Area Forecast Discussion
Issued by NWS Flagstaff, AZ

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FXUS65 KFGZ 181148

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

.SYNOPSIS...After a warmer and sunnier day today, expect an extended
period of winter weather to arrive by Thursday. A series of 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 storm systems, with significant accumulations of
higher elevation snow expected. Hazardous driving conditions should
be anticipated for several days, beginning Thursday.


.DISCUSSION...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 state.

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 12Z package...VFR conditions are expected
to prevail across the area, though some cloudiness will slowly exit
the area of far eastern Arizona this morning. Expected southwesterly
breezes after 18Z today. Aviation discussion not updated for TAF



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




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