655
FXUS65 KFGZ 291123
AFDFGZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
423 AM MST Tue Sep 29 2026

.SYNOPSIS...Widespread showers, along with increased thunderstorm
activity, is expected today, continuing the heightened risk of
flooding. A Flood Watch remains in effect for northern Arizona
through this evening. Chances for showers and thunderstorms
continue across eastern Arizona on Wednesday, before warmer and
drier weather returns Thursday and into the weekend.

&&

.DISCUSSION...The mid/upper-level trough with a closed low at its
base is starting to push into Arizona as tropical moisture
continues to sit across northern Arizona. Meanwhile, Hurricane
Polo moving across Baja California. Radar shows heavier showers
and thunderstorms are developing across eastern AZ, and this will
be pushing W to NW across the State today as the trough and close
low move eastward today. This will support impactful weather
across northern AZ today, with a greater focus over eastern AZ
this evening and Wednesday.

From this morning through Wednesday morning, the low is forecast
to move across northern Arizona. As it does so, additional
atmospheric moisture from Hurricane Polo will be entrained into
the low. With increased synoptic-scale forcing associated with the
passing low, greater storm activity and higher rainfall rates are
forecast. High-resolution model guidance continue to highlight
the eastern Mogollon Rim and White Mountains as the area with the
highest flood risk with 24 hour rainfall totals up to 3 inches. An
another signature of an inch or greater is starting to appear in
the 3-hr QPF HREF guidance near the UT and AZ border, near Lake
Powell, this afternoon and early evening hours so this will be a
trend to watch. We will also see higher 0-6km Bulk Wind Shear,
with values ranging from 40-60 kts. Despite the strong shear,
forecast CAPE values at or below 600 J/kg may limit the overall
severe thunderstorm threat, though isolated severe storms cannot
be ruled out given the benefit of forcing from the low. So, all
things considered, we are looking at a moderate/high risk of
flooding/flash flooding, with a lower risk of strong storms
producing large hail and severe wind gusts. A Flood Watch remains
in effect for northern Arizona through Tuesday evening.

On Wednesday, the low center moves into New Mexico, with chances
for showers and storms primarily remaining across eastern
Arizona. High pressure is forecast to bring a return of dry
weather, with daytime temperatures warming to near average on
Thursday and into the weekend.

&&

.AVIATION...Tuesday 29/12Z through Wednesday 30/12Z...Look for
isolated TSRA and scattered to numerous SHRA through the period.
Brief IFR conditions in heavier showers and thunderstorms, or
patchy fog. Showers and storms most active along and south of a
KGCN-KFLG-KSOW line through 00z. After 00Z, the most active area
is expected to shift north of the above line, though additional
SHRA/TSRA are expected on the back side of the trough/closed low
as it moves eastward across AZ. Winds south 5-15 kts daytime,
light and variable overnight. Gusty and erratic winds near storms.

OUTLOOK...Wednesday 30/12Z through Friday 02/12Z...Expect
scattered to numerous showers and thunderstorms area wide through
Tuesday night with the focus of precipitation then shifting
towards eastern Arizona on Wednesday. Look for areas of MVFR
conditions with brief IFR conditions in heavier showers and
thunderstorms. On Thursday, VFR conditions and fair weather
arrives. Daytime winds, west to northwest at 5-15 kts Wednesday,
turning variable on Thursday. Winds light and variable at night.

&&

.FIRE WEATHER...Today through Wednesday...Precipitation chances
will remain high today with widespread wetting rain and isolated
embedded thunderstorms across the region, becoming more focused
over eastern Arizona this evening into Wednesday. This will
present a moderate flood and burn scar flash flood risk. Western
Arizona will start drying out Wednesday. Winds N-NE 10-20 mph
today, NW-N 5-15 mph on Wednesday.

Thursday through Saturday...Dry with no precipitation across the
state, minimum RH drops to the 20s and 30s percent by Saturday.
Daytime high temps will also become near to slightly above normal
across western AZ and near to just below normal for eastern AZ.
Winds light and variable 5-10 mph Thursday, light and variable most
areas Friday/Saturday with the exception of some winds E 5-15 mph
along the Rim.

&&

.FGZ WATCHES/WARNINGS/ADVISORIES...
Flood Watch through this evening for AZZ004>018-037>040.

&&

$$

PUBLIC...Schank
AVIATION...Schank
FIRE WEATHER...Schank

For Northern Arizona weather information visit
weather.gov/flagstaff