Flash Flood Warning 205, NWS Flagstaff, AZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
1043 AM MST Wed Aug 18 2021

.SYNOPSIS...Scattered showers and thunderstorms will become
more widespread this afternoon and evening across northern
Arizona. Flash flooding will be possible in areas of heavy
rainfall. Drier conditions are expected Thursday through the
weekend. Cooler temperatures are also expected through the rest of
the week.

&&

.UPDATE...The latest high-res models prog thunderstorms developing
near the Prescott area this afternoon between the 2pm-6pm MST time
frame. Given the ample moisture in place, went ahead and expanded
the flash flood watch to include Yavapai County through this
evening.

Another active monsoon thunderstorm day is expected as plenty of
moisture, instability, and lift remains in place. However, storm
motions will be to the north-northeast and will be much faster
than yesterday given a strong low pressure system entering Idaho.
Better organized storms will be possible near the AZ/UT border
this afternoon closer to the strongest wind shear. Will continue
to monitor afternoon/evening trends.

&&

.PREV DISCUSSION /255 AM MST/...A few isolated showers have begun
to develop over the lower elevations south of the Mogollon Rim.
This activity is expected to continue to increase in coverage
through this morning. Heavy rainfall is expected to lead to a few
localized areas of flash flooding this morning over Gila County.
Showers and thunderstorms are expected to increase in coverage
this afternoon and into the evening, especially for areas along
and north of the Mogollon Rim. With increased moisture in place
once again and many areas saturated from heavy rainfall
yesterday, an enhanced threat of flash flooding remains over
portions of central and northwester Arizona. The Flash Flood
Watch has been extended as a result to include areas along the
Mogollon Rim northwestward into the Coconino and Kaibab Plateau
where HREF guidance continues to indicate the greatest potential
for heavy rainfall. While flash flooding will be the primary
threat this afternoon, a few strong to severe storms are also
possible with the potential to produce large hail and damaging
winds.

Longwave trough continues to move into the Intermountain West
today, with the center of the trough passing over Utah during the
day Thursday. Breezy and cooler conditions are expected as a
result today and again on Thursday. As the trough passes to the
north, the monsoonal moisture in place gets swept away with dryer
conditions expected in its wake Thursday and into the weekend.
Shower and thunderstorm chances do remain over mainly in the high
terrain of far northern Arizona near the Utah border Thursday and
Friday.

Dry conditions remain over much of the areas through the weekend.
Though temperatures begin to warm slightly each day as heights
rise from a ridge gradually building in from the east. Monsoonal
moisture does begin to creep back into Arizona, especially over
the eastern portions of the state, towards the first half of next
week as the ridge builds. However, confidence in any widespread
coverage of showers and thunderstorms is low at this point.

&&

.AVIATION...For the 18Z package...MVFR ceilings near KGCN-KFLG
should dissipate after 19Z. Showers and thunderstorms will become
widespread over northern Arizona this afternoon. Isolated IFR in
heavier storms with hail and gusty winds also possible. Outside of
storm activity, mainly VFR conditions and southwest winds around
10-15 kts with gusts around 25 kts. Aviation discussion not
updated for TAF amendments.

&&

.FIRE WEATHER...Scattered to numerous showers and thunderstorms
are expected again today. Large hail, localized flash flooding, and
very gusty outflow winds will be the main hazards. Winds will also
become breezy out of the southwest today with afternoon gusts around
30 mph. Much drier conditions are forecast Thursday with a continued
chance for storms along the far northern zones.

Friday through Sunday...Drier weather is expected through the
weekend, with below normal temperatures and breezy southwest winds.

&&

.FGZ WATCHES/WARNINGS/ADVISORIES...Flash Flood Watch through this evening FOR AZZ004>009-012-015-
016-018-037-038.

&&

PUBLIC...TM/Humphreys
AVIATION...TM
FIRE WEATHER...MCT

For Northern Arizona weather information visit
weather.gov/flagstaff

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PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
1121 AM MST WED AUG 18 2021

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

0845 AM     FLASH FLOOD      12 SW STRAWBERRY        34.28N 111.64W
08/18/2021                   GILA               AZ   MESONET

            EAST VERDE RIVER NEAR CHILDS (EVDA3)
            INDICATED A 2.9 FT. RISE BETWEEN 8:00AM MST
            AND 8:45AM MST.

&&

TM

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
1126 AM MST WED AUG 18 2021

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

1100 PM     FLASH FLOOD      9 WNW CAMERON           35.93N 111.56W
08/17/2021                   COCONINO           AZ   MESONET

            THE LITTLE COLORADO RIVER NEAR CAMERON
            STREAM GAGE (LCCA3) INDICATED A 2.9 FT. RISE
            BETWEEN 8:15PM AND 11:00PM MST.

&&

TM

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
1131 AM MST WED AUG 18 2021

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

1030 AM     FLASH FLOOD      2 SSE JAKES CORNER      33.98N 111.30W
08/18/2021                   GILA               AZ   MESONET

            THE TONTO CREEK ABOVE GUN CREEK STREAM GAGE
            (TNRA3) INDICATED AT 3.1 FT. RISE BETWEEN
            8:45AM MST AND 10:30AM MST.

&&

TM

Special Weather Statement
National Weather Service Flagstaff AZ
1254 PM MDT Wed Aug 18 2021

AZZ010-181930-
Chinle Valley-
1254 PM MDT Wed Aug 18 2021

...A strong thunderstorm will impact portions of Apache and Navajo
Counties near Dennehotso through 130 PM MDT...

At 1252 PM MDT, Doppler radar was tracking a strong thunderstorm 14
miles southwest of Mexican Water, or 18 miles south of Mexican Hat,
moving northeast at 25 mph.

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

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 and Dennehotso.

This includes the following highways...
 Highway 160 between mile markers 413 and 440.
 Highway 191 between mile markers 508 and 510.

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 3695 10952 3674 10986 3687 11002 3700 10990
      3700 10958
TIME...MOT...LOC 1852Z 224DEG 20KT 3686 10986

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

EL

Special Weather Statement
National Weather Service Flagstaff AZ
1201 PM MST Wed Aug 18 2021

AZZ008-037-181945-
Yavapai County Valleys and Basins-Yavapai County  Mountains-
1201 PM MST Wed Aug 18 2021

...A strong thunderstorm will impact portions of Yavapai County near
Black Canyon City through 1245 PM MST...

At 1200 PM MST, Doppler radar was tracking a strong thunderstorm over
Black Canyon City, or 11 miles north of New River, moving northeast
at 20 mph.

HAZARD...Winds in excess of 40 mph, half inch hail, and heavy
         rainfall.

SOURCE...Radar indicated.

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

Locations impacted include...
Rock Springs and Black Canyon City.

This includes Interstate 17 between mile markers 242 and 257.

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 3405 11215 3405 11216 3404 11216 3403 11217
      3405 11221 3436 11207 3423 11179 3402 11196
TIME...MOT...LOC 1900Z 208DEG 19KT 3409 11209

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

EL