183
FXUS64 KHUN 261127
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
627 AM CDT Thu Jun 26 2025

...New AVIATION...

.NEAR TERM...
(Today)
Issued at 301 AM CDT Thu Jun 26 2025

An early morning round of thunderstorms is slowly making its way
into the Tennessee Valley, with thunderstorms currently located
south of the TN River. With the outflow boundary well out ahead of
this convection, expect these storms to remain below severe limits
and to be more pulse like in nature as they move north/northwest.
Frequent lightning, heavy downpours, and wind gusts up to 40mph
may accompany any stronger storms.

Previous discussion:
Expect instability to slowly lessen over time this morning.
However, still expect 1000 to 3000 J/kG of elevated CAPE to be in
place after midnight into the early morning hours in those areas.
Several models show 2 to 6 km lapse rates remaining between 6.0
and 7.0 degrees overnight. Thus, some strong thunderstorms
producing gusty winds and small hail could linger overnight.
Expecting severe weather to remain more into central and southern
Alabama though. 20 to 30 PoP was added for primarily Cullman,
Marshall, and southern DeKalb counties after 6Z given this
expected combination of forcing and instability.

Light winds and clear skies are currently in place across much of
the area. Patchy/areas of fog may occur through midnight or 1 AM,
especially north of the Tennessee River, where heavier rainfall
occurred earlier in the afternoon. Further south, cloud cover
after midnight and scattered showers/storms may keep fog from
forming. Lows via advection of drier air from the NE into the area
in the boundary layer and clear skies should enable lows to drop
into the lower 70s in most locations. This should help to
dissipate fog that forms through 1 or 2 AM. The exception to this
may be near in portions of Cullman county where lows may be
slightly higher with more moisture advection possibly occurring in
the boundary layer there.

Models continue to show 925 mb heights between 4 and 7 PM on
Thursday climbing to between 23 and 27 degrees. Expect more cloud
cover though by 4 PM and more widespread shower and thunderstorm
activity than earlier this afternoon as stronger forcing develops
in the mid to late afternoon hours on Thursday over the area.
Some of these storms could be strong to severe given instability
forecast by models (3000 to 6000 J/KG) and steep 2 to 6 km lapse
rates (7.0 to 8.0 degrees /km). Luckily, no strong shear
accompanies this stronger forcing. DCAPE again climbs above 1000
J/KG in the afternoon. This should all add up to similar
thunderstorm development as we saw earlier this afternoon, mainly
microburst storms capable of damaging winds (>60 mph), large hail,
and very heavy rainfall.

This more widespread convection and cloud cover help keep actual
temperatures in the 92 to 96 degree range primarily. A bit lower
than the mid to upper 90s we saw earlier this afternoon. NBM
ensemble has trended much lower with dewpoints this run. However,
given how high they were today, if light westerly flow in the
boundary layer continues into the day on Thursday, dewpoints may
be much higher than the NBM ensemble is forecasting. Thus, kept
higher dewpoints in the forecast and the heat advisory going for
Thursday afternoon.

&&

.SHORT TERM...
(Thursday night through Saturday)
Issued at 1158 PM CDT Wed Jun 25 2025

Mainly diurnal activity is expected, though convection could
linger slightly longer Thursday night. Overall parameters don`t
change a lot Friday into the weekend, with the upper ridge
weakening and a weak upper low remaining in place over the
southeast (most likely over Georgia somewhere). Shear remains very
weak, but instability continues to be high in the afternoon and
early evening. Luckily, more widespread cloud cover and convection
will keep high temperatures more in the upper 80s to lower 90s.
This will make it a little tough to reach heat advisory criteria
with a moist boundary layer in place. However, kept dewpoints a
bit above guidance on Friday with a heat advisory in effect
through 6 PM on Friday.

By Saturday, more guidance mixes drier air into the boundary
layer a bit more. This may keep heat index values from reaching
105 degrees. This pattern changes little on Sunday and again heat
index values may or may not reach criteria. Instability might not
be quite as higher either. However, strong storms will likely
continue to be possible.

&&

.LONG TERM...
(Saturday night through Wednesday)
Issued at 1158 PM CDT Wed Jun 25 2025

The weak upper low will be pushed towards the eastern seaboard
early next week as a low pressure system slides over the Great
Lakes and its associated cold front approaches the Tennessee
Valley. With this pattern, expect daily chances of showers and
storms (30-60% chance), especially during peak heating in the
afternoon/early evening. By Tuesday, rain and storm chances are
forecast to increase (40-70%) as the aforementioned surface front
approaches the region.

Model PWATs range between 1.7-1.9 inches from Saturday through
Monday and, when compared with BMX Sounding Climatology, fall within
the 75-90th percentiles. PWATs increase to over 2 inches by midweek,
which would be greater than the 90th percentile. Thus, showers will
be efficient rainfall producers and could outperform current forecast
rainfall totals for the long term. At least nuisance flooding will
therefore be possible this weekend through early next week. As for
any chance of severe storms, instability will be sufficient but bulk
shear values are low. So, confidence is low in severe storm
occurrence.

The good news is that with the return of shower/storm chances will
come cooler daytime temperatures. Highs in the 85 to 90 degree
range are anticipated from Tuesday and Wednesday due to the
higher rain chances. Lows, however, will remain in the upper 60s
to lower 70s each night.

&&

.AVIATION...
(12Z TAFS)
Issued at 627 AM CDT Thu Jun 26 2025

VFR to MVFR conditions are prevailing this morning as a line of
thunderstorms continues to lift north and west of the area. Expect
this activity to be mostly out of here by 13z, with VFR conditions
prevailing from there. Scattered thunderstorms will be possible
once again this afternoon, with higher confident in occurrence
near KHSV where a PROB30 group for rain was given between 22-00z.
Amendments may be needed as these thunderstorm complexes evolve.

&&

.HUN WATCHES/WARNINGS/ADVISORIES...
AL...Heat Advisory until 7 PM CDT Friday for ALZ001>010-016.

TN...Heat Advisory until 7 PM CDT Friday for TNZ076-096-097.

&&

$$

NEAR TERM...25
SHORT TERM....KTW
LONG TERM....KTW
AVIATION...25