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Area Forecast Discussion (AFD)

Issued by Huntsville, AL (HUN)

FXUS64 KHUN 171724 AAC

Area Forecast Discussion...UPDATED
National Weather Service Huntsville AL
1224 PM CDT Wed Oct 17 2018

For 18Z TAFS.


.NEAR TERM...(Rest of Today)
Issued at 900 AM CDT Wed Oct 17 2018

A few light sprinkles remain possible across the far southern
portions of the area through about 10 AM. But with cooler/drier air 
pushing south into the area expect these light showers and the low 
level clouds to clear out through the morning hours. With a ridge 
over the eastern Gulf of Mexico, winds aloft remain out of the W/SW 
and based on water vapor imagery this should allow for a continued 
stream of high level cirrus. Even with the mostly sunny skies, think 
the continued CAA should keep temps below the 70 degree mark with
afternoon highs in the mid to upper 60s. Current forecast is in good
shape and made only minor tweaks to the sky, pop, and temp trends 
over the next few hours. 

.SHORT TERM...(Tonight through Friday Night)
Issued at 742 AM CDT Wed Oct 17 2018

With the diminishing cloud cover during the day, mostly clear skies
will allow for some radiational cooling to get temps into the 
low/mid 40s. The sfc high will continue to build into the region on
Thursday and keep skies mostly sunny. Daytime highs will be just a
tad warmer in the mid/upper 60s. With the return of some cloud cover
Thursday night, overnight lows will be in the upper 40s/lower 50s. By
Friday, the sfc high will be across the Mid Atlantic and start to 
return southerly flow to the region. Meanwhile, the ridge across the
SW is flattened as a trough digs into the Northern Plains. The 
associated low will be all the way up near the Hudson Bay in Canada, 
however it will have a strong cold front that drapes back into the MS
Valley. The front will push SE through the day and will not make it 
into the region until early Saturday, however there could be a few 
pre frontal showers Friday afternoon and evening. With the cold front
moving through after midnight, numerous showers will be possible
across the forecast area. The southerly flow will help daytime temps
return to normal in the lower 70s, and the increase in cloud cover 
throughout the day will keep temps in the mid 50s. 

.LONG TERM...(Saturday through Tuesday) 
Issued at 742 AM CDT Wed Oct 17 2018

A cold front will be just south of the area by daybreak on Saturday,
with light post-frontal rainfall continuing across the TN Valley. As
the drier airmass filters into the region, rain will push out of the
area, with mostly dry conditions expected by Saturday afternoon.
Strong northwesterly flow in the lower and mid levels, along with
a relatively strong Canadian high pressure system moving in, will
bring a sharp cool-down across the TN Valley. This is expected to
linger through the weekend, with temps as much as 15 degrees below 
normal. The coldest night/day will be on Sunday, when cold air 
advection will be strongest. Despite mostly clear skies during the 
day, highs will struggle to make it out of the upper 50s for most 
locations. These clear skies will persist through the overnight hours
and winds will become calm, helping temps fall into the upper 30s to
lower 40s. These temperatures may lead to the development of frost 
in our TN counties and in valley locations, however if dewpoints are 
as cold as currently forecast, coverage may be very limited. 

The center of the surface high will move northeast of the area,
shifting winds more to the east on Monday. Meanwhile, upper ridging
will slowly build eastward and into the area. This will begin a
moderating trend across the region. The ridge will move east of the
TN Valley Monday night, with nearly zonal flow taking hold through
the end of the period. Given some return flow in the lower and mid
levels, moisture will increase and help send our overnight lows
closer to seasonal norms Monday and Tuesday nights. Meanwhile, during
the day, plentiful sunshine and rising upper heights will warm highs
into the upper 60s by Tuesday. 


.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1224 PM CDT Wed Oct 17 2018

VFR conditions will prevail at each terminal through the period.
Behind the front, 10 kt NNE flow will persist through the early
evening, before weakening to 5 kt or less after sunset. Some
scattered to broken decks of mid to high clouds may filter across the
region overnight -- followed by a mostly clear sky on Thursday as
winds veer slightly to the NE. 




NEAR TERM...Stumpf

For more information please visit our website 
at weather.gov/huntsville.