526
FXUS64 KHUN 171612
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
1112 AM CDT Wed Jul 17 2024

...New AVIATION...

.NEAR TERM...
(Rest of Today)
Issued at 814 AM CDT Wed Jul 17 2024

An active day of weather across the Tennessee Valley is likely
this afternoon, with medium/high chances for showers and
thunderstorms in the forecast. The remnants of a MCS to the WNW
over central Arkansas has sent an outflow boundary propagating ESE
toward northwest Alabama. This feature will likely be our trigger
for convection by 17-18z, with fairly widespread (60-80%)
coverage forecast later in the afternoon as this activity gets
going. SBCAPE values will likely peak in the 1500-2000 J/kg range
with the heating that will take place this morning -- coupled with
slightly higher values of 0-3/0-6 km shear around 25-30 kts. This
could allow for a few organized line segments in addition to a
wet microburst threat (per the inverted-v sounding profiles).
Thus, a localized gusty damaging wind threat may exist with a few
strong to perhaps a marginally severe storm possible. Otherwise
another hot/humid day, with highs in the low to mid 90s and peak
heat index values between 98 to 104 degrees.

&&

.SHORT TERM...
(Tonight through Saturday)
Issued at 329 AM CDT Wed Jul 17 2024

Storm coverage will remain high across the CWFA this evening and
throughout the morning hours on Thursday as the actual cold front
makes its way southward into the region. However, we expect
instability to diminish with the loss of insolation this evening
and CAPE values will not recover much during the day tomorrow due
to widespread convective overturning and debris cloudiness. Thus,
our primary focus will shift from strong storms to locally heavy
rainfall, as many locations will receive multiple rounds of heavy
precipitation. Present indications are that the front will stall
near or immediately southeast of the forecast area from Thursday
night-Friday night, and our highest POPs have been reserved for
the southeastern zones with this in mind. Fortunately, highs will
only reach the m-u 80s, with no heat-related concerns on either
Thursday or Friday.

&&

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