264
FXUS64 KHUN 201235 RRB
AFDHUN

Area Forecast Discussion...DELAYED
National Weather Service Huntsville AL
735 AM CDT Fri Sep 20 2024

...New NEAR TERM...

.NEAR TERM...
(Rest of Today)
Issued at 735 AM CDT Fri Sep 20 2024

A clear start to the day was in progress. Mornings lows were in
the upper 50s to lower 60s. Expect temperatures to rise quickly
into the 80s later this morning with lower 90s this afternoon. A
couple of spots may peak at 95 in the bigger metro areas of HSV
and the Quad Cities. Expect a few to scattered cumulus this
afternoon, but otherwise no impact weather as a surface to 8h
ridge of high pressure drifts southeast through the TN Valley.


&&

.SHORT TERM...
(Tonight through Sunday night)
Issued at 429 AM CDT Fri Sep 20 2024

Short term model consensus suggests very little (if any) change
in the general weather regime across the TN Valley through the
upcoming weekend, as the subtropical ridge (noted above) will
remain the dominant weather feature for our region. A gradual
increase in high-level cloudiness within NW flow aloft will begin
tonight, which will result in warmer overnight lows (m-u 60s) but
should also reduce the overall coverage of fog on Saturday
morning. During the day on Saturday, a weakening cold front will
shift southeastward across Middle TN as the parent mid-level wave
digs southeastward over the eastern Great Lakes. Although a few
showers and thunderstorms may occur as the wind shift axis enters
the northern portion of the forecast area on Saturday
afternoon/evening, POPs at this point remain in the 5-10% range.
With abundant sunshine during the afternoon hours, highs will once
again reach the l-m 90s on Saturday.

Light SW return flow in the low-levels is predicted to begin on
Saturday night and will persist through Sunday night as as upper
low lifting northeastward from the Four Corners region into the MO
Valley induces development of a frontal wave that will shift
northeastward from the southern High Plains into southeastern MO
by Monday morning. Boundary layer moisture advection will
strengthen in this regime, and (combined with a decent coverage of
high clouds) will result in lows in the u60s-l70s for many
locations on Sunday/Monday mornings, further reducing the risk for
fog. Highs will once again reach the l-m 90s on Sunday, with a
few showers and storms possible north of the TN River as the
initial front begins to return northward, but POPs remain 10-15%.

&&

.LONG TERM...
(Monday through Thursday)
Issued at 429 AM CDT Fri Sep 20 2024

Extended range guidance from the most recent suite of global
models suggests that an upper low (initially across the MO Valley)
will open into a trough as it shifts northeastward into the Lower
Great Lakes by Tuesday. The surface frontal wave will move in
conjunction with the trough, with a trailing cold front predicted
to enter the region at some point Tuesday afternoon. Thus,
although POPs will remain fairly low across the area on Monday, we
do anticipate a general increase in the spatial coverage of
showers and thunderstorms beginning in the northwest early Tuesday
morning and continuing for the entire region during the day.
Although forecast soundings depict a general increase in
instability during this timeframe (due to higher surface
dewpoints), profiles will remain dry aloft, and for this reason we
will keep rain chances in the low-medium (20-30%) chance range.

Forecast uncertainty increases considerably by Wednesday and
Thursday, as the global models offer vastly differing solutions
regarding how far south/east the cold front will track before
stalling in response to the development of a cutoff upper low over
the Mid-MS Valley. If a deeper cool/dry airmass manages to
penetrate through the entire CWFA, then we will remain in a dry
weather pattern during the mid-week period. However, current
thinking is that the front will stall in our region (or perhaps to
our immediate south/east), which could support the development of
widespread anafrontal precipitation across our region. We have
indicated a low POP to account for this level of uncertainty, but
these values will likely be adjusted over the coming days. Temps
will also be impacted by the ultimate outcome of the forecast, but
at this point we have indicated highs falling back into the l-m
80s.

&&

.AVIATION...
(12Z TAFS)
Issued at 640 AM CDT Fri Sep 20 2024

Although patchy BR/FG is currently being observed in a few
locations across northern AL, prevailing vsby reductions have not
yet occurred at the terminals. Thus, we will maintain a VFR
forecast featuring development of a sct Cu field arnd 16Z and a
gradual increase in high-lvl clouds beginning early this evening.
Fog may become an issue once again early Saturday morning, but due
to low confidence, we will not include in the forecast attm. Sfc
winds will remain lgt/vrbl-calm for much of the TAF period.

&&

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

$$

NEAR TERM...17
SHORT TERM....70
LONG TERM....70
AVIATION...70