965
FXUS65 KFGZ 231939
AFDFGZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
1239 PM MST Sun Aug 23 2026

.SYNOPSIS...Moderate monsoon activity will continue through
Monday, mainly along the higher terrain during the afternoon and
evening hours. Then, as high pressure builds over Arizona, hot
weather and a decline in storm activity is expected to develop as
the flow of moisture northward into the region diminishes.

&&

.DISCUSSION...Upper-air analysis shows the 500mb subtropical high
pressure cell centered across central New Mexico, with a
northeastward-moving shortwave trough draped across the Yavapai
and Coconino County border. This system is actively supporting
showers and thunderstorms across western Yavapai and Coconino
Counties, while aiding convective initiation along portions of the
Mogollon Rim.

Moderate monsoon conditions persist today with storms drifting
northeastward on average. The forecast favors high-terrain
locations, with a chance for showers and thunderstorms between
30-60% in the mountains. However, mid-level warming is limiting
deep atmospheric instability, keeping the threat for severe
weather low. Given the presence of slow-moving storms, there is a
low to medium risk for flash flooding. This threat is tempered by
atmospheric moisture (precipitable water) values ranging from
0.75-0.85 inches north of the Mogollon Rim and 0.85-1.15 inches
south of the Rim. Outflow wind gusts between 35-45 mph are
possible in the vicinity of storms.

Storm activity is forecast to decline after sunset. High-
resolution model guidance indicates overnight showers and
thunderstorms may move into the region from the south, impacting
areas west of a Payson to Flagstaff to Page line. Similar
convective coverage is forecast on Monday, though a surge of
moisture northward from the Gulf of California will likely shift
the main axis of high storm coverage into Coconino and Yavapai
Counties, with more isolated activity expected elsewhere.

By mid-to-late week, guidance generally agrees that the
subtropical high pressure circulation will strengthen over
Arizona. This will introduce more stable atmospheric conditions
and a noticeable downturn in storm coverage, leaving only low-
grade monsoon activity through the remainder of the week.
Temperatures are forecast to warm during this period, with daytime
temperatures approaching 10 degrees above normal across much of
the area. Excessive Heat products may become necessary for lower
elevation areas, including portions of Yavapai County and Grand
Canyon country.

&&

.AVIATION...Sunday 23/18Z through Monday 24/18Z....Mainly VFR
conditions. Isolated to scattered SHRA/TSRA starting to develop
at 18Z and continuing through at least 03Z. There is the potential
that SHRA/TSRA in south-central AZ could produce an outflow
boundary that will trigger another round of SHRA/TSRA late tonight
or early Monday morning for KPRC-KSEX-KFLG-KINW between 9Z and
18Z. Brief MVFR conditions and gusty/erratic wind possible in
heavier SHRA/TSRA. Otherwise, look for south to southwest winds
at 5-15 kts, with variable or terrain wind-driven winds overnight.

OUTLOOK...Monday 24/18Z through Wednesday 26/18Z...Expect mainly
VFR conditions. Scattered afternoon/evening SHRA/TSRA Monday, with
coverage decreasing to isolated by Tuesday. Outside of
gusty/erratic outflow driven winds, look for daytime winds mainly
southwest to west 5-15 kts. Light and variable winds at night.

&&

.FIRE WEATHER...Rest of today through Tuesday...Expect daily chances
for showers/thunderstorms, with the greatest coverage across the
higher terrain. Activity will ramp up around midday then continue
through the evening hours. Drier conditions are possible starting
Tuesday, with low-grade monsoonal conditions developing. Outside of
gusty and erratic storm driven winds, look for southwest to west
winds generally 10 mph or less during the day and variable at night.

Wednesday through Friday...Drier, low-grade monsoonal conditions
will likely continue, with activity becoming more limited to the
White Mountains. Daytime highs are forecast to become quite hot,
reaching up to 10-15 degrees above normal. Look for southwest winds
5-15 mph each afternoon.

&&

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

&&

$$

PUBLIC...RR
AVIATION...Schank
FIRE WEATHER...McCollum

For Northern Arizona weather information visit
weather.gov/flagstaff