605
FXUS65 KFGZ 201127
AFDFGZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
427 AM MST Sun Jul 20 2025

.SYNOPSIS...Scattered shower and thunderstorm activity is forecast
to bring some localized, heavy rainfall today. Isolated to
scattered thunderstorms will continue Monday and Tuesday,
followed by a declining trend in precipitation chances around the
middle of next week.

&&

.DISCUSSION...Northern Arizona remains sandwiched between a 500 mb
low centered over southern California and an elongated
subtropical high pressure system draped across the central and
southeast United States. Southerly flow between these features
continues to draw monsoon moisture into the state, with the
deepest moisture over eastern Arizona and drier air to the west.

Overnight satellite imagery shows an MCS over the Sierra Madre
Occidental mountain range in northern Mexico that is slowly
pushing northward into southern Arizona. Moisture associated with
this system is expected to continue its northward trajectory,
eventually interacting with the mountains of northern Arizona to
serve as a focus for shower and thunderstorm development this
afternoon and evening. It`s hard to say exactly how far west the
remnant moisture will spread, but it will likely impact portions
of Yavapai and Coconino Counties.

For today, the existing monsoon moisture plume and influences from
the aforementioned MCS will bring a round of isolated to scattered
showers and thunderstorms to northern Arizona, primarily along
and south of the Mogollon Rim, with shower activity expanding to
include the Grand Canyon country later in the afternoon and
evening. Similar to yesterday, a mid-level cap and a general lack
of instability due to cloud cover should inhibit vigorous
convective activity, except perhaps on the periphery of the
monsoon plume where we see better surface heating. Today`s storms
will bring a low risk of localized flash flooding due to slow
storm motion. The severe threat is minimal given the overall lack
of instability.

Overnight, the Southern California low will begin to fill and
lift to the northeast. As it does so, shower activity may continue
through the overnight hours over portions of Yavapai and Coconino
Counties as it interacts with lingering moisture there.

The filling low swings across the area as an open wave on Monday.
As a result, more widespread shower and thunderstorm activity is
forecast due to influences from the passing trough. Another round
of scattered showers and thunderstorms is forecast on Tuesday,
followed by a decline in monsoon activity beginning Wednesday as
a deep, West Coast low pushes the monsoon plume east of the state.

&&

.AVIATION...Sunday 20/12Z through Monday 21/12Z...Isolated to
scattered showers and thunderstorms AFTER 20/18Z. Brief MVFR
visibilities and gusty winds possible near thunderstorms.
Otherwise winds light and variable or terrain driven overnight,
SW-W 5-15kts, gusts 20kts daytime.

OUTLOOK...Monday 21/06Z through Wednesday 23/06Z...VFR conditions,
Isolated to scattered showers and thunderstorms each afternoon
between 18Z and 03Z. Brief MVFR and gusty winds possible near
thunderstorms. Otherwise winds SW-W 5-15kts, gusts 20kts daytime,
light and variable or terrain driven overnight.

&&

.FIRE WEATHER...Sunday and Monday...Isolated to scattered
showers and thunderstorms are expected each afternoon and evening,
with the potential for showers to continue across Yavapai and
Coconino Counties tonight. Mainly southwest winds in the daytime,
10 to 15 mph on Sunday, increasing to 10 to 20 mph on Monday.
Winds may be highly erratic near storms and around outflow
boundaries.

Tuesday through Thursday...Scattered showers and thunderstorms
Tuesday, becoming more isolated Wednesday and Thursday. Southwest
winds 10 to 20 mph each day.

&&

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

&&

$$

PUBLIC...RR
AVIATION...RR
FIRE WEATHER...RR

For Northern Arizona weather information visit
weather.gov/flagstaff