094 
FXUS62 KJAX 080853
AFDJAX

Area Forecast Discussion
National Weather Service Jacksonville FL
453 AM EDT Thu Oct 8 2020

...WIDESPREAD DENSE FOG EXPECTED ACROSS SOUTHEAST GEORGIA AND 
PORTIONS OF NORTHEAST FLORIDA THIS MORNING...

.NEAR TERM [Today Through Tonight]...

Currently, diffuse low level trough, oriented west-east, continues
to be placed over northeast FL between Ocala and Live Oak, 
separating moist, slightly unstable conditions and weak east- 
southeast flow from drier air and northerly flow over south 
central GA and points northward. PWATs upwards of 2.2 inches noted
around Marion county, dropping to 1.5 inches over Alma, GA. Mid 
level ridge continues over central FL. Main story is that fog has 
become widespread enough for dense fog advisory which for now 
encompasses almost all of southeast GA and a small part of 
northeast FL. Going south of I-10, mid clouds and more unstable 
conditions resulting in less widespread fog potential. Current temps
are around 70-75.

Today, mid/upper level high centered over the region will shift 
slightly west and then shift east of the area by Friday morning, 
while Hurricane Delta moves northwestward over the Gulf of Mexico 
staying well west of our region. High pressure at the surface will
rebuild to the north and move slowly eastward through the day and
position over Mid Atlantic states at ~1024 mb by 12Z Friday. The 
combination of building high pressure north of the area and Delta 
will ensure low level winds remain northeast to east. High 
moisture levels will be in place over over northeast FL and 
combined with diurnal heating will produce isolated to scattered 
mainly aftn convection today. Best chances (~30-50%) will be over 
northeast FL with chances of AOB 20% north of a line from 
Kingsland to Homerville. High temperatures will be in the mid to 
upper 80s inland with low 80s along the coast. Tonight, with high 
pressure building to the north, the weak trough of low pressure 
over northeast FL will be drifting southward, displacing moisture
a little further south and instability south of the area. Still, 
some isolated weak convection is expected across northeast FL and 
the adjacent coastal waters where frontal convergence is expected.
Patchy to areas of fog expected to form again nrn zones, but some
limitations on areal coverage and fog intensity will be slightly 
stronger winds just above the surface and a weaker radiation 
inversion. Low temps from upper 60s to lower 70s.

.SHORT TERM [Friday Through Saturday Night]...

Deep moisture will pool along a backdoor frontal boundary that 
will stall along the FL/GA border as surface ridging slides off
the Mid-Atlantic coast. Meanwhile, Delta will likely be a large 
and Major Hurricane over the western half of the Gulf of Mexico 
early in the day, with some weakening expected later in the day 
as the hurricane approaches the western or central Louisiana 
coast due to strengthening wind shear and cooler shelf waters. 
This weather pattern will result in a tightening pressure
gradient and breezy onshore winds developing at coastal locations
by the mid-morning hours. Convergent easterly flow in the low 
levels will likely drive scattered showers onshore for locations 
from St. Augustine southward during the morning hours. 

Persistent ridging aloft over our region will slide eastward by 
Friday afternoon, setting up a veering wind profile during the 
afternoon hours per forecast model soundings. Numerous showers 
and a few embedded thunderstorms will develop along and south of
the frontal boundary across most of northeast and north central
FL on Friday afternoon. Convection will likely drift slowly 
north-northwestward during the afternoon and evening hours, with
locally heavy rainfall possible. Activity should begin to lift
into inland portions of southeast GA by the late afternoon and 
evening hours as the frontal boundary begins to lift slowly 
northward as a warm front. Abundant cloud cover and increasing
coverage of rainfall will keep highs on Friday in the mid 80s,
with breezy onshore winds keeping coastal highs mostly in the lower 
80s.

Flow in the low levels will continue to veer to southeasterly on
Friday night as Delta makes landfall over coastal Louisiana. 
Scattered showers will be possible throughout the night along
the I-95 corridor, with isolated convection possible along the 
warm front from I-10 northward. A warm and humid air mass will
keep lows in the 70-75 degree range. Deep southerly flow will
then develop on Saturday morning as Delta moves inland across the
lower Mississippi Valley. A slightly drier air mass will temporarily
advect over our region from the south on Saturday morning, which
should allow for breaks to develop in the multi-layered cloud cover
that will be in place locally. Filtered sunshine should boost highs
to the mid and upper 80s, with deeper moisture then expected to 
advect back over our region during the afternoon hours. 

Model soundings continue to depict weak instability and marginal 
ML CAPE values of 1,000 - 1,500 j/kg, but the Gulf coast sea 
breeze will move inland past the I-75 corridor and should become 
the focus for numerous showers and embedded thunderstorms during 
the late afternoon and early evening hours, particularly along the
U.S. Highway 301 and I-95 corridors. Deep-layered flow will 
continue to veer on Saturday night and Sunday as Delta's remnant 
circulation moves into the Tennessee Valley, with additional waves
of convection possible overnight in the Suwannee Valley and 
inland portions of southeast GA. Lows will only fall to the low 
and mid 70s. 

.LONG TERM [Sunday through Wednesday Night]...

Deep tropical moisture will remain in place across our region on 
Sunday, tied in with the remnant circulation of Delta that will be
weakening over the southern Appalachians. Numerous showers and 
thunderstorms are expected to traverse our region from southwest 
to northeast, followed by a dry slot advecting into our area from 
the northeast Gulf of Mexico by early Sunday evening. Weakening 
southwesterly flow will continue through early Tuesday, but a 
drier air mass will limit diurnal convective coverage to widely 
scattered early next week. Highs will continue to reach the mid to
upper 80s, but lows will begin to fall back into the mid and 
upper 60s at inland locations by Monday night as the drier air 
mass overspreads our area. 

A more substantial cold front will then cross our region from 
northwest to southeast on Tuesday afternoon and evening, with 
light northwesterly winds advecting a much drier air mass into our
area, allowing dewpoints to fall into the 50s by early Wednesday 
for inland southeast GA. Lows will fall into the 60s region-wide 
on Tuesday night, with highs on Wednesday only climbing to the 
upper 70s and lower 80s. Northerly low level flow and fair skies 
will result in lows falling into the 50s at most inland locations 
on Wednesday night, ranging to the 60-65 range at coastal 
locations. 

&&

.AVIATION...
[Through 06Z Friday]

Some light mist is forming over the area so far tonight and will 
continue to see a drop in vsby and cigs through the early morning 
hours, with maybe a delay in conditions dropping for KGNV and
around JAX metro terminals where mid clouds are still around. 
Still a good chance of IFR cigs/vsby developing by about 09Z-10Z 
with LIFR to VLIFR likely between 10Z-13Z, and then lifting vsby 
and cigs in the 13Z-15Z time frame. A chance of showers expected 
for SGJ and GNV today and for now just included VCSH by the aftn 
hours. 

&&

.MARINE...

Light north-northeast flow this morning will turn more easterly 
but winds will be about 10 kt or less, and seas near 2-4 ft with 
period about 8-10 seconds. Impacts early today will be some patchy
fog generally north of Mayport and mainly over the GA waters. 
Winds will gradually increase tonight and Friday, with at least 
SCEC headline needed Friday as backdoor front moves down the coast
and pressure gradient increases. Front will move back north as a 
warm front on Saturday and winds will shift around to the south 
and southeast. Unsettled weather for the weekend with a chance of
showers and storms. A trough of low pressure will pass through
Sunday night resulting in some lower rain chances Monday.

Rip Currents: Moderate risk of rip currents will persist today, 
with increased surf from stronger onshore flow Friday into the 
weekend resulting in at least as a strong moderate risk.

&&

.HYDROLOGY...

The coastal flood advisory was continued for St Johns River areas
south of downtown Jacksonville as area gauges are still peaking 
into minor flood stage around 1.5 ft MHHW. Also have kept the 
Coastal Flood statement for rest of coastal Northeast Florida. 
Going forward into the weekend, unfortunately, with increased 
onshore flow and current anomaly of about 1+ ft in the St Johns 
River basin, a continuation of elevated water levels are 
expected.

&&

.PRELIMINARY POINT TEMPS/POPS...

AMG  88  67  85  71  87 /  10  10  30  30  60 
SSI  84  72  82  74  83 /   0  10  20  30  50 
JAX  87  72  85  72  88 /  20  10  50  30  60 
SGJ  85  75  83  75  86 /  30  20  50  40  70 
GNV  88  73  85  72  89 /  50  20  70  20  60 
OCF  89  73  88  72  89 /  40  10  60  10  60 

&&

.JAX WATCHES/WARNINGS/ADVISORIES...
FL...Dense Fog Advisory until 10 AM EDT this morning for Coastal 
     Nassau-Inland Nassau.

     Coastal Flood Advisory until 6 PM EDT this evening for Clay-
     Inland Flagler-Inland St. Johns-Putnam.

GA...Dense Fog Advisory until 10 AM EDT this morning for Appling-
     Atkinson-Bacon-Brantley-Coastal Camden-Coastal Glynn-Coffee-
     Inland Camden-Inland Glynn-Jeff Davis-Northeastern Charlton-
     Northern Ware-Pierce-Southern Ware-Wayne-Western Charlton.

AM...None.
&&