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Area Forecast Discussion (AFD)

Issued by Huntsville, AL (HUN)

FXUS64 KHUN 152007

Area Forecast Discussion
National Weather Service Huntsville AL
307 PM CDT Mon Oct 15 2018

.NEAR TERM...(Tonight)
Issued at 307 PM CDT Mon Oct 15 2018

Quite the temperature gradient across the Southern/Central United
States, thanks to a strong cold front that is slowly creeping toward
the Tennessee Valley. As of 20z, temperatures range from 83 degrees at
Huntsville to 56 degrees at Nashville, and 52 degrees at Memphis. 
This frontal boundary will continue to drop into the region late 
this afternoon and evening, prompting a wind shift to the northwest 
and bringing in this cooler air. By 00z, the boundary should make it 
close to the HSV Metro and through the area by 03-06z. Temperatures 
will fall into the 60s in its wake, and eventually the 50s by early 
Tuesday morning. Enough forcing is taking place along and ahead of 
the boundary to generate some isolated to widely scattered light 
showers. This will continue this evening and into the overnight 
hours, though QPF amounts will be very light. In fact, most areas 
will remain dry. The more synoptic scale forcing that help generate 
the heavier precipitation over West and Middle Tennessee earlier 
today has since lifted into the Ohio Valley, so rainfall totals will 
be much lower across North Alabama. Overall a quiet night, with a 
persistent northerly wind, helping to usher in a new, cooler air 

.SHORT TERM...(Tuesday through Wednesday)
Issued at 307 PM CDT Mon Oct 15 2018

Changes coming to the forecast as the aformentioned boundary sags
south into the Tennessee Valley, bringing cooler air, and serving as
a focus for scattered to perhaps numerous showers Tuesday and Tuesday
night. A mostly cloudy sky and a cooler air mass will keep highs in
the low to mid 60s, reinforced by northerly winds. Some upper 50s
highs are not totally out of the question across far Northwest

Speaking of precipitation, another feature will assist in 
providing the necessary lift for this activity. A shortwave trough 
that will rotate along the southern edge of a broad upper-trough over
the Great Lakes/Ohio Valley, helping to regenerate rain showers 
Tuesday afternoon and evening, and providing some periods of light to
moderate showers across the region. The greatest coverage will be 
closest to the boundary which is progged to stall south of the 
Tennessee River. The front will continue to move into Central Alabama
by Wednesday morning, sharply tapering off rain chances after 12-15z
Wednesday. A strong push of dry air will move into the region by 18z
Wednesday, scouring out any lingering cloud cover and resulting in 
mostly sunny conditions later in the day. A stout northerly flow will
keep temperatures around 10 degrees below normal however, with 
readings in the mid to upper 60s. 

.LONG TERM...(Wednesday night through Sunday)
Issued at 307 PM CDT Mon Oct 15 2018

Large dome of high pressure out of the Plains states will continue 
to build sewd into the Midwest/OH Valley regions with the start of 
the latter portion of the forecast package. This should translate 
into some quiet/tranquil wx conditions for the cntrl TN Valley going 
into the end of the work week. Afternoon temps look to trend 
seasonably cool for both Thu/Fri, with highs mainly in the upper 
60s/near 70F. Overnight temps will also trend near/perhaps slightly 
below normal, with lows ranging predom from the mid 40s/around 50F 
into early Fri. The latter half of the global models then remain 
consistent with the sfc high translating to the east heading into the
weekend period, as the influx of moisture increases into the region 
out of the south. The latest model runs are also hinting at a weak 
sfc/tropical wave forming over the extreme wrn Gulf in the Thu/Fri 
time frame. This energy/moisture looks to be diverted to the NE this 
weekend as it becomes embedded within a WSW flow regime ahead of an 
oncoming upper trough axis out of the Plains states. Much of the 
associated shower activity also looks to be picked up by the approach
of another cold front out of the NW, as rainfall begins to spread 
ewd into the area around the first half of the weekend period. The 
rainfall though quickly moves east of the region by Sun with the 
passage of the cold front. This should allow for some additional 
cooler air to filter into the area heading into the new week, with 
highs both Sat/Sun struggling to get past the lower/mid 60s, while 
overnight lows this weekend fall well into the lower 40s/around 40F 
in most spots.


.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1209 PM CDT Mon Oct 15 2018

VFR conditions will prevail at each terminal through late this
afternoon when a cold front will drop into the area. This boundary
will prompt a wind shift to the northwest by 00z. Accompanying this 
front will be a few scattered light showers, though coverage will 
not be high enough to warrant anything greater than a VCSH mention at
this time. MVFR ceilings will build in as low clouds prevail through
the night into Tuesday morning. 





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