984
FXUS65 KFGZ 162014
AFDFGZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
114 PM MST Fri Aug 16 2024

.SYNOPSIS...Warm and mostly dry conditions continue this
afternoon, before chances for showers and thunderstorms return
to northern Arizona over the weekend and into next week.

&&

.DISCUSSION...So far today, quiet weather has been observed
across northern Arizona. Satellite imagery shows some cumulus
development over the White Mountains and eastern Mogollon Rim.
Hi-Resolution model guidance continues to predict the development
of some isolated showers and thunderstorms within the cumulus
field this afternoon, with dry weather elsewhere.

Surface observations in far southwest Arizona indicate that a
moist southerly flow has developed there. This minor surge of
Gulf of California moisture will continue to spread northward into
the lower deserts and up the Colorado River basin through the
evening and overnight hours.

As monsoon moisture moves into northern Arizona, a corresponding
increase in shower and thunderstorm activity is expected on
Saturday. The greatest storm coverage is forecast to be west of a
line from Prescott to Flagstaff to Page. Tomorrow`s storms will be
fast moving, with storm motions to the north between 20-30 mph.
However, due to the potential for training storms and the
existence of several flash-flood-prone areas, a Flash Flood Watch
has been issued from Saturday morning through Saturday evening for
western Coconino County. We are particularly concerned about
flash flooding in and around Havasupai Creek, the side canyons of
the Grand Canyon, the Mangum Fire near Jacob Lake, and the various
slot canyons of northwest Arizona including Water Holes and
Antelope Canyon. In addition to the threat for flash flooding,
strong storms capable of producing large hail and damaging winds
due to the presence of moderate CAPE and deep-layer wind shear
cannot be ruled out.

Model guidance is generally in agreement that the subtropical
high responsible for transporting moisture into northern Arizona
will remain in a favorable location to keep daily chances for
showers and thunderstorms going through at least the end of next
week. However, spread regarding the exact location of the ridge
axis grows as the week progresses. Little to no model guidance
predicts a complete shutdown in storm activity, but the overall
coverage and intensity of the convective activity are uncertain at
this point.

&&

.AVIATION...Friday 16/18Z through Saturday 17/18Z...Primarily VFR
conditions will prevail today. Scattered TSRA possible from KSOW
southeast, with dry conditions elsewhere. Winds outside of any
storms, SW at 10-20 kts, becoming light after 02Z. There`s a
20-50% chance of morning showers west of KFLG after 12Z Sat.

OUTLOOK...Saturday 17/18Z through Monday 19/18Z...Scattered
SHRA/TSRA each afternoon/evening with coverage favoring areas from
KFLG westward. Brief MVFR to IFR conditions in stronger storm
cells. Away from storms, expect southerly winds 10-20 kts during
the daytime.

&&

.FIRE WEATHER...Tonight through Sunday...Scattered thunderstorms
will be confined to the White Mountains today with dry conditions
continuing elsewhere. Moisture and thunderstorm chances increase
Saturday through the weekend. Storm coverage and the best chances
for wetting rain will favor northwestern Arizona. Outside of
thunderstorm outflow winds, expect southerly winds 10 to 20 mph.

Monday through Wednesday...Expect daily chances for showers and
thunderstorms to continue. Winds will be southwest around 10 mph or
less away from any thunderstorms and/or outflows.

&&

.FGZ WATCHES/WARNINGS/ADVISORIES...
Flood Watch from late tonight through Saturday evening for
AZZ004>007.

&&

$$

PUBLIC...RR
AVIATION...MCT
FIRE WEATHER...MCT

For Northern Arizona weather information visit
weather.gov/flagstaff