Roper, Georgia Weather Forecast Discussion

180
FXUS62 KJAX 171810
AFDJAX
Area Forecast Discussion
National Weather Service Jacksonville FL
210 PM EDT Wed Sep 17 2025
...SEASONABLY WARM TEMPERATURES CONTINUE THROUGH FRIDAY...
...INLAND FOG POTENTIAL EARLY ON THURSDAY AND FRIDAY MORNINGS...
...ANOTHER WEEKEND NOR`EASTER EXPECTED AT COASTAL LOCATIONS...
For the latest NE FL and SE GA Daily Key Messages please visit:
https://www.weather.gov/media/jax/briefings/nws-jax-briefing.pdf
.SYNOPSIS...
Issued at 210 PM EDT Wed Sep 17 2025
Early afternoon surface analysis depicts high pressure (1020
millibars) that was sprawling across the southeastern states,
while weakening, occluded low pressure (1014 millibars) was
moving slowly northward across the Delmarva region. Meanwhile,
weak troughing associated with this feature extends along the Gulf
Stream waters off the southeastern seaboard and across south FL.
Aloft...cutoff troughing continues to spin over the Chesapeake
Bay, with the axis of this trough extending into eastern portions
of the Gulf. This weather pattern continues to create brisk
southwesterly flow aloft above 500 millibars (around 20,000 feet)
per the morning sounding at Jacksonville. Otherwise, a shortwave
trough embedded within this deep southwesterly flow pattern was
traversing the southeastern Gulf, with this feature developing
convection over the northwestern Bahamas and across south FL, the
FL Keys, and the southeastern Gulf. Latest GOES-East derived Total
Precipitable Water imagery indicates that an unseasonably dry air
mass prevails across most of our area, with PWAT values generally
in the 1 - 1.25 inch range for southeast GA and northeast FL,
while values of 1.4 - 1.6 inches were located to the south of
Gainesville in north central FL. A few showers were developing in
this moistening air mass along the Interstate 4 corridor in
central FL, while brisk southwesterly flow aloft was transporting
a veil of high altitude cirrostratus that was emanating from
convection over the southeast Gulf across north central and
northeast FL. Fair skies prevailed across southeast GA, while a
flat cumulus field was developing beneath the cirrostratus shield
across north central FL. Temperatures were uniformly in the mid to
upper 80s at inland locations as of 18Z, while a light onshore
breeze was keeping coastal temperatures mostly in the low to mid
80s. Dewpoints ranged from the mid to upper 50s across inland
portions of southeast GA and the Suwannee Valley to the 60s
elsewhere.
&&
.NEAR TERM...
(through Tonight)
Issued at 210 PM EDT Wed Sep 17 2025
Deeper moisture located to the south of Gainesville may foster
isolated to widely scattered shower development from late this
afternoon through the early evening hours across north central FL,
mostly along the I-75 corridor, where the Atlantic and Gulf coast
sea breezes collide. An overall subsident air mass will likely
prevent thunderstorm development, and any showers that manage to
develop later today will likely be brief in duration. Meanwhile,
troughing over the southeastern states could develop a few light
showers or sprinkles over inland portions of southeast GA towards
sunset, but the overall dry and subsident air mass in place will
likely prevent measurable rainfall across our interior southeast
GA counties this evening. The cirrostratus shield streaming across
north central and northeast FL is expected to progress eastward
after midnight, with clearing skies from west to east setting the
stage for patchy to possibly areas of fog formation at inland
locations west of the I-95 corridor in northeast and north central
FL during the predawn and early morning hours, with fog possibly
extending northward to the Okefenokee Swamp for locations south
and east of Waycross. We will continue to undercut model blend
output for low temperatures tonight given the overall dry and
subsident air mass in place, with clearing skies and radiational
cooling after midnight allowing lows to again fall to the 60-65
range for most inland locations, ranging to the upper 60s to
around 70 for north central FL and coastal locations.
&&
.SHORT TERM...
(Thursday through Friday)
Issued at 210 PM EDT Wed Sep 17 2025
Predominantly dry weather conditions will continue through the end
of the week with a slight chance for isolated showers developing
over inland areas during the afternoon hours and the highest
chances for convection occurring over north central Florida and
extending though Flagler and St Johns counties. Prevailing flow
will shift about to become more out of the east by the end of the
period, bringing in gradually increasing moisture levels going
into the weekend. High temperatures during this period will reach
up into the lower 90s for inland areas and in the mid 80s for
areas along the coast. Overnight low temperatures will drop down
into the mid to upper 60s for inland areas and in the lower 70s
near the shoreline.
&&
.LONG TERM...
(Saturday through Tuesday)
Issued at 210 PM EDT Wed Sep 17 2025
Prevailing flow will shift to become more out of the south by the
beginning of next week as high pressure ridging to the north pulls
away and moist air with PWAT values measuring above 2 inches is
drawn into the forecast area resulting in increased chances for
more widespread convection by Monday and Tuesday. High
temperatures for the weekend and into the beginning of next week
will drop to be slightly below the seasonal average with overnight
low temperatures dropping down to be near and slightly above
average for this time of year.
&&
.AVIATION...
(18Z TAFS)
Issued at 210 PM EDT Wed Sep 17 2025
VFR conditions will prevail at the regional terminals through at
least 04Z this evening. IFR to LIFR conditions are expected to
develop at VQQ after 05Z, with MVFR conditions expected to develop
at GNV towards 09Z. Periods of IFR conditions will be possible
at GNV during the predawn and early morning hours, with VFR
conditions then expected to prevail at VQQ and GNV by 14Z
Thursday. Periods of MVFR visibilities will also be possible at
the rest of the terminals around sunrise after high altitude cloud
cover departs during the predawn hours, but confidence was too
low to indicate fog formation at JAX, CRG, SSI, and SGJ. Mainly
easterly surface winds sustained at 5-10 knots this afternoon will
shift to southeasterly while gradually weakening this evening.
Light and variable surface winds are then expected during the
early morning hours before east-northeasterly winds develop during
the mid- morning, with sustained speeds increasing to 5-10 knots
by 16Z.
&&
.MARINE...
Issued at 210 PM EDT Wed Sep 17 2025
Weak high pressure will remain situated over our region through
Thursday. Strong high pressure will then build southeastward from
Hudson Bay, Canada late this week, with this feature then shifting
over New England by Saturday as it wedges down the southeastern
seaboard. Seas of 2-4 feet will prevail both near shore and
offshore through Friday night. Coastal troughing will sharpen
over our near shore waters this weekend, resulting in
strengthening onshore winds, building seas, and an increasing
coverage of showers and thunderstorms. Seas will build to 3-5 feet
on Saturday as sustained speeds climb to Caution levels of 15-20
knots both near shore and offshore. Small Craft Advisory
conditions are possible late this weekend and early next week, as
seas likely build to at least Caution levels of 4-6 feet
throughout our local waters by early Sunday.
Rip Currents: A lingering northeasterly swell will combine with
breakers of 2-4 feet at area beaches to keep a moderate risk in
place through Thursday. Strengthening northeasterly winds on
Friday will likely yield a higher end moderate risk on Friday at
area beaches, with a high risk possible during the afternoon hours
along the northeast FL beaches, where surf heights will gradually
build. A high risk is likely this weekend and early next week as
rough surf conditions prevail.
&&
.FIRE WEATHER...
Issued at 210 PM EDT Wed Sep 17 2025
An unseasonably dry air mass this afternoon will drop minimum
relative humidity values to the 30-35 percent range across inland
southeast GA, the Suwannee Valley, and portions of north central
FL. Light westerly transport winds and elevated mixing heights
will create good daytime dispersion values this afternoon for
locations north of Alma in interior southeast GA. Meanwhile,
prevailing easterly surface and transport winds across northeast
and north central FL will combine with elevated mixing heights
across to create good daytime dispersion values this afternoon for
the Suwannee Valley and portions of north central FL, while fair
values generally prevail elsewhere. Light and variable surface and
transport winds on Thursday will result in poor to fair daytime
dispersion values for most of inland southeast GA, while easterly
surface and transport winds persist across northeast and north
central FL, where elevated mixing heights will generally yield
good daytime dispersion values for inland locations, with fair
values forecast elsewhere. East-northeasterly transport winds will
gradually strengthen on Friday, with breezy surface winds
developing along the northeast FL coast during the afternoon
hours. These strengthening winds will combine with elevated mixing
heights to create good daytime dispersion values at most
locations.
&&
.COASTAL/TIDAL FLOODING...
Issued at 210 PM EDT Wed Sep 17 2025
Strengthening onshore winds this weekend will combine with
marginally elevated astronomical tides to potentially create minor
coastal flooding along the Atlantic coast by late Sunday or
Monday. Minor tidal flooding will also be possible late this
weekend and early next week within the St. Johns River basin, with
areas from downtown Jacksonville southward expected to initially
experience water level rises on Sunday, expanding to the rest of
the basin and its tributaries early next week.
&&
.PRELIMINARY POINT TEMPS/POPS...
AMG  64  91  65  91 /  10  20   0  20
SSI  70  86  71  85 /  10  10   0  10
JAX  66  90  69  89 /  10  10   0  10
SGJ  70  87  72  87 /  10  20  10  10
GNV  66  93  67  92 /  10  10   0  10
OCF  67  90  68  91 /  20  20   0  10
&&
.JAX WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AM...None.
&&
$$

NWS JAX Office Area Forecast Discussion