Damaging Wind in Wyoming, April 20, 2001

Name: Damaging Wind in Wyoming, April 20, 2001
Start: 2001-04-20T13:00
End: 2001-04-20T13:00
Location: Wyoming

April 20, 2001 · NWS RIW · 1 event in 1 county or zone

Rain gutters damaged on apartment building, shed adjacent to apartment building severely damaged, car windows broken out. Damage occurred over a small area.

Where it happened

Every event with a place to put it. Tap one for its entry below.

Tornadoes
Tropical storms and surge
Floods
Wind
Hail
Winter weather
Heat and drought
Cold
Fire, smoke and dust
Marine and coastal
Other

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The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 1

Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.

What happened

The episode as NWS RIW wrote it up.

Rain gutters damaged on apartment building, shed adjacent to apartment building severely damaged, car windows broken out. Damage occurred over a small area.

What forecasters said that day

The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Riverton, WY wrote its last area forecast discussion before the first event at Apr 20, 12:45 PM MST, 15 minutes earlier.

Area forecast discussion, Apr 20, 12:45 PM MST, 15 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
145 PM MDT FRI APR 20 2001

BUSY AFTERNOON WITH A COUPLE OF BRIEF TORNADO TOUCHDOWNS IN JAMESTOWN
AND PEA TO 1/2 INCH HAIL REPORTS...ALONG WITH HEAVY SHSN HERE AT
RIW. AT THE SFC...HIGH PRESSURE WAS RIDGING FROM CAN INTO NE WY AND
A LARGE COMPLEX AREA OF LOW PRESSURE EXTENDED FROM CTRL ID SE ACROSS
WY INTO CO. KRIW RADAR SHOWING LARGE AREA OF SHOWS EAST OF THE
DIVIDE WITH EMBEDDED -TSRA.

PREFER THE AVN MODEL OVER THE FASTER AND FURTHER SOUTH SOLN OF NEXT
UPPER LOW CURRENTLY JUST OFF THE NRN CA COAST. CURRENT WAVE WILL
LIFT INTO THE NRN FA BY 00Z SAT. SNOW ACCUM INDICATES CHANCE FOR 4 TO
8 INCHES OF SNOW IN THE BIG HORN MTNS TONIGHT AND UP TO 4 INCHES IN
EAST JOHNSON CO. THIS AREA IN BEST H3 DIVERGENCE BULLSEYE AND
UPSLOPE. WILL GO WITH SNOW ADVISORY THOSE ZONES FOR TONIGHT. THE BIG
HORN BASIN AND CODY FOOTHILLS WILL SEE FROM 1 TO 3 INCHES. THE NEXT
ROUND OF SHOWERS SHOULD START AFT 06Z IN THE SOUTHWEST AND PROGRESS
ACROSS THE FA THROUGHOUT THE DAY SATURDAY. BY 06Z SAT THE H7 LOW IS
OVER SRN UT WITH DYNAMICS/SFC-H7 UPSLOPE OVER THE FA THROUGH 00Z MON.
THE -SN SHOULD TAPER TO FLURRIES SUN EVE IN THE EAST AS H7 WND TURNS
NRLY.

IN THE EXTENDED...UPPER RIDGE BEGINS TO BUILD INTO THE FA MONDAY FOR
A MAINLY DRY FCST LASTING THROUGH FRIDAY AS AXIS MOVES OVER THE FA.
ONLY EXCEPTION WILL BE CHANCE FOR SHOWERS TUE AS SHTWV DIVES ACROSS
THE AREA IN NW FLOW. TEMPS WILL REMAIN COOL MONDAY BUT MAKE GOOD
RECOVERY DURING THE REST OF THE PERIOD WITH H7 TEMPS WARMING TO
ABOUT 7 DEGREES.

.RIW...SNOW ADVISORY TONIGHT FOR BIG HORN MTNS AND EAST JOHNSON CO
       WYZ026>028.

FS

In the hours before

Local storm report, Apr 20, 11:59 AM MST, 1 hour 1 minute before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE RIVERTON, WY
1259 PM MDT FRI APR 20 2001

TIME(MDT)  .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

1245 PM    JAMESTOWN                 WY   TORNADO
04/20/01   SWEETWATER                     *** 0 INJ ***
                                          COUPLE OF SHEDS DESTROYED
                                          BY 2 TORNADOES

The radar

The national radar mosaic for the moment the first event began.

Open the radar archive at this moment

Event by event

1 thunderstorm wind. Local standard time, as filed.

Thunderstorm Wind, Natrona

When: April 20, 1:00 PM MST
Where: Natrona County, Casper
Measured: 61 kt (70 mph)
Reported by: GENERAL PUBLIC
Coordinates: 42.833, -106.317

What these are

Thunderstorm Wind: Winds from a thunderstorm of 50 knots (58 mph) or more, or lower winds that caused damage or casualties. Measured gusts are marked MG, estimated EG.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in Wyoming in 2001 Every state in 2001 This day in weather history Warnings in Wyoming, April 2001

Sources

NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 5239371.