633
FXUS64 KHUN 230453
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
1153 PM CDT Wed May 22 2024

...New AVIATION...

.NEAR TERM...
(Rest of tonight)
Issued at 958 PM CDT Wed May 22 2024

A belt of moderately strong (30-40 knot) WSW flow aloft will
persist across the TN Valley region overnight, maintaining an
overcast coverage of high-level convective debris clouds across
the region (originating from multiple clusters of thunderstorms
currently in progress from southeastern AR into central TX).
Recent high-resolution model guidance suggests that light rain
along the northeastern flank of the loosely organized MCS to our
WSW will spread east-southeastward through northern AL between
3-9Z, perhaps bringing some measurable precipitation to mainly the
southwestern corner of the forecast area. We have left a low-
medium (20-40% POP) in the grids during this timeframe to address
this scenario, with chances for rain lower across the northeastern
corner of the CWFA as coverage should diminish with eastward
extent. Although elevated CAPE in the 500-1000 J/kg range would
normally support a risk for thunderstorms, lightning activity has
recently been on a downward trend from the Arklamiss region
northeastward, and we will only include a very low probability for
embedded thunderstorms overnight. Present indications are that
the greatest concentration of nocturnal convection should be
displaced to our northwest, where a convectively-induced vort max
will shift northeastward and interact with a subtle low-level
convergence boundary. Due to the presence of thick clouds and
abundant low-level moisture (dewpoints in the mid 60s), lows will
be very mild and in the 65-70F range.

&&

.SHORT TERM...
(Thursday through Saturday)
Issued at 255 PM CDT Wed May 22 2024

Thursday morning we will be greeted again by the lingering front
promoting more widespread showers and perhaps a few rumbles of
thunder across the area. Rain and thunder chances will decrease
through mid day as the front moves on. Chances for storms will
then transition to being driven by day time heating. If we can
clear out and heat up, strong to severe storms will be again
possible Thursday afternoon. Beyond Thursday afternoon, several
shortwaves will ripple NE through the area and promote high
chances for rain overnight on Thursday and through the day on
Friday. This will be mostly rinse and repeat into Saturday as
rain and storm chances again pick back up in the afternoon.

Each day storms will pose a threat for hail, gusty winds, and
frequent lightning. Those with outdoor activities this weekend
will need to remain vigilant. Aside from storm chances, our temps
will remain in the mid to high 80s making for very muggy
conditions during the dry slots of the day.

&&

.LONG TERM...
(Saturday night through Tuesday)
Issued at 255 PM CDT Wed May 22 2024

No big changes made to the extended portion. A powerful system moving
from the south/central Plains to the southern Great Lakes will keep
chances of showers and thunderstorms in the forecast for the Tennessee
Valley this weekend into Tuesday. More numerous, and possibly strong
to severe storms look more probable Sunday into Memorial Day. These
will be preceding, and possibly accompanying a cold front moving
across the area Monday. Dry weather and slightly cooler conditions
return late Tuesday into Wednesday.

Previous discussion...
Issued at 354 AM CDT Wed May 22 2024

A more vigorous shortwave will pivot from the central/southern
Plains into the Ohio Valley/Great Lakes on Sunday, bringing
widespread convection to portions of the Mid South and lower Ohio
Valley -- including the potential for a regional outbreak of
severe weather over those regions. Closer to home here in the
Tennessee Valley, a threat for strong to severe thunderstorms will
also exist. Guidance hints at an initial wave of prefrontal
convection during the morning hours on Sunday, followed by an
additional round during the evening hours (into portions of the
overnight hours) directly along the cold front has it pushes
through the area. This second round would be more likely to pose a
threat for severe weather given the potential storm environment in
place. However, it is too early to get too specific on timing
given uncertainties in the evolution of this system and what
exactly the storm environment would support. Still this bears
close watching in the coming days, especially given that it will
occur during the busy Memorial Holiday weekend. Additional chances
for showers and storms will exist Monday (40-60%) and Tuesday
(20-30%) before ridging helps to dry us out by the middle of next
week. By Tuesday, guidance favors a subtle air mass chance as
drier air works its way in and highs in the upper 70s to lower 80s
will be common.

&&

.AVIATION...
(06Z TAFS)
Issued at 1153 PM CDT Wed May 22 2024

VFR conditions will persist at the HSV/MSL terminals overnight,
featuring bkn-ovc layers of high-level clouds, a lgt SSE wind and
perhaps a few sprinkles of rain. Models suggest that thunderstorm
coverage will increase well to our NW in the 6-12Z timeframe, as
an upper-lvl disturbance lifts northeastward and interacts with a
subtle low-level convergence boundary. Based on latest high-res
model data, it appears as if this activity may congeal into a
small cluster of storms as it spreads southeastward late Thursday
morning, and timing of PROB30 groups has been adjusted accordingly
to reflect 17-21Z/MSL and 18-22Z/HSV. Additional storms will be
possible into the late aftn/evening hours along a trailing outflow
boundary that will likely be in the general vicinity of northern
AL, but confidence is not high enough to include additional
convection in the TAFs attm. Sfc winds will remain from the SSE at
night and SSW during the day, with prevailing speeds of 5-10 kts.

&&

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

&&

$$

NEAR TERM...70/DD
SHORT TERM...RAD
LONG TERM...AMP
AVIATION...70/DD