Florence, Alabama Weather Forecast Discussion

748
FXUS64 KHUN 161734
AFDHUN
Area Forecast Discussion
National Weather Service Huntsville AL
1234 PM CDT Tue Sep 16 2025
...New AVIATION...
.NEAR TERM...
(Rest of Today and Tonight)
Issued at 1115 AM CDT Tue Sep 16 2025
In the mid/upper-levels, NNE flow of 15-25 knots will continue
across the TN Valley today, before diminishing into the 5-15 knot
range overnight as an upper-level cyclone shifts north-
northeastward across eastern portions of NC/VA. At the surface,
our forecast area will remain within a region of light SSE-
light/variable flow between a weakening area of high pressure
across western VA/NC and an ill-defined surface trough arcing from
the Lower MS Valley northeastward into northern portions of the
TN Valley. Latest model guidance suggests that at least 1-2
distinct but fairly small vorticity maxima (embedded within the
flow around the low to our east) will provide sufficient lift to
generate scattered showers and thunderstorms (beginning early this
afternoon in the general vicinity of the surface confluence axis
to our north), which should spread generally southward with time
and impact the local forecast area later today. For this reason,
we have increased POPs into the low chance range for the entire
CWFA this afternoon. Although the combination of afternoon
temperatures in the m80s-l90s and dewpoints in the u50s-l60s will
yield CAPE of 500-1000 J/kg (perhaps a bit higher in the
northwest), a shallow inversion in the 600-700 mb layer will
likely limit updraft intensity, yielding lightning, locally heavy
rainfall and perhaps a brief wind gust up to 30-40 MPH as the main
storm impacts.
Present indications are that there will be essentially no change
in the general synoptic pattern (described above) overnight, and
we will continue to advertise a low chance POP for the entire
forecast area. Although the risk for lightning and thunder will
gradually diminish due to nocturnal stabilization of the boundary
layer, POPs may actually be a bit on the low side and may need to
be increased in future forecast updates. In anticipation of mostly
cloudy skies and little change in the thermodynamic properties of
the local airmass, overnight lows will be a bit warmer (compared
to previous nights) and in the l-m 60s.
&&
.SHORT TERM...
(Wednesday through Friday)
Issued at 1115 AM CDT Tue Sep 16 2025
Short range model data is in fairly good agreement in depicting a
lighter (5-15 knot) northerly flow aloft to continue across the
TN Valley on Wednesday and Wednesday night, in the wake of an
upper low that will begin to accelerate northeastward across the
Mid-Atlantic states before phasing with the northern branch of the
jet. Although a couple of additional (but weaker) disturbances
aloft may initiate additional showers and thunderstorms on
Wednesday afternoon/evening, latest solutions from both the CAMs
and global models suggest a lower spatial coverage, which may
ultimately be focused south of the TN River (as a slightly drier
airmass will begin to spread into the region from the northeast).
For this reason, we have indicated a gradual decreasing trend in
rain chances beginning tomorrow afternoon/evening. Highs tomorrow
will once again be in the m80s-l90s, and with similar values of
CAPE anticipated, impacts from any thunderstorms should be similar
to what we experience today. Lows on Thursday morning will remain
in the l-m 60s.
During the period from Thursday-Friday, a 500-mb shortwave ridge
will translate southeastward across the region to the east of a
complex upper low (featuring several embedded circulations) over
the northern Plains. Profiles will dry considerably as this
occurs, and with PWAT values predicted to fall from 1.2-1.3"
(currently) to near or slightly less than 1" we will maintain a
dry forecast for this timeframe. A subsequent increase in
afternoon temperatures is also expected, with highs for most
valley locations reaching the l-m 90s by Friday.
&&
.LONG TERM...
(Friday night through Tuesday)
Issued at 856 PM CDT Mon Sep 15 2025
Our pattern looks to change slightly through the long term with
the blocking pattern finally being disrupted. By the start of the
weekend troughing will have significantly elongated over the
Atlantic allowing ridging to cover most of the eastern CONUS.
Without any resistance, high pressure ridging looks to gradually
be pushed into the Atlantic as a deepening trough builds in the
plains and pushes east through the start of the new work week.
Locally this will result in a slow increase in Pops as the
attached surface cold front looks to brush the TN Valley. Models
currently struggle to take the front all the way through thus Pops
remain at or below 30% from Saturday through Tuesday. Coverage of
showers and storms will have an impact on our temperatures as
well leading to a little bit more uncertainty in seeing any
significant break from the summer like conditions. We will
continue to monitor this trend as it draws closer.
&&
.AVIATION...
(18Z TAFS)
Issued at 1234 PM CDT Tue Sep 16 2025
Conditions are predicted to remain VFR for the majority of the
upcoming forecast period at both terminals. However, there will
likely be some impacts from convection at various points that
could result in temporary reductions in both cig/vsby and may
warrant amendments to the TAFs. Present indications are that
showers and a few thunderstorms will begin to develop early this
aftn along a convergence boundary across Middle TN. This activity
will progress southward with time, but may not arrive in northern
AL until early this evening as instability is on a diminishing
trend. Thus, we have included PROB30 groups for SHRA at both
airports from 6-12Z, which is the general timeframe when showers
(and perhaps a few storms) are most likely to impact the airports.
Conditions will begin to improve late in the period (12-18Z) as
the focusing mechanism for shower development tracks further
southward and away from the terminals. Aside from impacts from
storms, prevailing sfc winds will range from lgt SSE to lgt/vrbl.
&&
.HUN WATCHES/WARNINGS/ADVISORIES...
AL...None.
TN...None.
&&
$$
NEAR TERM...70/DD
SHORT TERM...70/DD
LONG TERM...RAD
AVIATION...70/DD

NWS HUN Office Area Forecast Discussion