790
FXUS65 KFGZ 212013
AFDFGZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
113 PM MST Fri Jun 21 2024

.SYNOPSIS...Look for daily chances for showers and thunderstorms
over the weekend and into the middle of next week. Otherwise, muggy
and hot conditions will continue.

&&

.DISCUSSION...Model soundings are indicating and mesoscale forecast
models are showing a downturn in the coverage of shower and
thunderstorm activity today compared to Thursday. The main change
to the forecast for today was to lower the chance of showers and
thunderstorms across the area near the Arizona/Utah border and
Four Corners. The net result will be about 30-40% coverage of
showers and storms toward the Arizona/Utah border and Four Corners
with lesser coverage further south. We continue to see a decent
amount of vertical shear in the environment and there will remain
a threat of an isolated severe thunderstorm or two across northern
Arizona into the evening hours. The main threat for severe storms
will be along the Arizona/Utah border and Four Corners. We have
already seen on isolated severe storm west of Page producing
radar indicated 2.00 inch diamter hail. Wind gusts in excess of
60 mph will also be possbile should a severe storm develop.
Otherwise, look for hot and somewhat muggy weather to continue as
we make our first foray into a true monsoon pattern.

For Saturday through Wednesday...High pressure will build over
Arizona as the remnants of Alberto move across the southern portion
of the Gulf of California. In addition, thunderstorm activity over
the Sierra Occidental of northwest Mexico is expected to ramp-up.
The result will be a surge of additional moisture from over the Gulf
of California into Arizona. The input of deep monsoon moisture with
the combination of high pressure setting up over Arizona will
introduce the threat of daily showers and thunderstorms through the
period. Winds will be much lighter with a less vertically sheared
environment so storms will be more of the up/down pulse variety.
You can expect that hot and muggy monsoon feeling each day with a
chance of afternoon relief should you be lucky enough to get a
shower or storm overhead.

From Thursday onward...Models are indicating a downturn in shower
and thunderstorm activity with the passing of a drying and
stabilizing trough from the west. In reality, for monsoon
forecasting, that`s a bit far off to have much condfidence.

&&

.AVIATION...Friday 21/18Z through Saturday 22/18Z...Mainly VFR
expected. MVFR in SHRA/TSRA between 18Z-03Z, mainly along and east
of KGCN-KPAN line with ISO SHRA through 12Z/Sat. S-SW winds 15-25
kts with gusts 30-40 kts. Erratic and gusty winds in the vicinity
of storms.

OUTLOOK...Saturday 22/18Z through Monday 24/18Z...Mainly VFR
expected. Expect SHRA/TSRA between 18Z-03Z each day. S-SW winds
5-15 kts each afternoon. Erratic and gusty winds in the vicinity
of storms.

&&

.FIRE WEATHER...Saturday and Sunday...Expect scattered to widespread
showers and thunderstorms each afternoon. Wetting rains are likely
with any storms, as well as gusty and erratic outflow winds up to 45
mph. Outside of outflow winds, expect south to southwest winds at 10-
15 mph both days.

Monday through Wednesday...Chances for showers and thunderstorms
continue Monday, mainly along and south of the Mogollon Rim and the
White Mountains. Storm activity may decrease on Tuesday and
Wednesday. A gradual warming trend leads to above normal
temperatures by Tuesday. Otherwise, light southwesterly winds around
10-15 mph each afternoon.

&&

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

&&

$$

PUBLIC...McCollum
AVIATION...RR
FIRE WEATHER...RR

For Northern Arizona weather information visit
weather.gov/flagstaff