-- Discussion containing changed information from previous version are highlighted. --
103
FXUS64 KHUN 260448
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
1148 PM CDT Tue Jun 25 2024

...New AVIATION...

.NEAR TERM...
(Rest of tonight)
Issued at 946 PM CDT Tue Jun 25 2024

A subtle mid-level vort max (located across the high Plains of
western SD/NE earlier this evening) will progress southeastward
into northwestern MO overnight in the gradient flow between a
northern stream trough shifting east-southeastward along the
U.S.-Canadian border and a subtropical high centered across NM.
This feature and a related frontal wave at the surface will
contribute to multiple clusters of thunderstorms that will spread
generally east-southeastward from the Mid-MO Valley into the Lower
OH-Valley, with most high-resolution model guidance suggesting
that a large MCS will evolve out of this activity across southern
IA/northern MO later this evening before dropping south-
southeastward early Wednesday morning.

Although our entire CWFA will likely remain dry through 12Z
Wednesday, there are indications that a smaller MCS may develop
out of convection currently across southeastern MO and track in
the same general direction, perhaps approaching northwest AL by
sunrise. A few showers and thunderstorms may also develop shortly
before sunrise across northern MS/southwestern TN within a regime
of strengthening SW low-level flow preceding the MCS, and for this
reason we have included a very low (15-20%) POP along the AL-MS
border during the early morning hours.

Otherwise, the combination of slightly higher dewpoints (ranging
from the l-m 60s SE to m-u 60s NW) and an increasing coverage of
high-level debris clouds will support warmer low temps ranging
from the u60s (E) to m70s (W).

&&

.SHORT TERM...
(Wednesday through Friday)
Issued at 243 PM CDT Tue Jun 25 2024

A weakness in the ridge takes place Wednesday as a short wave
trough dives to the southeast across the lower Midwest and into
the TN Valley. Timing on this appears to be after 18z for western
portions of the area, to around 00z Thursday for the lower
Appalachians. There does exist the possibility of isolated strong
to severe storms along the disturbance. Steeper lapse rates, along
with moderate CAPE values may help with promoting stronger
storms. Most storms should remain linear as bulk shear values are
forecast to be low-moderate. Following this short wave, the ridge
rebuilds from the west on Thursday. Highs on Thursday and Friday
should be lower than on Wednesday, but still warm, around the low
90s. Dewpoints do remain higher, closer to 70-75.

&&

.LONG TERM...
(Friday through Monday)
Issued at 1222 AM CDT Tue Jun 25 2024

From Friday into the weekend, southerly flow will redevelop in
low levels, elevating dew points into the lower to perhaps middle
70s. With highs staying in the lower to middle 90s, heat index
values may reach 105+ in some areas, mainly central and west both
days. The good news is, pulse afternoon convection is expected to
develop Saturday afternoon, and then another cold front undercuts
the 5h ridge across the region and arrives sometime Sunday
depending on the model solution. So, we may get breaks in the heat
at times both days due to thunderstorms. However, the front will
be weakening and will likely lift back north by late Monday.

&&

.AVIATION...
-- Changed Discussion --
(06Z TAFS)
Issued at 1148 PM CDT Tue Jun 25 2024

VFR conditions will persist at the terminals overnight beneath an
increasing coverage of mid/high-level convective debris clouds.
Any development of BR/FG btwn 8-13Z will be confined to locations
near large bodies of water, and we will not include vsby
reductions in the TAFs attm. There is some concern that a
developing MCS across southeastern MO may drop south-
southeastward, potentially impacting MSL around sunrise, with
additional but isolated SHRA/TSRA possible thru the late morning
hours. However, the greatest coverage of convection will likely
occur btwn 20-02Z as an outflow boundary from a larger MCS across
MO/AR shifts eastward into the TN Valley, and PROB30 groups have
been included at both airports during this timeframe. Lgt SSE sfc
flow will veer to SW and increase to 5-10 kts by 15Z.
-- End Changed Discussion --

&&

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

&&

$$

NEAR TERM...70/DD
SHORT TERM...Serre
LONG TERM...17
AVIATION...70/DD