Area Forecast Discussion
Issued by NWS Huntsville, AL

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FXUS64 KHUN 270751

Area Forecast Discussion
National Weather Service Huntsville AL
251 AM CDT Tue Sep 27 2016


For the first full 7 day forecast with mostly autumn temperatures,
anticipating mostly dry and seasonably cool conditions to prevail.
This is in large part due to the first cold front of the season
passing over the TN Valley, yesterday. The upper flow pattern has
already shifted with the upper vortex over Ontario/Great Lakes
playing the major part in the weather for the upcoming days. Its
wobble south will bring a reinforcing cold front and the next
possibility for isolated showers over NE AL/S Middle TN on Wednesday




For today, anticipating cloud cover and any remaining patchy dense
fog over NE AL to slowly recede/dissipate to the SE as the cold front
shifts further south and a sheared shortwave trough rotating around
the primary upper low gradually moves south. There is some indication
that weak lift may cause very isolated showers over the Cumberland
plateau, but not enough residual saturation aloft is present to
warrant adding showers to the forecast. For now, will maintain a low
end 10% POP over NE AL. In conjunction with the slowly receding cloud
cover, the dewpoint temperatures should continue to drop throughout
the day with air temperatures rising into the low 80s.

As cold air advection continues through the day, also anticipating
much cooler overnight lows tonight in the low to mid 50s. There may
be patchy fog formation during the overnight hours in the protected
valleys and lakes of DeKalb, Jackson, and Marshall Counties. However,
will likely be quite isolated and have not added into the forecast at
this time.

Daytime highs in the upper 70s to low 80s occur again on Wednesday
as the now cutoff low over the eastern half of the country wobbles
south in response to the strengthening ridge over the central
Atlantic. This wobbling south of the cutoff low will push a
reinforcing cold front southward across the TN valley on Wednesday
night. There is some mid-level saturated levels within this upper low
that may be enough to cause isolated showers over NE AL/S Middle TN
late on Wednesday night. Otherwise, a distinct cool cP airmass will
result in overnight lows dropping to 50 degrees in the northern
portions of S Middle TN. But the other main impact will be the brisk
10-15 MPH northerly surface wind on Thursday which will definitely
make it feel like autumn! Temperatures will struggle on Thursday to
reach into the 70s.

For the rest of the forecast this coming weekend: the model
solutions diverge somewhat with an oncoming upstream trough over the
Intermountain West. The timing of this digging trough will affect the
opening of the cutoff low and its ultimate merging with the polar jet
sometime during the weekend. Though timing is still uncertain, it
does look as if temperatures will warm back close to 80 degrees by
Saturday/Sunday. So, in a nutshell, nice and pleasant conditions will
prevail, but needed rainfall is scarce for the forecast.



(Issued 1155 PM CDT Mon Sep 26 2016)
For 06Z TAFs:
VFR conditions will generally prevail overnight and through the TAF
period. May see brief MVFR cigs or MVFR visby before sunrise, but not
overly confident and will TEMPO as needed.



Huntsville    83  52  82  53 /  10   0  10  10
Shoals        80  53  81  53 /   0   0   0  10
Vinemont      83  53  81  53 /  10   0  10  10
Fayetteville  79  52  79  50 /  10   0  10  20
Albertville   83  56  81  53 /  10   0  10  10
Fort Payne    82  54  79  52 /  10  10  10  20




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