1 high wind, as filed by the National Weather Service.
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.
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 Billings, MT wrote its last area forecast discussion before the first event at May 20, 1:15 PM MST, 15 minutes earlier.
SOUTH CENTRAL AND SOUTHEAST MONTANA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
215 PM MDT SUN MAY 20 2001
.MON AND TUE...
UPPER LOW PULLS EAST TONIGHT...ALLOWING WINDS TO DECREASE IN EASTERN
ZONES. WILL KEEP SCATTERED POPS IN EASTERN ZONES TO COVER WRAP AROUND
THAT ROTATES THROUGH...WITH ISOLATED POPS FOR CONVECTIVE SHOWERS
ELSEWHERE. UPPER JET SHIFTS OVER CENTRAL MONTANA TONIGHT WITH GOOD
NORTHERLY LINKAGE WHICH SHOULD KEEPS WINDS UP A BIT AND KEEP
TEMPERATURES FROM DROPPING OFF TOO MUCH...AS WELL AS SOME CLOUDS.
MONDAY...JET STREAM SHIFTS FROM CENTRAL MONTANA TO EASTERN MONTANA
DURING THE DAY. FAIRLY WEAK PRESSURE GRADIENT BUT GOOD LINKAGE AGAIN FOR
BREEZY CONDITIONS. ATMOSPHERE STABILIZES WITH WARMING AT MID LEVELS FOR
DRY AND WARMER CONDITIONS. TUESDAY...UPPER RIDGE BEGINS TO MOVE INTO
AREA...700 MB TEMPERATURES CONTINUE TO WARM...FROM -5C 00Z TUESDAY TO
+4C BY 00Z WEDNESDAY FOR TEMPERATURES 10-15 DEGREES WARMER. RASCH
.WED...THU...FRI...SAT...SUN...
A RETURN TO ABOVE NORMAL TEMPERATURES ARE IN STORE FOR THE FORECAST
AREA...ALONG WITH DRY CONDITIONS. THIS IS SUPPORTED BY THE MIX-DOWN
TEMPERATURES FROM 700 MB.
COMPARISONS OF THE 20/12Z AVN...20/00Z MRF...20/12Z AND 00Z CANADIAN GEM
MODEL...AND THE 19/12Z ECMWF ARE IN GOOD AGREEMENT FOR THE EXTENDED.
THE MAIN DIFFERENCES ARE IN THE EASTERN U.S....BUT ARE SIMILAR IN THE
WEST. A BLOCKING RIDGE DEVELOPS OVER THE WESTERN ATLANTIC AND STRETCHES
NNW INTO THE MARITIME PROVINCES OF CANADA. THIS DEVELOPS A DEEP CUT-OFF
LOW OVER THE OHIO VALLEY AND MOVES IT VERY SLOWLY NE. THIS BLOCKED
PATTERN KEEPS A RIDGE OVER THE ROCKIES/NORTHERN PLAINS. THE ONLY SUBTLE
DIFFERENCE IS THAT THE 20/12Z AVN AND THE 19/12Z ECMWF BRING A WEAK
SHORTWAVE THROUGH AND FLATTEN THE RIDGE ON SATURDAY. ADDITIONALLY...A
FOUR CORNERS HIGH SETS UP WHICH WILL BEGIN TO BRING UP MID LEVEL
MOISTURE FROM MEXICO. HOWEVER...FOR NOW...WILL KEEP THE FORECAST OF
DRY THROUGH THE EXTENDED. STROBIN
MON TUE WED THU FRI SAT SUN
-----------------------------------------------------------
BIL 036/063 044/076 048/082 049/082 052/082 052/084 052/084
20/E 00/U 00/U 00/U 00/U 11/B 11/B
LVM 035/060 036/074 046/083 047/084 047/082 047/081 047/080
20/E 00/U 00/U 00/U 00/U 11/B 11/B
HDN 034/065 040/078 046/085 047/085 049/085 049/086 049/086
20/E 00/U 00/U 00/U 00/U 11/B 11/B
MLS 034/062 041/073 047/082 048/083 050/088 051/087 053/089
40/E 00/U 00/U 00/U 00/U 11/B 11/B
4BQ 033/061 040/072 046/081 047/082 049/087 050/086 052/089
20/E 00/U 00/U 00/U 00/U 11/B 11/B
BHK 032/060 039/071 046/080 046/081 048/085 049/086 050/089
40/E 00/U 00/U 00/U 00/U 11/B 11/B
SHR 030/063 038/074 045/080 045/080 047/083 047/084 048/085
20/E 00/U 00/U 00/U 00/U 11/tB 11/B1 high wind. Local standard time, as filed.
Winds of 40-50 mph with gusts to 63 mph reported by spotter 7 miles west of Sheridan.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2001Every state in 2001This day in weather historyWarnings in Wyoming, May 2001
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: 5241827.