Area Forecast Discussion
Issued by NWS Tucson, AZ
FXUS65 KTWC 180935
Area Forecast Discussion
National Weather Service Tucson AZ
233 AM 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 another storm system is likely early next week.
.DISCUSSION...A weak ridge of high pressure aloft will provide dry
conditions today into early Thursday before a series of storm
systems impact the region. The first storm will bring a chance of
showers Thursday evening into Friday. This system will be followed
by a stronger one that will impact the area Friday night into
Saturday. Models were in good agreement that southeast Arizona will
experience a significant rain and snow event Thursday night into
Saturday. Confidence was high enough to post a Winter Storm Watch
for both systems. That said, the precipitation will be accompanied
by strong and gusty winds, with the highest speeds up to 50 mph in
the mountains. The snow level could drop as low as 4,000 feet around
daybreak Saturday resulting in accumulating snow in the valleys east
of Tucson. Improving weather can be anticipated late Saturday and
Sunday, before another storm system enters the region around Monday
into Tuesday. Daytime temperatures will remain below normal this
.AVIATION...Valid through 19/12Z.
SCT locally BKN clouds around 5k-9k ft AGL will continue through
about 20/00Z before diminishing. However, SCT-BKN clouds mainly
above 20k ft agl will then move in starting this evening. A few
patches of fog are possible early this morning mainly for KOLS/KDUG
but confidence too low to include in TAFS. Otherwise, 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 with snow levels near 6000 feet Thursday
night and Friday dropping as low as 4000-5000 feet Saturday morning.
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
Winter Storm Watch from Thursday evening through Saturday morning
Winter Storm Watch from Friday afternoon through Saturday
morning for AZZ512-513.
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