Area Forecast Discussion
Issued by NWS Huntsville, AL

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FXUS64 KHUN 232325 AAA

Area Forecast Discussion...UPDATED
National Weather Service Huntsville AL
625 PM CDT Sat Sep 23 2017

For 00Z TAFS.


.NEAR TERM...(Tonight)
Issued at 307 PM CDT Sat Sep 23 2017

Isolated showers continue to develop along the Cumberland Plateau in
TN and weaken as they progress into northern AL. This activity will
ween with sunset.

Warmer than normal afternoon temps will cool down into the mid 60s
tonight. With light winds and mostly clear skies, patchy fog is
possible again tonight, especially in valley locations, near bodies
of water and where rain fell this afternoon.

.SHORT TERM...(Sunday through Monday night)
Issued at 307 PM CDT Sat Sep 23 2017

Patchy fog will dissipate shortly after sunrise. Daytime highs will
continue to be warmer than normal as we head into next week. An
upper low anchored in the northern Gulf will lift northwest into
central Mississippi on Sunday, with weak height falls across the TN
Valley. This will allow temps to be a degree or two cooler than the
past few days, mid 80s, and a few showers/storms Sunday afternoon,
mainly in the western half of the forecast area. Monday on the other
hand will be dry as a ridge to our northeast builds further south
thanks to Hurricane Maria.

.LONG TERM...(Tuesday through Friday)
Issued at 307 PM CDT Sat Sep 23 2017

The TN Valley will remain under the influence of an upper level
ridge and surface high pressure at the start of the long term
period. Meanwhile, an upper trough will slowly eject east of the
Rockies and push in the Central Plains on Tuesday, while TC Maria
continues its slow northward progression off the Atlantic Coast.
Given the high in place, dry conditions will continue through the
day on Tuesday, with the continuation of above normal temperatures
as highs warm into the upper 80s across the area.

As the upper trough continues to move east on Wednesday, an upper
ridge will build from the central Gulf Coast and into the TN Valley.
Meanwhile, high pressure to the north will shift winds to a more
northerly direction during the day. Temperatures will be hot once
again due to the increase in thicknesses, however with northerly
flow returning, dewpoints will be a couple of degrees cooler. The
upper trough will essentially flatten as it moves into the area,
leaving near zonal mid level flow across much of the region on
Thursday and continuing through the weekend.

A reinforcing cold front will swing across the area late Wednesday
night, bringing a nice change across the area beginning as early as
Thursday. As the stronger surface high builds in from southern
Canada, cooler air will filter southward. Latest guidance shows very
little in the way of precip with this front, as we get cut off from
the moisture ahead of it and the forcing associated with the actual
front remains weak. Therefore, have removed pops from the forecast
on Thursday. Temperatures will be the noticeable difference behind
the front, with highs on Thursday remaining near seasonal norms in
the lower 80s. As the high continues to move southward, even cooler
temperatures are forecast, with highs on Friday and Saturday
struggling to make it out of the 70s. Dewpoints will also cool, and
help overnight lows drop into the 50s for the latter part of the
extended forecast period.


.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 624 PM CDT Sat Sep 23 2017

VCTS will hang on at KHSV for another hour, before dissipating
quickly with the loss of heating. Moist boundary layer conditions
overnight will result in some light MVFR/IFR fog development at each
terminal, with the potential for brief MVFR conditions around sunrise
at KMSL. Thereafter, a mostly clear sky and light winds will
continue through the remainder of the period.





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