Area Forecast Discussion
Issued by NWS Flagstaff, AZ
FXUS65 KFGZ 210344
Area Forecast Discussion
National Weather Service Flagstaff AZ
844 PM MST Fri Jan 20 2017
.SYNOPSIS...Two additional winter storms will affect the region,
the first tonight through Saturday and the second late Sunday
through Monday. These will be cold systems, with heavy snow
accumulations across the high country. Hazardous driving
conditions should be anticipated. Expect precipitation to wind
down Tuesday with very cold temperatures through Thursday.
.DISCUSSION...Rain and snow showers continued to increase and
spread across northern Arizona during the evening. The only real
adjustment to the forecast package will be to lower snow levels
slightly south of the Mogollon Rim where observer reports are
indicating some snow as low as 4500 feet. All else is as
.PREV DISCUSSION /326 PM MST/... The second winter punch is moving
towards northern Arizona this afternoon. Heavy snow showers have
developed along the Mogollon Rim with visibilities down to 1/4
mile at times. Area radars to our west are showing increasing
coverage of precipitation. This due to the approach of the cold
front and vort max now in Srn California. So expect rain and
snowfall intensity to increase this evening from west to east. We
did increase snow ratios and liquid accumulations for tonights
event, which raised forecast snowfall a few inches for areas above
6500 feet. A Snow Advisory is now in effect for the Window Rock,
Sanders and Springerville areas for tonight-mid day Sat. The
Winter Storm Warning remains in effect as rain and snow amounts
will be prolific tonight, with snowfall rates of 1 possibly 2
inches per hour at times. Southwest winds of 20-30 mph with higher
gusts will cause blowing snow. This is a dangerous storm, only
travel if absolutely necessary. Creeks and rivers coming off the
Mogollon Rim should show rises on Saturday, and caution is urged
around those as well.
Models continue to show precipitation tapering off from west to
east Saturday afternoon. Dry weather is expected Saturday night.
As far as the third storm goes, progs seem to have slowed the
eastward progression of this system through the northland by about
12 to 18 hours, now moving the cold front into western AZ Monday
morning. We are not ready to buy into this later arrival
completely, but have reduced precip chances by about 10% on Sunday
for now. Regardless of when it arrives, expect another strong
system with heavy rain and snow (most likely on Monday), and
perhaps the fastest surface winds of the 3 systems. Stay tuned.
From Monday night onward, a cold and unstable airmass will sit
over northern AZ through at least Wednesday. Expect a drying trend
though some daytime mountain snow showers are possible. Max and
min temperatures to be around 15 degrees below normal, with single
digit or below zero lows for much of the high country that has
.AVIATION...For the 06Z package...Rain and snow intensities will
continue to increase overnight, with widespread LIFR ceilings and
visibilities in heavy rain and snow likely - especially for locations
above 5500 feet, and on south facing slopes along and south of the
Mogollon Rim. In addition, expect south to southwest winds with
gusts into the 25 to 35 knot range.
Precipitation will begin to taper off from west to east after 15Z,
but periods of MVFR/IFR ceilings and visibilities in rain and snow
showers over higher terrain will likely continue through 00Z. After
00z look for mainly MVFR conditions with a slight chance of showers.
Aviation discussion not updated for TAF amendments.
1) Winter Storm Warning until 6 PM MST Saturday FOR AZZ016>018.
2) Winter Storm Warning until noon MST Saturday FOR
3) Winter Weather Advisory until noon MST Saturday FOR
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