116
FXUS65 KFGZ 151744
AFDFGZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
1044 AM MST Mon Sep 15 2025

.SYNOPSIS...High pressure over the Southwest will result in
seasonable temperatures, light winds, and mostly dry conditions
through the next few days. Chances for showers and thunderstorms
look to return by the second-half of the week.

&&

.DISCUSSION...Today...Weak ridging remains in place over northern
Mexico, keeping cooler temperatures and mainly dry conditions in
place across northern Arizona. The only real shot at a couple
afternoon showers and storms today look to be over the White
Mountains, but even then, activity looks to be minimal.

Tuesday and Wednesday...Tropical Storm Mario off the tip of Baja
California looks to initiate a moisture surge up the Gulf, with
moisture increasing over southern Arizona each day. While at the
same time, the ridge looks to retrograde and become elongated
from Nevada across Arizona into New Mexico. These two contradicting
forces look to create a sharp moisture souht-north gradient
somewhere across northern Arizona, with the drier northwest flow
cutting off any sub-tropical moisture advection. Current guidance
looks to cut off any of the deeper moisture near the Mogollon
Rim, thus any chances for precipitation through the middle of the
week will largely be from the Rim and south. Model soundings also
show a fairly significant subsidence inversion aloft with the
ridge in place, which will also limit the overall coverage of
storms. Warmer, but still seasonable temperatures also look to set
in through Wednesday.

Thursday through Sunday...By the end of the week, guidances has the
remnants of Mario ejecting off the Pacific into southern
California, before being absorbed into the mean flow. Flow begins
to shift to favor increased moisture advection over a larger
portion of the area as a result. There are many moving parts here,
and the exact timing and track of each part will greatly impact
the extent of the moisture push. The operational guidance still
varies greatly on where the low ejects, so confidence remains low,
however ensemble members do seem to be favoring an increase in
PWAT more so than in previous runs. Outside of the precipitation
chances, cooler temperatures look to return to northern Arizona to
close out the week.

&&

.AVIATION...Monday 15/18Z through Tuesday 16/18Z...VFR conditions
will continue. Isolated -TSRA possible in the White Mountains SE
of KSOW 20-02Z. SW winds 10-15 kts gusting near 20 kts through 02Z
before becoming light and variable.

OUTLOOK...Tuesday 16/18Z through Thursday 18/18Z...VFR conditions
expected. Isolated to scattered -TSRA in the White Mountains each
afternoon. W/SW winds Tuesday 10-15 kts gusting 20 kts, shifting
to W/NW on Wednesday at 5-15 kts. Winds becoming light and
variable overnight.

&&

.FIRE WEATHER...Today and Tuesday...Mostly dry with near-average
temperatures. Slight chance for showers and thunderstorms in the
White Mountains each afternoon. Afternoon winds west/southwest 5-15
mph with minimum RH 10-25% each day.

Wednesday through Friday...Chances for showers and thunderstorms
increasing each day, mainly along and south of the Mogollon Rim.
Daytime winds west/northwest 5-15 mph, becoming southwest by Friday.
Minimum RH 10-25% through Thursday, increasing to 20-40% on Friday.

&&

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

&&

$$

PUBLIC...Humphreys
AVIATION...MCT
FIRE WEATHER...Humphreys

For Northern Arizona weather information visit
weather.gov/flagstaff