652
FXUS64 KHUN 121739
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
1239 PM CDT Fri Jun 12 2026

...New AVIATION...

.KEY MESSAGES...
Updated at 1037 AM CDT Thu Jun 11 2026

 - Strong to severe thunderstorms may develop from the late
   morning into the evening, with damaging wind gusts and
   localized flash flooding the primary threats.

-  Heat index values of 95 to 103 degree range today.

 - Additional rounds of showers and thunderstorms are forecast
   Saturday through Tuesday. Strong gusty outflow wind gusts, and
   locally heavy rainfall and flash flooding will continue to be
   a concern during this timeframe.

&&

.NEAR TERM...
(Rest of Today and Tonight)
Issued at 1037 AM CDT Fri Jun 12 2026

A generally zonal (west to east) mid and upper level flow pattern
was in place across the greater Tennessee Valley. This flow in
part was rounding the southern half of an upper low over Ontario.
This setup should continue as we go into the weekend. A frontal
boundary was located from north of Lake Erie, across the Ohio
Valley to western Kentucky, to across the Ozarks and TX/OK Red
River Valley. That boundary should move southward, becoming
stationary across and near the forecast area over the weekend.

Of more concern is an area of convection moving to the ESE across
western and middle Tennessee. This convection, that was part of a
mesoscale convective system that impacted the western Ohio Valley
last night. This convection was moving mainly to the east, but
also building southward, forming over and north of a southward
moving outflow boundary. This makes for difficult attempt in
determining timing on how quickly (or slowly) will they move to
the SE. Adding to that complexity is when development could occur
along and south of the boundary from daytime heating and resultant
higher instability.

Before the showers arrive, heating along with an increase in
environmental instability will create conditions favorable for
scattered to at times numerous showers and thunderstorms. At the
moment, our latest timing has the showers reaching our NW Alabama
and Middle Tennessee group in the next hour or two. More
convection is likely in the afternoon. The recent 12Z sounding
from Nashville shows a modestly unstable environment, with surface
CAPE and DCAPE of 1200 and 1100 J/kg respectively, precipitable
water amounts of 1.7" and bulk shear of ~20kt and 0-3 helicity
~100. This would support storms producing strong to severe outflow
wind gusts. Sounding freezing levels at 14kft and locally over
15kft make hail unlikely. Locally heavy rainfall, with a risk that
excessive rainfall and flooding cannot be ruled out. In locations
before shower activity begins, high temperatures should rise into
the upper 80s to lower 90s, with corresponding heat index values
of 96 to 103 degrees.

Convection that forms should fade quickly in the early evening
with a loss of daytime heating. Lows should cool to around 70. We
cannot rule out patchy fog development in the late night, mainly
in and near areas that receive earlier wetting rain (1/10 of an
inch or greater).

&&

.SHORT TERM...
(Saturday through Sunday)
Issued at 1037 AM CDT Fri Jun 12 2026

The above mentioned frontal boundary should move a bit more to our
south over the weekend. The presence of that boundary, along
with passing upper level disturbances will keep some chance of
showers and thunderstorms in the forecast Saturday into Sunday. A
first round of convection should occur in the afternoon to the
early evening. Before shower activity, expect another very warm to
hot day with highs rising into the upper 80s to lower 90s, and
corresponding heat index values in the mid 90s to 103 degrees. A
thunderstorm complex moving late Saturday night could impact the
Tennessee Valley before daybreak Sunday. This next complex coming
in from the WNW could bring strong winds gusts and heavy downpours
for Sunday morning. Otherwise after lows Sunday morning in the
lower 70s, highs later in the day should be a tad cooler, mainly
in the mid/upper 80s.

&&

.LONG TERM...
(Sunday night through Thursday)
Issued at 957 PM CDT Thu Jun 11 2026

The primary concern for early to mid next week will be a continued
risk of flash flooding due to antecedent rainfall and subsequent
saturated soils. Multiple days of rainfall are forecast as a series
of shortwaves traverse eastward over the TN Valley. Models continue
to indicate there will be plenty of moisture to work with over the
area as southerly flow will bring PWATs around 1.8-2.2", which is
above the 90th percentile per BMX climatology. Therefore, these
storms will be efficient rainfall producers. There continues to be
model disagreement in the long term period, which greatly influences
how widespread rainfall is as well as if there`s a risk for stronger
storms. Currently, instability continues to look unimpressive with
relatively weak shear and poor lapse rates. However, depending on
frontal placement/timing, this could easily change over the weekend.
For now, have continued with blended guidance and urge everyone with
outdoor interests to check back in for forecast updates.

&&

.AVIATION...
(18Z TAFS)
Issued at 1240 PM CDT Fri Jun 12 2026

An area of showers and thunderstorms from a decaying MCS were
progressing mainly eastward across the TN Valley, while an outflow
boundary from previous convection heads southward. Locally strong
outflow winds gusting to 40kt could occur with storms that form
this afternoon, with CIG/VSBY reductions to MVFR. Shower coverage
should end this evening with a loss of daytime heating. Patchy
fog development cannot be ruled out in the late night, primarily
in/near where heavier rainfall recently fell. Not enough
confidence to add it to the TAF given uncertainty with future rain
coverage. Low chances for shower/thunderstorm development returns
by early Sat afternoon; chances however are too low for inclusion
in the TAF.

&&

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

$$

NEAR TERM...RSB
SHORT TERM....RSB
LONG TERM....HC
AVIATION...RSB