-- Discussion containing changed information from previous version are highlighted. --
523
FXUS64 KHUN 210528 CCA
AFDHUN

Area Forecast Discussion...CORRECTED
National Weather Service Huntsville AL
1228 AM CDT Sat Sep 21 2024

...New AVIATION...

.NEAR TERM...
(Tonight)
Issued at 910 PM CDT Fri Sep 20 2024

Surface high pressure centered east of the Tennessee Valley, and
upper level ridging building in from the SW, should help continue
a dry forecast. Overnight lows should cool into the mid 60s (with
a few upper 60s) and light winds. These conditions (clear skies,
light winds, a longer night time) could be favorable for the
development of fog. MOS guidance the past few nights has been
hinting at fog with little of it forming so far. Will stay with a
lesser fog trend, with patchy predawn fog in the grids. The
on-going forecast otherwise has a good handle on things, thus no
updates are needed at this time.

&&

.SHORT TERM...
(Saturday through Sunday night)
Issued at 100 PM CDT Fri Sep 20 2024

The 5h ridge and 8h high looks to stay in about the same place
Saturday into Sunday as a shortwave/upper low ejects from the Four
Corners region into the central Plains. This will keep innocuous
weather going in our area through the weekend. There will be a
weak shortwave dropping southeast through the 5h ridge position
Saturday night which may bring mid and high clouds through TN into
north AL. Will keep the suggested 5-10% PoP in far north AL and
southern middle TN on Sunday, but looks like vast majority will
stay dry. Temperatures will be fairly persistent as well, with
highs in the upper 80s to lower 90s and lows in the middle 60s to
around 70.

&&

.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...
-- Changed Discussion --
(06Z TAFS)
Issued at 1228 AM CDT Sat Sep 21 2024

With high pressure layered across the southern states, VFR conds
are generally expected thru the TAF period. The exception may be
some -br/MVFR vis early this morning and a TEMPO group has been
maintained in the 09-12Z time frame. Light/var winds will also
become WSW near 5-7kt late Fri morning.
-- End Changed Discussion --

&&

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

$$

NEAR TERM...RSB
SHORT TERM....17
LONG TERM....70
AVIATION...09