512
FXUS65 KFGZ 010504
AFDFGZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
1004 PM MST Sat Oct 31 2026

.SYNOPSIS...Isolated to scattered showers continue through this
afternoon, then become more widespread tonight through Sunday. Heavy
rain is expected with flash flooding possible across the entire
region. This is a serious situation. Stay tuned to your favorite
weather source and find a way to receive warnings. Stay away from
waterways. Turn around, don`t drown.

&&

.DISCUSSION...A soggy Halloween weekend is expected overall but
Halloween night is shaping up to be dry in most places.

Moisture continues to surge northward ahead of an approaching trough
this afternoon. The trajectory of the moisture combined with some
shallow instability, will allow for upslope showers to develop and
continue into this afternoon, especially along and south of the
Mogollon Rim.

The deepening west coast trough will be the catalyst for the next
round of heavy rainfall from late tonight through Sunday. As we head
into this evening, moisture continues to increase and with the mid-
level flow strengthening and rain becoming more widespread across
the region. Expect increased activity with moderate to heavy rain to
continue from late tonight into Sunday. On Sunday, the trough starts
to push to the east. This will drag a strong cold front through the
area, further enhancing the heavy rain into Sunday evening, plus
adding a marginal severe risk for Sunday. Main severe hazards will
be a damaging wind threat. While conditions are not ideal for
rotating storms, we cannot rule out an isolated tornado, mainly
across the southern most parts of our forecast area. Models continue
to hit the precipitation aspect of the event hard, especially along
and south of the Mogollon Rim. PWATs remain well above normal with
values ranging between 1.0"-1.5" through much of the region. The
already saturated grounds will exacerbate flooding concerns and in
some areas we may see sharp rises on creeks and streams with what we
would normally consider relatively light rainfall amounts. Rainfall
totals remain highest along and south the Mogollon Rim, with totals
between 3"-6". Other areas may see 1"-3" with locally 4"+ possible.
The Flash Flood Watch remains in effect through late Sunday night
for the entire forecast area. It is not often we see a moderate
excessive rainfall outlook across our area from the Weather
Prediction Center, so please heed all warnings and road closures
throughout the event.

** There is potential for significant hydrological issues to
continue due to the very wet antecedent conditions. Both flash
flooding and river flooding will be a problem, with some area
waterways remaining elevated for days beyond the main event. Be
prepared in case you need to take action or need to head to higher
ground. Have a way to receive warnings and always remember, TURN
AROUND, DON`T DROWN! **

In addition to the rain, there is the potential for a period of
strong, gusty winds from late tonight through Sunday, especially
along and east of the Mogollon Rim. The pressure gradient really
tightens up in advance of the approaching trough and winds may gust
30-40 mph at times. Event through the winds look to largely remain
below advisory levels, with the very wet conditions some trees may
be at risk of uprooting/falling.

The trough finally moves out of the area on Monday, with a few
lingering showers possible across eastern Arizona. Conditions
quickly dry out but with colder air arriving, some areas may see
rain turn to snow before all is said and done. Best chances for any
accumulating snow looks to be across the Kaibab Plateau, San
Francisco Peaks, and Buffalo Pass/Chuska Mountains.

A ridge tries to build in behind the departing trough but a low
remaining off to our north helps to flatten out the flow through the
middle of the week. Overall, looks like to may be a brief period of
warming and drying out before the next trough/cur-off low moves
towards our area.

&&

.AVIATION...Sunday 01/06Z through Monday 02/06Z...WDSPRD MVFR/IFR
through the TAF period. Periods of IFR/LIFR possible in +RA and lows
CIGS over the higher terrain. Winds SE-SW 5-10 kts through 15Z, then
becoming S/SW 10-20 kts with gusts 30-40 kts.

OUTLOOK...Monday 02/06Z through Wednesday 04/06Z...WDSPRD MVFR/IFR
in +RA/RA through 12Z-16Z Monday, then VFR. Areas of LIFR possible
in FG/low CIGS over the higher terrain. Winds W/NW 5-15 kts Monday,
becoming NW-NE Monday night into Tuesday.

&&

.FIRE WEATHER...Rest of today through Monday...Isolated showers
expected mainly along and south of Mogollon Rim through the late
afternoon hours of today, then steadily increasing through the
evening and then expanding northward. By tonight, a major rainfall
event will begin. Expect an extended period of moderate to heavy
rainfall, along with embedded thunderstorms. lasting through Monday
morning. Southerly winds today, 10 to 20 mph. Winds increase Sunday,
especially over the eastern zones, with southwest winds 15 to 25 mph
and gusts around 30 to 35 mph, potentially reaching as high as 35 to
45 mph in the higher terrain. A cold front will push most of the
precipitation out of the region late Monday morning or early Monday
afternoon. Winds are also expected to shift west through northwest
around 10 to 20 mph, with gusts around 25 mph in eastern Arizona.

Tuesday through Thursday...A drier weather pattern is expected
through this period. Easterly winds 5 to 15 mph Tuesday, turning
back southwesterly 5 to 15 mph for Wednesday. Winds are then
expected to become light Thursday.

&&

.FGZ WATCHES/WARNINGS/ADVISORIES...
Flood Watch from 11 PM MST /midnight MDT/ this evening through
late Sunday night for AZZ004>018-037>040.

&&

$$

PUBLIC...Meola
AVIATION...Humphreys
FIRE WEATHER...Schank

For Northern Arizona weather information visit
weather.gov/flagstaff

NWS Flagstaff Office