Area Forecast Discussion
Issued by NWS Flagstaff, AZ

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FXUS65 KFGZ 240332

Area Forecast Discussion
National Weather Service Flagstaff AZ
832 PM MST Fri Feb 23 2018

.SYNOPSIS...Improving weather to move in from west to east
late tonight, but very cold temperatures will mean slick roads
for much of our area. Dry and slightly warmer weather is on tap
from Saturday through Monday. Another winter weather system looks
to impact the area Tuesday and Wednesday.


.UPDATE...The bulk of the snow activity is currently located
generally east of I-17 extending along a line from Camp Verde to
Winslow. This activity will continue to move east overnight as its
parent upper trough pivots across northern Arizona.

Isolated to scattered convective snow showers will continue to
develop west of I-17 overnight as the upper trough`s cold pool
rotates across the region. Cooling temperatures aloft should
continue to allow for an unstable environment for brief snow
showers to develop.

Given the isolated/scattered nature of this activity, went ahead
and allowed the Winter Weather Advisory to expire. The main
impacts overnight will be brief snow showers reducing visibilities
on already slick roadways from the snow earlier today.

Only made minor adjustments to the forecast based on current
obs/trends. The updated gridded and text products have been sent.


.PREV DISCUSSION /244 PM MST/... Short term...Tonight - Monday

Surface observations show the cold front along a line roughly
from the Four corners - Kykotsmovi - Flagstaff and through
Prescott. Bands of moderate to heavy snow to persist along the
Mogollon rim west of Happy Jack through mid evening. We have had
reports of 4 inches of snow in 2 hours in Flagstaff. There is a
small break in the weather behind the front but scattered showers
are moving into NW Coconino county now as the 500 mb cold pool
arrives with temps down to -33C. We will continue the winter
weather advisories for now, and let them expire at 5 pm for the
Grand Canyon area and 8 pm for Williams and Flagstaff areas.
Surface air temps now are the mid teens to mid 20s, and we should
all be ready for very slick roads through mid morning Saturday as
lows move into the single digits.

Showers to expand in coverage across Navajo and Apache counties
through the afternoon, but with less vigor than the NW part of
the state has seen. Overnight accumulations look to be in the 1-3
inch range. Southwest winds gusting from 40 to 50 mph have been
reported across the southern halves of Navajo and Apache
counties. This prompted a Wind Advisory that will run through 7 pm

Dry conditions are forecast for all on Saturday. Progs continue
to show increasing cloud cover and very light QPF associated with
a shortwave trough crossing far northern Arizona late Saturday
night. So at this time expect mostly cloudy skies north of I-40
and a few flurries over the highest terrain.  Northwest flow
aloft Sunday morning becomes southwesterly by Monday. Dry weather
is expected with a slow warming trend.

LONG TERM Monday night through Thursday...

The active weather pattern will continue over the Southwest next
week. Current forecast models show another trough pushing down the
West Coast on Monday. The European is more aggressive (and
slower) with the system, developing a closed low off the SoCal
coast early on Tuesday. The GFS is the coldest, with 700mb temps
around minus 10C (low snow levels again). In any case, looks like
another progressive Winter event will impact the area early next
week, perhaps as soon as Tuesday afternoon. We`ve provided a
compromise solution with moderate precipitation amounts and low
snow levels 3500-4500`. The storm will exit the area by late
Wednesday, with dry and cool conditions are expected the rest of
the week.


.AVIATION...For the 06z package...MVFR conditions with -SHSN and
local IFR/LIFR in heavier showers through 06Z-08Z over the
higher terrain. These conditions will shift to areas generally east
of a line from KPAN-K0V7 from 08Z-12Z. Precipitation ending for
all areas after 12Z, with VFR conditions returning most areas
on Saturday. Aviation discussion not updated for






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