Area Forecast Discussion
Issued by NWS Jacksonville, FL

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FXUS62 KJAX 071811

Area Forecast Discussion
National Weather Service Jacksonville FL
111 PM EST Wed Dec 7 2016

...Cooling trend with late night Fog...
...Inland Freeze Likely Fri Night...

.SHORT TERM...This afternoon through Thu...

A pressure lull existed across the local area with a poorly defined
trough axis across GA and weak high pressure across the Carolinas
and the Fl peninsula. Abundant low level stratus clouds blanketed
much of SE GA this afternoon with some recent erosion from the
south. High clouds continued to stream over NE Florida under the
subtropical jet stream with partly cloudy to mostly sunny skies.
Temperatures ranged in the mid to upper 60s early this afternoon.
Through the remainder of the afternoon and into the early
evening...light and variable winds will continue less than 10 mph
with low clouds expected to gradually begin filling across SE GA
into the evening under the low level inversion.

Trended the sky and fog near-term forecast for tonight and Thu toward
the NAM/SREF/HRRR which initialized well today with low level moisture
observations. Tonight low clouds were expected to cover much of SE
GA and edge southward toward the I-10 corridor through sunrise...while
less cloud cover with subsidence across NE Florida should favor fog
development. At this time indicated patchy fog for all zones and areas
of fog with locally patch dense across inland NE Florida through early
Thu morning. Confidence of a widespread dense fog event tonight
not high at this time given elevated westerly winds near 15 kts
above the surface. Low temps will trend in the mid/upper 40s
inland under a low level NW drainage flow to the low 50s along the
Atlantic coast and St. Johns River Basin.

Thu dry and slightly cooler with the passage of the weak trough axis
to our south and low level NW flow under partly cloudy skies. NW
winds will increase across SE GA late in the day as the pressure
gradient strengthens ahead of a much stronger surface cold front.
High temperatures will range in the 60s under partly cloudy skies
once morning and low stratus lift.

.SHORT TERM /Thursday night through Saturday/...

The next cold front on tap for the area will swing through
Thursday. Subsequently...a 1042mb high pressure area will slide
down the Rockies front range Thursday night. This high pressure
area will weaken some as it moves into the Mid South Friday
afternoon encompassing most of the southeast on Friday night. The
high will move over the Carolinas on Saturday. This will usher is
some of the coldest air of the season thus far for the southeast
United States heading into the first part of the weekend.
Precipitation chances will be near with not much moisture to work
with due to the previous front earlier this week on Tuesday.
Moderately strong cold air advection will set the stage for below
normal temps Thursday night through Friday night. Min temps
Thursday night will range from the mid to upper 30s interior SE
GA, upper 30s to lower 40s interior northeast Florida, to the mid
40s north central Florida and NE FL beaches and intercoastal. On
Thursday night, winds will be 8 to 12 mph inland with stronger
winds near the coast at 10 to 15 mph with some gusts to 20 mph
along the St. John`s River and Beaches. Friday will be sunny and
cool with northerly winds around 10 to 15 mph. A light freeze is
expected well inland Friday night. On Saturday...winds will become
ENE with sfc high near the Carolina coast. There may be a few
showers developing off the coast over the adjacent Atlantic, but
land areas will remain dry. Highs on Saturday will be below normal
with Highs in the mid 50s SE GA, and in the 60s across NE FL.

.LONG TERM /Saturday night through Tuesday/...

Saturday night min temps moderate some with an easterly flow
developing, more pronounced over the coastal counties and adjacent
Atlantic. Lows Saturday will be in the upper 30s to lower 40s
interior SE, lower to mid 40s interior NE FL and lower to mid 50s
St. Johns River and area beaches. On Sunday, the high pressure
area moves into the Western Atlantic with moderating temps and
dewpoints back to near normal levels as low level flow veers to
the southeast. Model blends indicate a slight chance of showers
along the immediate coast Saturday night and Sunday, and then a
20-30% chance of showers on Monday as moist southwest flow
increases ahead of the next cold front. Above normal temps on
Monday to move a little closer to normal on Tuesday in weak cold
air advection pattern and drier air behind the front.



MVFR cigs impacted SSI this afternoon and expect this pattern will
continue through tonight. VFR conditions across FL terminals this
afternoon with very light and variable winds generally 6 kts or
less. Low level moisture will edge gradually southward with low
cigs possibly impacting JAX/CRG later this evening...but
confidence is higher for fog development across NE Florida tonight
due to moisture pooling and light winds. Could have some low
stratus clouds (less 1 kft) more inland from the Gulf late tonight
and impact GNV and VQQ. At this time trended TAFs across NE toward
LIFR/VLIFR at GNV and VQQ late tonight/early Thu morning with
MVFR at JAX/CRG and SGJ at this time...where confidence of low
visibility was not as high.



Variable winds over the waters than 10 kts will become more ENE
along the coast this afternoon then will become offshore
overnight as a very weak surface trough axis slides across the
local waters tonight. Combined seas 3 ft or less will prevail.
Offshore flow continues into Thu and increases late Thu night
ahead of a much stronger surface cold front. Marginal small craft
advisory conditions are forecast over the outer waters Fri and Fri
night. Winds relax into the weekend as high pressure builds over
the Carolinas and flow veers onshore...but elevated seas will
continue with exercise caution sea heights probable over the outer
waters through early next week.

Rip Currents: Low risk today and Thu. Increased rip current risk
this weekend and early next week with return of onshore flow.



Humidity will stay above critical levels today and Thursday. The
main fire weather concern will be patchy fog late tonight/Thursday
morning. Near critical RH values are possible Friday behind the
front, with min RH between 24 to 28 percent across the interior of
SE GA and the Suwannee Valley of North FL. However, winds will
light out of the north at 8 to 12 mph.


AMG  47  64  36  54 /   0   0   0   0
SSI  51  66  41  55 /   0   0   0   0
JAX  50  67  42  57 /   0   0   0   0
SGJ  52  67  46  58 /   0   0   0   0
GNV  48  69  41  59 /   0   0  10   0
OCF  50  69  44  60 /   0   0  10   0




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