319
FXUS65 KFGZ 201839
AFDFGZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
1139 AM MST Thu Jun 20 2024

.SYNOPSIS...Daily chances for showers and thunderstorms are
forecast through the weekend and into early next week, along with
warming temperatures.

&&

.DISCUSSION...Moisture from what is now Tropical Depression Alberto,
currently located over central Mexico, has pushed across the
eastern third of Arizona. The deepest moisture and most unstable
air mass according to model soundings will be along and north of a
line extending from Heber to Show Low to Springerville and
includes the Chuska Mountains, Defiance Plateau and the Chinle
Valley. Storms today will move generally from south to north and
will be capable of producing 0.50 to 1.00 inch downpours, wind
gusts in excess of 50 mph and localized storm runoff. The western
boundary of the moisture extends as far west as Flagstaff and Page
but a mid-level cap of relatively warm air will likely result in
extremely isolated storms that far west. Shower storm activity
will continue overnight but gradually diminish in coverage and
intensity.

On Friday...Moisture from Alberto spreads further north and west
with at least a slight chance of showers even across our lower
elevations locations of Bagdad and Black Canyon City. Elsewhere,
deep moisture and unstable lapse rates will result in a good
chance of showers and thunderstorm especially during the afternoon
with daytime heating. Activity will diminish but likely not end
overnight.

For Saturday into Tuesday...High pressure expands across Arizona.
The flow around the high will phase will the remnants of Alberto to
the south to induce our first surge of moisture from over the Gulf
of California. The onset of deep easterly flow over Mexico and the
predominate flow being from sea to land with daytime heating
indicates that our first monsoon pattern of the year will set upon
us. Look for daily chances for showers and storms with day-to-day
variations in storm intensity and coverage. Decent rainfall
accumulations will be observed during this period exactly where is
part of the mystery of the monsoon.

From Wednesday onward...A drying trough from the west will push
monsoon moisture eastward taking most of northern Arizona out of the
action. However, moisture will likely linger in the vicinity of the
eastern Mogollon Rim and White mountains for a continued shower and
storm threat.

&&

.AVIATION...Thursday 20/18Z through Friday 21/18Z...Mainly VFR
conditions persist through the TAF period with FEW-BKN cloud
cover after 19Z. Expect isolated to scattered -SHRA/-TSRA from
20Z-03Z with brief periods of MVFR VIS and CIGS, confined along
and east of a KGCN-KFLG-KPAN line. Showers and BKN clouds look to
continue through the night near the Four Corners region.
Anticipate south-southwest winds, 20-30 kts, becoming south 5-15
kts after 03Z.

OUTLOOK...Friday 21/18Z through Sunday 23/18Z...Another round of
scattered to widespread -SHRA/-TSRA is expected on Friday from
19Z-03Z with showers continuing into the night. Greatest coverage
will likely be along the Utah and New Mexico borders. Moderate
chances for -SHRA/-TSRA continue through the weekend across all of
northern Arizona. Anticipate enhanced south to southwest winds on
Friday afternoon, 20-30 kts, becoming much lighter for Saturday
and Sunday, outside of any gusty outflows from storms.

&&

.FIRE WEATHER...Friday and Saturday...With moisture increasing into
the weekend, expect rounds of scattered to widespread showers and
thunderstorms each afternoon. Wetting rains (>0.10") are likely with
any storms as well as gusty and erratic outflow winds up to 40 mph.
Showers could continue overnight with good humidity recovery.
Outside of any outflow winds, anticipate enhanced south to southwest
winds, 25 to 35 mph, on Friday followed by much lighter southerly
winds, 10 to 15 mph, on Saturday.

Sunday through Tuesday...The active monsoonal pattern persists
through Monday with 40 to 60% chances for showers and thunderstorms
along and south of the Mogollon Rim and White Mountains. By Tuesday,
chances decrease, however, isolated to scattered activity is
forecast at this time, mainly along the higher terrain. Temperatures
remain seasonal throughout this time with light southwesterly flow,
10 to 15 mph, each afternoon.

&&

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

&&

$$

PUBLIC...McCollum
AVIATION...LaGuardia
FIRE WEATHER...Meola

For Northern Arizona weather information visit
weather.gov/flagstaff