Alert archive / Wyoming / Special Weather Statements in 2024

Special Weather Statement, NWS Cheyenne, WY

July 19, 2024Laramie County, Wyoming

NWS Cheyenne, WY issued this special weather statement at Jul 19, 2024, 6:55 PM MDT for Laramie County, Wyoming. It was in force for 35 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
Jul 19, 2024, 6:55 PM MDT (00:55 UTC)
Expired
Jul 19, 2024, 7:30 PM MDT
In force
35 min
Issued by
NWS Cheyenne, WY
Hail
0.00 in
Wind
50

County Laramie County, WY

The radar

The Cheyenne radar (KCYS), 4 km from the middle of the area, began a volume at 00:57 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

N. Platte/Lee Bi, NE (KLBF), launched 00:00Z, 0.9 hours before the alert went out and 351 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, N. Platte/Lee Bi, NE at 00:00Z on 2024-07-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2300 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, N. Platte/Lee Bi, NE at 00:00Z on 2024-07-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 105 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
2300 J/kg
Mixed-layer CIN
-41 J/kg
Mixed-layer LCL
1031 m above ground
0-6 km bulk shear
49 kt
0-1 km storm-relative helicity
105 m²/s²
0-3 km storm-relative helicity
290 m²/s²
Significant tornado parameter
2.9
Supercell composite
19.8

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 Jul 19, 5:41 PM MDT, 1 hour 14 minutes earlier. Its key messages:

  • Severe weather is possible today as a cold front moves across the region. Damaging winds and isolated large hail are possible as the cold front moves through. Cooler temperatures for Saturday.
  • Cooler weather expected this weekend into Monday ahead of a gradual warming trend to above average temperatures through next week.
Area forecast discussion, Jul 19, 5:41 PM MDT, 1 hour 14 minutes before
Area Forecast Discussion
National Weather Service Cheyenne WY
541 PM MDT Fri Jul 19 2024

.KEY MESSAGES...

- Severe weather is possible today as a cold front moves across
  the region. Damaging winds and isolated large hail are
  possible as the cold front moves through. Cooler temperatures
  for Saturday.

- Cooler weather expected this weekend into Monday ahead of a
  gradual warming trend to above average temperatures through
  next week.

&&

.MESOSCALE /THROUGH TONIGHT/...
Issued at 221 PM MDT Fri Jul 19 2024

Widespread thundershowers have popped up across portions of
southeast WY the past 1-2 hrs as we see sufficient daytime heating
ans surface convergence displayed well via satellite and radar.
Northwest flow aloft is providing weak steering flow at H7. Surface
temperatures range from the middle 80s to lower 90s for most of the
eastern tier of our cwa, with slightly cooler temperatures along the
I-80 corridor between the I-80 Summit and Rawlins. As of 20Z,
sub-severe thunderstorm activity remains ahead of the cold
front. SPC Mesoanalysis has low-level and mid-level lapse rates
8-10 degrees C/km. MLCAPE readings as of 20Z are 1000-1500 J/kg
for areas east of the Laramie Range where peak heating has
assisted with making the environment conditionally unstable.
Effective bulk wind shear is meager...20-30 knots from 0-6km.
Short term hi-res model data continues to suggest that we will
see convection through the 2z-3z hour for most of the cwa, and
then it will push further south. Can't rule out an isolated
severe thunderstorm this afternoon to the early evening. The
strongest threat looks to be a marginal potential for strong
wind gusts via straightline winds from thunderstorm outflow. The
cold front should arrive much later this evening, and those
outdoors will see a much cooler weather pattern behind the
FROPA.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
Issued at 221 PM MDT Fri Jul 19 2024

The models are in pretty good agreement in showing the upper
level ridge building over the area through mid week. This will
essentially strengthen the cap as the week wears on and limit
the convection chances. The precipitable water values are
progged to be closer to 1 inch on Monday over the Nebraska
panhandle while the rest of the CWA will be less than an inch.
NBM probabilities are showing CAPE values 500 j/kg or less over
the Nebraska panhandle. If we can get enough instability over
the the Laramie Range and Pine Ridge, we may be able to spark
some isolated convection with the main threat being gusty winds.
As we head into mid week, the WPC clusters are showing the upper
level ridge dominating the area which will limit any convection
development. Was tempted to lower pops over the higher terrain
during this timeframe, but will hold things off for now and see
how the ridge materializes. We did raise temperatures a bit
towards the end of the week which is when the models are trying
to flatten the ridge a bit which may enhance the downslope flow.
In addition, the flattening of the ridge will also tend to
increase the precipitation chances as we head into next weekend.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 540 PM MDT Fri Jul 19 2024

Northwest flow aloft will continue.

Wyoming TAFS...Scattered to broken clouds from 6000 to 10000 feet
will prevail, with occasional thunderstorms until 02Z, producing
wind gusts to 35 knots and visibilities to 5 miles. Outside of
thunderstorms, winds will gust to 25 knots until 02Z, and to
22 knots at Rawlins and Cheyenne after 18Z Saturday.

Nebraska TAFS...Scattered to broken clouds from 8000 to 10000 feet
will prevail, with occasional thunderstorms until 02Z, producing
wind gusts of 35 to 45 knots along with visibilities from 3 to 5
miles. Outside of thunderstorms, winds will gust to 25 knots until
02Z.

&&

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

&&

SHORT TERM...BW
LONG TERM...REC
AVIATION...RUBIN
Hazardous weather outlook, Jul 19, 5:33 AM MDT, 13 hours 22 minutes before
Hazardous Weather Outlook
National Weather Service Cheyenne WY
533 AM MDT Fri Jul 19 2024

NEZ002-003-019>021-054-055-095-096-WYZ101>103-106>108-117>119-
201145-
Dawes County-Box Butte County-Scotts Bluff County-Banner County-
Morrill County-Kimball County-Cheyenne County-
Northern Sioux County-Southern Sioux County-
Converse County Lower Elevations-Niobrara County-
North Laramie Range-
Central Laramie Range and Southwest Platte County-
East Platte County-Goshen County-South Laramie Range Foothills-
Central Laramie County-East Laramie County-
533 AM MDT Fri Jul 19 2024

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

.DAY ONE...TODAY AND TONIGHT

Severe weather is possible Friday as a cold front moves across the
region. Damaging winds and isolated large hail are possible as the
cold front moves through. Cooler temperatures for Saturday.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

Cooler weather expected this weekend into Monday ahead of a gradual
warming trend to above average temperatures through next week.

.Spotter information statement...

Spotter activation will not be needed.

WYZ104-105-109>116-201145-
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-
South Laramie Range-
533 AM MDT Fri Jul 19 2024

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

.DAY ONE...TODAY AND TONIGHT

Isolated showers and thunderstorms possible this afternoon and
evening. Cooler temperatures expected tomorrow.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

Cooler weather expected this weekend into Monday ahead of a gradual
warming trend to above average temperatures through next week.

.Spotter information statement...

Spotter activation will not be needed.

In the hours before

Special weather statement, Jul 19, 6:19 PM MDT, 36 minutes before
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Local storm report, Jul 19, 6:22 PM MDT, 33 minutes before
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Local storm report, Jul 19, 6:26 PM MDT, 29 minutes before
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Special weather statement, Jul 19, 6:36 PM MDT, 19 minutes before
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Local storm report, Jul 19, 6:51 PM MDT, 4 minutes before
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Special weather statement, Jul 19, 6:55 PM MDT, 0 minutes before
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The office that day

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

IssuedProductOfficeCountiesLasted
Jul 19, 6:29 PM MDTSevere Thunderstorm WarningCYSLaramie31 min
Jul 20, 1:08 PM MDTSevere Thunderstorm Warning Considerable damage threatCYSNiobrara37 min
Jul 20, 1:45 PM MDTSevere Thunderstorm WarningCYSGoshen, Niobrara30 min
Jul 20, 3:27 PM MDTSevere Thunderstorm WarningCYSGoshen, Platte33 min
Jul 20, 3:59 PM MDTSevere Thunderstorm WarningCYSGoshen, Platte46 min
Jul 20, 4:42 PM MDTSpecial Weather StatementCYSLaramie33 min
Jul 20, 4:45 PM MDTSevere Thunderstorm WarningCYSGoshen, Laramie45 min
Jul 20, 5:16 PM MDTSpecial Weather StatementCYSLaramie29 min
Jul 20, 5:27 PM MDTSevere Thunderstorm WarningCYSLaramie48 min
Jul 19, 6:01 PM MDTSpecial Weather StatementCYSMorrill44 min
Jul 19, 6:22 PM MDTSevere Thunderstorm WarningCYSCheyenne, Morrill53 min
Jul 19, 6:36 PM MDTSpecial Weather StatementCYSCheyenne39 min
Jul 19, 7:01 PM MDTSevere Thunderstorm WarningCYSCheyenne44 min
Jul 19, 7:11 PM MDTSpecial Weather StatementCYSCheyenne34 min
Jul 19, 7:17 PM MDTSevere Thunderstorm WarningCYSCheyenne, Kimball28 min
Jul 20, 12:38 PM MDTSpecial Weather StatementCYSScotts Bluff37 min
Jul 20, 1:26 PM MDTSevere Thunderstorm Warning Considerable damage threatCYSBanner, Morrill, Scotts Bluff49 min
Jul 20, 2:14 PM MDTSevere Thunderstorm WarningCYSCheyenne, Morrill32 min
Jul 20, 3:38 PM MDTSevere Thunderstorm WarningCYSKimball23 min
Jul 20, 3:53 PM MDTAreal Flood AdvisoryCYSScotts Bluff3 hr
Jul 20, 4:06 PM MDTSevere Thunderstorm WarningCYSBanner, Scotts Bluff39 min

Nearby

Special Weather Statements in Wyoming, 2024Every special weather statement in 2024

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.