Area Forecast Discussion
Issued by NWS Jacksonville, FL

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FXUS62 KJAX 231843
AFDJAX

Area Forecast Discussion
National Weather Service Jacksonville FL
243 PM EDT Mon Oct 23 2017

.NEAR TERM (Tonight)...
A short wave rotating through the base of the upper level trough
is giving is a bit of a negative tilt and a low level jet streak
moving out of the Gulf and across the southeast is gouging out the
shower and thunderstorm activity over the region. Still expect to
see a broken line of showers and thunderstorms near and ahead of
the frontal surface later this afternoon and tonight. Not sure we
are going to see strong or severe activity and believe it will be
over the higher instability air over the coastal waters if it does
happen. Looks like the majority of the prefrontal shower activity
should be clearing the southeastern counties between 10 p.m. and
midnight with a very thin band of light rainfall or drizzle along
the frontal surface overnight. Behind the front and with the
925-850 mb trough still over the region look for low cloudiness to
hang in until we get enough sunshine on Tuesday for diurnal
heating to erode them away. Overnight lows are going to dip into
the mid 50s over Georgia and the Suwannee valley with a 4 to 8 mph
northeasterly flow overnight will be jacket and sweatshirt weather
for the morning commute.

&&

.SHORT TERM (Tuesday and Wednesday)...
With the upper level trough still to the west of the region and a
low level flow coming in off the Gulf will see low cloudiness
hang on until late morning. Still we are not at the time of year
where sun angles and temperatures are low enough to allow it to
hang on all day, so expect the low deck to lift to about 5 KFT
between 10 a.m. and noon in most places. Should see some
visibility restrictions in the early morning hours but generally
between 4 to 6sm in light fog. Of course some local areas will
drop down lower and might see 2 to 4 Sm in some of the more fog
prone areas. High temperatures tomorrow will be in the mid 70s to
near 80 with the warmest temperatures in the southern areas and
along the immediate coast. Minimum afternoon relative humidity
values should be in the mid 30 to lower 40 percent range.

By Wednesday, reinforcing shot of colder air arrives behind
today`s front as a shortwave moves off the upper level low in the
Great Lakes. Despite the sunshine, daytime highs in the mid 60s
across southeast Georgia and low 70s across northeast Florida are
expected. Lows Wednesday night will reach the low 40s inland, and
low to mid 50s at the beaches.

.LONG TERM (Thursday through Monday)...
Heights rise quickly behind the shortwave and flow turns more
westerly aloft. At the surface, high pressure develops across the
southern tier States and moves north across the Carolinas. Plenty
of sunshine will allow an afternoon high around 70 across the area
which is still a few degrees below normal for late October. With
clear skies to start, and mainly offshore flow expected radiational
cooling Thursday night could lead to another cool evening with
temperatures dropping into the 50s and upper 40s before midnight.
Overnight, surface flow shifts onshore and upper level flow
becomes more southwesterly, and low stratus ceilings and/or fog
could develop during the predawn hours on Friday, especially east
of Highway 301 in northeast Florida. The overall dry air mass and
clear skies will be slow to erode locally, but afternoon highs on
Friday should rebound to the mid 70s.

Deep long wave trough expected to develop this weekend across the
Plains and move into the Midwest. Another cold front will likely
push southward towards the Southeast sometime during the weekend,
though timing shifts between model runs. A surface low is also
expected to develop across the eastern Gulf, and some low end
chances PoPs remain in the forecast for the weekend though the
exact track and development are not clear at this time.

&&

.AVIATION...
Should see a band of showers and thunderstorms this afternoon
between 21-01 UTC with ceilings between 2.0-3.5 KFT, Beyond 02 utc
a low deck of stratus with ceilings between 500-1,500 feet AGL
should advect in over the main fields and will take into mid
Tuesday morning for that deck to burn off. Some visibility
restrictions of 1/2 to 2 SM expected from near sunrise to about 16
UTC in the main problem areas such as KJAX, KVQQ and KGNV

&&

.MARINE...
Expect the Small Craft Advisory Conditions to continue over the
Offshore leg and the Exercise Caution over the near shore leg
through Monday night as the frontal passage takes place overnight.
With the front pushing south of the waters on Tuesday winds will
be light north to northwesterly and then as the high builds in
over Tuesday Night and Wednesday we will increase winds to Small
Craft Advisory conditions for Wednesday into Thursday.

Rip Currents...Moderate risk of rip currents on Tuesday due to the
remaining swell.

&&

.HYDROLOGY...
One more day of possible tidal flooding for the St Johns River
Basin in Putnam County before flooding is expected to subside with
offshore winds.

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  58  76  46  66 /  40  10   0   0
SSI  68  80  56  68 /  60  10   0   0
JAX  63  80  52  69 /  50  10   0   0
SGJ  67  81  56  70 /  50  20  10   0
GNV  63  79  48  69 /  40  10   0   0
OCF  65  80  51  70 /  50  10   0   0

&&

.JAX WATCHES/WARNINGS/ADVISORIES...
FL...Coastal Flood Advisory until 6 AM EDT Tuesday for Putnam.

GA...None.
AM...Small Craft Advisory until 6 AM EDT Tuesday 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.

&&

$$

Sandrik/Elsenheimer


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