Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 182220
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
320 PM MST Wed Jan 18 2017

.SYNOPSIS...A series of storms will spread valley rain, mountain
snow and gusty winds over Arizona Thursday night into Saturday.
Snow levels will lower through that time potentially reaching the
valley floors east of Tucson by Saturday. After a break in the
weather on Sunday another storm system is likely on Monday and
Tuesday.

&&

.DISCUSSION...A little more cloud cover than expected on back side
of upper level trof as sunshine works on lingering moisture over the
area. Highs so today were running a few degrees below normal.

Short wave ridge passing overhead tonight in advance of what will be
a series of Pacific weather systems that will bring widespread
valley, gusty winds, and periods of heavy mountain snow to southeast
Arizona starting Thursday night and continue until Saturday.

Clouds on the increase tonight with a few light showers/sprinkles
possible Thursday afternoon mainly west and north of Tucson. Showers
will be spreading west to east Thursday night into Friday morning
with the best chances for rainfall and accumulation mountain snows
being from Tucson north and northeast. The winter storm watch was
upgraded to warning, first starting with the mountains near Tucson
northeast to the White mountains for Thursday night into Friday
morning. Snow levels lowering down into the 4500 to 5500 foot level
with accumulating snows above 5500 feet.

There will be a break in rainfall and mountain snow intensity
between storms as snow levels rise a bit before the second stronger,
colder and wetter system starts to impact the area later Friday and
continuing into Saturday. Snow levels down into the 4000 to 5000
foot level with significant snow accumulations above 5500 feet where
a Winter storm warning continues for the higher terrain above 5500
feet. Strong gusty winds will bring periods of blizzard like
conditions to the mountains Friday night into Saturday. Wind speeds
at the lower elevation could reach wind advisory criteria on Friday.

Two day storm totals for valley rainfall range from 0.50" to 1.75"
with locally higher amounts over 2" possible, especially north of
Tucson. Snowfall amounts were also increased with totals above 5500
feet in the 12 to 36 inch range with locally higher amounts
possible. Minor snow accumulations are possible down to 4000 feet by
Saturday morning.

Conditions improve west to east Saturday night into Sunday with
colder overnight lows likely Sunday morning with eastern valleys
seeing temperatures in the 20s.

The storm parade continues early next week as long wave trof axis
remains over the western CONUS.

High temperatures for the next 7 days will remain below normal
with coolest highs occuring Friday and Saturday.

&&

.AVIATION...Valid through 19/12Z.
SCT to lcly BKN clouds around 5k-9k ft AGL mainly E of KTUS thru
19/03z. Later tonight SCT-BKN clouds mainly above 20k ft agl will
then move in from the west. Surface winds will exhibit typical
diurnal trends and generally be less than 10 kts. Aviation
discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Dry weather into early Thursday with generally
light winds and elevated humidity levels. Then a series of storms
will spread a good amount of precipitation across the area late
Thursday into Saturday. Gusty west to southwest winds are expected
at times through this period especially Friday night and across the
mountains. Dry weather returns Sunday before another storm affects
the area Monday into Tuesday.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
 Winter Storm Warning from Thursday evening through Saturday morning
  for AZZ510-511-514.

 Winter Storm Warning from Friday afternoon through Saturday morning
  for AZZ512-513.

&&

$$

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