Special Weather Statement, NWS Flagstaff, AZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
900 PM MST Sun Aug 15 2021

.SYNOPSIS...Scattered thunderstorms will continue each day through
Monday, with the best coverage along and south of the Mogollon Rim
where a few strong to severe storms are possible. Expect more
widespread showers and storms and cooler temperatures by mid next
week before a drying trend arrives toward the end of the week.

&&

.UPDATE...Strong thunderstorms are still ongoing this evening near
I-40 at Bellemont and Parks along with areas in northern and
central Gila County. Flash flooding, hail, gusty winds, and
frequent lightning are being observed. Be sure to never attempt to
cross flooded roadways and head indoors if there is a thunderstorm
near you. These storms are producing dangerous cloud to ground
lightning. Showers and thunderstorms will continue through
midnight. Isolated showers and storms will continue overnight but
coverage will decrease over the next 3-4 hours. Updates were made
to precipitation chances to fit current radar trends. Otherwise,
no major forecast updates are expected this evening.

&&

.PREV DISCUSSION /248 PM MST/...Thunderstorms have developed early
this afternoon over the higher terrain of Coconino County as well
as the Black Mesa and Chuska Mountains region. A few of the storms
have been severe with hail to 1" indicated by radar. Storm motion
is toward the southwest. As the storms over Coconino County move
into an area of even higher instability and increased wind shear
over Yavapai County, there will be a threat for additional severe
weather and an isolated flood threat through mid evening. The
storms over Navajo Nation should push southwestward toward Winslow
and the I-40 corridor over the next few hours, as well as the
White Mountains region.

For Monday - the mid level steering flow turns more northerly as
the high pressure center shifts over central California. Moisture
remains plentiful along and south of the Mogollon Rim. Model data
has been consistent indicating a disturbance rotating southward
from UT/CO into Arizona during the afternoon. Several of the hi-
res models show a couple of lines of thunderstorms moving south
across areas from the Mogollon Rim/White Mtns into Yavapai and
Gila counties during the late afternoon and evening. With a very
moist and unstable environment in place, there will be a threat of
severe thunderstorms and localized flash flooding in these areas
and this is reflected in both the SPC and WPC outlooks for severe
weather and excessive rainfall.

Tuesday and Wednesday - a trough dipping down into the northwest
US will turn the steering flow from the west and eventually
southwest. Moisture should flow farther north and give areas along
and north of the Mogollon Rim higher storm chances and keep them a
bit lower for Yavapai especially by Wednesday. The risk of
localized flash flooding and a few strong storms will persist.

Thursday into next weekend - looking like at least a brief period
of drier conditions following the trough passage. Chance of storms
lingers Thursday but isolated at best by Friday and beyond. A
gradual warming trend but only back to near normal.

&&

.AVIATION...For the 06Z package...Look for mainly VFR conditions
over the next 24 hours. Thunderstorms continue west of a line from
KGCN to KFLG. Locally heavy rain and wind gusts to 40 kts
possible near any storms. Otherwise, generally light winds.
Another round of thunderstorms is expected to develop after 19Z
Monday. Coverage of storms should increase from Sunday with some
storms along/south of a KFLG-KSJN line possibly severe, with hail
and wind gusts 40+ kts. Aviation discussion not updated for TAF
amendments.

&&

.FIRE WEATHER...Shower and thunderstorm coverage is expected to
increase Monday and Tuesday. Localized flash flooding and very gusty
outflow winds are the main hazards. Winds outside storms will be
light, with temperatures cooling slightly on Tuesday.

Wednesday through Friday...Chances for showers and thunderstorms
remain high on Wednesday, with a gradual downturn by Friday.
Temperatures are expected to be slightly below normal.

&&

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

&&

PUBLIC...ET
AVIATION...ET
FIRE WEATHER...JJ

For Northern Arizona weather information visit
weather.gov/flagstaff

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
643 PM MST SUN AUG 15 2021

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

0550 PM     HAIL             2 WSW NUTRIOSO          33.95N 109.25W
08/15/2021  E0.70 INCH       APACHE             AZ   PUBLIC

            SPOTTER REPORTS DIME SIZE HAIL.

&&

ET

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
1133 PM MST SUN AUG 15 2021

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

1105 PM     HAIL             2 NNW PAULDEN           34.91N 112.48W
08/15/2021  E0.50 INCH       YAVAPAI            AZ   PUBLIC

            SPOTTER REPORTS 0.50 INCH HAIL IN PAULDEN.

&&

ET

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
1137 PM MST SUN AUG 15 2021

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

1129 PM     NON-TSTM WND GST 6 NNE IRON SPRINGS      34.66N 112.53W
08/15/2021  M58 MPH          YAVAPAI            AZ   MESONET

            MESONET STATION FW7304 PRESCOTT.

&&

ET

Special Weather Statement
National Weather Service Flagstaff AZ
1150 PM MST Sun Aug 15 2021

AZZ008-037-160715-
Yavapai County Valleys and Basins-Yavapai County  Mountains-
1150 PM MST Sun Aug 15 2021

...A strong thunderstorm will impact portions of Yavapai County
through 1215 AM MST...

At 1149 PM MST, Doppler radar was tracking a strong thunderstorm over
Yavapai Campground, or 7 miles west of Prescott Valley, moving
southwest at 30 mph.

HAZARD...Winds in excess of 40 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...
Prescott, Yavapai Campground, Downtown Prescott, Ponderosa Park,
Prescott Airport, Williamson Valley, Indian Hill West Prescott, Oak
Knoll Village, Prescott Gateway Mall, Iron Springs, Lower Wolf Creek
Campground and White Spar Campground.

This includes the following highways...
 State Route 89 between mile markers 302 and 322.
 State Route 89A between mile markers 318 and 321.
 State Route 69 between mile markers 294 and 296.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

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 3472 11256 3464 11236 3443 11247 3452 11271
TIME...MOT...LOC 0649Z 027DEG 27KT 3458 11253

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...40 MPH

ET