Alert archive / Wyoming / Special Weather Statements in 2018

Special Weather Statement, NWS Cheyenne, WY

August 6, 2018Laramie County, Wyoming

NWS Cheyenne, WY issued this special weather statement at Aug 6, 2018, 6:29 PM MDT for Laramie County, Wyoming. It was in force for 31 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 6, 2018, 6:29 PM MDT (00:29 UTC)
Expired
Aug 6, 2018, 7:00 PM MDT
In force
31 min
Issued by
NWS Cheyenne, WY

County Laramie County, WY

The radar

The Cheyenne radar (KCYS), 29 km from the middle of the area, began a volume at 00:32 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 (KDEN), launched 00:00Z, 0.5 hours before the alert went out and 176 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 00:00Z on 2018-08-07Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1181 joules per kilogram.LCLEL10008507005003002001001 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 00:00Z on 2018-08-07The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 37 square meters per square second.19395878Sfc1 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
1181 J/kg
Mixed-layer CIN
-2 J/kg
Mixed-layer LCL
1882 m above ground
0-6 km bulk shear
48 kt
0-1 km storm-relative helicity
37 m²/s²
0-3 km storm-relative helicity
146 m²/s²
Significant tornado parameter
0.1
Supercell composite
4.5

Open this sounding in Storm Lab

The text

As transmitted.

<!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.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

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 6, 6:09 PM MDT, 20 minutes earlier.

Area forecast discussion, Aug 6, 6:09 PM MDT, 20 minutes before
Area Forecast Discussion
National Weather Service Cheyenne WY
609 PM MDT Mon Aug 6 2018

.SHORT TERM...(This evening through Wednesday)
Issued at 255PM MDT Mon Aug 6 2018

Another active afternoon today with strong to severe thunderstorms
developing over far southeast Wyoming. A Severe Thunderstorm Watch
is in effect for extreme southeast Wyoming and the southern
Nebraska panhandle until 9 PM late this evening. One of these
thunderstorms, which went over western and southern Cheyenne,
produced up to golf ball sized hail as it moved south into
Colorado. Expect a few more strong to severe thunderstorms to form
in and near the Watch area this afternoon through this evening.
Hail will be the primary threat with these thunderstorms with some
localized flash flooding and strong winds. Active should push
southeast of the area by 9 or 10 pm.

Similar conditions are expected on Tuesday, although there will be
somewhat less of a severe weather threat with long/narrow CAPE on
model soundings. A few thunderstorms may become strong, but should
be rather isolated and occur later in the day. Models show some
drier air moving into the area for Wednesday which will limit
thunderstorm coverage to isolated, and mainly over southeast
Wyoming.

.LONG TERM...(Tuesday - Sunday)
Issued at 412 AM MDT Mon Aug 6 2018

In general, a warmer and drier period of weather should prevail as
upper-level ridging builds across the western CONUS. An occasional
disturbance/ridge-runner will yield a convective risk from time to
time, but do not expect to see any organized precipitation chances
through the extended forecast period.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 609 PM MDT Mon Aug 6 2018

Scattered thunderstorms will continue to move southeastward across
the region through early evening, with thunderstorms developing
along I-80 east of Laramie potentially affecting Cheyenne and
Sidney through 03Z. We are also watching the Chadron area as
outflow boundaries from storms to the northeast move through,
potentially kicking off storms in the vicinity of Chadron through
03Z as well. Otherwise, expect VFR overnight into tomorrow morning
with the exception of Laramie, Cheyenne, Sidney and Alliance where
fog could be an issue toward early morning in areas that saw
heavier precipitation today. We also bring in another mention of
thunderstorms tomorrow afternoon late in the forecast period for
Cheyenne and Sidney.

&&

.FIRE WEATHER...
Issued at 143 PM MDT Mon Aug 6 2018

Fire Weather concerns are expected to be low through this weekend.
Showers and thunderstorms will continue for mostly southeast Wyoming
through Wednesday of this week. Warmer and drier conditions are
expected by the end of the week and into the weekend, but wind
should remain light over the next 7 days. Daytime minimum relative
humidities will lower to around 15 to 20 percent, each day, west
of Interstate 25 but light winds should keep concerns minimal.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&

SHORT TERM...TJT
LONG TERM...CLH
AVIATION...JG
FIRE WEATHER...TJT
Hazardous weather outlook, Aug 6, 2:45 PM MDT, 3 hours 44 minutes before
Hazardous Weather Outlook
National Weather Service Cheyenne WY
245 PM MDT Mon Aug 6 2018

NEZ002-003-019>021-054-055-095-096-WYZ101>103-106>108-116>119-
071245-
Dawes-Box Butte-Scotts Bluff-Banner-Morrill-Kimball-Cheyenne-
North Sioux-South Sioux-Converse County Lower Elevations-
Niobrara County-North Laramie Range-
Central Laramie Range and Southwest Platte County-
East Platte County-Goshen County-South Laramie Range-
South Laramie Range Foothills-Central Laramie County-
East Laramie County-
245 PM MDT Mon Aug 6 2018

This hazardous weather outlook is for portions of western
Nebraska...east central Wyoming and southeast Wyoming.

.DAY ONE...TODAY AND TONIGHT

A Severe Thunderstorm Watch is in effect for far southeast Wyoming
and the southern Nebraska panhandle until 900 PM MDT. Scattered
showers and thunderstorms are expected to continue into this
evening. A few storms may be strong to severe, mainly along and east
of the Laramie Range. Large hail and damaging winds will be the
primary hazards.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

Thunderstorms will continue Tuesday and Wednesday, especially over
southeast Wyoming and the southern Nebraska panhandle.

.Spotter information statement...

Spotter activation will not be needed.

WYZ104-105-109>115-071245-
Ferris/Seminoe/Shirley Mountains-Shirley Basin-
Central Carbon County-North Snowy Range Foothills-
Southwest Carbon County-Sierra Madre Range-
Upper North Platte River Basin-Snowy Range-Laramie Valley-
245 PM MDT Mon Aug 6 2018

This hazardous weather outlook is for portions of south central
Wyoming and southeast Wyoming.

.DAY ONE...TODAY AND TONIGHT

Scattered showers and thunderstorms are expected this afternoon
and evening. Severe weather is not expected.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

The probability for widespread hazardous weather is low.

.Spotter information statement...

Spotter activation will not be needed.

In the hours before

Local storm report, Aug 6, 4:00 PM MDT, 2 hours 29 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHEYENNE WY
400 PM MDT MON AUG 6 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0355 PM     HAIL             ALLIANCE                42.10N 102.87W
08/06/2018  E1.00 INCH       BOX BUTTE          NE   TRAINED SPOTTER

            JUST A FEW.

&&

DDEAL
Local storm report, Aug 6, 4:47 PM MDT, 1 hour 42 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHEYENNE WY
447 PM MDT MON AUG 6 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0427 PM     HAIL             7 NE ANGORA             41.95N 103.02W
08/06/2018  M2.50 INCH       MORRILL            NE   STORM CHASER

            REPORTS OF VEHICLES WITH SMASHED WINDSHIELDS.

&&

ABRAUN
Local storm report, Aug 6, 4:49 PM MDT, 1 hour 40 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHEYENNE WY
449 PM MDT MON AUG 6 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0446 PM     HAIL             7 N ANGORA              42.51N 103.78W
08/06/2018  E2.50 INCH       SIOUX              NE   BROADCAST MEDIA

&&

DDEAL
Local storm report, Aug 6, 4:55 PM MDT, 1 hour 34 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHEYENNE WY
455 PM MDT MON AUG 6 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0427 PM     HAIL             7 NE ANGORA             41.95N 103.02W
08/06/2018  M3.00 INCH       MORRILL            NE   STORM CHASER

            A COUPLE 3+ INCH STONES ON HWY 385 NEAR MILE MARKER 95.

&&

ABRAUN
Special weather statement, Aug 6, 6:05 PM MDT, 24 minutes before
Special Weather Statement
National Weather Service Cheyenne WY
605 PM MDT MON AUG 6 2018

WYZ117-118-070030-
Central Laramie County WY-South Laramie Range Foothills WY-
605 PM MDT MON AUG 6 2018

...SPECIAL WEATHER STATEMENT...

At 605 PM MDT, Doppler radar was tracking a strong thunderstorm over
Cheyenne, moving southeast at 20 mph.

Half inch hail and winds in excess of 30 mph will be possible with
this storm.

Locations impacted include...
Cheyenne, South Greeley, Ranchettes, Warren AFB, Frontier Park, North
Cheyenne, Warren Af Base, Fox Farm-College and South Greeley High.

This includes the following highways...
 Interstate 25 in Wyoming between mile markers 9 and 15.
 Interstate 80 in Wyoming between mile markers 360 and 376.

A Severe Thunderstorm Watch remains in effect until 900 PM MDT for
southeastern Wyoming.

LAT...LON 4114 10489 4125 10480 4113 10445 4100 10458
      4100 10468
TIME...MOT...LOC 0005Z 304DEG 15KT 4115 10481

Braun
Special weather statement, Aug 6, 6:29 PM MDT, 0 minutes before
Special Weather Statement
National Weather Service Cheyenne WY
629 PM MDT MON AUG 6 2018

WYZ118-119-070100-
Central Laramie County WY-East Laramie County WY-
629 PM MDT MON AUG 6 2018

...SPECIAL WEATHER STATEMENT...

At 628 PM MDT, Doppler radar was tracking a strong thunderstorm near
Hillsdale, or 10 miles east of Cheyenne, moving east at 25 mph.

Half inch hail and winds in excess of 30 mph will be possible with
this storm.

Locations impacted include...
Burns and Hillsdale.

This includes Interstate 80 in Wyoming between mile markers 370 and
397.

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.

&&

A Severe Thunderstorm Watch remains in effect until 900 PM MDT for
southeastern Wyoming.

LAT...LON 4110 10466 4121 10467 4127 10415 4108 10414
TIME...MOT...LOC 0028Z 267DEG 20KT 4116 10459

Braun

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 6, 6:05 PM MDTSpecial Weather StatementCYSLaramie25 min
Aug 7, 1:46 PM MDTSpecial Weather StatementCYSLaramie44 min
Aug 7, 2:14 PM MDTSpecial Weather StatementCYSLaramie46 min
Aug 7, 3:12 PM MDTSpecial Weather StatementCYSLaramie33 min
Aug 7, 3:25 PM MDTSpecial Weather StatementCYSLaramie50 min
Aug 7, 3:35 PM MDTSpecial Weather StatementCYSLaramie25 min
Aug 7, 3:57 PM MDTAreal Flood AdvisoryCYSLaramie3 hr
Aug 7, 4:01 PM MDTSpecial Weather StatementCYSLaramie29 min
Aug 7, 4:05 PM MDTSevere Thunderstorm WarningCYSLaramie25 min
Aug 7, 4:06 PM MDTFlash Flood WarningCYSLaramie3 hr
Aug 7, 4:09 PM MDTSpecial Weather StatementCYSLaramie51 min
Aug 7, 4:27 PM MDTSevere Thunderstorm WarningCYSLaramie48 min
Aug 7, 4:50 PM MDTSevere Thunderstorm WarningCYSLaramie25 min
Aug 7, 5:06 PM MDTSpecial Weather StatementCYSLaramie39 min
Aug 7, 5:11 PM MDTSpecial Weather StatementCYSLaramie34 min
Aug 6, 6:03 PM MDTSevere Thunderstorm WarningCYSDawes27 min
Aug 6, 7:16 PM MDTSpecial Weather StatementCYSScotts Bluff44 min
Aug 6, 7:50 PM MDTSpecial Weather StatementCYSKimball40 min
Aug 6, 7:57 PM MDTSpecial Weather StatementCYSDawes33 min
Aug 6, 8:04 PM MDTSpecial Weather StatementCYSScotts Bluff26 min

Nearby

Special Weather Statements in Wyoming, 2018Every special weather statement in 2018

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.