244
FXUS65 KFGZ 120343
AFDFGZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
843 PM MST Thu Jul 11 2024

.SYNOPSIS...Hot temperatures will continue through Friday, with a
slight cooling trend for the weekend. Moisture will slowly return
to the region, with chances for afternoon showers and thunderstorms
increasing each day, becoming widespread by the weekend and into
early next week.

&&

.UPDATE...Storm activity has diminished across northern Arizona
this evening. Today`s storms were mainly focused along and south
of the Mogollon Rim. Severe storms did impact the Prescott area
this afternoon, with hail as large as one inch observed there.

For tonight, expect quiet conditions, although some briefly gusty
winds are possible from outflows originating from distant
storms in southern Arizona and New Mexico. Otherwise, expect low
temperatures to range from the low-50s to low-70s across the
majority of northern Arizona`s High Country.

&&

.PREV DISCUSSION /434 PM MST/...Anomalously strong high pressure
remains positioned over southern NV/UT and northwestern AZ
today. This continues to drive our hot summer weather pattern,
while keeping monsoon activity limited to the Mogollon Rim and
southward so far. Steering flow today is again from the north
which will keep the focus of afternoon/evening thunderstorms south
of the Rim in Yavapai/Gila counties, where the best moisture and
instability reside (on the order of 500-1000 J/kg of CAPE). Some
vertical wind shear (20-30 kts) is present across central AZ today
and will help lead to a few severe and/or prolonged storms
capable of hail, damaging wind and brief heavy rain. Storms will
dissipate later this evening and overnight with the loss of
daytime heating.

The high pressure center begins to slowly drift eastward tonight
and Friday, centering closer to the four corners for the upcoming
weekend. This will open the door to increasing moisture and
thunderstorm chances during this period. The moisture still looks
relatively high-based on Friday with the low levels beginning to
moisten up and more widespread activity expected for Saturday
through Monday. Strong wind gusts will remain a high concern
through Friday, transitioning to more of a heavy rain threat over
the weekend.

In terms of heat, the Excessive Heat Warnings remain in effect
for the lower valleys of Yavapai county through tonight and
Grand/Glen Canyons through Friday. The additional storm coverage
and cloud cover on Friday is expected to limit the heat threat in
Yavapai county Friday, but less cloud cover and closer proximity
to the high pressure center will keep the heat warnings going for
Grand Canyon. There is potential for the Grand Canyon heat
warnings to be extended, but confidence is not high enough with
the increasing moisture to extend just yet.

The moderate monsoon pattern will continue through early next week
as the high pressure center makes little movement. However,
confidence in the moisture sticking around begins to decrease late
next week. Models are suggesting another amplification of the
western U.S. ridge parking itself over Nevada, which is a nearly
identical pattern to what we`re seeing right now. Under this
pattern, it`s likely far northern AZ will see drying with areas
south of the Rim continuing to see thunderstorm chances. Hot
temperatures are likely to develop again, and we`ll have to watch
for additional heat impacts.

&&

.AVIATION...Friday 12/00Z through Saturday 13/00Z...Scattered
showers and thunderstorms across Yavapai County will continue to
move southwest and weaken, with little to no storm activity
across northern Arizona after 02Z. Quiet conditions overnight.
Another round of scattered thunderstorms will form after 19Z
Friday, with the greatest activity along and southwest of a KSOW-
KFLG-KGCN line. Strong wind gusts 40-50 kts, hail, and brief heavy
rain possible with stronger storms. Outside of storms, look for
winds 5-15 kts varying in direction.

OUTLOOK...Saturday 13/00Z through Monday 15/00Z...Shower and
thunderstorm activity is forecast to increase in coverage and
spread across all of northern AZ on Saturday and Sunday. Brief
MVFR conditions possible under stronger storms, otherwise VFR
conditions. Outside of thunderstorms, expect prevailing winds
generally 10 kts or less.

&&

.FIRE WEATHER...Today through Saturday...Hot temperatures
continue through Friday with scattered thunderstorms focused along
and south of the Mogollon Rim. Strong outflow winds, hail and
brief heavy rain possible in the strong storms. Expect increasing
moisture, lower temperatures, and more widespread thunderstorm
activity beginning Saturday.

Sunday through Tuesday...Seasonable temperatures return along
with scattered to widespread showers/thunderstorms. A mixture of
wetting rains, hail, and gusty winds are possible. Outside of
storm driven winds, expect generally west through southwest winds
5-15 mph.

&&

.FGZ WATCHES/WARNINGS/ADVISORIES...
Excessive Heat Warning until 8 PM MST /9 PM MDT/ Friday for
AZZ005-006.

&&

$$

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

For Northern Arizona weather information visit
weather.gov/flagstaff