626
FXUS64 KHUN 091147
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
647 AM CDT Sun Jun 9 2024

...New AVIATION...

.NEAR TERM...
(Today)
Issued at 422 AM CDT Sun Jun 9 2024

A regime of light SSW flow in the low-levels continues across the
TN Valley this morning, as the region is currently located to the
north of a Bermuda high (extending southwestward into the eastern
Gulf of Mexico) and to the south of a deepening area of low
pressure tracking into the northern Mid-Atlantic states. Aloft,
WNW winds in the 30-40 knot range will gradually increase to 40-50
knots by sunrise, as the height gradient contracts between a mid-
level ridge centered over the northern Gulf and a 500-mb
shortwave trough digging southeastward across the eastern Great
Lakes. The remnants of thunderstorm activity (which developed
yesterday evening in the vicinity of the surface lows trailing
cold front across southern MO) continues to spread east-
southeastward across Middle TN and will likely impact the
northeastern portion of the CWFA in the 10-14Z timeframe. Although
the convection has exhibited a weakening trend over the last
couple of hours, brief wind gusts of 40-45 MPH, frequent lightning
and heavy rain may accompany this activity.

To the northwest of the local area, regional radar data indicates
that additional thunderstorms have developed along an axis from
southwestern MO into northeastern AR (in the vicinity of a
trailing outflow boundary in the wake of the initial MCS).
Although this activity will have a similar tendency to spread
east-southeastward with time, guidance from the 0Z CAMs suggests
that the majority of this convection will remain displaced to our
north due to little southward movement of the outflow boundary.
Thus, we will gradually decrease POPs through the late morning
hours, as a broad coverage of mid/high-level debris clouds will
likely have a substantial impact on diurnal destabilization.

Later this afternoon, most high-resolution models indicate that
scattered thunderstorms should redevelop to our southwest (in the
vicinity of a differential heating zone across northern MS), with
a more isolated coverage of storms occurring along a frontal wind
shift axis dropping southward through western/Middle TN. For this
reason, we have indicated a gradual increase in POPs between 21-0Z
(and especially across the southwestern portion of the CWFA as
storms developing across northern MS may tend to grow into another
east-southeastward propagating cluster). Although uncertainty
regarding storm coverage during this period remains rather high,
mid-level WNW flow of 40-50 knots will support a risk of locally
damaging winds and large hail if temps manage to rise into the m-u
80s, supporting CAPE in the 1500-2000 J/kg range.

&&

.SHORT TERM...
(Tonight through Tuesday night)
Issued at 422 AM CDT Sun Jun 9 2024

We will carry a medium-high (50-70%) POP in the grids early this
evening to reflect the potential for both convective regimes
(discussed above) to continue for a few hours past sunset, and
although POPs begin to decrease after Midnight, a narrow band of
showers (and perhaps a few thunderstorms) will accompany the
actual cold front as it shifts southward across the forecast area.
Present indications are that the front will exit our southeastern
zones between 12-15Z Monday, with any lingering shower activity
expected to end with its passage. By Monday, afternoon,
strengthening NNW winds will advect a cooler/drier Canadian
airmass into the region, with dewpoints falling back into the mid
50s as temperatures struggle to reach the u70s-l80s. This will set
the stage for a clear and cool night, featuring lows in the m-u
50s early Tuesday morning. Temperatures will exhibit little
fluctuation on Tuesday and Tuesday night, with dry conditions
continuing as a low-amplitude mid-level ridge translates eastward
ahead of a weak southern stream trough tracking east-southeastward
over OK/TX.

&&

.LONG TERM...
(Wednesday through Saturday)
Issued at 422 AM CDT Sun Jun 9 2024

Although specific details remain unclear at this point, most of
the global models now suggest that that southern stream trough
(discussed above) will travel southeastward into the northern Gulf
of Mexico during the first half of the extended period, before
evolving into nearly stationary cutoff low on Friday/Friday night.
Any northward movement of the low next weekend will likely be
dictated by the strength and orientation of a blocking mid-level
ridge to its north, which will in all likelihood lie across the TN
Valley, providing an extended period of warm and dry conditions
that could potentially extend into the first part of the following
week. That said, we have included a very low (15-20%) POP across
our southeastern counties on Friday and Saturday afternoons, due
to a gradual increase in low-level moisture which will translate
to a notable increase in CAPE given hot daytime temperatures.
Highs will quickly warm into the lower 90s for most valley
locations by Thursday/Friday/Saturday, with lows more gradually
returning to the u60s-l70s by Saturday morning.

&&

.AVIATION...
(12Z TAFS)
Issued at 647 AM CDT Sun Jun 9 2024

There have been no significant changes to previous aviation
forecast reasoning, although we have removed TEMPO groups that
were in place for the initial MCS now that it is to the S/E of
HSV. Partial clearing in the wake of the MCS is still expected to
occur later this morning (by 15Z), with redevelopment of
additional TSRA possible this afternoon both in the vicinity of a
mesoscale boundary across northern MS and along a southward-
moving cold front across western/Middle TN. Should this activity
impact either terminal, it would likely be btwn 22-02Z, which is
also the timeframe of concern for lightning and wind-related AWWs.
Additional SHRA will be possible until a cold front arrives arnd
6Z, veering sfc winds to NNW.

&&

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

&&

$$

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