Area Forecast Discussion
Issued by NWS Flagstaff, AZ

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FXUS65 KFGZ 302136

Area Forecast Discussion
National Weather Service Flagstaff AZ
236 PM MST FRI SEP 30 2016

.SYNOPSIS...Expect quiet weather and near average temperatures on
Saturday, although a few light showers will be possible over
higher terrain. Increasing winds are forecast ahead of an
approaching low pressure system on Sunday, followed by strong
southwest winds and noticeably colder temperatures on Monday and


.DISCUSSION...On Saturday, northern Arizona will be under the
influence of high pressure. Most of northern Arizona is expected
to experience dry weather, near average temperatures and partly
cloudy skies. With that said, some model guidance suggests there
may be just enough low level moisture for a few showers. Decided
to go with a slight chance of showers over higher terrain,
although stable conditions may lead to the formation of an
extensive cumulus field and nothing in the way of precipitation.

On Sunday, things begin to change as a deep low pressure system
approaches the state from the northwest. While daytime
temperatures will remain near seasonal averages, breezy southwest
winds will foreshadow the passage of an unseasonably cold low on
Monday and Tueday. The newest GFS model run shows a south to north
oriented line of light showers crossing the region, likely in
response to a subtle increase in moisture and weak forcing from a
fast moving, low level thermal gradient. Decided to add slight
chance pop`s to the forecast during this time to account for this,
but confidence is very low at this point.

The bulk of the cold air arrives on Monday as the west coast low
crosses the state. Expect very strong southwest winds and a
noticeable drop in temperatures. Wind gusts in excess of 40 mph
will be possible. Daytime temperatures are expected to drop by
around 10 degrees as compared to Sunday at most places, which
would be around 10 degrees below average for this time of year.
The coldest low temperatures of the last several months are
forecast on Tuesday morning. A hard freeze will be possible above
6000 feet. Similar temperatures are forecast for Tuesday, with
winds weakening and shift to the northeast on heels of the
departing low.

On Wednesday and Thursday, a zonal flow pattern and a warming
trend are forecast in the wake of the departing weather system.


.AVIATION...For the 00Z package...Scattered SHRA/TSRA have
developed this afternoon and will continue into the evening.
MVFR conditions should be expected in heavier showers. Isolated
showers may be possible into the overnight hours and again
Saturday. Aviation discussion not updated for TAF amendments.






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