Area Forecast Discussion
Issued by NWS Flagstaff, AZ

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170
FXUS65 KFGZ 172316
AFDFGZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
416 PM MST Fri Feb 17 2017

.SYNOPSIS...A Pacific low pressure system will bring cooler
temperatures, breezy winds, and periods of rain and high
elevation snow to northern Arizona through the weekend. Dry
weather and warming temperatures are forecast for early next work
week. Another round of showers is possible around the middle of
the next work week.

&&

.DISCUSSION...Current radar and satellite imagery reveals a
closed low currently centered just off the West Coast near San
Francisco. This system is forecast to move southeast, bringing
heavy rain, high elevation snow and gusty winds to the area
through Sunday.

Some light rain and snow showers are possible across portions of
northern Arizona tonight, but chances for showers really begin to
increase Saturday morning. The area of primary concern will be
for locations along and south of the Mogollon Rim. A plume of
moisture will be forced to rise along the rim, resulting in
periods of moderate to heavy precipitation there, especially
along south facing slopes. As a result, expect elevated flow
through creeks and streams in Yavapai and northern Gila Counties.
Areas along washes and streams will be susceptible to flooding,
and low water crossing in the area will likely become impassable
at times. Periods of heavy rainfall are forecast to continue
through most of Saturday, with rain rates beginning to decrease
Sunday morning. In total, a broad area between 1 to 2 inches of
rain are forecast south of the Mogollon Rim. Isolated areas above
2.5 inches is not out of the question. A Flash Flood Watch has
been issued for Yavapai and northern Gila Counties from late
tonight through Sunday afternoon.

Higher elevations are forecast to receive snow this weekend. On
Saturday, snow levels are expected to range from 6500 to 8000
feet. The lowest snow levels are forecast to be along the Kaibab
Plataea, and highest snow level are forecast in the White
Mountains. While snow will be possible below 7000 feet, warmer
temperatures should lead to mostly light accumulations. Beginning
Saturday evening, the coldest air is set to arrive as the system
passes overhead as a negatively tilted trough. As a result, snow
levels are forecast to drop into the 6000 to 7000 foot range, and
better chances for significant snow accumlations are expected
during this time. A Winter Weather Advisory has been issued from
5 PM MST Saturday to 5 PM MST Sunday above 6000 feet for the
Mogollon Rim and White Mountains regions. In this area, 1 to 6
inches of snow is possible between 6000 to 8000 feet, with 6 to 12
inches of snow possible above 8000 feet and along certain south
facing slopes of the Mogollon Rim.

Tight surface pressure gradients will keep gusty winds blowing
overnight tonight, generally within the 15 to 25 mph range.
However, winds downsloping to the south of higher terrain may be
much higher. Isolated wind gusts in excess of 40 mph are not out
of the question. This includes the Highway 89 corridor from Doney
Park to Cameron. On Saturday, strong winds are forecast to become
more widespread, with gust above 40 mph possible over higher
terrain, especially for areas west of Flagstaff.

.LONG TERM (Monday through Thursday night)

Short wave ridging is forecast to influence northern Arizona on
Monday and Tuesday. Expect temperatures near average on Monday,
rising to around 5-10 degrees above average on Tuesday. The NAEFS
indicates moisture transport around the 90th percentile for a brief
period across far northern Arizona on Wednesday in association with
strong winds caught between a weakening ridge to our east and a
trough over northern CA/the Great Basin. We are keeping precip
chances on Wednesday and Wednesday night in the 40-60% range from
the Kaibab Plateau southeast to around Heber-Overgaard. In addition,
a fairly noticeable temperature drop is forecast from Wednesday
night into Thursday in association with a strong cold front. Winds
both ahead of the front Wednesday and behind the front Thursday
could be quite gusty. High temperatures several degrees below
average are forecast Thursday, with near average low temperatures
Thursday night.

&&

.AVIATION...For the 00Z package...VFR conditions are expected to
persist through approximately 08-09Z. Aft 08-09Z...areas of IFR/MVFR
cig/vsby expected to develop along/SW of a line from KGCN-KFLG-KSOW
in association with -RA/-SN. Snow level appx 6500-7500 ft. Expect
precip intensity to increase with cig/vsby to worsen with time
during the day on Sat. S winds expected throughout TAF period with
gusts to 30-35 kt possible. Aviation discussion not updated for
TAF amendments.

&&

.FGZ WATCHES/WARNINGS/ADVISORIES...Winter Weather Advisory above
6000 feet from 5 PM Saturday to 5 PM MST Sunday for AZZ015>017.

Flash Flood Watch from late tonight through Sunday afternoon for
AZZ008-018-037.


&&

$$

PUBLIC...RR
AVIATION...AT


For Northern Arizona weather information visit
weather.gov/flagstaff



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