Area Forecast Discussion
Issued by NWS Jacksonville, FL
FXUS62 KJAX 081719
Area Forecast Discussion
National Weather Service Jacksonville FL
1219 PM EST Thu Dec 8 2016
This afternoon and evening...Northerly winds 8-12 mph this
afternoon will keep temperatures near seasonal levels in the lower
to mid 60s SE GA to upper 60s NE FL. Temperatures will cool rather
rapidly toward twilight into the evening hours. By 00z...temps
drop into the upper 40s across interior SE GA and upper 50s across
north central FL. By midnight, temperatures will be into lower 40s
across interior SE GA and lower 50s across north central FL. High
clouds will continue to stream into the region through the
afternoon and evening hours with strong baroclinic westerly flow
aloft at 80 to 95 knots prevailing with broad upper level trof
over eastern half of the CONUS.
Tonight and Friday...Strong surface high pressure will build into
the Ozarks by late tonight and then nudge eastward into the Mid
Mississippi River Valley by late Friday. Abundant mid/high clouds
are still expected across the region with mostly cloudy skies
across NE FL with partly cloudy skies across SE GA with broad
upper level long wave trof over the eastern CONUS. Expect dry and
considerably colder conditions than previous days. Temps will fall
into the mid/upper 30s across inld SE GA/Suwannee River Valley of
North FL with 40s elsewhere by morning and will be due mostly to
cold air advection. The NW/N winds will remain elevated at 10-15
mph through the night and this will lead to widespread wind chill
indices in the 30s by morning with some readings in the upper 20s
across inld SE GA but still well above any need for advisories
tonight. Highs on Friday will struggle to get into the lower to
mid 50s across SE GA while NE FL gradually warm between 55 and 60
degrees. Friday will be a dry and cool day. Clearing skies will be
on tap in the wake of an exiting of upper level trof off the
eastern seaboard into the Adjacent Atlantic.
.SHORT TERM...Fri night through Sun night...
Fri night...Strong 1035 mb surface high pressure will build over
TN with cold air advection in full force across the deep south.
Temperatures will fall below freezing with values in the upper 20s
across parts of inland SE GA and the Suwannee River Valley under
NNE drainage flow with frost not expected given elevated low level
winds of 3-8 mph which will make for wind chills in the low to mid
20s Sat morning across many inland areas. A bit more of an onshore
wind component will keep coastal areas and our Fl zones from
approximately St. Augustine to Vocal more mild with lows in the
40s under passing high cirrus. Will issued a freeze watch for Fri
night for inland SE GA and the northern Suwannee River Valley
where sub-freezing temperatures are expected for about 5-8 hrs.
Freezing temps are expected across portions of inland
Nassau...Duval...and western parts of Clay...Bradford and Alachua
counties...but at this time the expected duration of freezing
temps is only 1-2 hrs.
Weekend...Cold snap will be short-lived as onshore flow increases
over the region Sat as the surface high builds east toward the
mid-Atlantic through Sat night. A coastal trough will form along
the local coast late Sat into Sun and lift northward through the
period with an low chance of coastal showers...breezy
winds...passing low level clouds and moderating temperatures.
After daytime highs in the 50s and 60s Sat high temps will rise
back into the 70s for much of NE Fl Sun. Low temps will moderate
into the 40s/low 50s for most areas Sat night with mid/upper 30s
possible across our NW Ga zones with frost potential not overly
likely at this time given increasing cloud cover from the south.
Min temps will warm further Sun night with values in the 50s
inland to 60s coast.
.LONG TERM...Mon through Thu...
Mon-Tue...Weak pressure pattern over the area Mon into Tue as the
coastal trough breaks down and lifts north of the region and a
surface ridge axis builds across south Florida. This regime will
bring a warmer and more moist SSW low level flow across the local
area with a moderation in temperatures back into the 70s for highs
and generally 50s/60s for minimum values. Will also advertise a
low chance of showers as there is some model inconsistency with
regard to a very weak surface trough axis sliding across the local
area late Mon into Mon night from the west. Rain chances only 20%
at this time.
Wed-Thu...Model discrepancies continued mid-week with the GFS
indicating a more organized pre-frontal line of showers approaching
the local area late Wed/Wed night...while the ECMWF advertised a
messy stalled front scenario across the deep south this period.
Both models indicated a drier and cooler airmass by Thu into Fri
as front pushes south of the region and high pressure builds to
the NNW. At this time still only indicated rain chances of 20-40%
given inconsistent dynamical forcing between the models with this
next storm system. Temperatures will trend near to above normal
Wed then cool back to below normal values by the end of the week.
VFR conds with a high cirroform cloudiness. Light to moderate NW
winds at terminals through the period. NW winds generally at 7 to
10 knots tonight with slightly stronger NW winds over coastal
terminals (St. Augustine and St. Simons) particularly during the
day Friday with prevailing winds at 12 to 14 knots with some gusts
to 20 knots as winds mix down to the surface an hour or so after
NW/N flow tonight, increasing to around 20 knots, prompting the
raising of SCA flags for both the Nearshore and Offshore waters as
CAA will have a good bite on the warmer waters and expect at least
7 ft seas offshore. North Winds will weaken late on Friday over
the waters and SCA flags will come down nearshore but the elevated
seas will likely linger over the offshore waters through Friday
Night. Winds will register onshore over the weekend, ENE on
Saturday and SE on Sunday, but still expect SCEC levels with
speeds in the 15-20 knot range and seas 4-6 ft as sfc high shifts
from the Carolina coast Saturday settling in between the Carolina
coast and Bermuda on Sunday.
Rip Currents: Low Risk through Friday then possible Moderate Risk
this weekend with the heightened onshore flow.
Minimum humidity will fall between 25-30% across inland SE GA and
parts of the northern Suwannee River Valley Fri afternoon
generally along and west of a Jesup to Waycross to Lake City line.
Winds will near 10-15 mph by midday...then decrease as RHs
fall...so the timing of the stronger winds Fri is not expected to
coincide with the drier RHs. Red flag conditions are not expected
with fuel moisture elevated across SE Ga and ERC values near 27
units across the Suwannee River Valley.
.PRELIMINARY POINT TEMPS/POPS...
AMG 63 35 53 28 / 0 0 0 0
SSI 64 42 54 37 / 0 0 0 0
JAX 67 41 57 35 / 0 0 0 0
SGJ 67 46 58 44 / 0 10 10 0
GNV 68 42 58 34 / 0 10 10 0
OCF 70 44 59 37 / 0 10 10 0
FL...Freeze Watch from late Friday night through Saturday morning for
GA...Freeze Watch from late Friday night through Saturday morning for
Echols-Inland Camden-Inland Glynn-Jeff Davis-Pierce-Ware-
AM...Small Craft Advisory from 9 PM this evening to 4 AM EST Saturday
for Waters from Altamaha Sound GA to Fernandina Beach FL
from 20 to 60 NM-Waters from Fernandina Beach to St.
Augustine FL from 20 to 60 NM-Waters from St. Augustine to
Flagler Beach FL from 20 to 60 NM.
Small Craft Advisory from 9 PM this evening to 4 PM EST Friday
for Coastal waters from Altamaha Sound to Fernandina Beach
FL out 20 NM-Coastal waters from Fernandina Beach to St.
Augustine FL out 20 NM-Coastal waters from St. Augustine to
Flagler Beach FL out 20 NM.