Area Forecast Discussion
Issued by NWS Flagstaff, AZ

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FXUS65 KFGZ 291120
AFDFGZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
420 AM MST Fri Mar 29 2024

.SYNOPSIS...An approaching winter storm will bring gusty winds
for today and Saturday, along with chances for widespread rain and
snow late Saturday into Monday. Warmer and drier conditions
return for the middle of next week.

&&

.DISCUSSION...Today and Tonight...Some areas of light rain/snow
showers and low clouds are settling into northwestern Arizona
early this morning. Much of this activity, if anything, will be
light and shoudn`t last much past day break. Seasonably mild
temperatures, with dry and windy conditions are expected for much
of the day ahead of the next storm system dropping southward along
the California Coastline. Wind gusts in excess of 35-45 mph will
be possible this afternoon, especially downwind of the higher
terrain.

Winds should relax some overnight as the boundary layer decouples
from the surface. However some locally gusty winds will remain a
possibility mainly immediately downwind of the Mogollon Rim
overnight.

Saturday through Monday...Winds increase even further on Saturday as
the pressure gradient tightens further with the approaching closed-
low. Another round of gusty winds is expected, though a bit stronger
and more widespread. Peak afternoon gusts over the higher terrain
look to be in the 40-50 mph range, with localized gusts up to 60 mph
in the usual windier locations. The Wind Advisory has been extended
into Saturday as a result. The higher terrain of Yavapai County and
areas in the Chinle Valley were also added for Saturday only.

Pacific moisture also streams into Arizona, resulting in an area of
rain and snow developing over far western Arizona by Saturday
afternoon. As the low ejects off the Pacific and moves into Arizona,
this area of precipitation will continue to move eastward across the
state Saturday night into Sunday. As the assocaited front moves
through, a period of heavy banded precipitation is expected to
develop during pre-dawn hours on Sunday and continue through the
rest of the morning. Strong frontogenetic forcing and moisture in
place will lead to the potential for significant preciptation
accumulations during this timeframe wherever the band ends up
setting up. In the higher terrain, snowfall rates in excess of 1-2
inches per hour will be possible during this time.

As for amounts, ensemble guidance still has a bit of a spread for
QPF, with the GEFS and EPS showing much higher preciptation amounts
than much of the CMCE members. This is largely in part do to the
differences in the exact placement of the banded precipitation. At
this point however, much of the higher terrain and areas south of
the Mogollon Rim look to see upwards of an inch or more of liquid
precipitation through Monday morning. To the north, lesser amounts
are expected, with a few hundredths in the lower elevations to up to
a third of an inch.

Temperatures also begin to fall Saturday afternoon into Sunday.
700mb temperatures start out around 0C to -2C, keeping snow levels
around 7000 feet at the onset of preciptation. However, as cold air
advection aloft increases, temperatures fall to around -4C to -6C,
thus allowing snow levels to drop to around 5500-6000 feet by Sunday
morning.

After the more intense band with the front, scattered rain and snow
showers are expected for Monday. Additional snow accumulations are
expected on Monday as a result, but given the more convective nature
of the precipitation, amounts will be highly variable. Additionally,
warming surface temperatures and a higher sun angle this time of
year will reduce the overall accumulations (i.e. the forecast snow
amount will likely not be on the ground all at once).

Tuesday through Thursday...Another round of rain and snow showers
looks to develop Tuesday afternoon behind the departing trough. Much
of the coverage looks to be limited to the eastern Mogollon Rim and
White Mountains at this time, and overall rain/snow accumulations
look to be minimal.

Drier conditions and warming temperatures set in for the middle of
next week as a shortwave ridge builds into Arizona. However, this
looks to be short-lived as windier and more unsettled weather looks
to return once again near the end of next week.


&&

.AVIATION...Friday 29/12Z through Saturday 30/12Z...VFR conditions.
Sfc winds increase to S-SW15-25g30-40kts AFT 17Z-19Z Friday. Winds
only decrease slightly tonight.

OUTLOOK...Saturday 30/12Z through Monday 01/12Z...Expect VFR through
Saturday evening. Areas MVFR/IFR developing west to east Saturday
night, mainly from the I-17 corridor westward. Then spreading over
all areas Sunday into Monday. Flight restrictions due primarily to
SHSN/SHRA/CIGS and ISOLD TSRA. Some spotty LIFR in heavier showers
and early Sunday morning. Sfc winds SW20-30g35-45kts through early
Sunday, then SW10-20g25kts behind the FROPA into Sunday afternoon
and night.

&&

.FIRE WEATHER...Friday and Saturday...Turning a bit cooler and
becoming very windy, especially on Saturday. Southwest winds 15 to
25 mph, with gusts from 35 to 45 mph Friday, increasing to 20 to 30
mph, with gusts from 40 to 50 mph on Saturday. Winds will not fully
decouple overnight, both Friday night and Saturday nights, but will
decrease slightly. Rain and snow becomes likely over the western and
central zones later Saturday night.

Sunday through Tuesday...Periods of rain and snow continue Sunday
and Monday, with a chance of thunderstorms each afternoon. Showers
become more isolated on Tuesday. Cold temperatures Sunday and Monday
will moderate by Tuesday. Southwest winds on Sunday from 15 to 25
mph, with gusts from 30 to 35 mph become westerly Monday and will
decrease to 10 to 20 mph, then northerly on Tuesday.

&&

.FGZ WATCHES/WARNINGS/ADVISORIES...

Wind Advisory from 11 AM MST /noon MDT/ this morning to 10 PM
MST /11 PM MDT/ Saturday for AZZ004-006-007-009-011>017-039-040.

Wind Advisory from 11 AM MST /noon MDT/ to 7 PM MST /8 PM MDT/
Saturday for AZZ008-010-038.

&&

$$

PUBLIC...Humphreys
AVIATION...Peterson
FIRE WEATHER...Peterson

For Northern Arizona weather information visit
weather.gov/flagstaff


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