Area Forecast Discussion
Issued by NWS Huntsville, AL

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FXUS64 KHUN 240757

Area Forecast Discussion
National Weather Service Huntsville AL
157 AM CST Tue Jan 24 2017

.NEAR TERM...(Today)
Issued at 157 AM CST Tue Jan 24 2017

Mostly clear skies made a brief come back yesterday evening and
overnight with low overcast clouds moving back after sunset,
specifically in areas around Huntsville and east. Meanwhile, to the
west it`s clear. Overall, guidance has not been handling the sky
cover and related low level moisture well the last few days and are
not even picking up on the current cloud cover. With similar and
actually slightly drier conditions aloft today versus yesterday,
these clouds should clear out by the late morning if not a bit

The cooler northwest flow will keep temps from rising much today
even with the slight increase in 850 temps and weak ridging aloft.
Highs will warm into the upper 50s, which is still a few degrees
above normal.

.SHORT TERM...(Tonight through Thursday Night)
Issued at 157 AM CST Tue Jan 24 2017

Dry conditions continue overnight as high pressure briefly builds
in. Winds start to turn southerly after sunset and will help keep
low temps mild and in the lower to middle 40s. Higher level clouds
should start to stream in from the west after midnight ahead of the
next system. This southerly flow will also help highs on Wed reach
into the middle 60s.

An upper trough will dig into the the southwestern states Wed
morning with a surface low forming over the upper midwest. This will
stretch a cold front south through Texas by Wed morning. The cold
front will move west to east across the local area starting around
15-18z and be out of the area by around 06z Thursday. The front is
wetter than the previous model runs with slightly more moisture being
forecast. Will have chance pops moving across the region in
association with the aformentioned timing. For now, have not
included thunder. The greatest lift is to the north and then behind
the front and the only instability noted is a little elevated
instability on the backside of the front. To note though, there is a
140kt upper jet transversing the region with this front which
probably is aiding in the additional shower development. Wouldn`t
rule out a rumble or two but confidence is not high enough to
include in the forecast.

"Much colder" air then filters in with this front with lows Wed
night dropping into the middle to upper 30s. Highs on Thursday with
strong cold advection will only reach into the middle to upper 40s.
Could be breezy as well on Thursday with gusts right now around 20-
25 mph but I could see that being increased as we get closer to
Thursday. Lows Thu night will be the coldest lows we have seen since
Jan 9 and will drop into the upper 20s to around 30. Those lows are
forecast with some cloud cover so if the clouds clear out quicker,
we could get lower. Wind chills values will also drop to the lower
20s Thu night.

.LONG TERM...(Friday through Monday)
Issued at 157 AM CST Tue Jan 24 2017

Surface high pressure, centered over the ArkLaTex at the start of
the long term period, will slowly build southeastward through the
day on Friday. Meanwhile, a broad upper level trough will generally
remain anchored over the NE CONUS, with nearly zonal flow persisting
across the TN Valley. Westerly flow at the surface, and a slight
northwest component to the mid and upper level winds will keep a dry
airmass in place, with not much change in the sensible weather
across the TN Valley Friday and Saturday. High temperatures will
generally remain in the mid 40s, with overnight lows around 30

Winds will briefly shift to the southwest on Sunday, as the
aforementioned surface high moves into the western Gulf of Mexico.
Meanwhile, the upper trough will amplify during the day on Sunday,
with a surface low developing over the Great Lakes. This will bring
a weak cold front through the area, though given the lack of
moisture return, the only impact looks to be an increase in clouds
and slightly cooler temperatures. Guidance is hinting at isolated
light showers. Of course, this being around 6 days out, there are
some differences in the timing a strength of the system. Given this,
along with the dry airmass in place, will leave precip out of the
forecast at this point.


.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1037 PM CST Mon Jan 23 2017

No changes to previous aviation forecast reasoning, with western edge
of stratus deck based between 2000-2500 ft expected to continue
shifting ewd btwn 24/06-09Z. As the low clouds dissipate and skies
become clear, patchy fog will develop as nnw winds fall below 5 kts.
Any fog will lift by 14Z, with skc and lgt/vrbl winds expected for
remainder of the day. A ssely return flow will begin by late aftn and
continue thru the evening, along with an increasing coverage of ci.





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