262
FXUS64 KHUN 042336
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
636 PM CDT Fri Apr 4 2025

...New AVIATION...

.NEAR TERM...
(Rest of Today and Tonight)
Issued at 1130 AM CDT Fri Apr 4 2025

Temperatures have already risen into the upper 70s to lower 80s,
despite some morning cloud cover. A thin layer of cumulus
continues to be in place, but insolation is still managing to help
warm temperatures due to its very thin nature.

The main frontal boundary with the system that has been causing so
much devastation over Mid-Mississippi Valley and Ohio valley
region has settled into the area that has seen training severe
storms over the last few days. Currently it stretches from extreme
southern Kentucky SSW through extreme western Tennessee and into
southern Arkansas. Near and south of this boundary is where the
warmer temperatures and better instability is in place. Most
storms and precipitation currently is occurring north of this
frontal boundary in the more stable airmass. As an area of low
pressure forms in eastern Texas further southeast along the
frontal boundary this afternoon into tonight, the warm sector
will push northeast and produce another round of higher impact
severe weather over NE Texas into Arkansas towards southeastern
Missouri. Unfortunately, the last thing they need.

Back to the Tennessee Valley area for the remainder of today,
the eastern portion of this front is draped from near Nashville,
TN to near the Corinth, MS area. A very strong Elevated Mixed
Layer (EML) can be seen in the Birmingham, AL 7 AM sounding run.
This is a layer of very warm/dry air that serves as a cap for
convection. Being closer to the front, and near the frontal
boundary, the atmosphere may not be quite that capped based on
forecast soundings from several mesoscale models. However, based
on how long convection held off yesterday with a boundary nearby
and a similar 7 AM cap showing up in soundings, today`s models
may be eroding that a bit too quickly.

Regardless, with temperatures likely climbing to the 85 to 90
degree range in most locations later this afternoon, think a
capped thermodynamic profile will likely become surface based
toward the mid to late afternoon hours. This will likely
correspond to a potential for isolated to scattered convection to
form just south of the frontal boundary mainly in NW AL into
southern middle Tennessee. Given MUCAPE values in forecast between
1000 and 2000 J/KG and that fuel for thunderstorm development
becoming surface based eventually during the afternoon hours,
strong to severe storms (only 20 to 30 percent coverage), should
develop later this afternoon. Luckily, helicity is very low and
not really sufficient for tornado development this afternoon.
Another limiting factor for severe weather in general will be
shear, which is very marginal as well. All that being said a few
strong to maybe severe storms could occur this afternoon, mainly
between 1 PM and 6 PM. However, some storms could produce some 1
inch hail or damaging winds.

Models show 925 mb temperatures this afternoon between 19 and 22
degrees. Given current temperatures already (lower 80s) and likely
a good amount of additional on and off sunshine due to the low
coverage of expected shower or thunderstorm activity later this
afternoon, raised highs to between 85 and 90 degrees. This would
likely produce a few record highs later this afternoon of 89 or 90
degrees. Given the mixing up to 700 mb with such warm
temperatures, sustained wind of 10 to 15 mph with some gusts to
around 25 mph are expected today.

&&

.SHORT TERM...
(Saturday through Monday)
Issued at 1130 AM CDT Fri Apr 4 2025

Expect evening cloud cover to quickly dissipate before cloud cover
increases again during the overnight hours. This and increasingly
strong southerly flow will help to keep temperatures from dropping
below the mid 60s to lower 70s overnight into Saturday morning.

As the upper level trough and subsequent cold front continues
eastward towards the Tennessee Valley Saturday, a gradual increase
in cloud cover is forecast from west to east throughout the day
along with increased chances of thunderstorm development, mainly
in the mid to late afternoon hours. The main risk of strong to
severe storms will be Saturday evening into Sunday morning as the
cold front pushes eastward through the area - bringing high
thunderstorm chances (80-90%) and all possible modes of severe
weather as well as a risk of flooding. Recent CAMs continue to
show some disagreement on timing of the storms due to disagreement
on the speed of the cold front. However, they have become a bit
more consolidated around the idea that overall timing could be a
few hours later (mainly pushing into NW AL between 1 and 3 AM).
The exiting time of rainfall and and lingering severe weather has
more spread in model guidance. That varies from early afternoon
hours into the late afternoon hours, depending on which model you
pick. We hope to refine timing over the next 12-24 hours as
models come into more agreement and range of the system.

In addition to the severe threat Saturday into Sunday, gusty non-
thunderstorm winds up to 25-30 mph are forecast as an increased
sfc pressure gradient occurs ahead of the cold front. If these
forecast gusts increase to 35-40 mph, a Wind Advisory will be
considered for the area.

We are forecasting a gradual end of rainfall from west to east
Sunday afternoon before dry weather returns to start the work
week. More on that in the long term section below.

&&

.LONG TERM...
(Sunday night through Thursday)
Issued at 945 PM CDT Thu Apr 3 2025

As the upper level trough pushes eastward through the area, post-
frontal conditions set in. Low temperatures Sunday night are
forecast to drop into the mid 40s before only rising into the
upper 50s to lower 60s Monday for highs. This will be around 20-30
degrees cooler than 48 hours prior. Dry conditions are forecast to
continue through mid week as upper level ridging works in from the
west.

For those who have agricultural interests, mid next week will be
concerning as frost becomes a potential concern. Tuesday morning,
a low chance of frost currently exists in portions of NE AL and
southern middle TN as low temperatures drop into the mid 30s.
Wednesday morning, frost chances increase with widespread low
temperatures in the low to mid 30s under clear skies.

A warming trend is forecast after mid week with highs rising into
the mid 60s Wednesday and Thursday. Thursday will also bring our
next chance of rain (20-30%) as a low pressure system moving
through the Great Lakes potentially brings a frontal boundary to
our area. However, low confidence in this for now as this is a
week out.

&&

.AVIATION...
(00Z TAFS)
Issued at 636 PM CDT Fri Apr 4 2025

VFR conditions are forecast to continue overnight for both KMSL
and KHSV. MVFR conditions are forecast to influence both sites
beginning Saturday morning as lowered ceilings move into the area
from west to east. A PROB30 Group was added to KMSL beginning late
Saturday afternoon through the evening hours to account for the
potential for thunderstorms to move into the area from the west,
bringing lowered visibilities. Throughout the TAF period, gusty
southerly winds up to 24 kts continue to influence the TN Valley.

&&

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

$$

NEAR TERM...KTW
SHORT TERM....KTW
LONG TERM....HC
AVIATION...HC