Alert archive / Arizona / Special Weather Statements in 2021

Special Weather Statement, NWS Flagstaff, AZ

August 1, 2021

NWS Flagstaff, AZ issued this special weather statement at Aug 1, 2021, 12:03 PM MST. It was in force for 27 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: Aug 1, 2021, 12:03 PM MST (19:03 UTC)
Expired: Aug 1, 2021, 12:30 PM MST
In force: 27 min
Issued by: NWS Flagstaff, AZ

The radar

The Flagstaff radar (KFSX), 141 km from the middle of the area, began a volume at 19:04 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, 7.1 hours before the alert went out and 219 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: 74 J/kg
Mixed-layer CIN: -65 J/kg
Mixed-layer LCL: 1273 m above ground
0-6 km bulk shear: 22 kt
0-1 km storm-relative helicity: 43 m²/s²
0-3 km storm-relative helicity: 71 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 Aug 1, 9:22 AM MST, 2 hours 41 minutes earlier.

Area forecast discussion, Aug 1, 9:22 AM MST, 2 hours 41 minutes before

Area Forecast Discussion
National Weather Service Flagstaff AZ
922 AM MST Sun Aug 1 2021

.SYNOPSIS...Scattered thunderstorm activity is expected again
today with lessening chances Monday. A drying and warming trend is
anticipated for Tuesday through Thursday as high pressure
strengthens over the area.

&&

.UPDATE...Very few changes were made to the short term forecast
this morning. Another round of scattered thunderstorms is forecast
this afternoon with storms moving slowly to the north throughout
the day. A few areas of flash flooding are possible where stronger
and/or training storms develop. Storm coverage should decrease by
late this evening.

&&

.PREV DISCUSSION /225 AM MST/...Quiet weather across the area this
morning aside from a few lingering showers in northeast Arizona.
Precipitable water values remain similar to what we saw on
Saturday. Therefore, expect another round of scattered showers and
thunderstorms, developing between 10 am - noon initially along the
higher terrain. Storms will continue through the afternoon and
early evening hours. The primary hazard will remain heavy rainfall
capable of producing localized flash flooding. Convection could
persist into the mid to late evening hours across northeast
Arizona before diminishing overnight.

High pressure begins to strengthen over the Desert Southwest on
Monday which will act to suppress storm activity. This will
continue Tuesday through Thursday as high pressure remains
overhead. At best, isolated coverage is expected on these days and
mainly in the White Mountains region. This looks to be the first
significant break in the monsoon that we have seen in the past few
weeks. With the strengthening high pressure and less cloud cover,
we will see daytime temperatures warm to around 5 degrees above
normal by mid-week. Make sure to prepare for the warmer
temperatures if you have outdoor plans.

Ensemble guidance indicates moisture will likely increase again
Friday into the weekend. At this time, it does not look like a
significant moisture surge but enough to bring back isolated to
scattered showers and storms each afternoon.

&&

.AVIATION...For the 18Z package...Mainly VFR conditions will
prevail. Scattered storms will develop again this afternoon and
evening, mainly along and north of a KPRC-KPAN-KJTC line. Periods
of MVFR/IFR conditions and gusty, erratic winds will occur in and
around thunderstorms. Storm activity will gradually diminish in
the mid to late evening hours. Aviation discussion not updated for
TAF amendments.

&&

.FIRE WEATHER...Another round of scattered storms is expected
today with more coverage likely for areas along the Mogollon Rim
and eastward. Lesser storm coverage is expected Monday. Light
winds are forecast outside of thunderstorm activity.

Tuesday through Thursday...Expect a drying and warming trend with
minimal thunderstorm coverage each afternoon. Seasonal winds
anticipated during this time.

&&

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

&&

PUBLIC...MCT/TPS
AVIATION...MCT
FIRE WEATHER...TPS

For Northern Arizona weather information visit
weather.gov/flagstaff

In the hours before

Local storm report, Aug 1, 11:27 AM MST, 36 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
1127 AM MST SUN AUG 1 2021

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

0330 PM     FLASH FLOOD      LABYRINTH SLOT CANYON   36.99N 111.29W
07/31/2021                   COCONINO           AZ   COUNTY OFFICIAL

            *** 1 FATAL ***

&&

TM

Special weather statement, Aug 1, 12:03 PM MST, 0 minutes before

Special Weather Statement
National Weather Service Flagstaff AZ
1203 PM MST Sun Aug 1 2021

AZZ014-017-011930-
Little Colorado River Valley in Apache County-White Mountains-
1203 PM MST Sun Aug 1 2021

...A STRONG THUNDERSTORM WILL REMAIN NEAR VERNON UNTIL 1230 PM MST...

At 1201 PM MST, Doppler radar was tracking a strong thunderstorm over
Vernon, or 18 miles east of Show Low, moving north at 10 mph.

Half inch hail will be possible with this storm.

Locations impacted include...
Vernon and Brown Creek Campground.

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.

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 3419 10959 3417 10981 3430 10985 3435 10985
      3438 10959
TIME...MOT...LOC 1901Z 172DEG 9KT 3426 10972

TM

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 31, 5:22 PM MST	Areal Flood Advisory	FGZ	Yavapai	113 min
Jul 31, 6:08 PM MST	Areal Flood Advisory	FGZ	Apache, Navajo	3 hr
Aug 1, 12:15 PM MST	Special Weather Statement	FGZ		30 min
Aug 1, 12:53 PM MST	Special Weather Statement	FGZ	Coconino	22 min
Aug 1, 1:08 PM MST	Special Weather Statement	FGZ		22 min
Aug 1, 1:14 PM MST	Special Weather Statement	FGZ		31 min
Aug 1, 1:30 PM MST	Special Weather Statement	FGZ	Navajo	30 min
Aug 1, 1:38 PM MST	Special Weather Statement	FGZ	Coconino	22 min
Aug 1, 1:53 PM MST	Special Weather Statement	FGZ		37 min
Aug 1, 2:03 PM MST	Special Weather Statement	FGZ	Navajo	27 min
Aug 1, 2:26 PM MST	Special Weather Statement	FGZ	Navajo	34 min
Aug 1, 2:55 PM MST	Special Weather Statement	FGZ		35 min
Aug 1, 3:12 PM MST	Special Weather Statement	FGZ		33 min
Aug 1, 3:15 PM MST	Special Weather Statement	FGZ		30 min
Aug 1, 3:21 PM MST	Special Weather Statement	FGZ		24 min
Aug 1, 3:58 PM MST	Flash Flood Warning	FGZ	Gila, Navajo	3 hr
Aug 1, 4:18 PM MST	Areal Flood Advisory	FGZ	Coconino	3 hr
Aug 1, 4:24 PM MST	Special Weather Statement	FGZ		51 min
Aug 1, 4:38 PM MST	Severe Thunderstorm Warning	FGZ	Apache, Navajo	37 min
Aug 1, 4:51 PM MST	Flash Flood Warning	FGZ	Gila, Navajo	3 hr
Aug 1, 4:52 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Apache, Coconino, Navajo	3 hr

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.