601
FXUS64 KHUN 161922
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
222 PM CDT Tue Jul 16 2024

...New NEAR TERM, SHORT TERM...

.NEAR TERM...
(Tonight)
Issued at 222 PM CDT Tue Jul 16 2024

Shower and thunderstorm activity is beginning to really pick up
over the last 30 minutes in southern middle Tennessee. A decaying
outflow boundary moving southeast into this moderately unstable
air is likely producing this uptick in activity.

Looking at current meso-analysis, DCAPE values have increased to
between 900 and 1300 J/KG near this boundary. 3000 to 3500 J/KG of
SBCAPE is shown as well ahead of it. With low level lapse rates
between 7 and 8 degrees/km in place as well, an isolated stronger
thunderstorm producing wind gusts to around 50 mph is possible.
Very heavy downpours and frequent lighting will also be possible
with any thunderstorms with PWAT values around 1.8 inches.

Not expecting this convergence boundary to move much as the
outflow boundary falls apart this afternoon over northern Alabama.
However, it should provide enough of a focus mechanism given the
moderately unstable environment for scattered showers and
thunderstorms until this evening, when we lose daytime heating and
they should dissipate. Given the morning rain/storms in NE
Alabama, not sure now much convection we will see there this
afternoon.

Based on current dewpoints and expected cloud cover/convection,
not sure we will quite get to 105 in many locations. However,
there may be some locations west of the I-65 corridor that could
briefly get there before the sun goes down. Thus, leaving the Heat
Advisory in place until 8 PM.

&&

.SHORT TERM...
(Wednesday through Friday)
Issued at 222 PM CDT Tue Jul 16 2024

A cold front currently stretching from the western Great Lakes SW
into Kansas will be the next major player in our forecast over the
next few days. This front will take some time to sink southeast.

However, disturbances ahead of the front will likely push far
enough south late tomorrow morning into the afternoon hours, to
produce more widespread shower and thunderstorm activity across
northern Alabama. During the morning hours, there should be some
sunshine though. This will likely allow highs to climb into the
upper 80s to lower 90s later in the day, despite increasing cloud
cover and shower/storm chances. Shear will again be very weak.
Again though high PWAT values, decent low level lapse rates, and
moderate instability will likely allow for some strong thunderstorms
producing gusty winds to around 50 mph, frequent lightning, and
maybe pea size hail in strongest storms. The bulk of the activity
should develop during the afternoon and early evening hours. Not
looking like much of a break in rainfall and storms Wednesday
night. Some isolated flash flooding is not out of the question.
Despite some humid conditions (Dewpoints in the 72 to 76 degree
range), the lower temperatures should keep heat index concerns at
bay.

The front seems to slow down a bit late Wednesday night into
Thursday, before pushing more quickly southeast Thursday night.
Given the high PWAT values and strong forcing, this could extend
a flash flooding/minor flooding threat into the day on Thursday.
At this time, shear remains weak. So mainly strong storms are
expected to develop. This will keep high temperatures quite a bit
cooler, in the mid to upper 80s both Wednesday and Thursday.

Thursday night, rainfall chances drop significantly. In later
updates, these rain chances may be able to be taken out. For now
though, there is some disagreement how far south the front moves.
Therefore kept low chance in the forecast into Friday morning.

Shower and thunderstorm chances will likely increase again, as the
front moves northward Friday afternoon into Friday night.

&&

.LONG TERM...
(Friday night through Monday)
Issued at 405 AM CDT Tue Jul 16 2024

Medium-high shower/storm chances continue through the weekend as
the aforementioned front is forecast to stall to our southeast,
allowing higher rain chances in our southeastern counties
(Cullman, Marshall, Dekalb, Jackson) Friday before lifting back
northward due to high pressure off the east coast of Florida. High
temperatures in the 80s continue during this time and the need for
any Heat Products is not expected.

&&

.AVIATION...
(18Z TAFS)
Issued at 1242 PM CDT Tue Jul 16 2024

VFR conditions continue at both TAF sites currently. However, at
least isolated to scattered -TSRA are expect to develop over the
next 4-6 hours near the TAF sites. Thus, a tempo group was included
between 18Z and 22Z at both terminals. This activity may not last
as long at KMSL. With around 40 percent PoP, confidence is not
high that MVFR CIGS or VSBYS will impact either terminal, but a
possibility during that window. VFR conditions should return after
00Z. However, winds should keep any fog from forming overnight
despite some clearing.

&&

.HUN WATCHES/WARNINGS/ADVISORIES...
AL...Heat Advisory until 8 PM CDT this evening for ALZ001>007-016.

TN...Heat Advisory until 8 PM CDT this evening for TNZ096.

&&

$$

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