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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS64 KHUN 150409
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
1109 PM CDT Fri Aug 14 2020

.UPDATE...
For 06Z TAFS.

&&

.NEAR TERM...(Rest of tonight)
Issued at 942 PM CDT Fri Aug 14 2020

Warm upper level ridging remained over the Desert SW, while upper
troughing was amplifying over eastern CONUS. A weak upper level low
within the troughing over the IN/OH border had trough extending
towards the Tennessee Valley. A vorticity maxima over western
Tennessee featured an area of showers and thunderstorms, moving to
the SE. This activity per the new NAM, along with hourly updates from
the RAP and HRRR had it gradually dissipating as it nears the
forecast area - with it generally gone after 2-3 AM.

Given uncertainty with this convection, left rain chances as is for
tonight. Will revisit this and raise rain chances for our NE areas
if the storms and other newer guidance keeps it going. The rest of
the forecast output looked okay for now.

.SHORT TERM...(Saturday through Sunday night)
Issued at 242 PM CDT Fri Aug 14 2020

Much of the central and western part of the forecast area may be
completely dry on Saturday in the wake of the trough passage. Our
eastern counties may experience a few more showers and thunderstorms,
mainly through early afternoon. However, coverage should not be
widespread. With afternoon mixing, dew points should lower below 70
degrees in many areas. The more noticeably airmass change will occur
after a cold front drops southeast on Sunday. So, one more muggy day
is expected just ahead of the front Sunday. Isolated thunderstorms
are possible, but with a more limited deep moisture profile and
generally weak QG forcing, will keep PoPs/coverage more limited.
Will not rule out a strong storm or two, but this doesn`t appear to
be a linear/widespread convective event. Noticeably drier air will
arrive by Monday morning when lows should dip into the 60s areawide
except near the larger lakes still retaining warmth. Went 1-2 degrees
above suggested blends for highs Saturday and Sunday.

.LONG TERM...(Monday through Thursday)
Issued at 242 PM CDT Fri Aug 14 2020

General pattern of ridging over the western CONUS will lead to
general troughiness over the eastern CONUS. This will lead to
northwesterly flow bringing drier air into the Tennessee Valley
through the first half of next week. This will limit the shower and
thunderstorm potential, with mostly dry weather Monday and Tuesday.
Both the GFS and ECMWF show a secondary wave developing, bringing a
low pressure system down out of Oklahoma into the Mississippi River
Delta region midweek. This will lift a warm front north and southerly
flow will bring back moisture to the Tennessee Valley maybe as early
as Wednesday, but more likely on Thursday. This will lead to
increasing shower and thunderstorm chances again later next week.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1109 PM CDT Fri Aug 14 2020

An area of showers moving SE over Middle TN could impact the KHSV
terminal at the start of the TAF. The showers should diminish during
the overnight. Tracking of this activity keeps it just east of KMSL.
Light winds and moisture remaining could become low clouds and/or
fog in the overnight. Have reduced CIG/VIS values for both terminals
until 14-16Z, when mixing from daytime heating should bring in VFR
conditions. Light and variable winds overnight, should become NW in
the 5-7kt range a few hours after sunrise. Winds should increase into
10-20kt range in the afternoon, as a front moves across the area. A
few showers and t-storms are possible Sat afternoon, but did not
include them this issuance given too much uncertainty.

&&

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

$$

NEAR TERM...RSB
SHORT TERM...17
LONG TERM...McCoy
AVIATION...RSB

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