Alert archive / Wyoming / Special Weather Statements in 2020

Special Weather Statement, NWS Cheyenne, WY

August 3, 2020

NWS Cheyenne, WY issued this special weather statement at Aug 3, 2020, 5:08 PM MDT. It was in force for 52 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 3, 2020, 5:08 PM MDT (23:08 UTC)
Expired
Aug 3, 2020, 6:00 PM MDT
In force
52 min
Issued by
NWS Cheyenne, WY

The radar

The Cheyenne radar (KCYS), 151 km from the middle of the area, began a volume at 23:10 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

Denver, CO (KDNR), launched 12:00Z, 11.1 hours before the alert went out and 341 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, Denver, CO at 12:00Z on 2020-08-03Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 57 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, Denver, CO at 12:00Z on 2020-08-03The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 22 square meters per square second.193958Sfc1 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
57 J/kg
Mixed-layer CIN
-477 J/kg
Mixed-layer LCL
1630 m above ground
0-6 km bulk shear
33 kt
0-1 km storm-relative helicity
22 m²/s²
0-3 km storm-relative helicity
40 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 Cheyenne, WY wrote its last area forecast discussion before this special weather statement went out at Aug 3, 2:22 PM MDT, 2 hours 46 minutes earlier.

Area forecast discussion, Aug 3, 2:22 PM MDT, 2 hours 46 minutes before
<!doctype html>
<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.
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Hazardous weather outlook, Aug 3, 4:06 AM MDT, 13 hours 2 minutes before
Hazardous Weather Outlook
National Weather Service Cheyenne WY
406 AM MDT Mon Aug 3 2020

WYZ104-109>114-041015-
Ferris/Seminoe/Shirley Mountains-Central Carbon County-
North Snowy Range Foothills-Southwest Carbon County-
Sierra Madre Range-Upper North Platte River Basin-Snowy Range-
406 AM MDT Mon Aug 3 2020

This hazardous weather outlook is for south central Wyoming.

.DAY ONE...TODAY AND TONIGHT

Isolated to widely scattered afternoon afternoon and early evening
thunderstorms will develop. Severe weather is not expected.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

Minimum humidity will fall below 15 percent with west winds gusting
to 30 mph Tuesday afternoon outside the mountains. Isolated to widely
scattered high based dry thunderstorms will be possible that may
result in additional fire starts. A Fire Weather Watch is in effect
for west and central Carbon County from 11 AM through 8 PM Tuesday.

Widely scattered afternoon thunderstorms will develop Wednesday
and Thursday, with more isolated coverage Friday and Saturday.
Severe weather is not expected.

.Spotter information statement...

Spotter activation will not be required.

NEZ002-003-019>021-054-055-095-096-WYZ101>103-105>108-115>119-
041015-
Dawes-Box Butte-Scotts Bluff County-Banner County-Morrill-
Kimball County-Cheyenne-North Sioux-South Sioux-
Converse County Lower Elevations-Niobrara County-
North Laramie Range-Shirley Basin-
Central Laramie Range and Southwest Platte County-
East Platte County-Goshen County-Laramie Valley-
South Laramie Range-South Laramie Range Foothills-
Central Laramie County-East Laramie County-
406 AM MDT Mon Aug 3 2020

This hazardous weather outlook is for the western Nebraska
Panhandle...east central Wyoming...and southeast Wyoming.

.DAY ONE...TODAY AND TONIGHT

Scattered thunderstorms will develop over the Laramie Range
during the early afternoon and move southeast onto the high
plains during the late afternoon and early evening. Isolated
strong to marginally severe thunderstorms producing hail up
to one inch and wind gusts of 50 to 60 mph will be possible.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

Scattered afternoon and evening thunderstorms will develop
Tuesday through Thursday, becoming more isolated and confined
to the mountains Friday and Saturday. Strong to severe
thunderstorms producing large hail, wind gusts of 60 mph and
locally heavy rain will be possible along and east of the
Interstate 25 corridor Tuesday.

.Spotter information statement...

Spotter activation will not be required.

In the hours before

Special weather statement, Aug 3, 5:08 PM MDT, 0 minutes before
Special Weather Statement
National Weather Service Cheyenne WY
508 PM MDT Mon Aug 3 2020

WYZ101-103-105-106-115-116-040000-
Shirley Basin WY-South Laramie Range WY-
Central Laramie Range and Southwest Platte County WY-
Converse County Lower Elevations WY-North Laramie Range WY-
Laramie Valley WY-
508 PM MDT Mon Aug 3 2020

...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN ALBANY AND
SOUTHWESTERN CONVERSE COUNTIES UNTIL 600 PM MDT...

At 508 PM MDT, Doppler radar was tracking strong thunderstorms along
a line extending from 7 miles north of Boxelder to 7 miles southwest
of Wheatland Reservoir 3. Movement was east at 20 mph.

Penny size hail and wind gusts up to 50 mph will be possible with
these storms.

Strong thunderstorms will be near...
  Wheatland Reservoir 3 around 525 PM MDT.
  Laprele Reservoir around 540 PM MDT.
  Douglas around 600 PM MDT.

This includes Interstate 25 in Wyoming between mile markers 135 and
153.

LAT...LON 4286 10533 4166 10532 4179 10593 4275 10594
TIME...MOT...LOC 2308Z 269DEG 18KT 4272 10584 4182 10583

Rubin

The office that day

Everything else NWS Cheyenne, WY issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 3, 1:38 PM MDTFire Weather WatchCYS25 hr
Aug 3, 1:38 PM MDTRed Flag WarningCYS30 hr
Aug 3, 5:19 PM MDTSpecial Weather StatementCYSLaramie41 min
Aug 3, 5:36 PM MDTSpecial Weather StatementCYSAlbany39 min
Aug 3, 5:46 PM MDTSpecial Weather StatementCYSLaramie44 min
Aug 3, 5:55 PM MDTSevere Thunderstorm WarningCYSAlbany35 min

Nearby

Special Weather Statements in Wyoming, 2020Every special weather statement 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.