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000
FXUS64 KHUN 230211
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
911 PM CDT Mon Apr 22 2024

...New NEAR TERM...

.NEAR TERM...
(Tonight)
Issued at 859 PM CDT Mon Apr 22 2024

Despite very light or calm winds under an area of high pressure
centered over southern AL/GA, dewpoints have risen over the past
few hours from the lower/mid 30s into the upper 30s/lower 40s.
This appears to be due to some weak low level moisture advection
just above the surface around 1000 mb that is impinging on the
surface high from the northwest. This advection is occurring
ahead of a cold front stretching from south central Canada into
northern Kansas.

Models show this weak moisture advection continuing overnight.
Thus, expecting dewpoints to slowly continue to rise a bit more
overnight. With dewpoints coming up due to low level moisture
advection, lows will have a hard time dropping below 40 degree
before midnight, despite calm winds and good radiational cooling
conditions.

Some model guidance slightly picks up the pressure gradient late
during the overnight period into the daybreak hours on Tuesday in
addition. All of these factors will likely keep lows bottoming
out in the 38 to 45 degree range in most locations, not much lower.
Expect the coolest temperatures to be in southern middle Tennessee
and NE Alabama, where some 37 to 40 degree looks look possible.

&&

.SHORT TERM...
(Tuesday through Thursday night)
Issued at 240 PM CDT Mon Apr 22 2024

Short term model consensus suggests that SSW return flow in the
low-levels will become established across the region on Tuesday
and Tuesday night as the ridge to our east migrates offshore and a
weakening northern stream shortwave trough and related surface
low track eastward across southern portions of Ontario/Quebec. A
cold front trailing southwestward from the surface low is
predicted to advance southeastward into the Upper Midwest on
Tuesday and into western TN/KY and adjacent portions of the OH
Valley by 12Z Wednesday, preceded by a band of light-moderate rain
and perhaps a few embedded thunderstorms. Present indications are
that the precipitation band will weaken with time as it
progresses southeastward into our CWFA before sunrise Wednesday
morning, as the northward return of low-level moisture will be
impeded by a ridge axis positioned along the central Gulf Coast.
Nevertheless, low POPs for light showers have been included for
much of the region during the late morning hours.

The weakening cold front will drift slowly southward during the
day on Wednesday, and may stall before it exits our CWFA. There is
some concern that thunderstorms may develop in the vicinity of
the boundary Wednesday afternoon, as warm sector dewpoints will
likely have recovered into the m-u 50s (supporting a modest
increase in CAPE within a very weak flow/shear environment).
Additional convection will likely develop upstream from the local
area (across central/eastern OK), where surface pressure falls in
the lee of the southern Rockies will force the boundary to retreat
northward as a warm front. Sufficiently strong NW flow aloft of
30-35 knots may allow some of this activity to organize into
clusters that could spread southeastward (in the vicinity of the
surface front) across AR and into northern MS/northwest AL at
various points Wednesday night and Thursday. Given the combination
of marginal shear for storm organization but an increasingly
moist/unstable warm sector to the south of the stalled boundary, a
few strong storms would be possible during this period. Overall
coverage of showers and thunderstorms across our region appears as
if it will be highest on Thursday night, which is when a
deepening low across the central High Plains will finally force
the stalled boundary to lift northward as a warm front. Highs will
be in the l-m 70s each day (Tuesday-Thursday), with lows warming
into the m-u 50s by Friday morning.

&&

.LONG TERM...
(Friday through Sunday)
Issued at 220 AM CDT Mon Apr 22 2024

Afternoon Update: Based on guidance from the 12Z suite of global
models, thoughts discussed below for the extended period remain
valid this afternoon, with no changes necessary.

A ridge axis will amplify over the Tennessee Valley Friday into
the upcoming weekend. Winds will veer to the SW/S, advecting in a
warmer, more moist air mass as highs return to the upper 70s to
lower 80s each day. Long range ensembles are still hinting at a
trough swinging from the Southern Plains into the Mid Mississippi
Valley late this weekend into early next week. At least low
chances for showers and storms may be needed in the forecast by
Sunday or next Monday as this system will provide our best chance
for precipitation in over a week.

&&

.AVIATION...
(00Z TAFS)
Issued at 548 PM CDT Mon Apr 22 2024

VFR conditions will persist through the TAF period at both
terminals as clear skies and light winds continue overnight. Some
patchy fog may develop into the early morning hours, but
confidence was not high enough to include in TAFs at this time.
Southwest winds may become gusty at times tomorrow, with sustained
winds between 10-15kts and gusts up to 20kts possible at times.

&&

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

$$

NEAR TERM...KTW
SHORT TERM....70
LONG TERM....AMP
AVIATION...25