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Area Forecast Discussion (AFD)

Issued by Melbourne, FL (MLB)

FXUS62 KMLB 160912

Area Forecast Discussion
National Weather Service Melbourne FL
412 AM EST Wed Jan 16 2019


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

TODAY/TONIGHT...Surface high pressure situated over the Deep South 
will offer a locally cool/dry airmass. However, as it transitions 
eastward, low level flow will veer to the NNE/NE during the day 
picking up a modest onshore component 10 mph or less. Anticipate 
only a scattering of CU/STRATOCU, as well as some CI. Winds will 
become light and variable for inland locations overnight, favoring a 
drainage flow until sunrise. Mostly sunny to partly cloudy skies 
today, and mostly clear overnight. High temps L/M60s north and west 
of I-4, and M/U60s south of there. Low temps generally fall back 
into the 40s, but L50s along the immediate Space and Treasure

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...As boundary layer winds veer 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 with ECM slightly faster than GFS. 
Have blended model solutions, but weighted toward faster/colder 
ECM. Scattered pre- frontal showers possible late Saturday night,
then likely showers/slight chance storms Sunday across all of EC
FL. Lingering showers are possible Sunday evening mainly across
southern sections, 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 Tuesday.


Generally VFR conditions next 24 hours with only SCT030-040 low 
levels and SCT250-300 high above. Sufficient T/Td spread and light
continental flow overnight will limit vsby BR concerns this 
morning. After 14Z, winds slowly veering during the day acquiring 
an onshore N-NE component. Winds become VRB03KT for inland sites 
in the evening. 


TODAY/TONIGHT...In the Gulf Stream, N-NE winds to 10-15 knots and a 
moderate NE swell will support continued poor boating conditions 
with seas up to 5-6 feet. This includes much of the offshore waters. 
Small craft should exercise caution until seas until seas more 
uniformally fall to 4-5 feet by Thursday morning. For the nearshore 
waters outside of the Gulf Stream, winds will be N-NE 10 knots or 
less, with seas 3-5 feet. Little to no shower activity.

Thu-Thu Night...Generally favorable boating conds, with light 
winds 10 knots or less as a high pres ridge settles over central 
FL. 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...High center migrates NE of the Bahama Bank. Light
North breeze to start will gradually become SE Fri night.  Seas 
subsiding to 2-3FT in a long pd swell. 

Saturday-Sunday...Tightening pressure gradient ahead of a strong
cold front will produce SE winds 10-15 kt on Saturday with seas 
2-3 ft.

Poor to hazardous conditions are expected to develop Saturday night 
into Sunday as the cold front nears and then moves through 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.


High pressure will move slowly eastward across the Southeast U.S.
mid week then will settle across Florida by late week. This 
pattern will keep a dry airmass across the region with decreasing 
winds. Min RH values will reach 35 percent across most of the 
interior counties each afternoon through Friday. Dispersion will 
be fair on Wednesday and poor on Thursday over the interior 
counties due to light surface and transport winds.


DAB  62  46  68  46 /   0   0   0   0 
MCO  65  46  71  49 /   0   0   0   0 
MLB  66  51  72  49 /   0   0   0   0 
VRB  67  51  72  49 /   0  10   0   0 
LEE  63  43  70  47 /   0   0   0   0 
SFB  64  45  71  48 /   0   0   0   0 
ORL  64  46  71  49 /   0   0   0   0 
FPR  68  52  72  49 /   0  10   0   0