437
FXUS65 KFGZ 261717
AFDFGZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
1017 AM MST Sat Sep 26 2026

.SYNOPSIS...A quiet day is expected Saturday with dry weather and
seasonal temperatures. Starting Sunday afternoon an incoming
trough from the West Coast will interact with tropical moisture
potentially bring heavy rain, strong thunderstorms and possible
flash flooding. Widespread precipitation chances continue through
Tuesday before declining by midweek.

&&

.DISCUSSION...Today...Following the passage of a weak upper-level
trough yesterday, brief ridging with much drier air has taken
hold today. Precipitation chances drop to zero across all of
northern Arizona as a result. Expect a pleasant day with south to
southwest afternoon breezes and near normal daytime temperatures.

Sunday through Tuesday...We are setting up to have an active stretch
of weather to begin the week. A pair of tropical systems in the
Pacific (Hurricane Polo and Hurricane Odalys) are forecast to drift
north through the period. Meanwhile, a deep west coast trough is
forecast to dive southeastward along the California coast on Sunday-
Monday, then eventually cross directly over Arizona. While the
remnant tropical circulations will not directly impact northern
Arizona, the trough will interact with the enhanced field of moisture
around the systems and we will see a deep surge of moisture into
the region.

Upper-level moisture looks to arrive as early as Sunday morning as a
subtle shortwave ripples ahead of the deeper west coast low. We may
begin the day with some high-based activity, but will quickly
moisten up in the lower levels by Sunday evening. Precipitation
chances ramp up Sunday night, becoming widespread by Monday as
moisture continues to stream in ahead of the approaching trough.
Given the setup, there is risk of heavy rainfall and flash flooding
through the period. The latest WPC ERO puts all of northern Arizona
in the Slight risk category on Monday. Also, enhanced shear from the
trough could allow for better storm organization and some threat of
severe storms. There still remains a degree of uncertainty among
ensemble guidance on how progressive the trough will be, however
confidence is increasing towards a slower set up that will bring
another active day on Tuesday with more flooding threats and severe
threats. Besides precipitation, expect breezy south-southwest winds
on Sunday and Monday and cool daytime temperatures to start the week.

Wednesday through Friday...By Wednesday, the trough axis will be
pushing out of our area. Precipitation chances will decline from
west to east as much drier air and subsidence follows in its wake.
Expect dry conditions with warming daytime temperatures to end the
week.

&&

.AVIATION...Saturday 26/18Z through Sunday 27/18Z...VFR
conditions. Winds SW-SE 5-15 kts through 02Z, light and VRB
otherwise.

OUTLOOK...Sunday 27/18Z through Tuesday 29/18Z....VFR conditions
through Sunday evening, with periods of MVFR expected in SCT-NMRS
SHRA/TSRA thereafter. Daytime winds are S/SW 10-15 kts gusting to
25 kts on Sunday, becoming S 10-20 kts on Monday. Overnight winds
light and variable. Gusty and erratic winds near storms.

&&

.FIRE WEATHER...Today through Sunday...Dry conditions are expected
today, then slight chances for showers and thunderstorms return by
late Sunday afternoon. Precipitation chances continue to ramp up
overnight Sunday. Winds are S-SW 5-15 mph on Saturday, then 10-20
mph gusting to 30 mph on Sunday.

Monday through Wednesday...Prolonged widespread precipitation
chances Monday through Tuesday as an approaching weather system
combines with tropical moisture. Precipitation chances decline from
west to east overnight Tuesday into Wednesday morning. There is a
threat of heavy rainfall and flash flooding on Monday-Tuesday for
all of northern AZ. Winds S-SW 10-20 mph on Monday, shifting N-NE 10-
20 mph on Tuesday, then NW-N 5-15 mph on Wednesday.

&&

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

&&

$$

PUBLIC...Lewandowski
AVIATION...Zanker
FIRE WEATHER...Lewandowski

For Northern Arizona weather information visit
weather.gov/flagstaff