Special Weather Statement, NWS Flagstaff, AZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
912 AM MST Wed Sep 29 2021

.SYNOPSIS...Scattered showers and thunderstorms will continue
across northern Arizona each day through Thursday. Drier and
warmer conditions are forecast for the weekend with a return to
more seasonable fall weather. Unsettled and cooler weather may
return early next week.

&&

.UPDATE...Forecast remains on track with minimal updates needed.
A few thunderstorms with frequent lightning have formed in
northeast Arizona this morning and are moving quickly towards the
east-northeast. Hi-res models continue to show the majority of
shower and storm activity will remain in this area this morning.
Better coverage can be expected by the afternoon with slight rain
chances expanding south and westward across much of the region.

&&

.PREV DISCUSSION /335 AM MST/...An area of low pressure over the
Great Basin continues to deepen just to our west. Satellite shows
dry mid-level air coming in across the area which is supported in
sounding analysis. A cold front associated with this feature will
sweep across our area today and Thursday. Expect precipitation
chances for today to be isolated to scattered. Hi-res models
indicate the best chances for development will remain north of
I-40 for Wednesday afternoon.

As the low deepens over Arizona on Thursday, flow turns southerly
with and uptick in moisture across the area as the low picks up
moisture over the Gulf of California. Overnight Wednesday into
Thursday, models prog that showers and thunderstorms will develop
to our south and spread into the eastern portions of our area by
early morning. Coverage will then increase, mainly in the eastern
portions of our area from Flagstaff and I-17 eastward, through the
day on Thursday as the low moves overhead.

As the system exits the area on Friday, we return to much drier
and warmer weather as a ridge builds in across the southwest.
Expect warmer days and chilly nights, especially Friday morning.
More unsettled weather may return early next week.

&&

.AVIATION...For the 18Z package...Areas of low clouds this morning
will produce localized IFR/MVFR through about 17Z, especially near
KGCN. Otherwise, expect mainly VFR conditions for the 24 hour
forecast period. Isold-sct -SHRA/-TSRA through this evening with
increasing coverage aft 06Z east of a KPAN - KINW line. Localized
MVFR in/near showers and storms. Sfc winds SW 5-15 kts gusting to
20kts. Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Well below normal daytime temperatures continue
today and Thursday, with a chance of showers and thunderstorms each
day. Chances for wetting rainfall are higher Thursday, especially
east of the I-17 corridor. Locally gusty southwest winds Wednesday
becoming lighter on Thursday.

Friday through Sunday...A dry and warmer period develops during this
time frame, with generally light winds.

&&

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

&&

PUBLIC...JM/ET
AVIATION...MCT
FIRE WEATHER...Peterson

For Northern Arizona weather information visit
weather.gov/flagstaff

Special Weather Statement
National Weather Service Flagstaff AZ
1016 AM MDT Wed Sep 29 2021

AZZ010-011-291645-
Chuska Mountains and Defiance Plateau-Chinle Valley-
1016 AM MDT Wed Sep 29 2021

...A strong thunderstorm will impact portions of Apache County
near Cove Chapter House through 1045 AM MDT...

At 1014 AM MDT, Doppler radar was tracking a strong thunderstorm near
Cove Chapter House, or 33 miles southwest of Shiprock, moving east at
20 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...
Red Rock and Cove Chapter House.

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 3648 10935 3666 10940 3677 10905 3650 10905
TIME...MOT...LOC 1614Z 254DEG 18KT 3660 10926

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

MCT

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
935 AM MST WED SEP 29 2021

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

0730 PM     FLASH FLOOD      9 SW JACOB LAKE         36.64N 112.35W
09/27/2021                   COCONINO           AZ   PARK/FOREST SRVC

            THIS IS A POST EVENT REPORT FROM MONDAY
            EVENING. KAIBAB NATIONAL FOREST REPORTS ROAD
            CLOSURES DUE TO FLOODING AND DEBRIS ALONG
            FOREST ROAD 22 FROM FOREST ROAD 422A TO BIG
            SPRINGS. TIME OF REPORT IS AN ESTIMATE.

&&

MCT

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

AZZ010-291945-
Chinle Valley-
108 PM MDT Wed Sep 29 2021

...A strong thunderstorm will impact portions of Apache County near
Mexican Water through 145 PM MDT...

At 107 PM MDT, Doppler radar was tracking a strong thunderstorm over
Mexican Water, or 19 miles southeast of Mexican Hat, moving northeast
at 20 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...
Mexican Water.

This includes the following highways...
 Highway 160 between mile markers 429 and 445.
 Highway 191 between mile markers 507 and 510.

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 3686 10965 3700 10977 3700 10934
TIME...MOT...LOC 1907Z 238DEG 16KT 3700 10960

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

MCT