian Inlet but do not expect a Small Craft Advisory will be 
needed. Seas 3-5FT Wed, building to 5-6FT in the Gulf Stream by 
daybreak Thu into Sat as the persistent erly flow begins to push 
increasing swells into the adjacent coastal waters. Isolated showers 
from time to time.

Sun-Mon...Winds will be more southerly with ridge axis being pushed 
farther south ahead of approaching weak frontal boundary. Southerly 
winds will be around 5-10 kt in the nearshore waters and closer to 
10 kt in the offshore waters. 3-4 ft seas nearshore will subside to 
2-4 ft by Monday with 4-6 ft seas in the offshore waters subsiding 
to 3-4 ft by Monday. 

&&

.PRELIMINARY POINT TEMPS/POPS...
DAB  69  80  65  79 /   0   0  20  20 
MCO  69  87  65  84 /   0   0  10  20 
MLB  73  83  70  81 /  10  10  20  10 
VRB  72  83  69  82 /  10  10  20  10 
LEE  70  86  65  84 /   0   0  10  20 
SFB  68  85  65  83 /   0   0  10  20 
ORL  69  87  66  85 /   0   0  10  20 
FPR  72  83  69  81 /  10  10  20  10 

&&

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

&&

$$

Short Term/Aviation...Bragaw
Mid Term..............Smith
Long Term.............Combs
WFO TBW Back-up.......Volkmer