Wildfire in Arizona, May 1 to 31, 2022

Area Forecast Discussion...UPDATED
National Weather Service Flagstaff AZ
856 PM MST Sat Apr 30 2022

.SYNOPSIS...Very dry and warm weather will continue across the
region well into next week. Strong southwest winds are expected on
Sunday with critical fire weather in the afternoon. A Red Flag
Warning and Wind Advisory are in effect for much of the area. Use
extreme caution and avoid open flame, sparks, and parking on dry
grass.

&&

.UPDATE...The short term forecast is in good shape with just a few
minor tweaks for the evening update. A dry airmass will support
some radiational cooling, though 700mb winds of 15-20 knots may be
enough to keep the PBL from completely decoupling. As such, I've
only lowered MinT's by 1-3 degrees in spots. The 00Z Sunday guidance
continues to offer high confidence in sustained winds of up to 30
mph with gusts of around 50-55 mph. Experimental NBM probability
of exceedance output does suggest a few areas (across the
Bradshaws, the San Francisco Peaks, and Kaibab) could see gusts in
excess of 55 mph, but the overall coverage doesn't appear to
warrant any alterations to the wind headlines, but trends will be
monitored overnight. Some of the HREF members do suggest high-
based convection across the Kaibab and northeast Mesa Sunday
afternoon and evening ahead of the main trough (characterized by
30 to 40 meter height falls). Forecast soundings in tandem with
700-500mb RH progs do show moistening of around 70% and this may
be sufficient to produce some high-based convection. At this time,
I don't anticipate measurable precipitation (only around a 10%
chance) and instability values remain below 10 J/kg (thus no dry
lightning), however, enhanced wind gusts...potentially exceeding
55 mph...are probable INVOF virga.

Otherwise, confidence is high that a critical fire weather threat
will materialize on Sunday with the aforementioned winds and
minimum afternoon RH falling to 15% or below for just about all
of the area. Please be vigilant and avoid activities that could
result in new fire starts and spread given the conditions!

&&

.PREV DISCUSSION /234 PM MST/...A few thin, mostly opaque high
clouds have begun to stream in along the axis of a trough that is
deepening across the Pacific Northwest. High clouds will increase
this evening as this feature approaches. This trough is projected
to continue to dig south and east overnight into Sunday. As west
to southwest gradients increase and an axis of strong mid to
upper level winds moves across northern Arizona on Sunday with
this trough passage, expect very strong southwest winds by the
afternoon with gusts 45-55 mph. A few localized gusts to 55+ mph
may occur in some of the favored downslope areas such as Doney
Park to I-40 east of Flagstaff and along the high terrain of the
Kaibab Plateau and Black Mesa. Areas of blowing dust will be
possible from the I-40 corridor northeast to the Four Corners. A
Wind Advisory has been issued for much of the area on Sunday
afternoon. The winds in combination with very dry fuels and
single digit to teen afternoon relative humidity will create a
period of critical fire weather as well. A Red Flag Warning has
been issued for all of northern Arizona on Sunday. The potential
for fires to spread rapidly will be very dangerous on Sunday. Be
sure to avoid anything involving an open flame or spark. Never
park vehicles on dry grass or dispose of cigarette butts onto the
side of the road or in dry grass.

Behind the trough, winds will be lighter on Monday but remain
breezy from the west. Temperatures will cool by a couple of
degrees, though it will likely not be too noticeable. Another wind
maker arrives on Tuesday as a low again digs southward into our
area. As we remain very dry, another period of critical fire
weather can be expected as winds increase on Tuesday. Models are
in somewhat better agreement this afternoon that beyond Tuesday, a
quick sliding ridge will build in with increasing heights and
warning temperatures. However, the exact amplitude of that feature
remains uncertain and the pattern to the north will remain very
active so it is likely more windy systems are in our future late
next week.

&&

.AVIATION...For the 06Z TAF package...Mainly VFR conditions are
expected for the TAF period. MVFR visibility reductions will be
possible between 18Z and 00Z Mon, mainly north and east of a KKNB-
KGCN-KINW-KXNI line. Winds remain light from the south/southwest
overnight, then increase after 18Z to around 20-30 kts with gusts 35-
45 kts. Winds begin to decrease from the west/southwest after 03Z
Mon to around 10-15 kts. Aviation discussion not updated for TAF
amendments.

&&

.FIRE WEATHER...Strong, gusty southwest winds are expected for
the afternoon on Sunday. Strong winds combined with very low RH
values will lead to widespread critical fire weather across all of
northern Arizona. Continued dry conditions with lighter southwest
breezes are expected for Monday.

Tuesday through Thursday...Southwest winds increase again on
Tuesday, with areas of critical fire weather conditions possible.
Lighter northwest winds are expected Wednesday and Thursday, along
with continued dry and mild conditions.

&&

.FGZ WATCHES/WARNINGS/ADVISORIES...Red Flag Warning from 11 AM to 7 PM MST Sunday
FOR AZZ104>118- 137>140.

Wind Advisory from 11 AM to 7 PM MST Sunday FOR AZZ004>018-
037>040.

&&

PUBLIC...Bain/ET
AVIATION...Humphreys
FIRE WEATHER...Humphreys/MCT

For Northern Arizona weather information visit
weather.gov/flagstaff