133
FXUS64 KHUN 210820
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
320 AM CDT Tue May 21 2024

...New NEAR TERM, SHORT TERM, LONG TERM...

.NEAR TERM...
(Today)
Issued at 320 AM CDT Tue May 21 2024

A large area of high pressure continues to be in place over much
of the southeastern CONUS. A frontal boundary is draped northwest
of this feature through the northern Great Lakes region southwest
into Iowa and extreme southeastern New Mexico.

Much of the weather across the country is focused along this front
with several impulses or areas of low pressure moving along it to
the northeast. One of these pieces of energy is centered over
central Michigan. Most of the energy associated with it remains
over the Great Lakes region, but a weak trough axis extends SSW
from it into central Ohio and SE Kentucky. This feature is helping
to produce just enough weak convergence for an area of cloud
cover that has developed over eastern TN and northern GA.

Most of the area in northern Alabama and southern middle
Tennessee is still experiencing clear skies though. Winds are
still light and variable (3 mph or less) across most areas near
and east of the I-65 corridor. Expect this to continue at least
through 4 AM or so in those areas. Given the current dewpoint
depressions in our typical fog prone areas near and east of the
I-65 corridor (0 to 4 degrees), patchy fog was added near Lewis
Smith Lake, the DeKalb Valley areas, and the Paint Rock River
Valley. Not sure if it will become dense or very widespread since
models do start to pick up winds to around 5 mph between 5 AM and
7 AM. The exception to this might be far eastern Alabama in the
valley areas, but confidence is too low to include that in the
forecast right now.

With winds picking up first west of the I-65 corridor already,
think that a pretty good gradient of temperatures will be
experienced when you wake up this morning. Lows west of the I-65
corridor will likely only drop to the mid to upper 60s. Further
east, lows will likely drop to between 60 and 65 degrees.

During the day today, the upper level ridging south of this front
remains fairly stout or strengthens a bit. This should continue
to keep showers and thunderstorms well north of the area. Another
disturbance along the front moves northeast into the western Great
Lakes area, bringing them more showers and thunderstorms. There
may be some isolated to scattered showers or storms develop to our
east in northern GA or eastern Kentucky, as the weak trough axis
producing cloud cover there now shifts a bit further east. This
cold produce enough cloud cover over portions of NE AL and
Franklin county (TN) to keep temperatures a tad cooler in the
afternoon than further east. Despite that it will be a very warm
day with highs in the mid to upper 80s there. Further west, expect
highs to reach the 85 to 90 degree range.

&&

.SHORT TERM...
(Tonight through Friday)
Issued at 320 AM CDT Tue May 21 2024

The axis of the upper level ridge (though still strong) weakens
and a weak pre-frontal axis extending SSW of the impulse moving
into the western Great Lakes region along the front makes some
headway east towards the area. This will likely be able to produce
some strong to severe storms near the axis of this pre-frontal
trough axis. However, this will still be centered to our west and
affect mainly the Mississippi Valley region. Further southeast,
the eastern edge of this activity could approach north central MS
and the Nashville area towards daybreak on Wednesday. Expect
mainly mostly clear to partly cloudy conditions tonight, but some
mostly cloudy conditions may start pushing into the area around
daybreak. Southerly winds will likely remain between 5 and 10
knots through much of the evening. The exception to this might be
in far eastern Alabama. There, some patchy fog may be possible.

With increasing moisture advection over the area and higher winds,
expect temperatures to only drop into the 65 to 70 degree range in
most areas. The exception might be again far eastern Alabama,
where some lows could drop into the 60 to 65 degree due to the
lighter winds in that area.


During the day on Wednesday, most guidance continues to flatten
out the ridge aloft a bit more over the southeast. However, it
still appears that the ridge is strong enough to stall the front
just northwest of the area during the day across eastern Oklahoma
NE into Kentucky. This will likely keep convection to our northeast
still. However, on and off mostly cloudy conditions will likely
occur. This should keep high temperatures a bit cooler than the
previous day, only climbing into the mid to upper 80s across the
area.

Winds could become lighter again Wednesday night. This could set
the stage for some more widespread fog development if thicker and
more persistent cloud cover wasn`t expected. Not much changes
Wednesday night, but models do slightly weaken the upper ridge
southeast of the front just a bit more. This could allow maybe for
a 20 to 40 percent coverage of showers or storms to make it into
areas mainly north of the Tennessee River. At this time, do not
think these would be severe.

On Thursday into Friday, things don`t change much as another
stronger impulse of energy forms along the stalled front over
eastern Texas. We will likely be on the very edge with similar
shower or thunderstorm chances. Again, more persistent cloud
cover will likely keep highs in the lower to mid 80s both days.
Lows will be very sultry only dropping into the 66 to 71 degree
range.

&&

.LONG TERM...
(Friday night through Monday)
Issued at 320 AM CDT Tue May 21 2024

This impulse along the front swings east Friday night and south of
the area Saturday night. This subsequently bring medium to high
(40-70%) chance for showers and storms to the area. General view
of the storm environment would favor plenty of CAPE with
sufficient shear to support at least a few organized strong
storms, with gusty winds and hail (along with locally heavy
downpours) being the main threats on Friday night into Saturday
night. We`ll remain in a fairly active pattern through the the
upcoming Memorial Day holiday weekend, with zonal low aloft
allowing for additional shortwaves to traverse the region.
Subsequently, medium chances (40-60%)for showers/storms will be
present in the forecast both Sunday and Monday.

&&

.AVIATION...
(06Z TAFS)
Issued at 1238 AM CDT Tue May 21 2024

Variable winds around 4 knots are expected at both terminals after
6Z. This should keep VFR conditions in place, given current
dewpoint depressions at the terminals and the expected increase
in winds to around 4 knots. Otherwise, southerly winds are
expected to become more established during the day today between 5
and 10 knots gusting to between 10 and 15 knots after 15Z. We
should lose the wind gusts tonight, as winds remain between 5 and
10 knots.

&&

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

$$

NEAR TERM...KTW
SHORT TERM....KTW
LONG TERM....KTW
AVIATION...KTW