-- Discussion containing changed information from previous version are highlighted. --
464
FXUS64 KHUN 180453
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
1153 PM CDT Tue Sep 17 2024

...New AVIATION...

.NEAR TERM...
(Tonight)
Issued at 909 PM CDT Tue Sep 17 2024

Local weather conditions across the TN Valley overnight will
continue to be dominated by an upper-level area of low pressure
that is predicted to remain nearly stationary across western SC
through the period. A broad area of altostratus clouds
(accompanied by a few sprinkles of rain) along the western
periphery of the low`s circulation spread westward into northern
AL earlier this evening, but recent trends in IR satellite data
and near term model guidance both suggest that the leading edge of
the cloud mass will continue to erode with time. Presuming that
skies indeed partially clear across the eastern half of the CWFA,
a light NE-calm wind and abundant boundary layer moisture will
support the development of fog shortly after Midnight (some of
which could become locally dense by sunrise). The alternative
scenario is that the cloud layer does not erode as quickly as
advertised, with a few sprinkles of rain possible across northeast
AL and adjacent portions of southern Middle TN overnight, along
with warmer low temps that would reduce concern for fog formation.
Regardless of which scenario unfolds, it will be a somewhat warm
and humid night with lows in the l-m 60s.

&&

.SHORT TERM...
(Wednesday through Friday)
Issued at 136 PM CDT Tue Sep 17 2024

The area of low pressure to our east will shift NE into the Mid
Atlantic region as a ridge of high pressure over south Texas
expands eastward into the Lower Mississippi and Tennessee Valley
mid to late week. The end result will be continued mostly clear
and dry weather and a gradual warming trend by the end of the work
week. Highs will gradually rise to the lower 90s by Friday, with
model soundings showing a very dry profile indicative of strong
subsidence from the ridge.

&&

.LONG TERM...
(Friday night through Monday)
Issued at 157 AM CDT Tue Sep 17 2024

High pressure will remain the dominating feature through the long
term forecast. Mid level ridging will build in from the SW and
remain through the weekend. While the overall trend will be clear
and dry conditions with temps in the high 80s to low 90s, we will
be monitoring any impacts from an upper low tracking east across
the CONUS. Being on the eastern periphery of high pressure will
place us in a NW flow regime marking a favorable pattern for SE
expansion of clouds and rain from the parent low. While the
current forecast is dry, we will be monitoring how these two
features interact (NW flow from high pressure and low pushing
east) over the next several days for any forecast changes.

&&

.AVIATION...
-- Changed Discussion --
(06Z TAFS)
Issued at 1153 PM CDT Tue Sep 17 2024

Overall, there have been no changes to previous aviation forecast
reasoning, as the recent clearing trend continues to raise
confidence in the development of BR/FG during the early morning
hours. We have specifically included a TEMPO group btwn 9-13Z,
which is the timeframe when fog should be most widespread and
perhaps locally dense. Any fog will lift shortly after daybreak,
with NNW flow of 5-10 kts and a sct-bkn Cu field developing by
14Z, but dissipating by 22Z.
-- End Changed Discussion --

&&

.HUN WATCHES/WARNINGS/ADVISORIES...
AL...None.
TN...None.

&&

$$

NEAR TERM...70/DD
SHORT TERM...AMP
LONG TERM...RAD
AVIATION...70/DD