Alert archive / Arizona / Areal Flood Warnings in 2021

Areal Flood Warning 6, NWS Flagstaff, AZ

August 18, 2021Gila County, Yavapai County, Arizona

NWS Flagstaff, AZ issued this areal flood warning at Aug 18, 2021, 10:41 PM MST for Gila County, Yavapai County, Arizona. It was in force for 10 hr. 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 18, 2021, 10:41 PM MST (05:41 UTC)
Expired
Aug 19, 2021, 8:30 AM MST
In force
10 hr
Issued by
NWS Flagstaff, AZ
Area
Storm-based polygon
Flood severity
None

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 05:41 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, 5.7 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 2021-08-19Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 510 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 2021-08-19The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 157 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
510 J/kg
Mixed-layer CIN
-174 J/kg
Mixed-layer LCL
1692 m above ground
0-6 km bulk shear
24 kt
0-1 km storm-relative helicity
157 m²/s²
0-3 km storm-relative helicity
230 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.7

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this areal flood 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 areal flood warning went out at Aug 18, 8:32 PM MST, 2 hours 9 minutes earlier.

Area forecast discussion, Aug 18, 8:32 PM MST, 2 hours 9 minutes before
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In the hours before

Special weather statement, Aug 18, 5:31 PM MST, 5 hours 10 minutes before
Special Weather Statement
National Weather Service Flagstaff AZ
531 PM MST Wed Aug 18 2021

AZZ008-037-190100-
Yavapai County Valleys and Basins-Yavapai County  Mountains-
531 PM MST Wed Aug 18 2021

...A strong thunderstorm will impact portions of Yavapai County
through 600 PM MST...

At 530 PM MST, Doppler radar was tracking a strong thunderstorm over
Iron Springs, or 9 miles west of Prescott Valley, moving northeast at
15 mph.

HAZARD...Winds in excess of 30 mph and half inch hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Prescott Valley, Prescott, Dewey-humboldt, Groom Creek Subdivision,
Prescott Airport, Prescott Gateway Mall, Iron Springs, Yavapai
Campground, Downtown Prescott, Ponderosa Park, Indian Hill West
Prescott, Oak Knoll Village, Wilhoit, Lynx Lake Dam, Prescott Valley
Event Center and White Spar Campground.

This includes the following highways...
 State Route 89 near mile marker 295, and between mile markers 299
and 325.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

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

&&

LAT...LON 3442 11259 3458 11269 3476 11240 3452 11224
TIME...MOT...LOC 0030Z 242DEG 15KT 3454 11256

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...30 MPH

DB
Local storm report, Aug 18, 6:33 PM MST, 4 hours 8 minutes before
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</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.
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      <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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Local storm report, Aug 18, 7:07 PM MST, 3 hours 34 minutes before
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      <p id="message1">
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      <p id="message2">
        Please try again in a few minutes.
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Local storm report, Aug 18, 7:32 PM MST, 3 hours 9 minutes before
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      <h1 id="headline">This service is currently unavailable.</h1>
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      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
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Local storm report, Aug 18, 7:33 PM MST, 3 hours 8 minutes before
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<head>
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  <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 18, 5:13 PM MSTFlash Flood WarningFGZYavapai3 hr
Aug 18, 5:17 PM MSTFlash Flood Warning Considerable damage threatFGZCoconino, Yavapai4 hr
Aug 18, 5:31 PM MSTSpecial Weather StatementFGZYavapai29 min
Aug 18, 5:43 PM MSTSevere Thunderstorm WarningFGZCoconino23 min
Aug 18, 7:59 PM MSTFlash Flood Warning Considerable damage threatFGZGila4 hr
Aug 18, 8:08 PM MSTFlash Flood Warning Considerable damage threatFGZYavapai6 hr
Aug 18, 11:56 PM MSTFlash Flood Warning Considerable damage threatFGZCoconino8 hr

Nearby

Areal Flood Warnings in Arizona, 2021Every areal flood warning 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.