942
FXUS65 KFGZ 200502
AFDFGZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
1002 PM MST Sat Sep 19 2026

.SYNOPSIS...Dry and mostly precipitation-free conditions will
continue through Sunday. Typical fall weather will occur, with
seasonable high temperatures and colder overnight lows. Shower
and thunderstorm chances begin to increase Monday, with more
widespread activity expected Tuesday as moisture returns to
northern Arizona. Unsettled weather is then expected to continue
through much of the remaining week.

&&

.DISCUSSION...A 500 mb longwave trough is slowly moving eastward
across northern Arizona. This system is pulling dry air into the
region. Satellite measurements of the atmospheric moisture (PW),
show values between 0.35-0.45 inches over the High Country, with
0.45-0.75 inches within the Little Colorado River Valley and the
lower deserts south of the Mogollon Rim. For comparison, PW was
significantly higher Thursday afternoon, with 0.75 to 1.25 inches
observed across the area.

This dry air, combined with a weak mid-level inversion around
560mb, will suppress thunderstorm activity this afternoon. This
will leave almost all of northern Arizona precipitation free,
except along the eastern Mogollon Rim and White Mountains (Heber-
Overgaard eastward), where the forecast calls for a 10-20% chance
of showers and thunderstorms there.

On Sunday, drier and more stable conditions will suppress shower
and thunderstorm activity area-wide. A few pockets of freezing
temperatures may develop in sheltered valleys above 6500 feet.

On Monday, an approaching West Coast low begins to influence
northern Arizona weather. Dry and stable conditions continue, but
model guidance suggests a return of isolated showers and perhaps
a thunderstorm or two are possible northwest of Flagstaff. The
current forecast calls for a 10-20% chance of showers there.

By Tuesday, the low moves far enough inland to transport moisture
into the area for an uptick in shower and thunderstorm activity
across much of northern Arizona. At this point, the main focus
areas for storms are over eastern Arizona and Grand Canyon
Country. In addition, southerly wind speeds are forecast to
increase, likely remaining below Wind Advisory level thresholds,
with gusts near 30 mph forecast over higher terrain.

On Wednesday, model guidance is in agreement that the low will
exit the area, but the development of another West Coast trough
combined with surges of tropical moisture keeps chances for
showers and thunderstorms in the forecast for the remainder of the
week.

&&

.AVIATION...Sunday 20/06Z through Monday 21/06Z...VFR conditions.
Winds are SW 10-15 kts from 17Z-02Z, light and VRB overnight.

OUTLOOK...Monday 21/06Z through Wednesday 23/06Z...Primarily VFR
conditions. Winds are S-SW 10-15 kts each afternoon, light and VRB
each night. ISO to SCT -SHRA/-TSRA may return Monday night.

&&

.FIRE WEATHER...Sunday and Monday...Staying mostly dry through
the period. Dry air will lead to much colder lows each morning.
Isolated showers and thunderstorms may return across northwest AZ
on Monday night. Southwesterly winds 5 to 15 mph each day.

Tuesday through Thursday...Chances for showers and thunderstorms
continue each day, with the best chances across eastern AZ. South
through southwest winds 10 to 20 mph with gusts up to 30 mph on
Tuesday, becoming light and variable on Wednesday and Thursday.

&&

.FGZ WATCHES/WARNINGS/ADVISORIES...None.

&&

$$

PUBLIC...RR
AVIATION...Zanker
FIRE WEATHER...Peterson

For Northern Arizona weather information visit
weather.gov/flagstaff