Area Forecast Discussion
Issued by NWS Huntsville, AL

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FXUS64 KHUN 290805
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
305 AM CDT FRI JUL 29 2016

.DISCUSSION...

An upper level trough extended southward across the MS Valley
region, while an upper ridge remained over the desert SW and the
subtropical ridge was situated just off the coast of FL. An area of
scattered showers, with embedded thunderstorms, has been ongoing to
our north, in response to a weak disturbance moving east around the
base of the upper trough. While an isolated light shower is possible
this far south, most of the energy/lift should remain to our north
and move to the northeast by daybreak. Temperatures as of 08Z were in
the lower 70s, and may drop a degree or two through the remainder
of the overnight period. Additionally, patchy fog was beginning
develop due to the abundance of moisture, and despite the low clouds
over the area.

The upper trough is expected to weaken somewhat during the day and
guidance is in fair agreement that another shortwave will move
through the area in the base of the trough during the day. However,
convection today is expected to be mostly diurnally driven, with
scattered thunderstorms possible during the afternoon and evening
hours. Forecast soundings show drier air in the mid levels, and with
instability expected to be sufficient for thunderstorm development,
an isolated storm or two may produce gusty winds. However, the
severe threat will remain low, as the presence of cloud cover will
limit how much instability is realized. Activity should come to an
end shortly after sunset.

The upper level trough axis will slowly shift east over the
weekend, however will all but flatten by Sunday. Weak low level
ridging may limit the coverage of thunderstorms on Saturday, and
especially on Sunday, however weak disturbances may propagate on the
northern periphery of the ridge. Additionally, we should not see as
much cloud cover, so daytime heating will provide greater
instability, thus scattered convection will be possible during the
afternoon. By Monday, strong northwest flow will set up, as the upper
level ridge begins to build eastward. A vort max is projected to move
southeastward and there is some indication that an MCS will develop
to our northwest and slide toward our area on Monday. Given the
uncertainty, will maintain the 40 PoPs in our forecast.

Upper level ridging will begin to dominate much of the CONUS by
Tuesday, and this pattern is expected to continue through much of
the remainder of the forecast period. Rain chances will become
limited, and more dependent on diurnal heating and mesoscale
boundaries to provide the focus for convection. Thus, have kept
blended guidance with scattered thunderstorms during the day and
isolated thunderstorms during the overnight periods.

73

&&

.AVIATION...
(Issued 1158 PM CDT THU JUL 28 2016)
For 06Z TAFs:

VFR conditions are expected to prevail for at least the next 4 hours
before IFR cigs develop and move east towards northern AL. Some
uncertainty exists with the timing of these low clouds. As a result,
have only added a tempo group fro this possibility btwn
29/07Z-29/11Z. In addition, there could be some isolated showers
btwn 29/06Z-29/12Z but have not added to TAF due to isolated nature.
Then as an upper disturbance moves across the region, TSRA are likely
after 29/17Z until around 29/01z when they become more isolated-
scattered.

SL.77

&&

.PRELIMINARY POINT TEMPS/POPS...
Huntsville    89  72  90  72 /  40  40  50  30
Shoals        88  72  90  72 /  40  40  50  30
Vinemont      87  71  89  71 /  40  40  40  30
Fayetteville  86  70  88  70 /  40  40  50  30
Albertville   87  71  89  71 /  40  40  40  30
Fort Payne    87  70  89  70 /  40  40  40  30

&&

.HUN Watches/Warnings/Advisories...
AL...NONE.
TN...NONE.
&&

$$

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


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