345
FXUS65 KFGZ 181737
AFDFGZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
1037 AM MST Tue Jun 18 2024

.SYNOPSIS...Temperatures will trend closer to normal through
Wednesday, before warming again late in the week. A chance of
thunderstorms will develop daily from Thursday through the
weekend.

&&

.UPDATE...Expect fair weather for today with lighter southwest
breezes, 15-25 mph, and seasonable temperatures. Conditions remain
dry across the Southwest due to an upper-level trough over much of
the West. Eventually by Thursday, this trough retrogrades towards
the west in response to a strengthening high pressure system over
much of the eastern half of the country. With potential tropical
storm moisture from Texas and the presence of this high pressure
system towards the east, this would allow moisture advection to
increase across Arizona from the southeast. Forecast dewpoints and
PWATs for Thursday and Friday have been on the upward trend,
suggesting that the dry thunderstorm development might not be as
dry as previously thought. The current forecast remains in good
shape with no changes needed at this time.

&&

.PREV DISCUSSION /335 AM MST/...A trough of low pressure entrenched
across the western U.S. is pushing a cool front across far
northern Arizona early this morning. This will ensure our
temperatures today remain a few degrees below average. Today will
see the lowest temperatures of the week with more significant
warming later this week into the weekend. The shortwave that
brought yesterday`s winds continues to push away to the northeast,
while a broad trough is forecast to settle over the southwest
through the remainder of the week. Though we won`t see winds like
yesterday, they will still remain breezy each afternoon with gusts
around 25-30 mph. Temperatures remain near to below average
through Wednesday.

From Thursday onward, high pressure building westward from the
southern plains begins to dominate the weather pattern. Rising
heights will lead to warming temperatures, reaching 5-7 degrees
above normal late this week into the weekend. Heat Risk does begin
to increase, but does not look to reach into critical levels. The
lowest elevations of the Grand Canyon could encroach on excessive
heat criteria and we`ll continue to watch for this.

As the high builds west, it opens the door to a southeasterly flow
that draws moisture across New Mexico and Arizona from Thursday
through the weekend. Models have been consistent in showing this
pattern shift over the last few days, and the ensemble guidance
this morning is even more supportive of the increasing moisture.
The best shower and thunderstorm chances will favor eastern and
northeastern Arizona Thursday through Saturday, but enough
moisture will stick around to trigger instability convection each
day into next week. Forecast precipitation amounts are not
impressive as we will be fighting a stout dry boundary layer, but
a few lucky areas may see >0.25". Early monsoonal storm threats of
lightning and gusty outflow winds will be of greatest concern and
could lead to new wildfire starts. Forecast confidence begins to
decrease by the middle of next week as there are differing signals
on how long the available moisture may stick around.

&&

.AVIATION...Tuesday 18/18Z through Wednesday 19/18Z...Expect VFR
conditions. Sfc winds W-SW10-15g20-25kts 10Z-02Z, otherwise variable
5-10kts.

OUTLOOK...Wednesday 19/18Z through Friday 21/18Z...Mainly VFR
through 18Z Thursday. -SHRA/-TSRA possible after 18Z Thursday that
may produce MVFR. Most activity north and east of a KCMR-KPAN line.
Localized MVFR and gusty, erratic outflow winds possible near TSRA.
Winds S 10-20 kts with gusts 20-30 kts each afternoon, with light
and variable winds during the overnight periods.

&&

.FIRE WEATHER...Today and Wednesday...Seasonable temperatures
and dry. Breezy west/southwest winds 10-15 mph today, becoming
south/southwest for Wednesday. Gusts up to 25 mph possible each
afternoon. Afternoon minimum RH 10-20%.

Thursday through Saturday...Warm, daily chances for showers and
thunderstorms. Breezy south/southwest winds, gusts 20-30 mph for
Thursday and Friday, becoming light on Saturday.

&&

.FGZ WATCHES/WARNINGS/ADVISORIES...None.

&&

$$

PUBLIC...LaGuardia/MCT
AVIATION...Peterson
FIRE WEATHER...Peterson

For Northern Arizona weather information visit
weather.gov/flagstaff