114 
FXUS65 KFGZ 210348
AFDFGZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
848 PM MST Sun Feb 20 2022

.SYNOPSIS...Windier and colder weather arrives for Monday and 
Tuesday, with scattered rain and snow showers expected over the 
high terrain. Widespread rain and accumulating snow down to 4000
feet set in late Tuesday into Wednesday, leading to potentially 
hazardous travel conditions across the region.

&&

.UPDATE...The southwest winds have decreased in intensity this
evening across north-central Arizona. Winds will remain breezy for
higher terrain locations tonight with increasing mid to high cloud
cover. This will result in low temperatures being a few degrees 
warmer compared to last night's.

The forecast is on track with a return to a more active winter
weather pattern for the first half of this week. First, the winds
and colder temperatures for Monday into Tuesday and then the rain
and accumulating snow for late Tuesday through Wednesday. Southwest
winds increase in intensity by Monday morning, peaking for the 
afternoon hours. Though Tuesday's winds are not expected to be 
quite as strong as Monday's, nevertheless they remain gusty. 
Please refer to the Wind Advisory for more details regarding wind 
speeds and impacts.

Scattered showers looks to develop later on Monday, mainly for 
areas near the AZ/UT border and around the Flagstaff region, but 
impacts (if any) will be minimal. The bulk of the precipitation 
for this week is expected for late Tuesday through Wednesday with 
accumulating snowfall down to 4000 feet. 

&&

.PREV DISCUSSION /225 PM MST/...Monday and Tuesday...A longwave 
trough developing over the Pacific Northwest digs southward into 
the Great Basin on Monday. As an initial shortwave moves into 
Arizona, the pressure gradient increases resulting in a strong 
upper-level jet developing. Consequently, winds increase over much
of the area during the late morning and into Monday night. Model 
soundings show vertical mixing through around 700-650 mb where 
winds initially in the 30-40 kt range. However, as the trough axis
draws the boundary layer depth decreases but at the same time 
low-level winds at the top of the boundary layer increase to 
around 50-60 kts, so the potential to mix down strong gusts looks 
to remain. Winds begins to die down over western Arizona by Monday
evening, however, winds remain locally gusty overnight, before 
increasing yet again Tuesday afternoon along and downwind of the 
Mogollon Rim. As a result, wind advisories have been issued for 
much of the area for wind gusts in the 40 to 50 mph range. The 
strongest winds are expected to be downwind of the Mogollon Rim 
during the afternoon Monday, where gusts up to 55 mph are 
possible. Consequently with the strong southwesterly flow, 
moisture is advected into the region with scattered rain/snow 
showers developing over the higher terrain by Monday afternoon. 
Shower coverage is expected to continue into Tuesday with a slight
uptick in coverage with increasing moisture. However, moisture 
initially remains fairly limited, with little in terms of coverage
and amounts expected. Snowfall amounts through Tuesday afternoon 
will generally be 1 to 2 inches for areas above 6000 feet.

Late Tuesday and Wednesday...Upper-level dynamic support increases
over the region as the mean trough axis approaches. As it does,
the base of the trough extends out off the California coast over
the Pacific allowing for increase moisture advection. This
increase in upper-level support combined with the increased
moisture will result in more widespread shower activity. Much
colder air also moves into the region, allowing for snow levels
to drop to around 4000 feet by Wednesday afternoon. At this time,
the time frame for the most significant impacts looks to be late
Tuesday night into Wednesday afternoon. Snowfall amounts look to
be generally 1 to 3 inches for areas between 4000 to 5500 feet and
4 to 8 inches above 5500 feet. Locally higher amounts of 8 to 12
inches will be possible along the high terrain of the Mogollon
Rim and White Mountains. Hazardous travel will be possible
Tuesday night and Wednesday, so be prepared for slippery and snow
covered roadways. Areas of gusty winds are expected to remain on
Wednesday, resulting in blowing and drifting snow which could
significantly reduce visibility at times.

Wednesday Night onward...As the trough begins to lift eastward,
precipitation begins to diminish from west to east late Wednesday
night into Thursday. Drier conditions with cooler temperatures and
light winds are expected to prevail from Thursday onward, with
heights beginning to rise with the ridge building back once again
off the Pacific.

&&

.AVIATION...For the 06Z package...VFR conditions prevail through 
Monday afternoon with variable mid to high cloud cover. Periods of 
MVFR VIS/CIGS are possible after 00Z Tue for KFLG-KGCN-KPGA due to 
isolated/scattered rain and snow showers. South-southwest winds 
remain overnight around 10 kts, increasing to around 20-30 kts by 
18Z. Gusts of 35-45 kts are anticipated in the afternoon, especially 
along and near a KGCN-KINW-KSJN line. Minor to moderate turbulence
is likely during this time. Winds remain breezy to gusty Monday 
night. Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Scattered rain/snow showers develop over the high
terrain late Monday and again on Tuesday. Colder temperatures along 
with gusty to strong southwest winds are also forecast. Expect 
widespread peak gusts of 30-50 mph for Monday afternoon, remaining 
gusty on Tuesday. 

Wednesday through Friday...Widespread rain/snow showers continue 
through much of Wednesday, tapering off from west to east overnight. 
Drier conditions with continued cooler temperatures continue through 
Friday. Breezy conditions remain on Wednesday, with lighter winds 
thereafter.

&&

.FGZ WATCHES/WARNINGS/ADVISORIES...Wind Advisory from 11 AM Monday to 
5 PM MST Tuesday FOR AZZ012>017.

Wind Advisory from 11 AM to 9 PM MST Monday FOR AZZ004>011-039-
040.

&&

$$

PUBLIC...LaGuardia/Humphreys
AVIATION...LaGuardia
FIRE WEATHER...LaGuardia


For Northern Arizona weather information visit
weather.gov/flagstaff