016
FXUS65 KFGZ 011142
AFDFGZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
442 AM MST Mon Sep 1 2025

.SYNOPSIS...Daily chances for showers and thunderstorms are
forecast this week, mainly along and south of the Mogollon Rim,
with activity spreading northward later in the week. Strong
outflow winds and localized flash flooding will be the primary
hazards.

&&

.DISCUSSION...For today, isolated to scattered showers and
thunderstorms are forecast primarily along and south of the Grand
Canyon, Mogollon Rim, and White Mountains. Storms will move slow,
generally drifting south or southwest at 5 to 10 mph. Moisture
and instability are somewhat limited, as surface dew points are
forecast to be in the 40-55 F range south of the Rim, and 30-40 F
range north of the Rim. In addition, forecast soundings show a
subsidence inversion aloft strong enough to inhibit all but the
strongest updrafts. There is a medium potential for strong to
severe outflow winds, and a low to moderate potential for flash
flooding. Given the general lack of instability and shear, the
potential for large hail remains low. Otherwise, expect near
normal high temperatures and light winds outside of thunderstorm
generated winds.

Based on consistency in ensemble means and cluster analysis,
confidence is high that northern Arizona will remain under the
influence of an amplified 500 mb ridge through the week. This
pattern will continue to draw atmospheric moisture into the area
leading to active monsoon conditions with good chances (20-60%)
for showers and thunderstorms, with activity spreading further
northward through the week. Strong outflow winds and an
increasing risk of flash flooding will be the primary hazards.

Uncertainty increases in the evolution of the weather pattern
beginning early next week (around Sunday, 9/7) as models indicate
the potential for a West Coast trough to influence the area. This
feature could lead to a drying trend, but the confidence in the
strength of this trough, and subsequent drying, is low at this
point.

&&

.AVIATION...Monday 01/12Z through Tuesday 02/12Z...A chance of
showers and thunderstorms exist starting at 18Z for the higher
terrain along the Rim and in the White Mountains, before storms
move to the south/southwest into the lower elevations. Mainly VFR
conditions are expected through the period, although brief MVFR
visibilities are possible under the strongest storms. Light N-NE
winds from 5-15 kts are forecast Monday afternoon, except in the
vicinity of storms where outflow wind speeds between 30-40 knots
are possible.


OUTLOOK...Tuesday 02/12Z through Thursday 04/12Z...VFR conditions
expected, brief MVFR possible near stronger SHRA/TSRA. Chances
for showers and thunderstorms increase gradually each day
throughout the period over Northern Arizona. Outside of any
erratic outflow winds from storms, anticipate SE-SW winds 5-15kts
for Tuesday, SW-W 5-15kts Wednesday.

&&

.FIRE WEATHER...Monday and Tuesday...Monsoonal moisture and
humidity will gradually increase each day, with the best chances
for showers and thunderstorms along and south of the Grand Canyon,
Mogollon Rim, and White Mountains. There is a 10-40% chance for
storms today, followed by a 25-50% chance on Tuesday. Winds will
remain light, 5 to 15 mph, from the east-northeast on Monday
followed by south-southwest winds on Tuesday.

Wednesday through Friday...A moderate monsoonal moisture surge is
looking more likely through the latter half of the week with
scattered showers and thunderstorms forecast each afternoon. Outside
of any erratic outflow gusts near storms, expect westerly winds 10
to 15 mph each day.

&&

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

&&

$$

PUBLIC...RR
AVIATION...RR
FIRE WEATHER...RR

For Northern Arizona weather information visit
weather.gov/flagstaff