Area Forecast Discussion
Issued by NWS Huntsville, AL

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FXUS64 KHUN 050446
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
1046 PM CST Sun Dec 4 2016

.UPDATE...
For 06Z TAFS.

&&

.NEAR TERM...(Tonight)
Issued at 843 PM CST Sun Dec 4 2016

With a weak wave moving across the area tonight, will maintain slight
pops of rain and keep patchy drizzle due to low clouds with ceilings
mainly below 500 ft. These low clouds will also produce areas of fog
overnight with vsby below one mile at time, especially in our higher
terrain locations. Otherwise temps will only drop a few degrees from
where they are attm. Already updated fcst a few hours and not
planning on any more updates attm.

.SHORT TERM...(Monday through Tuesday)
Issued at 305 PM CST Sun Dec 4 2016

After most areas get a short break from rain Sunday night, rain
chances return on Monday, and especially Monday night as the upper
low moves from Mexico, across south central Texas on Monday, and
reaches this region early Tuesday. A neutrally tilted 500mb trough
and decent diffluence east of the low will help create a sheared
environment. Model soundings indicate some instability present at
times during the night; thus will keep some mention of thunder in.
In this issuance, started a slight chance of thunder early Monday
afternoon for our southwestern areas, the remainder of the region
in the late afternoon. Went with isolated rather than scattered or
higher chances of thunder given weak instability numbers expected.
Forecast dewpoint values rise into the lower 50 degree range Mon
night. The stronger storms Monday night could produce gusty winds and
small hail. Shower activity should be lesser somewhat from west to
east on Tuesday as this next system exits the region. Total rainfall
amounts into Tuesday evening should range between one and two inches,
which will help alleviate drought conditions somewhat (at least short
term drought).

Dry weather is expected Tuesday night as a northerly flow and drier
air filters southward across the region. Lows Tuesday night should
cool to around 40.

.LONG TERM...(Wednesday through Saturday)
Issued at 305 PM CST Sun Dec 4 2016

Wednesday will have near seasonable temps in the mid 50s,
mostly cloudy skies but be dry for the first half of the day. An
upper-level trough from the Midwest with a trailing arctic cold
front will bring rainfall Wednesday evening through Thursday.

Models are coming into better agreement on the timing of the cold
front, early Thursday morning, however there is still a difference
in moisture.  Will have to see how moisture, temps and timing comes
together to see if we can get a wintry mix or not, especially since
temps have warmed up with the latest run. For now, kept it all as
rain.

Precip will taper off from west to east on Thursday as the cold front
pushes through. There is a slight chance late Thursday afternoon
that cold air could catch up before the precip is out of the area and
some snow could mix with rain. No accumulation is expected. The ECMWF
is slower than the GFS solution, so that one would be in favor of
this right now. Regardless, cold air will funnel in behind the front
and combined with mostly clear skies, overnight lows will tank into
the teens to lower 20s with windchills that could be in the single
digits!

Sfc high pressure builds in Friday and Saturday keeping conditions
dry but cold. Friday`s high temps will be only in the mid/upper 30s
with lows in the 20s. Saturday will be a littler warmer as the sfc
high moves eastward with highs in the mid 40s, lows still chilly in
the upper 20s/lower 30s.

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1045 PM CST Sun Dec 4 2016

8H wave axis in now over north central AL. Ceilings over KMSL have
risen to arnd 1200 ft while KHSV is ovc at 400 ft with -dz. As the 8h
wave moves out of the cwa (arnd 10z), the chc of -dz should begin to
taper off from w to e across the TN valley. However patchy fog will
still be possible especially over KHSV until 14z. There could be a
break in the chc of pcpn between 14z to 20z. More shra are then expected
to develop after 20z as a closed upper low approaches the area. The
coverage and intensity of shra will increase after 00z across the taf
sites. For now will keep all pcpn as shra since new NAM data brings
in the higher/best instabilities after 09z (early Tuesday mrng).
Otherwise mainly ifr conditions are expected thru 14z especially at
KHSV. After 14z mvfr conditions are expected at both taf sites.

&&

.HUN WATCHES/WARNINGS/ADVISORIES...
AL...NONE.
TN...NONE.
&&

$$

NEAR TERM...007
SHORT TERM...RSB
LONG TERM...JMS
AVIATION...007


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