050
FXUS64 KHUN 171814
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
114 PM CDT Wed Jul 17 2024

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

.NEAR TERM...
(Tonight)
Issued at 115 PM CDT Wed Jul 17 2024

Medium/high chances for showers and storms are forecast this
afternoon and evening across the Tennessee Valley as diurnally
driven convection initiates along residual outflow boundaries in
place over the area. Additionally, a more pronounced outflow
boundary from convection along the AR/TN Mississippi Delta region
is propagating toward northwest Alabama and triggering additional
storms that will work their way into the area by 19-20z. We are
primed for at least a few strong to marginally severe storms
through this evening, with SBCAPE values around 3000 J/kg and at
least some appreciable 0-3/0-6 km shear values of around 30 kts.
This could lead to a few organized line segments/multicells as
well as pulse storms capable of wet microbursts. Additional
rounds of showers/storms will likely redevelop overnight as
another shortwave ripples across the area -- along with the
actual cold front. Thus, have kept medium chances in the forecast
through the early morning hours. Main threat with any overnight
convection will be locally heavy rainfall under the strongest
cores.

&&

.SHORT TERM...
(Thursday through Saturday)
Issued at 115 PM CDT Wed Jul 17 2024

We remain in an active pattern late this week under the influence
of a broad mid/upper trough over the Ohio/Tennessee Valleys.
Medium to high chances (40-70%) are forecast during this
timeframe, with the highest values each afternoon/evening across
the region. The highest coverage will likely be along and south of
the Tennessee River, the area closest to where a weak front
and/or convergence boundary will be stalled over central Alabama.
The main threat with this activity will be locally heavy rainfall
and lightning which will impact though with outdoor plans. In
fact, hydro issues for localized flash flooding may become a
concern later in the week if we get several days of rainfall. The
higher rain chances and cloud cover will keep the dangerous heat
at bay, however, as high temperatures will actually trend below
normal for mid-July, peaking in the mid/upper 80s each day (about
5-7 degrees below normal).

&&

.LONG TERM...
(Saturday night through Tuesday)
Issued at 329 AM CDT Wed Jul 17 2024

The local forecast area will remain to the east of a mid-level
longwave trough (extending from the Great Lakes into the
northwestern Gulf of Mexico) for much of the extended period, with
initially light SSW flow aloft expected to strengthen by
Monday/Tuesday as the height gradient contracts between a
subtropical ridge retrograding across FL and a developing upper
low over the MO Valley. As this occurs, a weak area of surface low
pressure is expected to evolve across west-central TX Friday
night, which will force the stalled frontal boundary to lift
northwestward through the region once again on Saturday. Precisely
how far north and west the front makes it is highly uncertain at
this time, but regardless of position, we will be either
sufficiently close to the boundary or within the moist warm
sector, and this will promote several rounds of rain and
thunderstorms from Sunday-Tuesday (both during the day and at
night). Although shear may strengthen a bit by Monday/Tuesday,
deep moisture and weak lapse rates will limit storm intensity,
with lightning and locally heavy rainfall the main threats. Heat
Risk will not be a concern through the end of the extended period.

&&

.AVIATION...
(18Z TAFS)
Issued at 1112 AM CDT Wed Jul 17 2024

VFR conditions will be the predominant flight category the next
2-3 hours, before TSRA/SHRA increase in coverage early/mid
afternoon. These storms may produce MVFR to localized IFR
conditions due to reduced visibilities and ceilings during the
mid afternoon to early evening window and AWWs and amendments may
be needed during this timeframe. Additional convection late
tonight into early Thursday morning may also create additional
dips into the MVFR range at both sites and have handled this with
a PROB30 mention at both sites.

&&

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

$$

NEAR TERM...AMP.24
SHORT TERM....70
LONG TERM....AMP.24
AVIATION...AMP.24