Severe Thunderstorm Watch 512

Issued

Oct 5, 2021, 11:46 AM MST (18:46 UTC)

Expired

Oct 5, 2021, 8:00 PM MST

In force

8 hr

Issued by

the Storm Prediction Center

Largest hail expected

2 in

Strongest gust expected

70 kt

Counties Coconino County, AZ, Gila County, AZ, Graham County, AZ, La Paz County, AZ, Maricopa County, AZ, Mohave County, AZ, Navajo County, AZ, Pinal County, AZ, Yavapai County, AZ, Yuma County, AZ

The Flagstaff radar (KFSX), 57 km from the middle of the area, began a volume at 18:47 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.

Two or more tornadoes

20%

One or more EF2 to EF5 tornadoes

2%

Ten or more severe wind reports

40%

One or more gusts of 65 knots or more

30%

Ten or more severe hail reports

40%

One or more hailstones of 2 inches or more

30%

Six or more combined severe hail and wind reports

70%

• Mesoscale Discussion 1799 Severe potential...watch likelyOct 5, 11:18 AM MST
• Mesoscale Discussion 1800 Severe thunderstorm watch 512Oct 5, 1:55 PM MST
• Mesoscale Discussion 1801 Severe thunderstorm watch 512Oct 5, 3:53 PM MST
• Mesoscale Discussion 1803 Severe thunderstorm watch 512Oct 5, 5:51 PM MST

413 
WWUS20 KWNS 051842
SEL2  
SPC WW 051842
AZZ000-060300-

URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 512
NWS Storm Prediction Center Norman OK
1145 AM MST Tue Oct 5 2021

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of 
  Arizona

* Effective this Tuesday morning and evening from 1145 AM until
  800 PM MST.

* Primary threats include...
  Scattered damaging winds and isolated significant gusts to 80
    mph possible
  Scattered large hail and isolated very large hail events to 2
    inches in diameter possible
  A tornado or two possible

SUMMARY...Ahead of an upper system over southern California and the
Lower Colorado River Valley, strong to severe thunderstorms are
expected to develop within a very moist and unstable environment,
with the initial stronger storms expected across
west-central/south-central Arizona (including the Phoenix vicinity)
into parts of northern Arizona this afternoon. Large hail and
damaging winds are the primary risks through the late
afternoon/early evening hours.

The severe thunderstorm watch area is approximately along and 115
statute miles east and west of a line from 50 miles north northeast
of Grand Canyon AZ to 35 miles southeast of Gila Bend AZ. For a
complete depiction of the watch see the associated watch outline
update (WOUS64 KWNS WOU2).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for severe thunderstorms in and close to the watch area.
Persons in these areas should be on the lookout for threatening
weather conditions and listen for later statements and possible
warnings. Severe thunderstorms can and occasionally do produce
tornadoes.

&&

AVIATION...A few severe thunderstorms with hail surface and aloft to
2 inches. Extreme turbulence and surface wind gusts to 70 knots. A
few cumulonimbi with maximum tops to 500. Mean storm motion vector
21020.

...Guyer

Severe Thunderstorm Watches in Arizona, 2021Every severe thunderstorm watch in 2021

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.