Area Forecast Discussion
Issued by NWS Huntsville, AL

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FXUS64 KHUN 291158

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

For 12Z TAFs.


(Issued 305 AM CDT FRI JUL 29 2016)

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.



For 12Z TAFs: A very moist swly flow regime will continue thru the
valid TAF period, with low stratus clouds currently blanketing nrn
AL expected to remain intact for at least the next 24-hrs. Cigs are
currently in the 1500-2500 ft range, but may lift to 2500-3500 ft
with stronger mixing during the late morning/aftn. Latest radar data
suggests that -shra will be psbl early this morning, with a greater
threat for tsra during the aftn/early evening as clouds lift allowing
the atmosphere to become more unstable. Although a few storms may
persist well into the early morning hrs Saturday, it appears the
greater concentration will occur to the n/w of the local area and
only VCSH was included beyond 30/03Z. Stratus deck will begin to
lower once again after sunset, with combination of IFR stratus and
lgt br expected btwn 09-12Z. Sfc winds will remain from the sw thru
the period at speeds of 3-7 kts.



.HUN Watches/Warnings/Advisories...



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