Alert archive / Arizona / Special Weather Statements in 2021

Special Weather Statement, NWS Flagstaff, AZ

July 18, 2021

NWS Flagstaff, AZ issued this special weather statement at Jul 18, 2021, 3:54 PM MST. It was in force for 51 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Jul 18, 2021, 3:54 PM MST (22:54 UTC)
Expired: Jul 18, 2021, 4:45 PM MST
In force: 51 min
Issued by: NWS Flagstaff, AZ

The radar

The Flagstaff radar (KFSX), 121 km from the middle of the area, began a volume at 22:53 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Flgstf/Belemont, AZ (KFGZ), launched 12:00Z, 10.9 hours before the alert went out and 43 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 191 J/kg
Mixed-layer CIN: -101 J/kg
Mixed-layer LCL: 1511 m above ground
0-6 km bulk shear: 16 kt
0-1 km storm-relative helicity: 14 m²/s²
0-3 km storm-relative helicity: 46 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

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What forecasters said that day

The local office's own words before this special weather statement went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Flagstaff, AZ wrote its last area forecast discussion before this special weather statement went out at Jul 18, 2:56 PM MST, 58 minutes earlier.

Area forecast discussion, Jul 18, 2:56 PM MST, 58 minutes before

Area Forecast Discussion
National Weather Service Flagstaff AZ
256 PM MST Sun Jul 18 2021

.SYNOPSIS...Scattered to numerous showers and thunderstorms are
forecast to develop each afternoon through the week. Localized
flash flooding will be possible with the stronger storms.
Temperatures are expected to remain around normal to slightly
below normal.

&&

.DISCUSSION...Scattered to numerous showers and thunderstorms will
continue to develop over northern Arizona through the afternoon
hours. Isolated flash flooding will be possible across the
region, with the isolated large hail threat generally remaining
primarily over Gila and Yavapai counties this afternoon, where the
greatest instability will remain.

Not much change is forecast with regards to the overall upper
level pattern through the week. High pressure should remain
centered over the Four Corners Region, maintaining monsoonal flow
over Arizona. No one day looks better or worse for precipitation
chances, so maintained the diurnal pattern forecast of highest
chances during the afternoon hours each day.

&&

.AVIATION...For the 00Z package...Expect mainly VFR conditions
through the TAF period. Scattered to numerous showers and
thunderstorms are forecast through 03Z. Thunderstorms will be
possible again after 18Z Monday. MVFR conditions will be possible
in stronger storms. Surface winds outside of storms will generally
be light. Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Scattered to numerous showers and thunderstorms
will develop across northern Arizona Monday afternoon, and again
Tuesday afternoon. Wetting rains, flash flooding, and gusty
outflow winds will be possible.

Wednesday through Friday...Numerous showers and thunderstorms are
expected each afternoon. Outside of storms, expect light winds
and near normal high temperatures.

&&

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

&&

PUBLIC...TM
AVIATION...TM
FIRE WEATHER...TM

For Northern Arizona weather information visit
weather.gov/flagstaff

In the hours before

Local storm report, Jul 18, 12:35 PM MST, 3 hours 19 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
1235 PM MST SUN JUL 18 2021

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

1226 PM     HEAVY RAIN       12 ENE CLINTS WELL      34.63N 111.12W
07/18/2021  M1.20 INCH       COCONINO           AZ   PUBLIC

            PUBLIC REPORT OF 1.20 INCHES OF RAIN 12
            MILES EAST-NORTHEAST OF CLINTS WELL.
            REPORTED RAINFALL RATE OF 1.00 INCH PER
            HOUR.

&&

EL

Local storm report, Jul 18, 12:51 PM MST, 3 hours 3 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
1251 PM MST SUN JUL 18 2021

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

1245 PM     FLASH FLOOD      4 S PRESCOTT AIRPORT    34.60N 112.42W
07/18/2021                   YAVAPAI            AZ   OTHER FEDERAL

            USGS RIVER GAUGE, GRWA3, MEASURED A 5 FOOT
            RISE ON GRANITE CREEK NEAR WATSON LAKE DUE
            TO HEAVY RAIN FROM A THUNDERSTORM.

&&

EL

Special weather statement, Jul 18, 1:08 PM MST, 2 hours 46 minutes before

Special Weather Statement
National Weather Service Flagstaff AZ
108 PM MST Sun Jul 18 2021

AZZ016-182045-
Eastern Mogollon Rim-
108 PM MST Sun Jul 18 2021

...SIGNIFICANT WEATHER ADVISORY FOR NAVAJO COUNTY UNTIL 145 PM MST...

At 107 PM MST, Doppler radar was tracking a strong thunderstorm near
Heber-Overgaard. This storm was nearly stationary.

Half inch hail and winds in excess of 40 mph will be possible with
this storm.

Locations impacted include...
Heber-overgaard.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3438 11047 3428 11059 3435 11068 3448 11055
TIME...MOT...LOC 2007Z 143DEG 4KT 3437 11054

ET

Local storm report, Jul 18, 2:31 PM MST, 1 hour 23 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
231 PM MST SUN JUL 18 2021

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

0225 PM     HEAVY RAIN       4 WNW ARIZONA SNOWBOWL  35.36N 111.77W
07/18/2021  E2.55 INCH       COCONINO           AZ   PUBLIC

            SOCIAL MEDIA REPORT OF 2.55 INCHES OF HEAVY
            RAINFALL NEAR HART PRAIRIE.

&&

EL

Local storm report, Jul 18, 3:35 PM MST, 19 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
335 PM MST SUN JUL 18 2021

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

0332 PM     FLASH FLOOD      1 WSW HEBER-OVERGAARD   34.41N 110.59W
07/18/2021                   NAVAJO             AZ   FIRE DEPT/RESCUE

            A 10-12 INCH RISE WAS REPORTED ON HESS CREEK
            IN HEBER-OVERGAARD. THE CREEK CAME OUT OF
            ITS BANKS PUTTING DEBRIS ON THE ROADWAY AND
            THREATENING ONE RESIDENTIAL HOME WHICH HAD
            TO BE SANDBAGGED.

&&

TPS

Special weather statement, Jul 18, 3:54 PM MST, 0 minutes before

Special Weather Statement
National Weather Service Flagstaff AZ
354 PM MST Sun Jul 18 2021

AZZ007-008-015-182345-
Western Mogollon Rim-Coconino Plateau-Yavapai County  Mountains-
354 PM MST Sun Jul 18 2021

...STRONG THUNDERSTORM ALONG I-40 FROM ASH FORK TO WILLIAMS UNTIL
445 PM MST...

At 353 PM MST, Doppler radar was tracking a strong thunderstorm 10
miles east of Ash Fork, or 29 miles north of Chino Valley, moving
northwest at 5 mph.

Pea size hail and winds in excess of 40 mph will be possible with
this storm.

Locations impacted include...
Williams and Ash Fork.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3526 11213 3515 11215 3509 11227 3516 11253
      3538 11240
TIME...MOT...LOC 2253Z 115DEG 6KT 3517 11232

EL

The office that day

Everything else NWS Flagstaff, AZ issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 18, 10:58 AM MST	Severe Thunderstorm Warning	FGZ	Yavapai	32 min
Jul 18, 11:14 AM MST	Flash Flood Warning Considerable damage threat	FGZ	Yavapai	3 hr
Jul 18, 12:16 PM MST	Severe Thunderstorm Warning	FGZ	Coconino	29 min
Jul 18, 1:03 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Navajo	3 hr
Jul 18, 1:08 PM MST	Special Weather Statement	FGZ		37 min
Jul 18, 1:34 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Coconino	3 hr
Jul 18, 2:12 PM MST	Severe Thunderstorm Warning	FGZ	Gila, Navajo	33 min
Jul 18, 2:18 PM MST	Severe Thunderstorm Warning	FGZ	Gila	42 min
Jul 18, 2:31 PM MST	Areal Flood Advisory	FGZ	Coconino	100 min
Jul 18, 2:33 PM MST	Severe Thunderstorm Warning	FGZ	Navajo	42 min
Jul 18, 2:53 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Gila, Navajo	102 min
Jul 18, 3:02 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Coconino	108 min
Jul 18, 3:47 PM MST	Severe Thunderstorm Warning	FGZ	Gila	43 min
Jul 18, 4:10 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Yavapai	51 min
Jul 18, 4:32 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Navajo	4 hr
Jul 18, 4:59 PM MST	Severe Thunderstorm Warning	FGZ	Gila, Yavapai	46 min

Nearby

Special Weather Statements in Arizona, 2021 Every special weather statement in 2021

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.