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Area Forecast Discussion (AFD)

Issued by Huntsville, AL (HUN)

FXUS64 KHUN 172359

Area Forecast Discussion
National Weather Service Huntsville AL
659 PM CDT Mon Sep 17 2018

For 00Z TAFS.


.NEAR TERM...(Tonight)
Issued at 343 PM CDT Mon Sep 17 2018

Wrap around moisture from former Tropical Depression Florence
continued to bring clouds and isolated showers across parts of the 
Tennessee Valley. The center of Florence's circulation was situated 
over SW Pennsylvania, with it heading to the northeast. Showers 
around this system as they moved over nearby southern middle 
Tennessee and far northern Alabama were for the most part short 
lived. Otherwise, another very warm to hot late day continued across 
the region, as summer refuses to give up. High temperatures so far 
ranged in the mid 80s, with lower 90s in parts of NW Alabama, where 
solar insolation was less filtered by clouds.

The showers should taper off from SW-NE during the course of the
early evening, as the local atmosphere becomes more stable due to a
loss of daytime heating and a further departure of the tropical
system. With a moist atmosphere in place, night time low temperatures
will only cool into the upper 60s. The residual moisture, light winds
and near saturated relative humidity values will lead to patchy fog
formation during the overnight. The fog should be more prevalent
within and near sheltered valley locations and near large bodies of
water. Left fog as just patchy - but cannot rule out areas or higher
coverage if development is more than expected. 

.SHORT TERM...(Tuesday through Wednesday)
Issued at 343 PM CDT Mon Sep 17 2018

With the departure of the tropical system, dry and very warm to hot
conditions continue through the midweek. With more sun than clouds,
even with a light northerly flow, high temperatures both days should
rise into the upper 80s to lower 90s. Have inched temperatures to 
the mid 90s for Wednesday, as upper ridging builds over the region 
from the southwest. More unseasonably warm nights with lows in the 
mid 60s to around 70 are expected. For reference, normal highs this 
time of year are in the low/mid 80s and lows in the lower 60s. 

Even with the daytime warmth, enough moisture left over Tuesday night
could bring more patchy fog formation during the late night. Given 
uncertainly on coverage/density, left it as patchy this issuance. 

.LONG TERM...(Wednesday night through Sunday)
Issued at 343 PM CDT Mon Sep 17 2018

One more day of very warm/hot and dry weather continues on Thursday,
thanks to strong upper ridging in place across the southeastern 
CONUS. Highs should warm into the low 90s, with a few mid 90s very
possible, especially across northern Alabama west of the I-65

The upper ridge will shift east of the region for the upcoming
weekend, with weak troughing edging closer. E-SE winds on Thursday
will become more southerly during Friday and the weekend. This will
bring additional and deeper lower level moisture across the region.
This moisture and accompanied daytime heating produced instability
will return chances of showers and thunderstorms to the forecast -
just in time for the weekend. The deeper moisture, along with more
clouds than sun should result in slightly cooler temperatures going
into the weekend. Stayed on a diurnal trend, with higher rain 
chances in the day and lesser at night for Saturday and Sunday. 


.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 654 PM CDT Mon Sep 17 2018

VFR conditions will prevail at both terminals thru the period with
the exception of some MVFR fog shortly before/around daybreak. Patchy
fog will dissipate by 18/14Z, with a SCT deck of clouds developing
AOA 4kft by midday tomorrow, lingering thru the end of the TAF period
tomorrow evening. 





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