912
FXUS64 KHUN 260246
AFDHUN

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

...New NEAR TERM...

.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...
(00Z TAFS)
Issued at 741 PM CDT Tue Jun 25 2024

Conditions will remain VFR at the HSV/MSL terminals this evening
and overnight, with a notable increase in the coverage of high-lvl
convective debris clouds (originating from multiple clusters of
TSRA spreading east-southeastward from the Mid-MO Valley into the
Lower-OH Valley) anticipated during the early morning hours.
Although this will reduce the risk for nocturnal fog development,
some patchy BR/FG will still be possible btwn 8-13Z (but near
large bodies of water). Shortly after 12Z, we expect to see an
even greater increase in the coverage of mid/high-lvl clouds as a
developing MCS across southeastern MO begins to drop southward
thru the Mid-South region. Present indications are that the
eastern edge of this MCS may clip the western portion of our CWFA
(where moisture/instability will be greatest) tomorrow aftn, with
PROB30 groups for TSRA included at MSL/20-24Z and HSV/22-24Z. Lgt
NW sfc flow will back to SW later this evening, with prevailing
speeds increasing to arnd 10 kts tomorrow morning.

&&

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

&&

$$

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