Area Forecast Discussion
Issued by NWS Flagstaff, AZ

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FXUS65 KFGZ 230345
AFDFGZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
845 PM MST Fri Sep 22 2017

.SYNOPSIS...Cool conditions will persist over the weekend as
strong low pressure moves into the southern Great Basin. Expect
possible freezing temperatures for much of the high country by
Saturday, Sunday and Monday mornings.

&&

.UPDATE...At 845 PM MST...strong early season trough was centered
over Nevada with deep southwest flow over Arizona. A tight low
level moisture gradient exists over our area, with sfc dewpoints
in the teens/low 20s west of a Prescott to Kayenta line, and
30s/40s to the east. This is just enough moisture for some
localized upslope stratus and an isolated shower or two overnight.
Forecasts were updated to spread the low rain chances west to near
Flagstaff for the next several hours. Rest of forecast in good
shape.

&&

.PREV DISCUSSION /317 PM MST/...A large scale trough in place
across much of the western U.S. will keep northern Arizona much
cooler than average through the weekend. Breezy winds continue
this afternoon, particularly across eastern Arizona where gusts
have reached into the 40 to 50 mph range. These winds will
decrease, though remain breezy overnight. Some of the colder
northern Arizona mountain locations like Bellemont northwest
through the Grand Canyon region will likely see freezing
temperatures tonight, with more widespread freezing conditions
above 6500 feet along the Mogollon Rim and Coconino Plateau
expected Sunday morning.

The trough deepens while moving through the southern Great Basin
Saturday and Sunday ushering in even cooler air. Winds will remain
breezy, but will not be as strong as today. Limited moisture and
instability led to a few showers in the Flagstaff area this
afternoon. This favored area will shift east tonight through
Saturday with precipitation chances confined to eastern Arizona
tonight through Saturday. Any precipitation will remain light.

By late in the weekend the low fills in and heads northeast.
Another disturbance drops southward and reinforces troughing over
the southwest by the middle of next week. Temperatures may have a
chance to warm up slightly, but this second trough will keep them
cooler than average through next week. This will also introduce
additional chances for showers Wednesday through at least Friday.

&&

.AVIATION...For the 06Z package...Expect VFR conditions for the
next 24 hours with localized CIGS near 4 kft agl overnight and
into Saturday morning over higher terrain from KFLG eastward. There
is only a slight chance of a -SHRA/-TSRA mainly east of a KPAN-
KOV7 line through Saturday afternoon. On Saturday, afternoon winds
at 10-20 kts with gust to 25 kts are anticipated for most
locations. Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...On Saturday, Look for a bit lighter winds and below
normal temperatures with just a slight chance of thunderstorms over
far eastern Arizona. For Sunday, expect light winds and dry
conditions with a continuation of well below normal temperatures.

Monday through Wednesday...Expect light winds with temperatures
gradually climbing to near normal. Generally dry, but some
additional moisture will sneak over eastern portions of the area on
Tuesday and Wednesday for a slight chance of showers and
thunderstorms.

&&

.FGZ WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

PUBLIC...JJ/MCT
AVIATION...JJ
FIRE WEATHER...McCollum

For Northern Arizona weather information visit
weather.gov/flagstaff



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