537 
FXUS62 KJAX 182300
AFDJAX

Area Forecast Discussion
National Weather Service Jacksonville FL
700 PM EDT Sat Sep 18 2021

.AVIATION...
[Through 00Z Monday]

The Atlantic and Gulf of Mexico sea breeze front convergence
extends from near Ocala through Gainesville to Lake City and is 
nearly stationary. Showers and thunderstorms are slowly
dissipating as we loose diurnal heating. Will keep a Tempo for
showers in the KGNV TAF until 22 utc. Otherwise no issues of 
significance for the other fields. 

&&

.PREV DISCUSSION [336 PM EDT]...

.NEAR TERM [Through Tonight]...

A mid/upper low was moving slowly toward the Texas/Louisiana 
state border, allowing ridging to build westward from the Bahamas
across the FL peninsula and towards the southeastern Gulf of 
Mexico. This set-up will continue steer abundant tropical moisture
and impulses into the area. Scattered convection has developed
along the sea breezes and will become numerous as the boundaries
collide along the I-75 corridor by the late afternoon and evening
hours. With slow storm motion and PWATs over 2 inches, heavy 
rainfall and localized flooding will be possible this afternoon 
into evening for inland areas. Activity will diminish before 
midnight near the Suwannee River, with an uptick in coastal 
convection expected during the predawn and early morning hours as
onshore flow begins to deepen and shortwave energy moves 
overhead. Overnight lows will be in the 70s.


.SHORT TERM [Sunday Through Monday]...

A mid/upper low lingering over the lower Mississippi River Valley
will weaken, elongate and lift to the northeast by Monday. Deep
tropical moisture (PWATs > 2 inches) will continue to reside
across the area resulting in numerous to widespread showers/storms
mainly during the afternoon/evening hours into early next week.
Sunday into Monday, high pressure over New England will wedge down
the southeastern seaboard developing a coastal trough on Monday. 
This could result in short convective bands forming and dropping 
heavy rain along coastal areas. Areas of heavy rainfall and 
localized flooding may develop as cell motion will be on the slow 
side. Best chance will be in inland northeast Florida on Sunday 
and along the east coast on Monday. Temperatures will be around 
normal with highs in the mid to upper 80s and lows in the 70s.


.LONG TERM [Tuesday Through Friday]...

Numerous to widespread showers/storms continue into Wednesday as
deep tropical moisture lingers over the area. A weakening ridge 
of high pressure along the east coast will shift offshore as an 
upper trough digs into the eastern U.S. PWATS around 2 inches 
along with light steering winds will result in slow moving 
showers/storms with locally heavy rainfall and localized flooding 
as a continued threat. A cold front will push through the area
Wednesday night into Thursday. A cooler, drier airmass filters in
from the northwest for the end of the week lowering rain chances 
and overnight lows into the low to mid 60s for inland areas.


.MARINE...

Stronger high pressure builds southeastward from the Great Lakes 
towards New England. This feature will wedge down the southeastern
seaboard on Sunday, resulting in coastal trough development over 
our near shore waters by late Sunday and Monday. Abundant tropical
moisture will result in widely scattered thunderstorms over our 
waters through tonight, followed by increasing activity from 
Sunday night through Tuesday due to the presence of the coastal 
trough. A cold front will then enter the southeastern states 
towards midweek, passing through our waters on Thursday. Seas of 2-4
feet will otherwise prevail throughout our coastal waters through
midweek.

Rip Currents: Moderate risk of rip currents anticipated through
the weekend for all area beaches.


.HYDROLOGY...

Minor flooding continues along lower portions of the Santa Fe River
near the Three Rivers Estates gauge. Runoff from widespread 
convection will likely result in river rises further upstream 
along the Santa Fe as well as the St. Marys and Satilla River 
basins, although these river levels are currently expected to peak
in action stages rather than reaching flood stage through the 
middle portion of next week. This still is highly dependent on 
where the heaviest rain falls.

Locally heavy rainfall and localized flooding will be possible 
over the next few days with WPC showing marginal risk of excessive
rainfall. Estimated rainfall amounts into Monday are around 1-2 
inches, with locally higher totals possible.

&&

.PRELIMINARY POINT TEMPS/POPS...

AMG  72  86  71  85  71 /  20  50  30  80  30 
SSI  77  85  76  85  75 /  40  60  60  80  60 
JAX  74  87  74  86  74 /  40  70  40  80  40 
SGJ  76  85  74  85  74 /  40  60  40  80  50 
GNV  73  87  71  87  71 /  60  80  40  80  30 
OCF  73  88  73  88  73 /  60  80  30  80  30 

&&

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