588
FXUS64 KHUN 250455
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
1155 PM CDT Fri May 24 2024

...New AVIATION...

.NEAR TERM...
(Rest of tonight)
Issued at 955 PM CDT Fri May 24 2024

Scattered but intense thunderstorm activity which was occurring
earlier this evening in the vicinity of a mesoscale outflow
boundary across southeastern AR/northern MS will continue to
dissipate as it drifts southeastward late this evening. Attention
for the remainder of the overnight period will turn to a broad
axis of frontal convection currently in progress from southern
Lake MI southwestward into eastern OK/western AR.

Guidance from recent versions of the HRRR as well as most members
of the 12Z HREF suggest that a forward propagating MCS will
ultimately evolve out of this convection (likely the portion
currently extending from southeastern MO into western AR) and
spread southeastward into northern AL/southern TN early Saturday
morning. However, as is typically the case with these events,
there are subtle differences in timing, intensity and path of the
projected MCS. At this point, our best guess is that this feature
will arrive in the northwest portion of the forecast area by 4 AM
CDT (but could potentially arrive as early as 2-3 AM if a well
developed cold pool in its wake leads to east-southeastward
acceleration). Although some weakening may occur as the convective
complex spreads further southeastward through 7 AM, elevated CAPE
of 1000-1500 J/kg and modest WNW flow aloft of 20-30 knots will
support a risk of strong-severe storms, featuring wind gusts (up
to 50-60 MPH) and hail, in addition to frequent lighting and
locally heavy rain, which could result in minor flooding after
rainfall received earlier today.

POP and weather grids have been updated to reflect the scenario
mentioned above, and other elements of the forecast appear on
track. As temperatures begin to approach forecasted lows in the
m-u 60s, some patchy fog will be possible (particularly across
northeast AL).

&&

.SHORT TERM...
(Saturday through Monday)
Issued at 329 PM CDT Fri May 24 2024

This convection should fade in intensity a few hours after sunrise
as it moves to the SE. The rest of the day Sat for the most part
looks to be dry. That said, this area is in a conditionally
unstable environment, with daytime heating and steeper lapse
rates making a regeneration of afternoon showers and storms not a
zero chance. Staying with a dry forecast, muggy conditions are
expected to close out the week with highs rising into the
mid/upper 80s, and lows that night in the mid/upper 60s. Sunday
should be even warmer with highs topping out around 90, with
marginal shower and thunderstorm development possible.

Things look to change more dramatically Sunday night, as a system
now moving across central California heads rapidly to the east.
This system as it traverses the CONUS will help develop a synoptic
low near the Front Range on Sat, with this low moving to the Great
Lakes. As it nears the Great Lakes on Mon, it will bring a cold
front towards this area. Lift occurring east of this boundary and
our region in an unstable environment will be favorable for the
development of more organized convection.

A few items to note with this system. It appears to be taking a
more northward track per successive runs and was a bit slower. IF
this trend continues, it would help lower an overall severe
threat. A Slight Risk that this area is delineated in the Day-3
outlook has shifted a bit to the north. Also a greater distance
from the parent low would help in this regard. Despite those
items, the timing of the strongest forcing will be in the late
night into Monday morning. CAPE values in the 1000-2000 J/kg and
helicity values from 100-200 m/s and deep shear in the 40-55kt
would support all modes of severe weather, with damaging wind
gusts the main threat. A chance of showers and storms should
continue into Monday, as the main front finally moves in a NW-SE
manner across the area.

&&

.LONG TERM...
(Monday night through Thursday)
Issued at 247 AM CDT Fri May 24 2024

A broader troughing pattern sets up Monday night for the eastern
CONUS and will persist through the remainder of next week. While
our next chance at storms is a lower end potential on Wednesday,
the pattern overall looks to be drier with temperatures closer to
daily average values in the low to mid 80s.

&&

.AVIATION...
(06Z TAFS)
Issued at 1155 PM CDT Fri May 24 2024

There have been no significant changes to previous aviation
forecast reasoning, as VFR conditions persist across the region
early this morning, with lgt SSE flow and patchy BR/FG forming in
a few locations. Between 6-9Z, storms currently in progress across
eastern AR are predicted to grow into a forward propagating MCS
that should spread east-southeastward through northern AL in the
hours around sunrise. Due to increasing confidence in this
scenario, we have introduced TEMPO groups for MVFR cigs/vsby at
MSL/9-13Z and HSV/10-14Z. AWWs for lightning/strong winds and
perhaps some hail may be required during this timeframe. VFR
conditions will return by mid-morning; however, additional but
more isolated TSRA could redevelop across the region by 20-21Z
near a mesoscale boundary in the wake of the morning MCS and
linger thru 2Z before dissipating.

&&

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

&&

$$

NEAR TERM...70/DD
SHORT TERM...RSB
LONG TERM...30
AVIATION...70/DD