Area Forecast Discussion
Issued by NWS Flagstaff, AZ

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000
FXUS65 KFGZ 192202
AFDFGZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
302 PM MST Thu Jan 19 2017

.SYNOPSIS...A series of winter storms will affect the region from
today, through Monday or Tuesday of next week. These will be cold
systems, with heavy accumulations of snow across the high country.
Hazardous driving conditions should be anticipated for the next
several days.

&&

.DISCUSSION...

SHORT TERM...through Saturday afternoon.

The first short wave trough is making its way into Arizona this
afternoon from southern California. We are in a region of broad
lift ahead of the trough, and in fact a relatively large area of
light to moderate precipitation developed across southwestern
portions of Yavapai County and has begun to move across the
Prescott area. Webcams in downtown Prescott indicate snow falling,
but with wet roads and with no accumulation as of yet. Will
continue with a rain/snow mix through this afternoon in the
5000-5500 foot range, likely becoming all snow this evening as
snow levels drop to around 5000 feet by late tonight. We raised
snow amounts by a couple inches or so in the 5000-5000 foot range
with the event from now through tonight. Otherwise, precip and
snow amounts are relatively consistent with previous forecasts.
Hi-res models, including the experimental HRRR, show the heaviest
precipitation moving across northern Arizona from now through late
tonight, with some lingering showers through the early morning
hours especially in far northeast Arizona and the White Mountains
region.

Though snow showers will likely not completely stop especially
over high elevation locations, expect a brief break in moderate to
heavy precipitation on Friday morning in the wake of the first
short wave trough. The next trough is on the way quickly, with
lift influenced by this second trough initiating over northern
Arizona by early afternoon on Friday. The event from late Friday
afternoon through early Saturday morning will feature a moist
mid-level jet along the base of the trough. The strength of the
Friday evening system, combined with the amount of available
moisture, will enhance snowfall amounts in the higher elevations
as well as rainfall amounts in the low elevation upslope regions
of Gila and southern Yavapai County. The heavy snow and associated
hazardous winter conditions have been well advertised for many
days; we also need to be concerned about potential flooding in the
lower elevations of Gila/southern Yavapai county during and after
the rain on Friday night as the water runs off.

Precipitation will likely continue on the east Rim and over the
White Mountains during the day on Saturday, ending fairly rapidly
from west to east Saturday afternoon as the trough moves out of
northern Arizona.

LONG TERM...Saturday evening through Thursday morning.

Progs are in good agreement through this Wednesday. A fast moving
shortwave ridge will bring clearing conditions from west to east
across the northland Saturday night. This break to last less than
12 hours though as the 3rd winter system sets up off the west
coast on Sunday. This system to spread clouds across our area with
precipitation developing across western AZ. Snow levels should be
rising to between 5500 feet on the Kaibab Plateau to 7000 feet in
the White mountains Sunday afternoon and evening ahead of a strong
cold front. This front moves west to east across the area Sunday
night-Monday morning with gusty southwest winds. Snow levels to
fall to 4500-5500 foot range with precipitation likely. Still to
early for snow amounts. Models are insistent that h5 temps will be
around -30C overhead from Monday evening through at least
Wednesday. This will keep some instability showers going through
Tuesday. Temperature guidance showing max temps around 30 in the
high country with mid 40s in the lower valleys of Yavapai county.
Overnight lows in the single digits and teens for most of us by
Tuesday. These temp forecast may go lower as we move into next
week.

Slight chances of showers to continue Wednesday across Navajo and
Apache counties, otherwise it is just dry and cold.

&&

.AVIATION...For the 00Z package...2 storm systems to move west
to east across northern Arizona over the next 24 hours. Expect
widespread MVFR conditions and areas of IFR/LIFR conditions in rain
and snow showers. Aft 18z Friday The stronger of the 2 systems to
bring widespread IFR with steady rain and snow to areas west of
KPGA-KFLG-KSOW line. Aviation discussion not updated for TAF
amendments.

&&

.FGZ WATCHES/WARNINGS/ADVISORIES...Winter Storm Warning until noon MST Saturday FOR AZZ004-006>008-
015>018-038.


&&

$$

PUBLIC...AT
AVIATION...DL


For Northern Arizona weather information visit
weather.gov/flagstaff


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