080
FXUS64 KHUN 260851
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
351 AM CDT Sun May 26 2024

...New NEAR TERM, SHORT TERM, LONG TERM...

.NEAR TERM...
(Today)
Issued at 351 AM CDT Sun May 26 2024

A sfc low pressure system moving through the Central Plains is
forecast to continue northeastward into the upper MS Valley this
morning. An outflow boundary has formed ahead of a trailing cold
front, causing severe storm formation along it through northern
Arkansas and southern Missouri. As this boundary continues
eastward, we will be monitoring the potential for it to track into
our area. CAMs are continuing to keep the track north of us
(through central Tennessee). In the event this dips down into our
area, there is a low chance of strong to severe storms between
13-17Z. The main concern if this occurred would be gusty to
damaging winds and large hail as model soundings indicate abundant
instability (2000+ J/kg of CAPE), weak shear (~20 kts), and
decent mid level lapse rates (7.0-7.5 C/km). We have very low
confidence this will occur, however, it is something we will be
keeping a close eye on into the early afternoon hours. After this
period of concern, cloud cover will mostly clear and atmospheric
instability will increase with diurnal heating ahead of a cold
front-driven line of strong to severe storms moving in overnight
(to be discussed in the short term section below).

Otherwise, heat will be a concern today for those spending time
outdoors. Highs are forecast to reach the upper 80s to low 90s
under partly cloudy skies during the afternoon hours. Southerly
winds will be advecting moisture from the Gulf, contributing to
increased dew point temperatures and subsequent heat indices
around 95-100 degrees. Be sure to stay hydrated and limit time
outdoors. We are in a moderate HeatRisk which may affect most
individuals sensitive to heat, especially those without effective
cooling and/or adequate hydration.

&&

.SHORT TERM...
(Tonight through Wednesday)
Issued at 351 AM CDT Sun May 26 2024

Tonight, a line of strong to severe storms is forecast to impact
the Tennessee Valley from the northwest ahead of a cold front.
Models have begun becoming slightly more consistent with timing
for this, bringing the line into NW AL and portions of southern
middle TN around 6Z and pushing it southeastward until it exits
the area by around 12Z. With this primary line, the following
threats will be possible: large hail (medium confidence), damaging
winds (medium confidence), heavy rainfall/flooding (low- medium
confidence), and tornadoes (low confidence). MUCAPE of 2000+ J/kg
in addition to steep mid level lapse rates (7.5-8.0 C/km) will
allow large hail to be a medium threat, however, with high PWATs
(1.5-1.9" per the HREF, which is above the 90th percentile for BMX
climatology), there is a potential for melting of large hail.
Damaging winds will be supported by DCAPE values reaching 900+
J/kg as well as increased shear (30-50 kts). While heavy rainfall
is likely, flooding may be mitigated by fast storm motion. Our
tornado threat remains a low confidence one due to a cap that is
consistently in model soundings. However, if the cap erodes,
tornadoes will be more of a threat due to backed sfc winds and a
low level jet (40-50 kts).

However, the HRRR is indicating a potential for an outflow
boundary to move in from the northwest around 1Z. If this occurs,
this would force our severe timing window to be earlier than
previously discussed. This would also change our initial storm
mode to be supercell clustering that would eventually upscale
into a linear form. This would increase rain totals and cause
concern for flooding due to runoff.

Regardless of the arrival time, we have medium confidence storms
will exit the area by 12Z with low-medium chances (20-40%) of
lingering showers behind the cold front. Dry weather should return
to the TN Valley Monday night with clear skies as sfc high
pressure filters in from the Mississippi Valley. Highs on Monday
and Tuesday are forecast to reach the 80s with overnight lows in
the upper 50s/60s. Wednesday will be slightly cooler, but still
warm, with highs in the upper 70s to low 80s.

&&

.LONG TERM...
(Wednesday night through Saturday)
Issued at 351 AM CDT Sun May 26 2024

As upper level ridging moves in from the Mississippi Valley
through end of the work week, dry weather and mostly clear skies
will continue to dominate the long term period. Friday afternoon
through Saturday, low chances (30% or less) of showers/storms are
possible as an upper level shortwave forms in the lower
Mississippi Valley. Otherwise, high temperatures during this time
are forecast to be in the upper 70s to 80s with overnight lows in
the 50s/60s.

&&

.AVIATION...
(06Z TAFS)
Issued at 1244 AM CDT Sun May 26 2024

VFR conditions continue through the morning hours at both KMSL and
KHSV. Around 14-15Z, MVFR conditions are likely as low cloud cover
moves in. In addition to this, gusty SW winds up to around 15-20
kts are forecast through the afternoon into the evening hours.
During the evening hours, a PROB30 group has been introduced for
potential thunderstorm development causing lowered visibilities
and cloud cover. Just past the TAF period, there is a potential
for LLWS to impact both terminals and it will likely need to be
added in the next update.

&&

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

$$

NEAR TERM...HC
SHORT TERM....HC
LONG TERM....HC
AVIATION...HC