Severe Thunderstorm Warning 171, NWS Flagstaff, AZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
150 PM MST Sat Aug 28 2021

.SYNOPSIS...Isolated to scattered showers and thunderstorms will
continue into this evening mainly south of I-40. Expect another
round of showers and thunderstorms again Sunday afternoon.
Moisture and storm chances will increase significantly next week,
with some areas of heavy rainfall leading to potential flash
flooding by Tuesday through Thursday. Temperatures cool to below
normal by the middle and end of the week.

&&

.DISCUSSION...Weak sub-tropical high remains in place over the
southwest this weekend, allowing for monsoonal moisture over the
southern half of Arizona to sneak northward into the High Country.
Greatest moisture and instability remains backed up against the
Mogollon Rim this afternoon, as a result much of the activity this
afternoon will be mainly along and south of the Mogollon Rim.
Later in the evening, storms are expected to move south and off
the Rim into the lower elevations of Yavapai and Gila counties.
Main hazards from storms today will be brief heavy downpours
along with gusty winds and small hail in the strongest storms, but
organized severe weather is not anticipated. Much of the activity
is expected to diminish by late evening, with a few isolated
showers lingering through the early overnight hours in Yavapai
County. Sunday looks to be a similar scenario, with isolated to
scattered coverage south of I-40. With a slight increase moisture
Sunday, a slight increase in coverage over northwestern Arizona is
possible. Temperatures are expected to remain warm into Monday
before a more significant cooling trend begins for the rest of the
next week.

Early next week the ridge starts to become amplified as a trough
starts to descend into the Pacific Northwest. With the stronger
ridge in place over the Four Corners, more favorable southerly flow
will allow for monsoonal moisture to surge into northern Arizona
once again starting Monday. Towards the middle of next week, as the
trough approaches moisture becomes further enhanced over the region.
Additional enhancement of the tropical moisture will also be
possible from the remnants of Hurricane Nora as it approaches from
the south over the Gulf of California. Latest guidance continues to
still be largely in disagreement in the exact track and strength as
it enters the Gulf and continues its trek northward. As a result a
large amount of uncertainty exists in the exact implications and
interactions of Nora with the approaching longwave trough.
Regardless of the track of Nora, scattered to widespread coverage of
showers and thunderstorms is expected for next week, leading to the
potential for flash flooding from heavy rainfall. At this time,
the most impactful period is expected to be Tuesday through
Thursday.

&&

.AVIATION...For the 00Z package...Expect primarily VFR conditions
over the next 24 hours. Look for scattered showers and thunderstorms
mainly along or south of the I-40 corridor, diminishing after 03Z.
Wind gusts to 35 kts in the vicinity of storms. Another round of
thunderstorms over the same area set for Sunday afternoon. Aviation
discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Expect generally light winds on Sunday and Monday
with a few afternoon gusts to 20 mph. Remaining hot on Sunday but
cooling by a few degrees on Monday as moisture and clouds increase.
Isolated to scattered showers and thunderstorms expected each
afternoon, with most activity along and south of the I-40 corridor.

Tuesday through Thursday...Moisture and thunderstorm chances will be
on the increase when areas of heavy rainfall will be possible.
Temperatures will steadily decrease through the period.

&&

.FGZ WATCHES/WARNINGS/ADVISORIES...NONE.

&&

PUBLIC...Humphreys
AVIATION...McCollum
FIRE WEATHER...McCollum

For Northern Arizona weather information visit
weather.gov/flagstaff

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
1259 PM MST SAT AUG 28 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1210 PM     FUNNEL CLOUD     1 SE FLAGSTAFF MALL     35.22N 111.57W
08/28/2021                   COCONINO           AZ   PUBLIC

            SOCIAL MEDIA REPORTS AND PHOTOS OF A FUNNEL
            CLOUD GENERALLY SOUTH OF THE FLAGSTAFF MALL
            BY ABOUT ONE MILE. LOCATION ESTIMATED BASED
            ON KNOWN LANDMARKS.

&&

NL