Area Forecast Discussion
Issued by NWS Huntsville, AL

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FXUS64 KHUN 250522
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
1122 PM CST Fri Nov 24 2017

.UPDATE...
For 06Z TAFS.

&&

.NEAR TERM...(Tonight)
Issued at 903 PM CST Fri Nov 24 2017

Dry weather prevailed across the greater Tennessee Valley this
evening, thanks to a weak, broad surface high pressure situated from
the Mid Atlantic to the NE Gulf region. A Nor`easter type storm
deepening east of the South Carolina coast will move further to the
north and east, and have no effects on our sensible weather.

The infrared/water vapor view over the CONUS indicated another stream
of moisture headed this direction from the west. Although it was
"mostly clear" at the present, high altitude clouds should increase
during the overnight as this moisture increases. Regional radar was
indicating some returns well to our north and west, with none noted
reaching the ground so far. Another cold front extending from western
Lake Michigan, to just east of Iowa and over SE Kansas continued
headed to the east. Per timing, it should move across this forecast
area during Saturday afternoon.

Before then with an increase in clouds can be expected during the
overnight as more moisture arrives from the west. The vast majority
of output from various long/short term models stayed on the dry side,
so followed likewise. Lows should cool into the low/mid 40s with
light south winds.

.SHORT TERM...(Saturday through Sunday night)
Issued at 135 PM CST Fri Nov 24 2017

Warm air and increasing moisture advection continues into Saturday,
as the southwest portion of the approaching frontal boundary moves
into the Tennessee Valley. Some guidance is forecasting a few
isolated showers along this front during the day as it pushes into
the area. However, based on the very dry air that is forecast to be
in place between 925 mb and 700 mb, not sure we will see any
precipitation make it to the ground. Thus, keeping isolated showers
out of the forecast, as has previous shifts. Expect warmer
temperatures on Saturday despite abundant cloud cover with highs in
the 60 to 65 degree range near and south of the Tennessee River (via
westerly flow just ahead of the front.

Some colder and drier air is expected to push south behind the front
on Saturday night and Sunday. Highs falling back into the 50s (some
lower 50s) look reasonable given decent advection and forecast 925 mb
temperatures. Lows should fall back into the lower 30s as well Sunday
night.

.LONG TERM...(Monday through Thursday)
Issued at 135 PM CST Fri Nov 24 2017

As we start the work week, global guidance is in good agreement with
the synoptic pattern. Models are depicting the remnant of a
mid/upper level wave progressing through the SE US, with deep layer
ridging quickly building in on the back side. Plenty of dry air and
subsidence lingering over the region will keep rain chances near 0
percent. Low level flow becoming more southerly Mon-Wed will help
trend toward warmer temps, potentially reaching the mid 60s area-wide
on Wednesday.

Expect a transition in overall pattern beginning Wed evening. Model
guidance starts to diverge with the position, timing, and intensity
of the next system progged to encroach on the region at the tailend
of the period. 12z Euro guidance has sped up from the previous run,
now pushing a potential potent front with upper level support for a
few storms on Thursday. However, much like the GFS, there has been a
lack of continuity on the back end of the forecast, regarding this
system. As such, have left out thunderstorms for Thursday but
maintained at least chance PoPs (around 30 percent).

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1122 PM CST Fri Nov 24 2017

VFR weather should continue for the TAF period. Weak high pressure
east of here will provide light southerly winds into the overnight.
A cold front is forecast to move in a NW-SE manner across the region
during Saturday afternoon (~18Z at KMSL and ~20Z at KHSV), with
winds becoming NW after the front passes. Given dry air either side
of the boundary, showers are unlikely with the frontal passage. A
plume of thickening high altitude moisture should produce broken to
overcast high clouds on Saturday.

&&

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

$$

NEAR TERM...RSB
SHORT TERM...KTW
LONG TERM...Barron
AVIATION...RSB


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