805
FXUS65 KFGZ 312318
AFDFGZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
418 PM MST Sun Aug 31 2025

.SYNOPSIS...Rain and thunderstorm chances will gradually increase
starting Monday and continue into next weekend. The best chance of
storms each day will be along and south of the Mogollon Rim, with
lower chances in northeast Arizona. Above average temperatures
Monday will cool slightly as the week progresses.

&&

.DISCUSSION...High pressure is centered over central Arizona this
afternoon, with warm temperatures and mostly sunny skies for most
areas. There is a sharp moisture gradient, with dry air to the
north (PW values 0.40" or lower from Flagstaff northward) and
deeper moisture toward southeast Arizona. Scattered showers have
developed over far southern Apache County including around Alpine
and Nutrioso, and these should remain limited to that area for the
remainder of this afternoon. There is good model agreement that
the center of high pressure will drift northward up into Utah over
the next few days would be favorable for advecting some of the
deeper moisture northward as well. This moisture push could be
aided by some outflow boundaries, including one that is in some of
the CAMs tonight. The last few runs of the HRRR indicates this
outflow boundary spreading north and west to at least Prescott and
Flagstaff overnight. With the additional moisture, there will be a
chance (20-40%) of afternoon showers and thunderstorms along the
Mogollon Rim and White Mountains for Monday, spreading southwest
toward Yavapai/Gila counties later in the afternoon and early
evening. Areas north of the rim look to remain dry. This general pattern
is forecast to persist through much of the coming week, with moisture
being enhanced further due to surges up the Gulf of California mid
to late week, induced by a possible tropical system off the Baja
coast. Daily storm chances go up to 40-60% from the Mogollon Rim
southward, with 10-30% north of the rim.

&&

.AVIATION...Monday 01/00Z through Tuesday 02/00Z...VFR conditions
expected. Showers and a few thunderstorms confined to the White
Mountains end around 03Z. A chance of showers and thunderstorms
exists starting at 18Z for the higher terrain along the Rim and
again in the White Mountains. Winds light and variable overnight,
although KSEZ could see some stronger NE downslope at 10-15kts
gusts to 20kts, then N-NE 5-15kts Monday afternoon.

OUTLOOK...Tuesday 02/00Z through Thursday 04/00Z...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 greatest chances (25-50%) for
showers and thunderstorms to develop along and south of the Grand
Canyon, Mogollon Rim, and White Mountains. 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...JJ
AVIATION...Bernhart
FIRE WEATHER...LaGuardia

For Northern Arizona weather information visit
weather.gov/flagstaff