Area Forecast Discussion
Issued by NWS Flagstaff, AZ

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FXUS65 KFGZ 170423

Area Forecast Discussion
National Weather Service Flagstaff AZ
920 PM MST Thu Feb 16 2017

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

.DISCUSSION...A weak trough is moving across northern Arizona this
evening with mostly high clouds. Only a few clouds are bring picked
up my area almost 20,000 feet MSL. 00Z model runs are
showing one or two hundredths precipitation by sunrise north of
Flagstaff. Will leave the already low POPS alone for the rest of the
night. Low temperatures are warm for this time of the year...and
will not change them given the amount of cloud cover tonight.


.PREV DISCUSSION /346 PM MST/...Model forecasts continue to predict
that a wet low pressure system will cause a period of active weather
across northern Arizona from Friday through the weekend.

On Friday, chances for showers are forecast to increase as a wave of
moisture moves into the area ahead of the developing low. At this
point, it looks like the best chances for showers will roughly be
northwest of a line from Prescott to Flagstaff to the Four Corners.
Any snow accumulations are expected to be light, with snow levels
varying within the 7000 to 8000 foot range. In addition, southwest
winds will begin to increase as pressure gradients tighten ahead of
the approaching system. The strongest winds are expected to be over
higher terrain in western Yavapai and far southwest Coconino
Counties. In these areas, wind gusts to 40 mph will be possible.
Elsewhere, wind gusts between 20 to 30 mph are forecast.

By Saturday morning, strong low pressure will push into the
western United States. In response, a moist southerly wind is
forecast to develop causing periods of heavier rainfall along
south facing slopes along and south of the Mogollon Rim. Elevated
flow through creeks and streams across Yavapai and northern Gila
Counties appear likely. Low water crossing in these areas may
become impassable at times. Snow levels may briefly drop below
7000 feet early Saturday morning, but are largely expected to
remain above 7000 feet throughout the day. Only light snow
accumulations are expected, except perhaps over the highest
mountain peaks. Similar to Friday, wind gusts may exceed 40 mph in
western Yavapai and far southwest Coconino Counties.

Uncertainty grows on Saturday night and Sunday as the low pressure
system crosses the state. Model forecasts generally agree that
good chances for precipitation will continue across the area.
Higher uncertainty exists with regards to the snow levels. At this
point, snow levels look to drop into the 6000 to 7000 foot range
as the coldest air arrives. Snow accumulations in the 1 to 3 inch
range above the 6500 feet are possible.

On Monday and Tuesday, fair and mild weather returns as the
system moves east of the region. On Wednesday, the next system
developing over the northwest US may bring increasing clouds and
a slight chance of precipitation.


.AVIATION...For the 06Z package...Expect VFR conditions and light
winds through this evening. Most clouds tonight will be AOA BKN150.
An approaching storm system will bring lowering and thickening
clouds after 16Z. Isold -SHRA possible through 16Z with SCT -SHRA
mainly north of a KPRC-KPGA line after 16Z. Aviation discussion not
updated for TAF amendments.






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