891
FXUS65 KFGZ 152335
AFDFGZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
435 PM MST Mon Sep 15 2025

.SYNOPSIS...High pressure over the Southwest will result in
seasonable temperatures and mostly dry conditions through the
next few days. Chances for showers and thunderstorms will increase
for the second-half of the week.

&&

.DISCUSSION...The weather pattern early this week will be
dominated by weak high pressure aloft resulting in mostly dry
conditions and seasonal temperatures. Any precipitation chances
will be confined to the White Mountains region through Wednesday,
where just enough moisture will allow the development of isolated
to scattered afternoon thunderstorms. High temperatures will be
near to slightly above average, while overnight lows will run a
few degrees below average. Some high elevation cold spots such as
Bellemont and the Grand Canyon have already seen lows in the
mid/upper 30s and will continue to for the next couple of nights.

As we are in prime "transition" season, the pattern begins to
shift later this week with the interaction of a weak trough and
remnant tropical moisture. Tropical Storm Mario is currently west
of the Baja Peninsula and will continue to track northward through
the week. The remains of Mario are forecast to get entrained in a
weak Pacific trough that eventually tracks over southern
California and Arizona Thursday night through Saturday. Blended
forecast guidance (NBM) today continues to show increasing
precipitation chances and cooler temperatures during this time
period. A majority of the ensemble guidance suggests the increase
in moisture and precipitation chances, giving us moderate
confidence in this pattern change. There are some indications
that a second and stronger trough could move into the area on
Sunday bringing additional precipitation chances, but any
confidence in this remains very low at this time. These early
autumn weather patterns are very dynamic with a lot of moving
parts. Any slight variations in the forecast track of the trough
will have dramatic impacts to the forecast. Stay tuned this week
as this pattern continues to evolve.

&&

.AVIATION...Tuesday 16/00Z through Wednesday 17/00Z...VFR conditions
will continue. Isolated -TSRA possible in the White Mountains
southeast of KSOW until 02Z. Southwest winds 10-15 kts gusting
near 20 kts through 02Z before becoming light and variable
overnight. On Wednesday, Look for another round of isolated -TSRA
in the White Mountains southeast of KSOW after 18Z. Gusty
southwest winds at 10-20 kts are forecast.

OUTLOOK...Wednesday 17/00Z through Friday 19/00Z...VFR conditions
expected. Isolated to scattered -TSRA in the White Mountains each
afternoon. West to southwest winds at 10-15 kts gusting 20 kts on
Tuesday, shifting to north to northwest on Wednesday at 5-15 kts,
then variable at 5-15 kts on Thursday. Winds becoming light and
variable overnight.

&&

.FIRE WEATHER...Tuesday and Wednesday...Mostly dry and seasonal
weather will continue, with isolated to scattered thunderstorms
in the White Mountains Tuesday and Wednesday afternoons. Winds
will be west to southwest at 10-20 mph Tuesday, shifting to west
to northwest on Wednesday around 5-15 mph.

Thursday through Saturday...Expect increasing moisture and
relative humidity, as well as increasing chances for wetting rain
and thunderstorms. Temperatures will remain near to below average.
Winds are forecast to remain 10-15 mph or less, with variable
directions Thursday, becoming west to southwest for Friday and
Saturday.

&&

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

&&

$$

PUBLIC...MCT
AVIATION...McCollum
FIRE WEATHER...MCT

For Northern Arizona weather information visit
weather.gov/flagstaff