Flooding and Heavy Snow in Arizona, March 20 to 26, 2023

Area Forecast Discussion
National Weather Service Flagstaff AZ
237 PM MST Mon Mar 20 2023

.SYNOPSIS...Scattered showers will continue through this evening as
the first of several storms affect Arizona. Periods of rain and snow
are expected for Tuesday and Wednesday, with increased chances for
river flooding. Unsettled weather will persist Thursday through the
weekend.

&&

.DISCUSSION...A shortwave crossing through northern Arizona this
afternoon has allowed for rain and snow showers to develop. Mainly
light amounts with areas above 6000 feet seeing a few tenths of
accumulation. With the precip falling during the day, it's not
really accumulating on surfaces other than snow boards. As we move
into tonight, the wave will push to the east as a strong low
pressure system starts to make its way to the California coast. With
the low off to our northwest, we will remain in a south to southwest
upslope flow with moisture continuing to stream across the region.
Snow levels look to remain around 6000-6500 feet with the bulk of
any accumulation snow remaining mostly north of the Western Mogollon
Rim. Snowfall will be most likely to accumulate through the
overnight hours when we see temps drop and any solar influence fade.
Amounts in the 3-6 inch range are expected for the Grand Canyon
South Rim down through Flagstaff. Areas across the Kaibab Plateau
will continue to see accumulating snow with 6-10 inches possible. No
changes to the winter headlines were made at this time.

As we move into Tuesday, we should see some warming occur as the
strong southwest flow continues and this will allow for a change
over from snow to rain, especially in areas below 8000 feet. Should
it remain snow during the day, it will be harder for it to
accumulate, especially on paved and treated surfaces.

The low moves into California but will remain to our northwest
before it starts to open up into a deep trough. As the low pushes to
the east, the gradient tightens up and we will see winds become
quite gusty by Tuesday evening. Winds may peak overnight and there
may be a few areas that see 40 to 50 mph gusts with some locally
higher gusts. A wind advisory may be needed so stay tuned.

The heaviest precipitation looks to fall late Tuesday into early
Wednesday as a strong shortwaves rotates through the mid level flow.
As the wave moves through, snow levels will fall down to around 5000
feet. Accumulating snow late Tuesday into early Wednesday will see
around 4-8 inches above 6000 feet with 1-4 inches for areas down to
5000 feet. Additional winter weather products may be needed during
this time frame so stay tuned for later statements.

While the higher elevations will be expecting accumulating snow, we
will also see a heavy rain threat across the lower elevations and
upslope areas in Yavapai county and Gila county. 1-3 inch rainfall
amounts are possible and some areas may locally see higher amounts.
With snow melt and rainfall, it is likely that we will see more
flooding occur and there could be significant rises on creeks,
rivers, and streams. The Verde and East Verde River, Oak Creek, Wet
and Dry Beaver Creek, West Clear Creek, and others will need to be
closely monitored. WPC has included parts of Yavapai and Gila
counties in a slight risk for excessive rainfall, as well. A Flood
Watch remains in affect for these areas for Tuesday morning through
Wednesday evening. There is also a chance that we could see some
isolated thunderstorms, mainly across Yavapai and Gila counties.

For the Tuesday through Wednesday period, hi-res guidance continues
to be overdone with QPF amounts too high so trimmed back values to a
more reasonable amount.

Beyond Wednesday, the active pattern will continue. The remnant
trough will cross the region on Thursday with another wave on the
backside of the through on Friday. Yet another trough will cross
Arizona on Saturday into Sunday. All of these troughs will keep a
chance for some showers across the region but this far out, amounts
look to be on the light side.

&&

.AVIATION...For the 00Z TAF package...A storm system will bring
increasing rain, snow, and southwest winds through the TAF period.
Conditions will become worse from west to east...with widespread
IFR/LIFR conditions expected overnight and Tuesday. The stronger SW
winds will be most pronounced along the Mogollon Rim and northward.
Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Rain showers and high elevation snow showers will
continue today along with breezy SW winds. Additional precipitation
is expected on Tuesday, with periods of heavy accumulation likely in
the afternoon. SW winds will increase and expand across the area
tonight through Tuesday night. The snow level will remain 6000-7000
through noon Tuesday then rise above 8000 feet through Tuesday
night...then drop again on Wednesday.

Thursday through Saturday...Rain/snow showers will continue through
Saturday with a decrease each day. West winds are expected Thursday,
becoming northwest on Friday and then westerly on Saturday.

&&

.FGZ WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning until 5 PM MST Wednesday for AZZ004-104.

Winter Weather Advisory from midnight MST /1 AM MDT/ tonight to
2 PM MST /3 PM MDT/ Tuesday for AZZ006-007-015-106-107-115.

Winter Weather Advisory until 2 PM MST /3 PM MDT/ Tuesday for
AZZ011-039-111-139.

Flood Watch from Tuesday morning through Wednesday evening for
AZZ018-037-038-118-137-138.

&&

PUBLIC...Meola
AVIATION...MAS
FIRE WEATHER...MAS

For Northern Arizona weather information visit
weather.gov/flagstaff