Special Weather Statement, NWS Flagstaff, AZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
317 PM MST Wed Sep 29 2021

.SYNOPSIS...Scattered showers and thunderstorms across northern
Arizona this afternoon will continue into the early evening.
Overnight and morning showers and storms are likely over the
White Mountains Thursday with rain chances lingering in the
afternoon. A warming and drying trend will begin Friday with seasonable
fall weather this weekend. Unsettled and cooler weather may
return early next week.

&&

.DISCUSSION...An upper-level trough is stretching southward into
Arizona bringing some breezy southwesterly winds this afternoon. A
cold front near the Utah-Arizona border is gradually moving
southward helping to trigger storms as it approaches. After some
storms in northeast Arizona developed this morning, thunderstorm
activity has expanded across much of the region with scattered
storms producing occasional to frequent lightning. Other hazards
associated with theses storms include periods of heavy rainfall,
strong gusty winds, and small hail. These storms are expected to
continue into the early evening hours as ample moisture from the
Gulf of California combines with CAPE values ranging from 500-1500
J/Kg. Storm are generally moving quickly to the east-northeast.

The trough will move eastward this evening, providing better
dynamics for numerous showers and storms to form over the eastern
Mogollon Rim and in the White Mountains late this evening and into
the morning hours. Lingering moisture will allow for a slight
chance of rain in other parts of the state on Thursday with the
majority of activity remaining east of I-17. By Thursday evening,
precipitation chances will begin decreasing with rain chances
primarily near the New Mexico border. The aforementioned cold
front will act to begin drying out northern Arizona. By Friday, a
ridge will begin to form, leading to a warming trend as the state
dries out. Afternoon temperatures will climb to seasonal norms
with bigger diurnal swings as dew points lower into the weekend.
While low temperatures may approach the mid 30s for some areas in
the early morning hours, enough moisture is likely to remain in
place to keep the minimums above freezing.

Another disturbance is possible towards the start of next week,
but models continue to be conflicted on the location of the low
pressure system when it moves into Arizona. Indications are that
the trough will approach and begin impacting the area sometime
between Monday evening to Tuesday afternoon. Stay tuned for
updates as the models begin to come to better agreement.

&&

.AVIATION...For the 00Z package...Isolated to scattered SHRA/TSRA
through this evening which may produce isolated MVFR/IFR. Look for
increasing coverage of SHRA/TSRA aft 06Z east of a KPAN-KINW line
with areas of MVFR developing. SHRA/TSRA spreading as far west as
KPRC-KFLG Thursday afternoon. Sfc winds SW 10-20 kts shifting to the
northeast at 10-15 kts on Thursday morning. Aviation discussion not
updated for TAF amendments.

&&

.FIRE WEATHER...Rain chances in the White Mountains and along the
Mogollon Rim continue Thursday with cooler temperatures expected.
By Friday, the region begins to warm and dry with generally light
winds each day.

Saturday through Monday...The warming trend will continue through
the weekend with no rain expected Saturday or Sunday. Another
disturbance could increase winds and bring a chance of
precipitation as early as Monday.

&&

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

&&

PUBLIC...JM
AVIATION...MCT
FIRE WEATHER...JM

For Northern Arizona weather information visit
weather.gov/flagstaff

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
1228 PM MST WED SEP 29 2021

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

1222 PM     HAIL             MEXICAN WATER           36.97N 109.64W
09/29/2021  E0.50 INCH       APACHE             AZ   PUBLIC

            MEXICAN WATER CHAPTER HOUSE REPORTED BETWEEN
            PEA AND DIME SIZED HAIL.

&&

MCT

Special Weather Statement
National Weather Service Flagstaff AZ
454 PM MDT Wed Sep 29 2021

AZZ010-011-292330-
Chuska Mountains and Defiance Plateau-Chinle Valley-
454 PM MDT Wed Sep 29 2021

...A strong thunderstorm will impact portions of Apache County
through 530 PM MDT...

At 453 PM MDT, Doppler radar was tracking a strong thunderstorm 7
miles north of Round Rock, or 32 miles north of Chinle, moving east
at 20 mph.

HAZARD...Winds in excess of 40 mph and nickel size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Cove Chapter House.

This includes Highway 191 between mile markers 479 and 492.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 3651 10956 3668 10962 3682 10920 3656 10911
TIME...MOT...LOC 2253Z 254DEG 15KT 3662 10951

MAX HAIL SIZE...0.88 IN
MAX WIND GUST...40 MPH

DB

Special Weather Statement
National Weather Service Flagstaff AZ
430 PM MST Wed Sep 29 2021

AZZ015-300000-
Western Mogollon Rim-
430 PM MST Wed Sep 29 2021

...A strong thunderstorm will impact portions of Coconino County
through 500 PM MST...

At 429 PM MST, Doppler radar was tracking a strong thunderstorm near
Mountainaire, or 8 miles south of Flagstaff, moving northeast at 15
mph.

HAZARD...Winds in excess of 40 mph and penny size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Mountainaire, Walnut Canyon National Monument, Kachina Village, Upper
Lake Mary, Upper Lake Mary Boat Ramps, Walnut Canyon Visitors Center,
Lower Lake Mary, Canyon Vista Campground and Lake View Campground.

This includes Interstate 17 between mile markers 334 and 335.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

&&

LAT...LON 3500 11163 3511 11170 3520 11152 3508 11133
TIME...MOT...LOC 2329Z 242DEG 14KT 3507 11157

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...40 MPH

DB

Special Weather Statement
National Weather Service Flagstaff AZ
519 PM MST Wed Sep 29 2021

AZZ008-037-300045-
Yavapai County Valleys and Basins-Yavapai County  Mountains-
519 PM MST Wed Sep 29 2021

...A strong thunderstorm will impact portions of Yavapai County
through 545 PM MST...

At 518 PM MST, Doppler radar was tracking a strong thunderstorm near
Bagdad, or 26 miles east of Wikieup. This storm was nearly
stationary.

HAZARD...Winds in excess of 40 mph and penny size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Bagdad.

This includes the following highways...
 State Route 97 near mile marker 166.
 State Route 96 between mile markers 0 and 6.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

&&

LAT...LON 3450 11326 3468 11324 3471 11307 3453 11303
TIME...MOT...LOC 0018Z 250DEG 1KT 3464 11315

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...40 MPH

DB

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
535 PM MST WED SEP 29 2021

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

0604 PM     HAIL             9 WSW JACOB LAKE        36.64N 112.35W
09/28/2021  E1.75 INCH       COCONINO           AZ   PARK/FOREST SRVC

&&

DM

Special Weather Statement
National Weather Service Flagstaff AZ
639 PM MDT Wed Sep 29 2021

AZZ010-039-300130-
Black Mesa Area-Chinle Valley-
639 PM MDT Wed Sep 29 2021

...A strong thunderstorm will impact portions of northern Navajo
County through 730 PM MDT...

At 638 PM MDT, Doppler radar was tracking a strong thunderstorm near
Kayenta, or 32 miles southwest of Mexican Hat, moving north at 10
mph.

HAZARD...Winds in excess of 30 mph and half inch hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Goulding and Monument Valley Visitors Center.

This includes Highway 163 between mile markers 399 and 416.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

&&

LAT...LON 3673 11025 3675 11043 3700 11044 3700 11010
TIME...MOT...LOC 0038Z 189DEG 8KT 3679 11033

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...30 MPH

DB