Area Forecast Discussion
Issued by NWS Flagstaff, AZ

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FXUS65 KFGZ 161043

Area Forecast Discussion
National Weather Service Flagstaff AZ
343 AM MST Tue May 16 2017

.SYNOPSIS...A low pressure system will bring even colder
temperatures to the area today, with a chance of showers and
thunderstorms. On Wednesday and Thursday, a stronger low will
produce gusty winds and good chances for showers and thunderstorms,
especially across northeast Arizona. Fair weather will return
from Friday evening through the weekend.


.DISCUSSION...A few days of unsettled weather are in store for
northern Arizona, with well below normal temperatures, a chance of
showers and thunderstorms (even some snow at higher elevations),
and strong wind at times.

The first low pressure system to affect northern Arizona is
currently centered near Las Vegas. Some moisture ahead of the low
will lead to a chance of showers this morning, mainly higher
elevations from near Flagstaff northward. Temperatures are cold
enough for snow possibly down to the 7000 ft level. Later this
afternoon as the low moves eastward across the state, a chance of
showers and a few thunderstorms will develop over much of the
area, with the best chances from around Flagstaff eastward. We
will be in between systems tonight with precipitation ending,
though it will remain locally breezy.

The second low pressure system (currently in the Pacific NW), will
move southeastward into Utah by Wednesday afternoon. Gusty winds
will develop from around the Mogollon Rim northward where gusts
in the 35 to 45 mph range are likely during the afternoon. A
strong east-west oriented cold front (cold for mid-May standards!)
is forecast to slide south across the UT/AZ line during the
afternoon, with showers and some thunderstorms developing.
Wednesday evening through Thursday morning, this cold front and
associated precipitation band is forecast to continue southward,
reaching the White Mtns by early Thursday morning. Models are
indicating precipitation amounts with the front of 0.10"-0.40"
with the higher amounts favoring the NE Arizona mountains. Snow
levels behind the front are expected to fall to 6500-7500 feet,
with some light accumulations of up to an inch or so mainly from
the Kaibab Plateau, to Black Mesa and Chuska Mtns and down to the
White Mtns. By Thursday, shower chances shift mainly to east
central Arizona, though all areas will remain 10-15 degrees cooler
than average for mid May.

The latest model runs continue to indicate a third and final
disturbance rotating around the main low, bringing colder air and
a chance of showers Thursday night into Friday morning. The best
chance of showers with this system appears to be across the
northern third of the state. Snow levels in this area could again
fall to 6500-7500 feet. For the weekend and early next week, much
warmer and drier weather conditions are forecast.


.AVIATION...For the 12Z package...Slight chances for -SHRA/-TSRA
will develop mainly along and NE of a KFLG-KSOW line today, with
some -SHSN, producing brief MVFR, possible above 7 kft MSL in
heavier showers. Sfc winds SW 10-20G25-30kts. Aviation discussion
not updated for TAF amendments.


.FIRE WEATHER...A weather disturbance will move across Arizona today,
with slight chances for showers and thunderstorms across the
district. Daytime temperatures will also be cooler. Expect another
disturbance on Wednesday. This will bring more strong winds and a
chance for showers and thunderstorms by the afternoon.

Thursday through Saturday...Temperatures will remain well below
normal Thursday and Friday, with a lingering chance of showers. On
Saturday, the weather disturbance will move eastward, leaving behind
warmer temperatures, dry conditions, and lighter winds for Saturday.






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