Dust Devil in Arizona, May 18, 2020

Area Forecast Discussion
National Weather Service Flagstaff AZ
245 PM MST Mon May 18 2020

.SYNOPSIS...A strong, late season low pressure system will bring
windy conditions and areas of critical fire weather to northern
Arizona today and Tuesday. The strongest winds will occur Tuesday
afternoon. Expect temperatures to cool through Wednesday, before
warming again late in the week.

&&

.DISCUSSION...A dry and windy day is underway across northern
Arizona in response to a cold trough moving onshore over northern
California. Tightening pressure gradients ahead of a cold front
moving through Nevada have led to gusty southwest winds across the
area this afternoon. A few gusts up to 40 mph have been reported
near Grand Canyon and the Mogollon Rim this afternoon with more
expected as the afternoon progresses. Winds will remain gusty
through early evening and a wind advisory remains in effect for
north-central Arizona through 6 PM MST. In addition, a red flag
warning remains in effect through 8 pm MST for areas of critical
fire weather. Elevated winds can be expected overnight in a
narrow corridor just to the north/northeast of the San Francisco
Peaks.

As the trough and cold front progress eastward on Tuesday, expect
even stronger south to southwest winds to develop. Wind speeds of
25 to 30 mph with gusts in the 45 to 55 mph range are expected.
Wind advisories have been issued for most of northern Arizona on
Tuesday, as well as red flag warnings for northeastern Arizona.
Winds may be strong enough Tuesday afternoon to kick up some areas
of blowing dust, especially in the Little Colorado River Valley
and Chinle Valley. Temperatures will begin to cool on Tuesday,
with continued cooling behind the trough passage on Wednesday.

A period of lighter winds and near average temperatures is
forecast through the end of the week. Gusty winds may develop
again over the weekend in response to a weak shortwave passage.
Dry weather looks to persist through the 7 day forecast with the
greater uncertainty being how warm temperatures will get early
next week.

&&

.AVIATION...For the 00Z package...VFR conditions will prevail for
the next 24 hours. Strong winds will slowly decrease overnight, but
remain locally breezy. Low level wind shear is likely at high
country terminals after 03Z. Wind speeds will increase again after
15Z and be around 15-30kts with gusts up to 45kts. Aviation
discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Strong winds will slowly decrease overnight, but
remain locally breezy. A Red Flag Warning remains in effect until 8
PM MST this evening. Cooler temperatures in western zones on Tuesday
will increase relative humidity values for some high terrain areas,
but continued strong winds and low relative humidity in eastern
Arizona will create critical fire weather conditions. A Red Flag
Warning has been issued for northeastern Arizona on Tuesday from 11
AM - 7 PM MST. Expect lighter winds and cooler temperatures
Wednesday.

.Thursday through Saturday... Temperatures will warm slightly each
day through Saturday with continued dry conditions. Breezy winds
possible Saturday.

&&

.FGZ WATCHES/WARNINGS/ADVISORIES...Wind Advisory until 6 PM MST this
evening FOR AZZ007-009-012-013-015-039-040.

Wind Advisory from 11 AM to 7 PM MST Tuesday FOR AZZ004>016-038>040.

Red Flag Warning until 8 PM MST this evening FOR AZZ104-106-107-
109-111>113-139-140.

Red Flag Warning from 11 AM to 7 PM MST Tuesday FOR AZZ105-
109>114-139-140.

&&

PUBLIC...MCT
AVIATION...NL
FIRE WEATHER...NL

For Northern Arizona weather information visit
weather.gov/flagstaff