Area Forecast Discussion
Issued by NWS Flagstaff, AZ

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FXUS65 KFGZ 181717

Area Forecast Discussion
National Weather Service Flagstaff AZ
1015 AM MST Wed Jan 18 2017

.SYNOPSIS...Look for a a warmer and sunnier day today.  A series of
winter storms will affect the region from Thursday through Saturday.
After a brief break on Sunday, additional storms are anticipated
early next week. These will be cold systems, with significant
accumulations of snow across the high country. Hazardous driving
conditions should be anticipated for several days, beginning


.DISCUSSION...Focus is on the series of winter storms to move across
the northland from Thursday through Monday. We will be upgrading the
winter storm watch to a warning with this afternoons forecast
package and lowering the snow levels for areas in the warning from
6000 to 5500 feet.


.PREVIOUS DISCUSSION 450 AM MST...A persistent upper low over New
Mexico will slowly push east today in response to an active storm
track developing in the eastern Pacific. Northerly flow aloft will
turn westerly this afternoon. Shallow status/cumulus production
should come to a halt as dry and warm air briefly moves across the

By late tonight and early Thursday, an active pattern will develop
across the southwest, with three storms affecting the area through
early next week. These storms will be cold and dynamic, driven by
the polar jet, as opposed to our series of sub-tropical systems
earlier in January. This means lower snow levels and strong
potential for heavy snow accumulations.

The highest confidence for higher snow accumulations will be above
6000 feet along and west of the Kaibab Plateau, Mogollon Rim and the
White Mountains. We have issued a rather long term Winter Storm
Watch for these areas from Thursday through Saturday. Other Winter
Weather headlines will likely materialize as each storm system moves
through the state, but we will wait on these finer details and stick
to what we have the highest confidence for at this time.

Here is the order of events:

Storm One - Light precipitation arriving in the western zones
Thursday morning and spreading east through the day. Heavier
precipitation arrives Thursday evening, spreading southwest Thursday
night. Snow levels initially 6500-7000 feet, falling to near 5000
feet late Thursday night.

Storm Two - After a lull for much of the day Friday, a second storm
arrives late Friday and Friday night. This storm is colder and will
contain better dynamics. Expect moderate to heavy precipitation late
Friday through early Saturday. Snow levels initially as high as 6500
feet as warm advection develops ahead of the wave, falling to 4500
feet by early Saturday.

Storm Three - Confidence building on the timing and location of a
third storm due Monday. This will also be a cold and dynamic storm
that is pointed right at central Arizona. Expect moderate to heavy
precipitation again Monday and Monday night. Details and confidence
should improve in the next few days.

QPF south of the Mogollon Rim may reach 2 to 3 inches, which may
cause some flooding issues in Yavapai and northern Gila counties.

Each storm will contain gusty southwest winds that will produce
severely reduced visibility due to blowing and drifting snow.


.AVIATION...For the 18Z package...Areas of MVFR Cigs over
mainly higher terrain east of a KPAN-K0V7 line this morning,
gradually improving by afternoon. Otherwise, VFR conditions are
expected to prevail across the area through 12Z Thursday. From 12Z
to 18Z Friday, an approaching storm system will cause deteriorating
conditions to spread from west to east. MVFR/IFR conditions in rain
and snow along/west of a KPRC-KFLG-KPGA line by 18Z. These
conditions will spread farther east Friday afternoon/evening.
Aviation discussion not updated for TAF amendments.



Winter Storm Watch from Thursday morning through Saturday morning
for AZZ004-006>008-015>018.




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