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Area Forecast Discussion (AFD)

Issued by Melbourne, FL (MLB)

FXUS62 KMLB 151950

Area Forecast Discussion
National Weather Service Melbourne FL
250 PM EST Tue Jan 15 2019


...Cool/Dry for Mid Week, Then Warming Up for Friday-Saturday...
...Turning Sharply Colder Sunday Night into Monday...

Tonight...High pressure will will build into the southeast states 
tonight with a cool dry northerly flow continuing. Forecast 
challenge will be extent of non-dissipation or regeneration of 
stratocu across nrn sections through the night underneath a strong 
inversion near 900 mbs. GFS indicates enough drying to not see much 
cloudiness while 12km NAM hints at a stubborn cloud deck lingering 
below the inversion. Will keep some clouds across the north through 
the night with mostly clear skies south. Lows will be chilly and 
drop into the 40s to around 50 along the Martin county coast.

Wed...Surface high pressure will draw closer to north FL with low 
level flow veering to the NNE/NE into the afternoon. Should be some 
morning stratocu across nrn zones and then some cirrus passing 
overhead through the day. Skies will be mostly to partly sunny. High 
temps will be below normal ranging from the mid 60s north to upper 
60s srn zones.

Thu-Fri...H30-H20 jet stream over the SE CONUS will maintain a 
dominant zonal component that will push an H100-H70 anticyclone from 
the wrn GOMex into the SW Atlc through late week...with the 
accompanying sfc ridge axis settling over central FL. GFS/ECMWF 
models continue in close agreement with this solution, with a very 
dry/stable airmass dominating the lcl WX pattern.

Motion of the anticyclone will allow sfc/low lvl winds to veer to an 
E/NE component on Thu, bcmg E/SE by late Fri. While the dvlpg 
onshore flow will allow some modification of the airmass, mean wind 
speed blo 10KTS thru the H100-H85 lyr will ensure any modification 
will be slow.  Indeed, both GFS/ECMWF indicate moderate to strong 
subsidence thru the H90-H70 lyr with PWat values btwn 0.50"-0.75" on 
Thu, creeping up to arnd 0.75" on Fri, much of which will be trapped 
abv the H50 lyr. Fcst will remain dry. 

The dvlp onshore flow will allow temps to recover to near climo avgs 
on Thu...and slightly abv avg on Fri. Thu mrng mins in the L/M40s 
along the I-4 Corridor, U40s/L50s along the Space/Treasure Coasts 
and Lake-O region...max temps warming into the U60s/L70s. Fri mrng 
mins recovering into the M/U40s along the I-4, and L/M50s along the 
coast and acrs the Lake-O region. 

Saturday-Tuesday(modified previous)...As boundary layer winds veer 
more SE Sat, an increasingly warm/moist air mass will return. Sat 
mins rebound to above normal (ranging from near 50 NW interior to 
near 60 SE coast) and maxes peaking in the upper 70s most areas. 

Axis of full-latitude trough reaches MS River Valley Sun then 
advances offshore SE Atlantic coast Mon. Timing differences between 
GFS and ECWMF have lessened, however ECM now is faster with FROPA 
compared to GFS, the opposite of 24 hr ago. Have blended model 
solutions, but weighted toward faster/colder ECM. Scattered pre-
frontal showers possible second half of Saturday night, then likely 
showers/slight chance storms north Sunday and good chance showers 
south half. Have expanded thunder chances slightly farther south 
since previous forecast. Lingering showers are possible Sunday 
evening, followed by clearing. Difficult temp forecast through the 
period given FROPA/CAA model differences and potential for quick 
post frontal veering winds. Trended max temps down Sunday given 
expected cloud/precip coverage, then strong CAA overnight with sub 
40 mins for the north half at least and lower to mid 40s farther 
south, with low wind chill readings likely throughout. Location of 
post frontal surface high Mon-Tue will dictate degree of onshore 
wind flow and possible temp modification across eastern sections, as 
well as prospect for coastal cloud cover. For now, have forecast 
partly/mostly sunny with max temps ranging from only low 50s far NW 
to lower 60s far SE. A warming trend is expected to begin next 


BKN clouds in the 025-030 range lingering from KLEE to KDAB should 
become scattered for a time into late afternoon with VFR conds at 
other area ECFL terminals. Past late evening and overnight, some 
regeneration of the stratocu deck may develop for nrn terminals from 
KLEE-KDAB have clouds in the scattered range but see some CIGs at 
times overnight. Aft 14z Wed, generally VFR conds with low level 
flow slowly veering to the N/NNE in the afternoon.


Tonight...A moderate NE swell combined with steeper wind waves 
across the gulf stream waters will build combined seas to 6 ft 
across the offshore and gulf stream. Will continue SCEC headlines 
for these areas with seas to 4-5 ft for the Brevard/Volusia near 
shore waters.

Wed...Northerly winds to 10-15 knots and a moderate NE swell across
the waters will keep poor conditions in the gulf stream and offshore 
waters into Wed with seas up to 5-6 ft offshore with lower sea 
heights in the 3-5 ft range close to shore.

Thu-Thu Night...Generally favorable boating conds, but with shifting 
winds as a high pres ridge settles over central FL. Light to gentle 
NE breeze early Thu mrng, bcmg a light to gentle E/NE breeze thru 
sunset. Vrbl winds Thu night into Fri as the center of the ridge 
passes midnight bcmg a light S/SW breeze north of Cape 
Canaveral...light E/SE south of the Cape, then bcmg a light W/NW 
breeze north of Sebastian Inlet and a light N/NE breeze south of the 
Inlet by daybreak Fri. Seas 3-4FT over the shelf waters and 4-5FT 
in the Gulf stream thru the day, subsiding to 2-3FT over the shelf 
waters and 3-4FT in the Gulf Stream overnight...wave heights mainly 
a 10-12sec long pd swell. 

Fri-Fri Night...Shifting wind pattern contg as the center of the 
ridge migrates NE of the Bahama Bank. Light N/NW breeze north of 
Sebastian Inlet and a light N/NE breeze south of the inlet thru 
midday, bcmg N/NE north of the Inlet and E/NE south of the Inlet 
thru late aftn, then a light to gentle SE breeze by midnight Fri 
into Sat. Seas subsiding to 2-3FT in a long pd swell.  

Saturday-Sunday...A gentle southeasterly breeze of 5-10 kt on 
Saturday will gradually veer southerly as high pressure is shoved 
east by an approaching low pressure system and cold front. Speeds 
will increase to 10-15 kt nearshore and 15 around 15 kt in the 
offshore waters with seas 2-3 ft.

Poor to hazardous conditions are expected to develop Saturday night 
into Sunday as the cold front approaches and then moves through some 
time on Sunday.  Winds will be southerly Saturday night into Sunday 
morning and then veering through the course of the day to westerly 
in the afternoon. Speeds will increase to around 20-25 kt offshore 
and around 20 kt nearshore. Seas will build to 4-5 ft nearshore and 
5-7 ft offshore.


Dry weather will continue into late week with Min RHs to 35 percent 
Wed/Thu and 35-40 percent across the interior Friday. Winds will 
remain below critical thresholds and become light into late week as 
high pressure builds nearby.


DAB  42  63  48  68 /   0   0   0   0 
MCO  44  67  43  71 /   0   0   0   0 
MLB  44  67  52  71 /   0   0   0   0 
VRB  46  68  52  72 /   0   0   0   0 
LEE  43  65  41  70 /   0   0   0   0 
SFB  43  66  43  71 /   0   0   0   0 
ORL  45  66  43  71 /   0   0   0   0 
FPR  46  69  52  72 /   0   0   0   0