Area Forecast Discussion
Issued by NWS Flagstaff, AZ

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FXUS65 KFGZ 091626

Area Forecast Discussion
National Weather Service Flagstaff AZ
926 AM MST Tue Jan 9 2018

.SYNOPSIS...Expect scattered rain showers and breezy conditions
today. By this evening, more widespread rain will develop and
spread east, transitioning to snow in the mountains by early
Wednesday. Light snow accumulations are likely by Wednesday
morning above 6000 feet, which may lead to icy road conditions.
Fair and mild weather returns Thursday through next weekend.


.UPDATE...The upper low is currently centered just off the
southern California coast this morning. A frontal precipitation
band is moving onshore, and will continue to march eastward into
Arizona later this evening and overnight. An early look at the
latest morning model runs shows little change from earlier runs,
and our current forecasts look to be on track for now. The main
challenge with tonight`s forecast will be timing the switchover
from rain to snow at higher elevations, and we will take a close
look at this for the afternoon package. Right now, it looks like
the changeover around 10 PM to midnight in the Flagstaff area. No
forecast updates needed at this time.


.PREV DISCUSSION /426 AM MST/...Low pressure currently spinning
off the southern California coast will move east over the next 36
hour bringing some long overdue rain and mountain snow across
northern Arizona. As the low tracks inland across southern
California today, Arizona will remain under a strengthening and
moistening pre-frontal air mass. Expect scattered showers to
increase through the afternoon hours across Coconino and Yavapai

The main precipitation event will arrive this evening and
overnight when the cold front associated with the low marches east
across the state. We expect mostly rain through the early evening
hours for all but the highest mountain peaks. Enough instability
may lead to a few thunderstorms south of the Mogollon Rim where
isolated stronger wind gusts are possible. The cold front and
heaviest precipitation will move into western Coconino and
Yavapai Counties this evening then head east into Navajo and
Apache Counties by early morning Wednesday. Snow levels will
quickly drop to around 6,000 feet behind the front with light snow
accumulations of generally 1 to 3 inches forecast. Locally higher
amounts will fall over the highest peaks. High resolution model
forecasts this morning hint at precipitation holding on a bit
longer over the Rim country Wednesday morning and have nudged
precipitation amounts slightly upward. In addition to the rain and
snow, expect increased wind speeds through Wednesday. Roads in
the high country may become quite slick for the Wednesday morning
commute after a period of rain followed by accumulating snowfall.
Be sure to allow extra travel time.

Showers will taper from west to east through the day Wednesday,
with a few showers lingering Wednesday evening in eastern Arizona.
By thursday, dominant high pressure returns with northwest flow
setting up over Arizona. Expect dry weather through the weekend
with warming daytime temperatures.


.AVIATION...For the 18Z package...Expect increasing clouds and
lowering ceilings this afternoon moving in from the southwest. Rain
showers will develop primarily west of I-17/US89. After 00z, heavier
showers will move across the area from west to east changing to snow
by about 07Z above 6000 feet MSL mostly along the Mogollon Rim to
the White Mountains. Isolated TSRA are possible across southern
Yavapai County late this evening. MVFR/IFR ceilings and visibilities
are likely near the showers, especially over higher terrain that
switch to snow, and are likely into Wednesday morning along and
southwest of the Mogollon Rim due to upslope flow. Aviation
discussion not updated for amendments.


.FIRE WEATHER...Southwest winds and rain shower activity will slowly
increase through this afternoon, ahead of an approaching cold front.
The front will cross the area from west to east tonight, leading to
widespread rain and snow. Isolated thunderstorms will be possible
along the front as it crosses Yavapai County late this evening. The
front begins to exit the area Wednesday, with lingering showers
possible through Wednesday evening. Strong southwest winds continue
over the eastern zones.

Thursday through Saturday...Drying and warming conditions develop
Thursday, lasting into the weekend.






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