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000
FXUS62 KJAX 041036
AFDJAX

Area Forecast Discussion
National Weather Service Jacksonville FL
536 AM EST Thu Mar 4 2021

.AVIATION...
[Through 12Z Friday]

Deck of IFR-MVFR cigs has pushed south of all TAF sites. Unlimited
cigs and vsbys with light winds through the period.

&&

.PREV DISCUSSION [313 AM EST]...

.NEAR TERM [Through Tonight]...

A very weak pressure pattern is in place over our area, with low
pressure continuing to move off to the northwest across the Nrn
Atlantic waters, a deep low pressure system spinning in place over
the northeastern US, and a surface ridge of high pressure in
Ontario that will dig slightly south toward the Great Lakes region
through tonight. Locally, this is bringing light, generally
northern winds and gradually clearing skies. Temperatures should
peak in the upper 60s to low 70s across most of the area, with mid
70s in the greater Ocala area. Overnight, temperatures will dip
into the low to mid 40s.


.SHORT TERM [Friday Through Saturday]...

Deepening troughing over New England will drive a backdoor cold
front southward down the Carolina coast on Thursday night. Our
local pressure gradient will begin to tighten from north to south
on Friday morning as this dry cold front passes southward across
our area, with northeasterly winds becoming breezy along the
Interstate 95 corridor during the afternoon hours. High cloudiness
will increase from the west during the afternoon hours, with
inland highs warming to around early March climatology, with upper
60s for inland southeast GA, lower 70s for inland northeast FL
and mid 70s for north central FL. Breezy onshore winds will keep
coastal highs in the 60s.

Meanwhile, a closed mid and upper trough migrating eastward
across the southern Plains and the Ozarks on Friday will
pivot southeastward on Friday night and will gradually weaken
as it encounters a confluent flow pattern aloft along the
eastern seaboard, compliments of the deepening trough over
New England. Weak low pressure will traverse the Gulf of Mexico
from Friday night through Saturday afternoon. Strengthening high
pressure over the Great Lakes region in the wake of the cold
frontal  passage will begin to wedge down the southeastern
seaboard, resulting in coastal trough development over our near
shore Atlantic waters on Friday night. Isentropic lift will
strengthen from west to east after midnight on Friday night, with
increasingly convergent low level onshore winds and the developing
coastal trough likely developing showers by the predawn hours
along the northeast FL coast, with light showers then
overspreading the rest of our area towards sunrise on Saturday.
Thickening cloud cover will keep lows in the mid to upper 40s for
inland locations along and north of I-10, ranging to the lower 50s
along the northeast FL coast, where breezy conditions will
continue overnight.

Steady rainfall will develop on Saturday morning for locations
along and south of I-10, with light rainfall expected for
southeast  GA that should depart before sunset as the
aforementioned weakening trough migrates across our area. A tight
local pressure gradient will exist throughout the weekend as
strong high pressure builds southward from the Great Lakes towards
the southeastern states. Cloud cover and rainfall will keep
highs on Saturday below climatology, with highs likely remaining
in the 55-60 range nearly area-wide. Rainfall amounts on Saturday
are expected to range from 0.5 - 0.75 inches for locations from
Gainesville to St. Augustine and points southward, while amounts
along the I-10 corridor will generally run around 0.25 inches,
with 0.10 or less for southeast GA. A few coastal showers may
linger on Saturday evening in northeast FL as breezy northeasterly
winds continue, while skies clear overnight from west to east.
Clearing skies and cold air advection will drive lows down to the
mid to upper 30s for inland southeast GA, with 40s elsewhere. Some
patches of frost may be possible at wind sheltered locations north
of Waycross towards sunrise on Sunday.


.LONG TERM [Sunday Through Thursday]...

Troughing aloft will persist over the eastern seaboard through
early next week, creating an extended period of deep and dry
northwesterly flow aloft that will keep temperatures below
climatology through Tuesday morning. Breezy onshore winds will
continue at coastal locations through at least Tuesday, and highs
will mostly remain in the 60s, except upper 50s for coastal
locations north of Jacksonville Beach on Sunday. Strong high
pressure will build over the southeastern states on Sunday night
and Monday. Frost appears to be increasingly likely across inland
southeast GA and northern portions of the Suwannee Valley on
Sunday night, as lows fall to the mid 30s, with lows elsewhere in
the upper 30s to lower 40s inland and mid to upper 40s at coastal
locations. Highs on Monday will remain in the 60s, except lower
70s for north central FL.

Troughing aloft will then de-amplify as it moves off the U.S.
eastern seaboard on Tuesday, with a dry west-northwesterly flow
pattern remaining in place locally for the remainder of the week.
Temperatures will rebound to near climatology on Tuesday, except
at coastal locations, where persistent onshore winds will keep
highs in the 60s. Onshore flow should weaken enough by Wednesday
to allow highs to reach the 70s for coastal northeast FL, while
lows continue to moderate to the 40s inland and 50s for coastal
locations beginning on Tuesday night.


.MARINE...

Offshore seas of 4 to 6 feet today will subside to 3 to 5 feet
by tonight. Generally north or northeast winds around 10 to 15
knots will prevail through the period, with a brief period of
cautionary 15 to 20 knot winds this weekend as another weak low
pressure system moves from the Gulf across central Florida.

Rip Currents: Moderate risk of rip currents through Friday.


.FIRE WEATHER...

A drier air mass will funnel into our region today as
northwesterly surface and transport winds increase to 5-10 mph
after sunrise, with winds inland shifting to north-northwesterly
this afternoon, while north-northeasterly winds increase to
around 10 mph at coastal locations this afternoon. Marginally low
daytime dispersion values are expected today for locations east
of I-95. Minimum relative humidity values will fall to around 30
percent inland this afternoon. Breezy northeasterly surface and
transport winds will then develop by the late morning hours on
Friday. Light showers will develop after midnight on Friday night,
followed by steady rainfall and likely low dispersion values on
Saturday for locations south of I-10. Only light showers are
expected for locations north of I-10. Breezy northeasterly winds
will continue, with windy conditions developing at coastal
locations on Saturday afternoon.


.HYDROLOGY...

Mostly minor river flooding continues for most of the main stem
rivers in southeast GA as well as the Suwannee Valley, with the
exception of Moderate Flooding on the lower Santa Fe near the Three
Rivers Estates gauge. Levels on the lower Santa Fe should fall back
to minor flood status by the weekend as the flood wave travels down
the lower portion of the Suwannee River.

&&

.PRELIMINARY POINT TEMPS/POPS...

AMG  69  42  68  44  59 /   0   0   0  20  30
SSI  68  49  61  49  56 /   0   0   0  20  40
JAX  71  46  69  49  57 /   0   0   0  30  60
SGJ  67  50  67  52  57 /   0   0   0  30  80
GNV  73  43  73  50  57 /   0   0   0  40  70
OCF  74  45  76  53  59 /   0   0   0  40  80

&&

.JAX WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AM...None.
&&