484
FXUS64 KHUN 232338
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
638 PM CDT Mon Sep 23 2024

...New AVIATION...

.NEAR TERM...
(Tonight)
Issued at 322 PM CDT Mon Sep 23 2024

Low chances (15-30%) of showers and storms (mainly along and
north of the Tennessee River) will persist into this evening
before diminishing due to the loss of daytime heating. Most of
tonight is forecast to then be rain-free; however, chances are
expected to increase to our northwest once again late tonight into
early Tuesday morning due to the approach of a surface cold
front. There is a low chance of patchy fog development tonight,
but this should be confined to areas near bodies of water and in
the more sheltered locations. Lastly, low temperatures tonight
will be warm, merely dipping into the upper 60s to lower 70s.

&&

.SHORT TERM...
(Tuesday through Wednesday Night)
Issued at 322 PM CDT Mon Sep 23 2024

A wet and unsettled pattern is expected to begin by Tuesday as a
deep, upper trough digs towards the Southeastern US. Additionally,
a surface cold front is forecast to approach the Tennessee Valley
on Tuesday, then eventually slow and stall over our west or just
to our west by midweek. This will lead to generally medium to high
chances (50-80%) of showers and storms Tuesday through Wednesday
night, with the time frame of the greatest rain chances being
Tuesday night through Wednesday.

Taking a look at the low chance of severe weather on Tuesday,
guidance suggests that instability and bulk shear are the greatest
along and west of I-65 during the day on Tuesday but may shift
towards the east into the evening hours. Instability looks to
range between 1500-2500 J/kg in the west and around 1000 J/kg in
the east. Furthermore, bulk shear values mainly range between
30-40 knots. Models indicate a stout upper level jet around 85-95
knots as well. The question will be just how unstable we actually
get during the afternoon, but the current thinking for timing of
any potential strong to severe storms will be from 11 AM through 7
PM. SPC has outlooked most of our local area in a Marginal Risk
(level 1 of 5) of severe weather tomorrow, primarily for damaging
winds. Heavy rain may also lead to nuisance flooding, with
forecast storm total rainfall between 1-3 inches (highest over
northeast Alabama and portions of southern middle Tennessee)
Tuesday through Wednesday night.

The increase in rain and storm chances will ultimately bring a
decrease in temperatures through midweek. Highs are expected to
reach the mid 80s to around 90 degrees on Tuesday but only top out
in the mid 70s to around 80 degrees for most areas on Wednesday.
Low temperatures will follow a similar trend, falling into the
lower to mid 60s by Wednesday night.

&&

.LONG TERM...
(Thursday through Sunday)
Issued at 137 AM CDT Mon Sep 23 2024

3PM UPDATE: Bottom line up front is that there remains a fair bit
of uncertainty in the track and evolution of Potential Tropical
Cyclone 9. However, at this time, it looks like our main hazards
with this system are shaping up to be heavy rain/flooding and
potentially gusty winds. The flooding threat will be exacerbated
by the rain from earlier in the week, with the potential for 5-7
inches of rainfall for northeast Alabama and portions of southern
middle Tennessee by Friday night. Ultimately, like the previous
shift mentioned, a westward shift in the track of the system would
increase the potential of these impacts while an eastward shift
would lessen the potential. We`ll continue to monitor this system
through the coming days, so please make sure to stay weather
aware!

The long term part of the forecast will be heavily dependent on a
potential tropical system out of the western Caribbean that will
lift northward potentially making landfall along the eastern Gulf
Coast in the Thu night/early Fri time frame. Where this system
then tracks will determine how much additional rainfall the mid TN
Valley may experience into the first half of the weekend period.
If this system tracks more to the NNE versus the NE, the area
could see some additional rainfall along with some gusty winds
Fri/Fri night. However, a more eastern track may limit the
rainfall/winds and provide more of a dry forecast this weekend.
Regardless, highs look to remain in the upper 70s/near 80F this
weekend, with lows more in the lower/mid 60s.

&&

.AVIATION...
(00Z TAFS)
Issued at 638 PM CDT Mon Sep 23 2024

VFR conditions continue at both KMSL and KHSV overnight into
Tuesday with calm winds and scattered cloud cover. Beginning
Tuesday morning at 15Z, a low chance exists for MVFR conditions as
a result of lowered visibilities during showers/storms over the
terminals. Later in the afternoon, a low chance for IFR conditions
exists as ceilings lower with greater thunderstorm chances during
peak heating (21Z through the end of the TAF period).

&&

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

$$

NEAR TERM...26
SHORT TERM....26
LONG TERM....26
AVIATION...HC