Hytop, Alabama Weather Forecast Discussion

059
FXUS64 KHUN 172345
AFDHUN
Area Forecast Discussion
National Weather Service Huntsville AL
645 PM CDT Wed Sep 17 2025
...New AVIATION...
.NEAR TERM...
(Tonight)
Issued at 226 PM CDT Wed Sep 17 2025
The previous forecast remains on track as a few showers and
thunderstorms have formed throughout northern AL and southern
middle TN. These storms are capable of moderately heavy rainfall
and lightning. If one over performs, a Special Weather Statement
may be issued for gusty winds. However, no severe weather is
anticipated. Rain chances are still forecast to decrease around
sunset with a threat of locally dense fog to follow overnight. Low
temperatures are forecast to drop into the low to mid 60s.
Previous Discussion:
A light (5-15 knot) north-northeast flow aloft will persist
across southern TN/northern AL today and tonight, as the local
forecast area will remain situated between an upper low (which
will open into a trough as it progresses northeastward off the
Mid-Atlantic Coast) and a deamplifying shortwave ridge extending
from the Arklatex region into the Great Lakes. At the surface, a
subtle area of low pressure will retrograde slowly westward across
southern AR, with an ill-defined trough axis (extending
northeastward from the low into TN) predicted to lift
northwestward into the Mid-MS Valley by 12Z Thursday. Aside from a
few showers already in progress across northeast AL, current
expectations are that a minor increase the coverage of convective
cells will evolve by early this afternoon, with showers and
thunderstorms initially developing in the vicinity of the low-
level wind confluence axis to our north and before spreading
southward with time throughout the afternoon. Although guidance
from the most recent suite of CAMs still suggests that
precipitation coverage may be slightly higher to the south of the
TN River (and particularly across southeastern portions of the
CWFA), we will maintain a low POP region-wide. With afternoon
temps expected to once again range from the l-m 80s (east) to l-m
90s (elsewhere), a minor increase in dewpoints into the mid 60s
will support slightly greater CAPE (1000-2000 J/kg), and thus a
risk for brief wind gusts up to 40-45 MPH with the most intense
updrafts. Otherwise, lightning and brief heavy rainfall will be
the most significant impacts.
Afternoon showers and thunderstorms will begin to dissipate
around or shortly before sunset, with remnant convection expected
to track southward into central AL early this evening. As PWAT
values begin to fall, the combination of mostly clear skies and
calm winds will provide a more favorable environment for the
development of fog early Thursday morning, and some could be
locally dense in locations that receive wetting rainfall later
today or early this evening. Lows will be in the l-m 60s.
&&
.SHORT TERM...
(Thursday through Friday night)
Issued at 1115 AM CDT Wed Sep 17 2025
Latest short range model guidance suggests that a weakening
shortwave ridge in the mid-levels will translate southeastward and
across the TN Valley on Thursday and Thursday night in the flow
to the east of a developing upper low over the northern Great
Plains. This will result in collapsing steering currents aloft and
in the absence of synoptic scale forcing for ascent, we will
maintain a dry forecast.
During the period from Friday-Friday night, a 500-mb shortwave
trough is predicted to cut off from the primary upper low (over
the northern Plains) and travel southeastward from the MO Valley
into the Mid-MS Valley by 12Z Saturday. Although the trough will
in all likelihood be rather weak, strengthening diffluent flow
aloft to the east of this feature will force a surface
trough/confluence axis (initially well to our northwest and across
the Mid-MS Valley) to develop southeastward with time, perhaps
supporting the development of showers and thunderstorms across the
western half of the forecast area Friday afternoon/evening. At
this time range, confidence in this scenario is not very high, but
we will need to monitor this window for a potential increase in
rain chances. With weak deep-layer shear and only modest values of
CAPE, storms are not expected to be organized, but may produce
gusty winds and a fair amount of lightning (especially Friday
afternoon). Highs on both Thursday and Friday will range from the
m-u 80s (east) to l-m 90s (elsewhere), with lows in the l-m 60s.
&&
.LONG TERM...
(Saturday through Tuesday)
Issued at 1014 PM CDT Tue Sep 16 2025
As we go into the weekend, another trough is forecast to form
over the northern plains. Strong moisture convergence along a
frontal boundary well to our north and west will keep the majority
of shower activity out of our area. But a few instances of lower
end shower/thunderstorm chances remains possible as we go onto the
weekend and early next week. Despite troughing, daily high
temperatures for the Saturday through Monday time will range from
the mid/upper 80s to the lower 90s. Low temperatures will cool
into the 60s. A bit cooler on Tuesday with highs in the 80s. In
the astronomical area, the first day of Autumn 2025 begins Monday
afternoon around 119 PM CDT.
&&
.AVIATION...
(00Z TAFS)
Issued at 645 PM CDT Wed Sep 17 2025
Shower/thunderstorm activity that recently impacted portions of
the Tennessee Valley has moved south of the area. Additional
convection is unlikely given it`s upper level support was also
heading southward. VFR weather is expected across the area this
evening. With light winds, clear skies, and good radiational
cooling, the formation of fog is possible in the late night
through daybreak Thu. Confidence was high enough for MVFR VSBY
reductions from fog/mist. VSBY values could fall into the IFR, if
not lower in those more fog prone spots, as well as areas that
recently received wetting rainfall. Any fog that forms should
dissipate shortly after sunrise Thu, with VFR weather returning in
the mid morning, continuing there after. Light winds tonight
should become NNW 5-7kt late Thu morning and in the afternoon.
&&
.HUN WATCHES/WARNINGS/ADVISORIES...
AL...None.
TN...None.
&&
$$
NEAR TERM...HC
SHORT TERM....70
LONG TERM....RSB
AVIATION...RSB

NWS HUN Office Area Forecast Discussion