1 flash flood, as filed by the National Weather Service.
Every event with a place to put it; 1 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
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 Great Falls, MT wrote its last area forecast discussion before the first event at Jul 31, 8:15 AM MST, 15 minutes earlier.
SOUTHWEST AND NORTH CENTRAL MONTANA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
915 AM MDT TUE JUL 31 2001
ZONES PREVIOUSLY UPDATED FOR THUNDERSTORMS OVER EASTERN CWA. A FLASH
FLOOD WARNING IS CURRENTLY OUT FOR BURN AREAS NEAR CANYON FERRY LAKE
UNTIL NOON. WITH CONTINUED SHOWERS EXPECTED AT LEAST THROUGH THE
MORNING...WILL CONTINUE THE WARNING. CURRENT WATER VAPOR IMAGE SHOWS
LOW CENTERED OVER WESTERN MT. 12Z ETA LIFTS LOW TO SOUTHWEST
SASK BY LATE AFTERNOON. TFX RADAR SHOWS WIDESPREAD RAIN WITH EMBEDDED
HEAVY SHOWERS ACROSS THE NORTHERN HALF OF THE CWA WITH A LINE OF
THUNDERSTORMS MOVING THROUGH EASTERN ZONES. SOME INSTABILITY REMAINS
TODAY ACROSS MAINLY THE NORTHERN ZONES AND DAKOTAS AND BELIEVE WILL
SEE SOME SHOWERS WITH ISOLATED THUNDERSTORMS THROUGH THE DAY.
SOUTHERN PORTION OF CWA SHOULD SEE DECREASING CLOUDINESS AND
PRECIPITATION WITH DRIER AIR WORKING IN FROM THE SOUTH. WEAK RIDGE
BEGINS REBUILDING WEDNESDAY...AND INSTABILITIES DIMINISH FOR
WARMER...DRIER CONDITIONS.
EXTENDED....UKMET HAS TROF OVER ERN PAC...ECMWF HAS IT OVER
OR/WA/NRN CA....AND NEW MRF DELAYS TROF APPROACHING ZONES THIS
WEEKEND. DISLIKE UPDATING BASED ON A CHANGE IN A SINGLE RUN HOWEVER
NEW RUN IS MORE CONSISTENT WITH ECMWF AND RIDGE COULD DELAY CHANCE
OF THUNDERSTORMS. HOWEVER...WITH SOUTHWEST FLOW AND INCREASING
SURFACE TEMPS...CONVECTION IS NOT OUT OF THE QUESTION AS EARLY AS
SATURDAY.
CCF NUMBERS
GTF RB 064/048 078/051 084 13911
CTB RB 063/046 075/050 076 13921
HLN WU 066/045 080/048 086 13611
BZN WB 070/042 080/046 081 13511
WEY WB 066/032 072/034 074 13511
DLN WB 065/042 078/046 081 13411
HVR RU 065/050 080/052 085 13931
{LWT WB 062/045 075/047 077 13811The national radar mosaic for the moment the first event began.
1 flash flood. Local standard time, as filed.
Actual event location is Cave Creek at marina on northern shore of Canyon Ferry Lake (approximately 20 E of Helena)...Rainfall onto scorched earth (from wildfire in 2000) caused flowing water and mud to wash out road...Monetary damage unknown.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2001Every state in 2001This day in weather historyWarnings in Montana, July 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: 5261014.