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Area forecast discussion
National Weather Service Jacksonville Florida
155 am EST Thu Dec 8 2016

..colder temperatures expected behind frontal passage tonight
through Saturday...

Near term /today-tonight/...

Early this morning...very similar conds to last night with patchy
dense fog expected across inld NE Florida...mainly south of a line from
gnv-sgj to impact Alachua/Marion/Putnam/Flagler/St Johns counties
with locally dense fog with vsbys <= 1/4 mile at times. Still not
expecting fog to organize enough to warrant dense fog advisory but
will continue to monitor. Still some lower stratus with ceilings
around 2000 feet pushing across southeast Georgia but visibilities remaining a
bit higher in the 3-5 mile range.

Today...cold frontal passage today will usher in drier airmass
with lower clouds/fog dissipating during the morning hours then
partial sunshine through the afternoon with periods of high clouds
at times. Max temps a bit cooler than yesterday with Lower/Middle
60s across southeast Georgia to upper 60s/near 70 degrees across NE Florida. Northwest
winds increasing to 10-15mph with a few gusts to 20 mph possible
acrs southeast Georgia.

Tonight...strong high pressure will build well northwest of the region
with much colder and drier airmass filtering into the region but
abundant mid/high clouds are still expected with mostly cloudy
skies across NE Florida with partly cloudy skies across southeast Georgia. Temps
will fall into the mid/upper 30s across inld southeast Georgia/Suwannee River
valley of North Florida with 40s elsewhere by morning and will be due
mostly to cold air advection and not radiational cooling. The northwest/north
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 southeast Georgia but still
well above any need for advisories.

Short term /Friday through Saturday night/...

High pressure will continue to build in from the northwest as the
parent high shifts east to the mid-Atlantic coast. Moderately
strong cold air advection and much drier air will set the stage
for below normal temps. Friday will be a cool day with clearing
skies in the wake of the cold front. Cold air advection still
appears favorable for a light freeze for areas generally along
and west of Highway 301 Friday night. Temps moderate some on
Saturday but still remain below normal. Rain showers will develop
along an inverted coastal trough over the coastal waters Saturday
night and there is a slight chance of a few light rain showers at
the coast.

&&

Long term /Sunday through Wednesday/...

The model blend yields a quick moderation to at or above normal
temps on Sunday as the flow veers to the southeast, and then firmly
above normal on Monday as moist southwest flow increases ahead of
the next cold front. The blend tool insists that temps will fall
back a little closer to normal on Tuesday within weak cold air
advection pattern behind the front. Confidence in this is low
however.

The blend shows dry conditions on Sunday and then a 20-40% chance
of light rain showers on Monday with the higher chances across
southeast Georgia. The blend keeps Tuesday dry and then brings in
a 30% chance of showers on Wednesday as a stronger cold front
moves through the area.

&&

Aviation...
brief burst of northwest winds at 5-10 knots around midnight scoured out
much of the evening fog formation, but still expect potential
IFR/LIFR ceilings/visibilities towards morning as winds drop off slightly.
MVFR stratus ceilings may impact kssi through the night while the NE
Florida taf sites will have a mix of fog/low stratus towards morning
with best chances of low vsbys at gnv/vqq. Conds still on track to
improve by 14z with VFR conds with a few high clouds and light northwest
winds around 8 knots or so.

&&

Marine...
northwest flow to slowly increase today with frontal passage then become
northwest/north tonight and increase to around 20 knots and will raise Small Craft Advisory
flags for both the nearshore and offshore legs as cold air advection 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 Small Craft Advisory flags will come down nearshore but the elevated seas will
likely linger over the offshore waters through Friday night. Winds
still clock onshore over the weekend but still expect just below
Small Craft Advisory levels with speeds in the 15-20 knot range and seas 4-6 ft.

Rip currents: low risk through Friday then possible moderate risk
this weekend in the onshore flow.

&&

Preliminary point temps/pops...
amg 64 35 54 29 / 0 0 0 0
ssi 65 42 54 36 / 0 0 0 0
jax 68 41 57 34 / 0 0 0 0
sgj 68 46 58 42 / 0 10 10 0
gnv 69 41 59 33 / 0 10 10 0
ocf 71 44 59 37 / 0 10 10 0

&&

Jax watches/warnings/advisories...
Florida...none.
Georgia...none.
Am...Small Craft Advisory from 9 PM this evening to 4 am EST Saturday
for waters from Altamaha Sound Georgia to Fernandina Beach Florida
from 20 to 60 nm-waters from Fernandina Beach to St.
Augustine Florida from 20 to 60 nm-waters from St. Augustine to
Flagler Beach Florida 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
Florida out 20 nm-coastal waters from Fernandina Beach to St.
Augustine Florida out 20 nm-coastal waters from St. Augustine to
Flagler Beach Florida out 20 nm.

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