Area Forecast Discussion
Issued by NWS Huntsville, AL

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FXUS64 KHUN 251102

Area Forecast Discussion
National Weather Service Huntsville AL
602 AM CDT Tue Oct 25 2016

For 12Z TAFS.


.NEAR TERM...(Today)
Issued at 207 AM CDT Tue Oct 25 2016

Weak ridging remains evident this morning over the local area as a
deep trough spins in the Canadian maritimes. The cirrus clouds that
were overhead yesterday have indeed pushed to the south with a weak
frontal boundary still sitting across northern Alabama as of 2AM.
"Frontal boundary" should be used loosely as there really isn`t much
of a boundary outside of light and variable winds to the south and
north winds around 3-5 knots to the north. Temps have been slow to
fall likely due to the front and with the front moving south, temps
are now falling into the lower 40s to middle 50s.

The center of the mid level ridge shifts slightly east today, giving
the area an east-southeast flow and sunny skies. There is some
cirrus trying to stream southeast along the ridge but the local area
is probably too dry to see any of those today. Highs today will be a
degree or two cooler than yesterday thanks to the cooler easterly
flow but they will still get into the upper 70s to around 80.

.SHORT TERM...(Tonight through Thursday Night)
Issued at 207 AM CDT Tue Oct 25 2016

The ridge continues to shift east keeping the mild temps and dry
conditions going through tonight. Radiational cooling will help
temps quickly cool but with the warmer overall conditions, lows will
only drop into the upper 40s to lower 50s.

As the ridge aloft breaks down, an upper trough and surface low
starts to develop over the upper midwest on Wednesday. Winds will
start to shift to a more southerly direction on Wednesday as the
surface high nudges east. Clouds will also be on the increase ahead
of the surface low previously mentioned. They will have little
effect on highs which will still reach into the upper 70 to around

Wednesday night, the surface high will remain anchored over the
northeast while the latest guidance shows the 850mb ridge remaining
anchored over South Carolina, with winds shifting back slightly from
the southeast. The surface high and mid level ridge will help push
the low off to the northeast and drag a weak cold front across our

Guidance continues to show little in the way of QPF with the 25/00z
ECMWF completely dry for the area. Will therefore not bring in any
rain until after midnight Wednesday night and keep it at slight
chance through the night. With this low quickly lifting north,
thinking the rain could end in NW AL by 12z Thursday. The GFS is
indicating that the surface boundary could linger in NE Alabama and
will therefore add some chance pops to that area and have all the
rain out by around 21z.

Thunder chances with this system are still very underwhelming. As
noted above, winds actually shift back to a more southeasterly
direction Wednesday night and don`t turn back southerly until right
before frontal passage. Given how dry we are, this is not a lot of
time for a good moisture return. Current forecast has dew points in
the western areas getting into the upper 50s but that may even be a
bit overdone. The majority of the lift with the system will be well
to the north with just a weak sliver crossing the area, which is
stronger in the GFS. Wind shear ramps up before 12z Thursday with
this boundary but drops off quickly after 12z. Instability is only a
few hundred J/KG at best and that`s probably just picking up on the
higher dew points with the moisture along the front. Will therefore
remove the thunder before 12z and will leave a slight chance after
12z to account for the lingering precip the GFS shows and maybe a
little time to destabilize.

This front does little in the way of cooling the temps with highs
Thursday only slightly cooler, in the middle to upper 70s. Ridging
and a surface high quickly builds back in Thursday night into
Friday. Lows Thursday night will be in the lower to middle 50s.

.LONG TERM...(Friday through Monday)
Issued at 207 AM CDT Tue Oct 25 2016

This timeframe will mainly be dominated by ridging across the region.
Last night GFS was showing a cdfnt on Saturday bringing cooler temps
by Sunday. Now the 00z/25 GFS shows no cdfnt with temps still above
normal, with highs arnd 80 and mrng lows in the mid 50s thru the
period. The normal temps for this time of the year are mid/upper 60s
for highs and mid 40s for lows. Also models are showing no rain thru
the period as well. The drought continues.


.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 601 AM CDT Tue Oct 25 2016

VFR conditions and light winds will continue through the TAF period.





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