Alert archive / Arizona / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 24, NWS Flagstaff, AZ

August 20, 2020Gila County, Yavapai County, Arizona

NWS Flagstaff, AZ issued this severe thunderstorm warning at Aug 20, 2020, 5:01 PM MST for Gila County, Yavapai County, Arizona. It was in force for 44 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 20, 2020, 5:01 PM MST (00:01 UTC)
Expired
Aug 20, 2020, 5:45 PM MST
In force
44 min
Issued by
NWS Flagstaff, AZ
Area
Storm-based polygon
Hail
1.0 in
Wind
70.0 mph

Counties Gila County, AZ, Yavapai County, AZ

The radar

The Flagstaff radar (KFSX), 61 km from the middle of the area, began a volume at 00:05 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

Phoenix, AZ (KPSR), launched 00:00Z, 0.0 hours before the alert went out and 90 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-pSkew-T log-p diagram, Phoenix, AZ at 00:00Z on 2020-08-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 879 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Phoenix, AZ at 00:00Z on 2020-08-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 43 square meters per square second.1939Sfc1 km3 km6 km9 kmRMLM
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
879 J/kg
Mixed-layer CIN
-222 J/kg
Mixed-layer LCL
3040 m above ground
0-6 km bulk shear
16 kt
0-1 km storm-relative helicity
43 m²/s²
0-3 km storm-relative helicity
107 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 20, 2:39 PM MST, 2 hours 22 minutes earlier.

Area forecast discussion, Aug 20, 2:39 PM MST, 2 hours 22 minutes before
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In the hours before

Special weather statement, Aug 20, 1:14 PM MST, 3 hours 47 minutes before
Special Weather Statement
National Weather Service Flagstaff AZ
114 PM MST Thu Aug 20 2020

AZZ016-018-202100-
Northern Gila County-Eastern Mogollon Rim-
114 PM MST Thu Aug 20 2020

...SIGNIFICANT WEATHER ADVISORY FOR GILA AND COCONINO COUNTIES UNTIL
200 PM MST...

At 113 PM MST, Doppler radar was tracking a strong thunderstorm over
Christopher Creek, or 8 miles west of Forest Lakes, moving southwest
at 5 mph.

Penny size hail and winds in excess of 30 mph will be possible with
this storm.

Locations impacted include...
Hunter Creek, Christopher Creek, Forest Road 9350 Campground, Forest
Road 169 Campground, Rim Campground, Spillway Campground, Christopher
Creek Campground, Woods Canyon Lake Campground, Sharp Creek
Campground, Forest Road 195 Campground, Mogollon Campground and Crook
Campground.

LAT...LON 3422 11095 3430 11107 3439 11096 3433 11087
TIME...MOT...LOC 2013Z 046DEG 6KT 3433 11096

McCollum
Special weather statement, Aug 20, 1:51 PM MST, 3 hours 10 minutes before
Special Weather Statement
National Weather Service Flagstaff AZ
151 PM MST Thu Aug 20 2020

AZZ016-202115-
Eastern Mogollon Rim-
151 PM MST Thu Aug 20 2020

...SIGNIFICANT WEATHER ADVISORY FOR COCONINO COUNTY UNTIL 215 PM
MST...

At 150 PM MST, Doppler radar was tracking a strong thunderstorm 7
miles north of Christopher Creek, or 13 miles northwest of Forest
Lakes, moving southwest at 5 mph.

Penny size hail and winds in excess of 30 mph will be possible with
this storm.

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

LAT...LON 3448 11101 3444 11095 3437 11101 3443 11109
TIME...MOT...LOC 2050Z 035DEG 5KT 3443 11102

McCollum
Special weather statement, Aug 20, 2:13 PM MST, 2 hours 48 minutes before
Special Weather Statement
National Weather Service Flagstaff AZ
213 PM MST Thu Aug 20 2020

AZZ016-202145-
Eastern Mogollon Rim-
213 PM MST Thu Aug 20 2020

...SIGNIFICANT WEATHER ADVISORY FOR COCONINO COUNTY UNTIL 245 PM
MST...

At 211 PM MST, Doppler radar was tracking a strong thunderstorm near
Starlight Pines, moving southwest at 5 mph.

Penny size hail and winds in excess of 30 mph will be possible with
this storm.

Locations impacted include...
Starlight Pines.

LAT...LON 3464 11111 3455 11101 3446 11108 3458 11121
TIME...MOT...LOC 2111Z 036DEG 5KT 3457 11111

McCollum
Special weather statement, Aug 20, 3:07 PM MST, 1 hour 54 minutes before
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Special weather statement, Aug 20, 4:16 PM MST, 45 minutes before
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<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <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.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
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The office that day

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

IssuedProductOfficeCountiesLasted
Aug 20, 5:41 PM MSTSpecial Weather StatementFGZ49 min
Aug 20, 6:02 PM MSTSpecial Weather StatementFGZ28 min
Aug 21, 12:40 PM MSTSpecial Weather StatementFGZ35 min
Aug 21, 1:25 PM MSTSpecial Weather StatementFGZ50 min
Aug 21, 1:47 PM MSTSpecial Weather StatementFGZ28 min
Aug 21, 2:14 PM MSTSpecial Weather StatementFGZ31 min
Aug 21, 2:46 PM MSTSpecial Weather StatementFGZ29 min
Aug 21, 3:13 PM MSTSpecial Weather StatementFGZ32 min
Aug 21, 3:40 PM MSTSpecial Weather StatementFGZ35 min
Aug 21, 3:53 PM MSTSpecial Weather StatementFGZ52 min
Aug 21, 4:06 PM MSTSpecial Weather StatementFGZ24 min
Aug 21, 4:19 PM MSTSevere Thunderstorm WarningFGZYavapai26 min
Aug 21, 4:43 PM MSTAreal Flood AdvisoryFGZYavapai3 hr
Aug 21, 4:46 PM MSTSevere Thunderstorm WarningFGZYavapai44 min

Nearby

Severe Thunderstorm Warnings in Arizona, 2020Every 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.