Flooding occurred on the Yellowstone River that had two crests. This is the first crest.
Every event with a place to put it. 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 episode as NWS GGW wrote it up.
Flooding occurred on the Yellowstone River that had two crests. This is the first crest.
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 Glasgow, MT wrote its last area forecast discussion before the first event at May 21, 3:53 AM MST, 5 hours 37 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GLASGOW MT 453 AM MDT SAT MAY 21 2011 .SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH MONDAY... A STRONG LOW PRESSURE SYSTEM CENTERED OVER SE MT/NW SD IS MOVING VERY LITTLE. THE UPPER CENTER HAS RE-FORMED FARTHER N...WHICH HAS RESULTED IN A VERTICALLY STACKED SYSTEM. THE AIRMASS THAT IS ASSOCIATED WITH THIS IS VERY MOIST AND GETTING EVEN MOISTER. MODELS SHOW PRECIP WATER REACHING AS HIGH AS 1.2 THIS AFTERNOON. DEW POINTS IN THE 50S. IT IS ALSO SOMEWHAT UNSTABLE...BUT WITH LIFTED INDEXES ABOVE ZERO. YESTERDAY THERE WAS A DRY SLOT ENTRAINED INTO THE LOW CENTER...HOWEVER THIS HAS FILLED IN AND PUSHED S. EXPANDING AND COOLING CLOUD TOPS SEEN THROUGHOUT E MT/ND/SD MOVING WNW IN VERY DEEP E FLOW AT ALL LEVELS. THIS WILL BRING MORE RAIN TODAY AND TONIGHT. MODELS SHOW WE CLOUD GET ANOTHER INCH JUST TODAY ALONE. THERE WERE LARGE DIFFERENCES IN AMOUNTS ACROSS THE CWA YESTERDAY THOUGH...WITH A COUPLE OF ISOLATED REPORTS OF 3 TO 4 INCHES...BUT MOST PLACES UNDER AN INCH. ALTHOUGH SOMEWHAT UNSTABLE AIRMASS...PRECIP LOOKING MORE STEADY-LIKE ON RADAR NOW...SO WILL GO WITH PERIODS OF RAIN IN WORDING. SIMILAR TO YESTERDAY...FORECAST LIFTED INDEXES AND SOUNDINGS INDICATE JUST ISOLATED THUNDERSTORMS IN OUR SE IN THE AFTERNOON. 850 MB WINDS INCREASE TO AS HIGH AS 45 KT THIS AFTERNOON. MOST SOUNDINGS LOOK TO HAVE LAPSE RATES HIGH ENOUGH TO MIX TO NEAR THIS LEVEL. THUS WILL ISSUE ANOTHER LAKE WIND ADVISORY. MOS INDICATES SUCH...BUT MAV CONTINUING A BIT TOO STRONG. NOT MUCH CHANGE IN AIRMASS...WILL GO BELOW MOS SUNDAY DUE TO CONTINUE RAIN OFF AND ON. THIS SYSTEM STARTS TO WEAKEN AS IT MOVES INTO MN SUNDAY EVE. WEAKENING DYNAMICS...BUT A LOT OF MOISTURE LINGERING OVER THE AREA SO EXPECT PRECIP TO TAPER OFF TO SCATTERED SHOWERS RATHER THAN END VERY QUICK. BY MONDAY...WE START TO GET THE IMPACTS OF A HIGH PRESSURE AREA FROM FAR N CANADA MOVING S WHICH WILL PUSH THE LINGERING MOIST BAND TO OUR S. HIGH CENTER IS WELL TO OUR NE...BUT DRYING ON E WINDS SHOULD CLEAR OUT MUCH OF OUR AREA IN THE AFTERNOON. THE AIRMASS ASSOCIATED IS A LITTLE COOLER...BUT BALANCED BY MORE SUNSHINE. SIMONSEN .LONG TERM...MONDAY NIGHT THROUGH SATURDAY... HIGH PRESSURE SYSTEM OVER MANITOBA AND NORTH DAKOTA WILL COMBINE WITH AN UPPER RIDGE TO BRING DRY WEATHER TO MOST OF THE AREA FROM MONDAY NIGHT THROUGH WEDNESDAY. COOL AIRMASS WILL KEEP TEMPERATURES BELOW NORMAL. THE SOUTHWEST ZONES ESPECIALLY PETROLEUM COUNTY COULD SEE A FEW SHOWERS AS AN UPPER LOW CENTERED OVER THE PACIFIC NORTHWEST WILL CONTINUE TO BRING MOIST AIR TO CENTRAL MONTANA MONDAY NIGHT AND TUESDAY. AT THIS POINT...IT LOOKS LIKE THE UPPER LOW WILL STAY TO THE SOUTH OF THE FORECAST AREA AS IT MOVES INLAND TUESDAY AND WEDNESDAY. MODELS BRING A SHORTWAVE TROUGH ACROSS MONTANA ON THURSDAY. MODELS DIFFER SOMEWHAT ON TIMING WITH ECMWF FASTER THAN GFS. WITH THE SLOW MOVING PATTERN OF LATE...WILL LEAN TOWARDS THE SLOWER GFS AND FOCUS THE BEST CHANCE OF SHOWERS FOR THURSDAY NIGHT WITH A SLIGHT CHANCE OF SHOWERS LINGERING THROUGH FRIDAY. MODELS DIFFER ON THE PATTERN GOING INTO NEXT WEEKEND. THE GFS HAS A RIDGE OVER THE DAKOTAS WITH SOUTHWEST FLOW ALOFT OVER MONTANA AND UPPER LOW NEAR SEATTLE. THE ECMWF HAS A LARGE RIDGE OVER THE WESTERN U.S. INCLUDING MONTANA AND UPPER LOW FURTHER WEST. GIVEN THAT IT IS THE RAINY SEASON...WILL HAVE A CHANCE OF SHOWERS AND THUNDERSTORMS FOR NOW. FORRESTER && .AVIATION... SHOWERS WITH EMBEDDED THUNDERSTORMS WILL MOVE ACROSS THE AREA IN WAVES THROUGH THE FORECAST PERIOD. EXPECT A MIX OF MVFR AND IFR CONDITIONS MOST OF THE TIME THROUGH SUNDAY. && .HYDROLOGY... WIDESPREAD RAIN WILL CONTINUE THROUGH SUNDAY. AN INCH OR MORE ADDITIONAL RAINFALL IS LIKELY MOST OF THE AREA. FLOODING OF MANY SMALL STREAMS...CREEKS...COULEES...LOW SPOTS...AND POORLY DRAINED AREAS CAN BE EXPECTED TO CONTINUE AND EXPAND AS THE GROUND IS SATURATED. THE YELLOWSTONE RIVER IS RISING VERY RAPIDLY AND MAY APPROACH FLOOD STAGE TODAY. SIMONSEN && .GLASGOW WATCHES/WARNINGS/ADVISORIES... LAKE WIND ADVISORY FROM 9 AM THIS MORNING TO MIDNIGHT MDT TONIGHT FOR FORT PECK LAKE. && WEATHER.GOV/GLASGOW
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE GLASGOW MT 411 AM MDT SAT MAY 21 2011 MTZ016-017-022-023-221000- CENTRAL AND SOUTHEAST PHILLIPS-CENTRAL AND SOUTHERN VALLEY- GARFIELD-MCCONE- 411 AM MDT SAT MAY 21 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHEAST MONTANA. .DAY ONE...TODAY AND TONIGHT A LAKE WIND ADVISORY IS IN EFFECT FOR FORT PECK LAKE UNTIL MIDNIGHT TONIGHT. FLOOD WARNINGS REMAIN IN EFFECT. RAINFALL WILL CONTINUE OFF AND ON THROUGH SUNDAY...WITH AT LEAST AN ADDITIONAL INCH OF RAIN EXPECTED. MANY SMALL STREAMS AND CREEKS WILL BE FLOODED...AS WELL AS LOW SPOTS AND POORLY DRAINED AREAS. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY THE FLOOD WARNINGS WILL CONTINUE UNTIL LATE MONDAY MORNING. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES. MTZ018>021-024>027-059>062-221000- DANIELS-SHERIDAN-WESTERN ROOSEVELT-PETROLEUM-RICHLAND-DAWSON- PRAIRIE-WIBAUX-NORTHERN PHILLIPS-SOUTHWEST PHILLIPS- NORTHERN VALLEY-EASTERN ROOSEVELT- 411 AM MDT SAT MAY 21 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHEAST MONTANA. .DAY ONE...TODAY AND TONIGHT FLOOD WARNINGS REMAIN IN EFFECT. RAINFALL WILL CONTINUE OFF AND ON THROUGH SUNDAY...WITH AT LEAST AN ADDITIONAL INCH OF RAIN EXPECTED. MANY SMALL STREAMS AND CREEKS WILL BE FLOODED...AS WELL AS LOW SPOTS AND POORLY DRAINED AREAS. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY THE FLOOD WARNINGS WILL CONTINUE UNTIL LATE MONDAY MORNING. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GLASGOW MT
711 AM MDT SAT MAY 21 2011
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0709 AM HEAVY RAIN S NAVAJO 48.79N 105.06W
05/21/2011 M1.81 INCH DANIELS MT TRAINED SPOTTER
24 HOUR RAINFALL MEASUREMENT. ALSO REPORTED 42 MPH WIND
GUST AT 830 PM
&&
JBPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GLASGOW MT
734 AM MDT SAT MAY 21 2011
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0729 AM HEAVY RAIN 5 S TAMPICO 48.23N 106.84W
05/21/2011 M0.75 INCH VALLEY MT TRAINED SPOTTER
24 HOUR RAINFALL MEASUREMENT...ALSO REPORTED ANTELOPE
CREEK WAS OUT OF ITS BANKS.
&&
JBPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GLASGOW MT
747 AM MDT SAT MAY 21 2011
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0745 AM HEAVY RAIN 2 WSW GLENDIVE 47.10N 104.75W
05/21/2011 M1.04 INCH DAWSON MT TRAINED SPOTTER
24 HOUR RAINFALL MEASUREMENT AS OF 7 AM
&&
JBThe national radar mosaic for the moment the first event began.
2 flood. Local standard time, as filed.
The river gauge reading at Glendive on the Yellowstone River crested at 56.38 feet on May 23rd. Flood stage is 53.5 feet.
The river gauge reading at Sidney on the Yellowstone River crested at 21.92 feet on May 25rd. Flood stage is 19 feet.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2011Every state in 2011This day in weather historyWarnings in Montana, May 2011
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: 321121, 321206.