Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 212108

Area Forecast Discussion
National Weather Service Tucson AZ
208 PM MST Sat Jan 21 2017

.SYNOPSIS...Showers will end later today with dry and cool weather
continuing into Sunday night. Another group of weather systems will
bring a threat of showers to the area Monday through Tuesday. Dry
conditions are expected Wednesday onward with cool temperatures
lingering through the week.


.DISCUSSION...Plenty of light to briefly moderate showers from
roughly a Tucson to Nogales line eastward with an apparent snow
level of around 5,500 feet. Also had several reports of ice pellet
showers. We are quickly losing forcing that would keep the showers
going as the system moves further east so I would expect a
diminishing trend to start kicking in over the next few hours then
really drop out after sunset and becoming mostly clear overnight. It
will be a rather cold morning to start our Sunday but with light
winds and a good amount of sunshine high temps will be about 5-8
degrees warmer in the afternoon than today. Still rather windy in the
advisory area east of Tucson so will leave the Wind Advisory up
through 5 pm after which time the winds will diminish fairly quickly.

After a short break in the action the longwave trough redevelops over
the western U.S. which will drive a couple of upper level features
across the area. The overall result will be a threat of showers
returning Monday into Tuesday with cool temperatures much of next
week. Much lighter precipitation totals expected with this next
system but should be good for a few more inches of snow across the
mountains. Good potential for cold morning low temperatures Wednesday
and Thursday mornings where lows near freezing are likely in the
Tucson area and generally 20s and a few teens in the colder eastern
and southern valleys.

The upper trough will push off to the east middle to late next week
as a ridge builds along the west coast which leaves our area under
dry northerly flow aloft late next week through the weekend.
So dry weather with temperatures in a gradual warming trend Thursday
onward but overall remaining below normal.


.AVIATION...Valid through 22/23Z.
Isolated to scattered valley -SHRA/mountain -SHSN thru 22/03Z,
mainly east of KTUS. Aft 22/03Z, just a slight chance of -SHSN in
the White Mountains, with dry conditions elsewhere. FEW-SCT clouds
at 5k-8k ft AGL west of KTUS thru 22/03Z, then clearing skies. East
of KTUS, SCT-BKN clouds at 4k-7k ft AGL thru 22/06Z, with decreasing
clouds thereafter. Surface wind wly/nwly at 15-25 kts with gusts of
25-35 kts thru 22/02Z. Surface wind rapidly diminishing aft 22/02Z,
and surface wind generally less than 12 kts by 22/05Z. Aviation
discussion not updated for TAF amendments.


.FIRE WEATHER...Expect isolated to scattered showers through the
early evening hours tonight before diminishing. There will be a
continued slight chance of snow showers in the White Mountains
through much of the night tonight. A slight chance of showers then
exists west-to-north of Tucson Sunday night, with scattered to
numerous valley rain and mountain snow showers areawide Monday and
Monday night. Precipitation chances decrease on Tuesday, with dry
conditions prevailing late Wednesday into next weekend. Gusty west
to northwest winds will continue through the early evening hours
tonight. Otherwise, 20-foot winds will mainly be terrain driven less
than 15 mph.


Wind Advisory until 5 PM MST this afternoon for AZZ507>509-




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