Area Forecast Discussion
Issued by NWS Jacksonville, FL

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FXUS62 KJAX 231744

Area Forecast Discussion
National Weather Service Jacksonville FL
1244 PM EST Sat Jan 23 2021

[Through 18Z Sunday]

Low stratus will continue at KGNV through the mid afternoon before
eroding, with VFR conditions prevailing elsewhere. Northeast winds
around 10 knots this afternoon will be 5-10 knots overnight and
then become east northeasterly around 10 knots on Sunday. Clouds
will lower across northeast Florida from south to north
overnight and into Sunday, with MVFR cigs expected at KGNV, and
possible across the rest of the northeast Florida TAF sites during
the day on Sunday.



.NEAR TERM [Through Tonight]...

High pressure will continue to strengthen as it builds into the
Ohio Valley, which will push the wavy frontal boundary positioned
across north central FL southward today, reaching south FL
tonight. Locally dense fog will continue to expand across inland
portions of southeast GA through the predawn hours as the
northern edge of the low stratus deck edges southward, while
drizzle and light showers sink to the south of the I-10 corridor
before sunrise. Fog may expand towards the I-10 corridor through
the early morning hours, while a drier air mass results in fog
dissipating towards sunrise for locations north of Waycross. Lows
early this morning will fall into the 40s for most of southeast
GA, with temperatures remaining in the 50s for northeast FL,
ranging to near 60 in north central FL.

Zonal flow aloft will continue across our region today, with
heights aloft rising slightly overnight as shortwave troughing
moves off the Mid-Atlantic coast. Surface ridging will wedge down
the southeastern seaboard this afternoon, resulting in a
tightening local pressure gradient and breezy northeasterly winds
developing at coastal locations. A drier air mass will briefly
advect southward over southeast GA and northeast FL as the day
progresses, but stratus and mid-level cloudiness will be slow to
erode over north central FL this afternoon as isentropic lift
begins to strengthen over the FL peninsula. Onshore winds will
keep highs in the upper 50s for coastal southeast GA and for
coastal locations north of St. Augustine. Highs elsewhere will
generally climb to the 60-65 degree range, except upper 60s in
north central FL.

Mid-level cloud cover will thicken from south to north tonight as
the frontal boundary stalls over south FL and then begins lifting
northward as a warm front late at night. High pressure will weaken
as it moves off the Carolina coast, resulting in veering low level
winds and coastal trough development over the near shore Atlantic
waters adjacent to northeast FL. Isentropic lift will also
strengthen from south to north after midnight, with isolated light
showers developing over north central FL during the predawn hours
as stratus develops, with coverage of this stratus reaching the
I-10 corridor towards sunrise, possibly accompanied by a few light
showers or drizzle. Lows will fall to the low and mid 40s for
inland southeast GA, where cloud cover will not thicken until the
predawn hours. Lows will only fall to the low and mid 50s for
locations south of I-10.

.SHORT TERM [Sunday through Monday Night]...

The surface ridge of high pressure will move off the mid-Atlantic
coastline Sunday, with the weak inverted coastal trough along the
FL Atlantic coastline slowly receding eastward through Sunday
night. The coastal trough will keep a slight (20%) chance for
showers in the forecast Sunday morning, with those showers
shifting eastward through the afternoon and evening hours. Sunday
will see highs in the low-mid 60s across SE GA, mid 60s-mid 70s
across NE FL. Sunday night, temperatures will only dip into the

On Monday, an upper level shortwave trough will eject into the
central Plains, developing a low pressure system which will drag a
cold front through the lower Mississippi Valley Monday and into
the southeast Monday night. Low end (20-30%) chances for showers
return to the Suwannee Valley Monday night. Ahead of this system,
temperatures will be warm with afternoon highs in the mid 70s to
around 80 and overnight lows in the low 60s.

.LONG TERM [Tuesday through Saturday]...

The upper level energy driving the approaching front will decay as
it lifts into the Ohio Valley, essentially stalling the front
across S GA near the FL-GA border by Tuesday night. Another upper
level shortwave will eject into the central Plains Tuesday night
however, helping to reinvigorate the stalled surface boundary and
allowing it to finally exit as a cold front Wednesday night.
Heading into the end of the work week, deep layer ridging will
build over the eastern CONUS and cooler, drier air will move into
our area. Inland frost is possible Friday night/Saturday morning.


A slow moving frontal boundary positioned across north central
Florida early this morning will sink southward through the Florida
peninsula this afternoon as strong high pressure builds over the
Ohio Valley and wedges down the southeastern seaboard.
Northeasterly winds will strengthen to 15-20 knots and seas will
build to Caution levels of 4-6 feet offshore this afternoon. Seas
will build to 3-4 feet near shore. Caution conditions will
continue offshore tonight as a coastal trough develops over the
near shore waters. Seas will remain in the 4-6 foot range on
Sunday as onshore winds prevail. High pressure will then weaken
as it slides off the Carolina coast by Sunday evening, followed by
the the front over the Florida peninsula lifting northward across
our waters on Sunday night. Meanwhile, low pressure developing
over Texas on Sunday night will lift northeastward across the
Ozarks on Monday. Southerly winds will increase over our waters on
Monday and will shift to southwesterly on Monday evening ahead of
a cold front that will be entering the southeastern states.
Caution conditions will prevail offshore on Monday and Tuesday,
with speeds just below Caution levels near shore. This front will
then stall over the Georgia waters by late Tuesday as a wave of
low pressure develops near our region towards midweek.

Rip Currents: Strengthening northeasterly winds and building seas
will create a moderate risk of rip currents at all area beaches
today. This moderate risk will continue into Sunday as onshore
winds persist.


A weak inverted coastal trough will develop today and remain in
place through Sunday. This will lead to generally light transport
winds and low mixing heights across the area and lower end
dispersions through the weekend. Today, dispersions will peak
around 25 to 35 across much of the area, but dispersions Sunday
will be even lower, around 15 to 25 across the area, with the
Suwannee Valley region seeing those 15 to 20 values. The pattern
will become more active with two cold fronts moving across the
southeast Tuesday and Wednesday, then we`ll end the week with
cooler, drier (min RH around 40%) conditions as high pressure
builds over the eastern CONUS.



AMG  42  61  52  74  61 /  10  20   0   0  10
SSI  48  61  54  71  59 /  20  20   0   0   0
JAX  52  66  56  77  60 /  20  20   0   0   0
SGJ  56  67  58  76  60 /  20  20   0   0   0
GNV  52  70  55  79  58 /  20  20   0   0   0
OCF  54  73  57  81  59 /  20  20   0   0   0


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