375
FXUS65 KFGZ 181836
AFDFGZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
1136 AM MST Fri Sep 18 2026

.SYNOPSIS...A few showers and thunderstorms will continue near the
New Mexico border and far northern Arizona through this evening,
with much drier air moving in from west to east for the weekend.
Expect warm high temperatures and cold overnight low temperatures
over the weekend, as shower chances disappear. This may last
through Monday, before unsettled weather returns for the rest of
next week.

&&

.DISCUSSION...Low pressure moving through the northern Rockies today
will continue to push a drier air mass eastward into our region.
This is reflected in the satellite precipitable water estimates
showing PW values falling to <0.50" over the high country
compared to 0.80"+ yesterday at this time. Enough moisture lingers
over the far eastern portions of the forecast area (Apache
County) for some isolated to scattered thunderstorm activity later
this afternoon, and some of this could produce additional
localized heavy rain. Also, as the trough axis swings by to our
north later this evening, a few showers or storms could develop
north of I-40 to the AZ/UT line, and a 10-30% PoP is in the
forecast in that area. By Saturday and Sunday, models show
continued drying as westerly flow persists. Precipitable water
values fall even more, to under 0.30" for most locations with
dewpoints in the 20s and 30s. Pleasant daytime temperatures close
to normal will be followed by some cool nights. With these lower
dewpoints, expect some high elevation locations to fall into the
30s overnight, with near-freezing temperatures Sat-Mon mornings at
the typical cold spots (Bellemont, Tusayan, Ft. Valley).

Monday through Tuesday - a low pressure system is forecast to cross
west to east across the region. Much of the guidance has it tracking
through southern NV into UT Monday night into Tuesday. Most of
Monday is looking dry at this time, with rain chances entering the
forecast Monday evening in NW Arizona, spreading eastward through
the night and into Tuesday. Moisture return ahead of the trough
looks sufficient for some showers and thunderstorms to develop, but
forecast PW values are nothing like we saw earlier this week so the
threat of heavy rainfall/flooding is fairly low. The exception may
be right along the AZ/NM state line as deeper moisture in New Mexico
could be drawn in to that area so that is something to watch.
Wednesday through Friday - majority of ensemble members indicate
high pressure strengthening over the south central United States,
with south-southwest flow aloft over our area. Moisture values are
forecast to remain sufficient for daily thunderstorm chances,
currently in the 20-50% range each day. Daytime temperatures
forecast to be within a few degrees of normal.

&&

.AVIATION...Friday 18/18Z through Saturday 19/18Z...Expect VFR
conditions. SCT -SHRA/-TSRA near the NM border this afternoon,
then ISOLD near the UT border this evening. Winds are SW 10-15 kts
gusting near 20 kts through 03Z, then light and VRB overnight.

OUTLOOK...Saturday 19/18Z through Monday 21/18Z...Expect VFR
conditions. ISOLD -SHRA/-TSRA near the NM border on Saturday,
then fully dry on Sunday. Winds are SW 10-15 kts gusting near 20
kts each day, light and VRB during the overnight periods.

&&

.FIRE WEATHER...Saturday and Sunday...Turning much drier this
weekend. Very isolated showers possible along the AZ-NM border on
Saturday, then fully dry on Sunday. Expect much colder overnight
lows, especially Saturday night. Winds are southwest 10-20 mph each
day.

Monday through Wednesday...Chances for showers and thunderstorms
return by Monday evening and continue through Tuesday and Wednesday.
Best chances each day will be across far eastern AZ. Winds are south
through southwest 5-15 mph on Monday and Tuesday, then light and
variable on Wednesday.

&&

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

&&

$$

PUBLIC...JJ
AVIATION...Lewandowski
FIRE WEATHER...Peterson

For Northern Arizona weather information visit
weather.gov/flagstaff