Alert archive / Arizona / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 45, NWS Flagstaff, AZ

August 30, 2020Yavapai County, Arizona

NWS Flagstaff, AZ issued this severe thunderstorm warning at Aug 30, 2020, 1:13 PM MST for Yavapai County, Arizona. It was in force for 32 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Aug 30, 2020, 1:13 PM MST (20:13 UTC)
Expired: Aug 30, 2020, 1:45 PM MST
In force: 32 min
Issued by: NWS Flagstaff, AZ
Area: Storm-based polygon
Hail: 0.75 in
Wind: 60.0 mph

County Yavapai County, AZ

The radar

The Flagstaff radar (KFSX), 124 km from the middle of the area, began a volume at 20:14 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, 8.2 hours before the alert went out and 98 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: 647 J/kg
Mixed-layer CIN: -2 J/kg
Mixed-layer LCL: 631 m above ground
0-6 km bulk shear: 36 kt
0-1 km storm-relative helicity: 44 m²/s²
0-3 km storm-relative helicity: 51 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this severe thunderstorm warning 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 severe thunderstorm warning went out at Aug 30, 10:00 AM MST, 3 hours 13 minutes earlier.

Area forecast discussion, Aug 30, 10:00 AM MST, 3 hours 13 minutes before

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In the hours before

Local storm report, Aug 30, 10:19 AM MST, 2 hours 54 minutes before

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  <meta charset="utf-8">
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  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
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        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
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Special weather statement, Aug 30, 11:51 AM MST, 1 hour 22 minutes before

Special Weather Statement
National Weather Service Flagstaff AZ
1151 AM MST Sun Aug 30 2020

AZZ008-037-301915-
Yavapai County Valleys and Basins-Yavapai County  Mountains-
1151 AM MST Sun Aug 30 2020

...SIGNIFICANT WEATHER ADVISORY FOR YAVAPAI COUNTY UNTIL 1215 PM
MST...

At 1150 AM MST, Doppler radar was tracking a strong thunderstorm near
Dewey-humboldt, or 13 miles southeast of Prescott Valley, moving
southeast at 5 mph.

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

This storm will remain over mainly rural areas of Yavapai County.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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 3449 11228 3458 11219 3453 11202 3437 11217
TIME...MOT...LOC 1850Z 308DEG 5KT 3449 11219

MCT

Special weather statement, Aug 30, 12:20 PM MST, 53 minutes before

Special Weather Statement
National Weather Service Flagstaff AZ
1220 PM MST Sun Aug 30 2020

AZZ008-037-301945-
Yavapai County Valleys and Basins-Yavapai County  Mountains-
1220 PM MST Sun Aug 30 2020

...SIGNIFICANT WEATHER ADVISORY FOR YAVAPAI COUNTY NEAR POLAND
JUNCTION UNTIL 1245 PM MST...

At 1219 PM MST, Doppler radar was tracking a strong thunderstorm near
Poland Junction, or 15 miles southeast of Prescott Valley, moving
east at 25 mph.

Penny size hail and wind gusts up to 50 mph will be possible with
this storm.

Locations impacted include...
Mayer, Poland Junction and Powell Springs 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 3436 11226 3451 11231 3461 11196 3439 11189
TIME...MOT...LOC 1919Z 252DEG 24KT 3447 11216

MCT

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 29, 5:13 PM MST	Special Weather Statement	FGZ		32 min
Aug 30, 12:01 AM MST	Flash Flood Warning Considerable damage threat	FGZ	Gila	4 hr
Aug 30, 3:19 AM MST	Special Weather Statement	FGZ	Navajo	26 min
Aug 30, 11:51 AM MST	Special Weather Statement	FGZ	Yavapai	24 min
Aug 30, 12:20 PM MST	Special Weather Statement	FGZ	Yavapai	25 min
Aug 30, 12:42 PM MST	Severe Thunderstorm Warning	FGZ	Yavapai	33 min
Aug 30, 2:10 PM MST	Severe Thunderstorm Warning	FGZ	Gila, Yavapai	35 min
Aug 30, 2:44 PM MST	Special Weather Statement	FGZ		31 min
Aug 30, 3:42 PM MST	Special Weather Statement	FGZ		33 min
Aug 30, 4:26 PM MST	Special Weather Statement	FGZ	Gila	34 min
Aug 30, 4:43 PM MST	Severe Thunderstorm Warning	FGZ	Yavapai	32 min

Nearby

Severe Thunderstorm Warnings in Arizona, 2020 Every severe thunderstorm warning in 2020

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.