A Pacific storm brought heavy snow to portions of Southwest Montana. Snow amounts up to 2 feet were reported.
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 TFX wrote it up.
A Pacific storm brought heavy snow to portions of Southwest Montana. Snow amounts up to 2 feet were reported.
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 May 5, 1:37 PM MST, 23 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREAT FALLS MT 237 PM MDT WED MAY 5 2010 .DISCUSSION... TONIGHT THROUGH FRIDAY...UPPER LEVEL LOW CENTERED OVER EASTERN WA THIS AFTERNOON WILL TRACK EAST ACROSS SOUTHERN ID TONIGHT WITH ASSOCIATED SFC AND MID LEVEL CIRCULATIONS INTENSIFYING AS THE UPPER LOW MOVES ACROSS WY THURSDAY. SNOW IS EXPECTED TO DEVELOP OVER SW MT LATE THIS EVENING AND INTENSIFY/SPREAD NORTHEASTWARD AS THE UPPER LOW TRACKS BY TO THE SOUTH. BEST CHANCE FOR HEAVY SNOW WILL OCCUR AFTER MIDNIGHT THROUGH EARLY THURSDAY MORNING AND WILL LIKELY BE FOCUSED ALONG AND SOUTH OF I-90. SNOW WILL WIND DOWN BY THURSDAY AFTERNOON AS THE LOW PULLS EAST OF THE REGION. CURRENT WINTER WEATHER HIGHLIGHTS APPEAR ON TRACK WITH ACCUMULATIONS IN EXCESS OF 6 INCHES MOSTLY CONFINED TO HIGHER ELEVATIONS OF SW MT WITH 2-5 INCHES EXPECTED AT LOWER ELEVATIONS FROM CENTRAL MT SOUTHWARD. OVER THE REMAINDER OF NORTH-CENTRAL MT...EXPECT LIGHT SNOW SHOWERS TO CONTINUE...ESPECIALLY ALONG THE CANADIAN BORDER AND EAST SLOPE AREAS...HOWEVER ANY ACCUMULATIONS SHOULD BE MINOR. MOIST AND UNSETTLED WEST TO NW FLOW ALOFT FOLLOWS THE EXITING UPPER LOW THURSDAY AFTERNOON THROUGH FRIDAY FOR CONTINUED COOL AND SHOWERY CONDITIONS WITH TEMPERATURES REMAINING WELL BELOW SEASONAL AVERAGES. HOENISCH FRIDAY NIGHT THROUGH SUNDAY NIGHT...MODELS IN AGREEMENT ON GENERAL TRENDS DURING THE PERIOD BUT DIFFER ON MOISTURE AND SHORTWAVE DETAILS. PERIOD WILL START OFF WITH NORTHWEST FLOW ALOFT THEN TRANSITION TO A SOUTHWEST FLOW ALOFT SATURDAY WHICH WILL CONTINUE THROUGH SUNDAY NIGHT. THROUGH THE PERIOD EXPECT UPSLOPE FLOW OVER THE PLAINS WITH A FAIR AMOUNT OF CLOUDINESS. THIS WILL KEEP TEMPERATURES ON THE COOL SIDE. THE SOUTHWEST VALLEYS SHOULD EXPERIENCE RELATIVELY WARMER TEMPERATURES. AN UPPER RIDGE IS EXPECTED TO MOVE THROUGH THE AREA FRIDAY NIGHT AND THIS PERIOD SHOULD SEE THE SMALLEST THREAT FOR PRECIPITATION. OTHERWISE EXPECT ISOLATED TO SCATTERED RAIN AND SNOW SHOWERS. DUE TO MODEL DIFFERENCES ON DETAILS WENT WITH A BROAD BRUSH APPROACH TO THE CHANCES OF PRECIPITATION. BLANK TUESDAY THROUGH WEDNESDAY...MODELS ARE IN POOR AGREEMENT DURING THIS PERIOD. THE ECMWF SHOWS A DEEP TROUGH OF LOW PRESSURE SYSTEM OVER THE GREAT BASIN WHILE THE GFS DEPICTS AN UPPER LEVEL SHORTWAVE APPROACHING FROM SOUTH CENTRAL CANADA. THE GFS SOLUTION HAS A SERIES OF WEAK DISTURBANCES IN A NORTHWESTERLY FLOW ALOFT ACROSS THE FORECAST AREA...WHILE THE ECMWF SWINGS THE TROUGH EAST OF THE REGION. AT ANY RATE...THIS IS EXPECTED TO BE AN UNSETTLED PERIOD. DUE TO THESE UNCERTAINTIES THIS FORECAST CALLS FOR A CHANCE OF SCATTERED SNOW SHOWERS OVER THE MOUNTAINS AND MUCH OF THE SOUTHWEST...WITH A SLIGHT CHANCE OF ISOLATED RAIN SHOWERS OR MIXED RAIN AND SNOW SHOWERS ACROSS THE PLAINS AND CENTRAL VALLEYS. DAYTIME TEMPERATURES WILL CONTINUE TO STAY WELL BELOW SEASONAL AVERAGES AT MOST LOCATIONS. JOH && .AVIATION... UPDATED 1750Z. UPSLOPE FLOW OVER CENTRAL AND NORTH CENTRAL WILL CONTINUE TO PRODUCE WIDESPREAD MVFR AND IFR CONDITIONS AND AREAS OF LIGHT SNOW OVER NORTH CENTRAL AND PARTS OF CENTRAL MT THIS AFTN/EVE. CONDITIONS IMPROVE TO MOSTLY VFR FOR LOCATIONS SOUTH OF KHLN TO THE MT/ID BORDER. HOWEVER...CLOUDS WILL STEADILY INCREASE OVER SOUTHWESTERN MT LATER THIS AFTN AS THE NEXT WEATHER SYSTEM...CURRENTLY IN FAR WESTERN IDAHO...MOVES TO NEAR KWYS OVERNIGHT. IFR/LIFR CONDITIONS WITH AREAS OF LIGHT TO OCCASIONALLY MODERATE SNOW ARE EXPECTED ACROSS THE REGION LATE TONIGHT AND THURS MORNING...ALONG WITH WIDESPREAD OBSCURATIONS OF HIGHER TERRAIN PEAKS. WINDS SHOULD REMAIN GENERALLY LIGHT AT ALL TERMINALS INTO TOMORROW MORNING. WARANAUSKAS && .HYDROLOGY... PRECIPITATION FROM THE LAST FEW STORM SYSTEMS HAS CAUSED SOME SMALL STREAMS AND RIVERS TO RISE...AND ADDITIONAL SNOWMELT WILL SUSTAIN THESE RISES. CURRENTLY...BEAVER CREEK IN HILL COUNTY AND SMALL STREAMS IN JUDITH BASIN COUNTY ARE RUNNING OUT OF THEIR BANKS. THEREFORE...SMALL STREAM FLOOD ADVISORIES FOR HILL COUNTY AND JUDITH BASIN COUNTY WILL REMAIN IN EFFECT. && .PRELIMINARY POINT TEMPS/POPS... GTF 26 39 23 44 / 70 40 30 20 CTB 26 37 22 44 / 50 50 30 20 HLN 29 41 26 48 / 90 60 20 20 BZN 29 40 22 50 / 100 90 20 20 WEY 19 35 15 42 / 80 80 20 30 DLN 25 39 20 45 / 100 90 20 20 HVR 28 42 27 47 / 30 50 30 30 LWT 25 34 24 39 / 90 80 30 30 && .TFX WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING UNTIL NOON MDT THURSDAY FOR ELEVATIONS ABOVE 6000 FEET FOR BEAVERHEAD...BROADWATER...GALLATIN... JEFFERSON...MADISON...MEAGHER. WINTER WEATHER ADVISORY UNTIL NOON MDT THURSDAY FOR ELEVATIONS BELOW 6000 FEET FOR BEAVERHEAD...BROADWATER...GALLATIN... JEFFERSON...MADISON...MEAGHER. WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO NOON MDT THURSDAY FOR ELEVATIONS ABOVE 4000 FEET FOR CASCADE...CENTRAL AND SOUTHERN LEWIS AND CLARK...FERGUS...JUDITH BASIN. SMALL STREAM FLOOD ADVISORY FOR HILL COUNTY THROUGH WEDNESDAY AFTERNOON. SMALL STREAM FLOOD ADVISORY FOR JUDITH BASIN COUNTY THROUGH WEDNESDAY EVENING. && SHORT TERM...HOENISCH LONG TERM...BLANK/JOH AVIATION...WARANAUSKAS WEATHER.GOV/GREATFALLS
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE GREAT FALLS MT 1050 AM MDT WED MAY 5 2010 MTZ009>011-013-044>049-061700- NORTHERN ROCKY MOUNTAIN FRONT-EASTERN GLACIER-HILL-CHOUTEAU-TOOLE- LIBERTY-EASTERN PONDERA-BLAINE-SOUTHERN ROCKY MOUNTAIN FRONT- EASTERN TETON- 1050 AM MDT WED MAY 5 2010 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTH CENTRAL MONTANA. .DAY ONE...TODAY AND TONIGHT LIGHT SNOW SHOWERS WILL CONTINUE THROUGH THIS AFTERNOON AND EVENING..HOWEVER ANY ADDITIONAL ACCUMULATIONS WILL BE LIGHT. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES. MTZ008-015-052>055-061700- BEAVERHEAD-MADISON-JEFFERSON-BROADWATER-MEAGHER-GALLATIN- 1050 AM MDT WED MAY 5 2010 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHWEST MONTANA. .DAY ONE...TODAY AND TONIGHT WINTER STORM WARNING IS IN EFFECT FROM 4 PM THIS AFTERNOON TO NOON MDT THURSDAY FOR ELEVATIONS ABOVE 6000 FEET. A WINTER WEATHER ADVISORY IS IN EFFECT FROM 4 PM THIS AFTERNOON TO NOON MDT THURSDAY FOR ELEVATIONS BELOW 6000 FEET. THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY THE WINTER STORM WARNING IS IN EFFECT UNTIL NOON MDT THURSDAY FOR ELEVATIONS ABOVE 6000 FEET. THE WINTER WEATHER ADVISORY IS IN EFFECT UNTIL NOON MDT THURSDAY FOR ELEVATIONS BELOW 6000 FEET. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES. MTZ012-014-050-051-061700- CASCADE-CENTRAL AND SOUTHERN LEWIS AND CLARK-JUDITH BASIN-FERGUS- 1050 AM MDT WED MAY 5 2010 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL MONTANA AND SOUTHWEST MONTANA. .DAY ONE...TODAY AND TONIGHT A WINTER WEATHER ADVISORY IS IN EFFECT FROM 6 PM MDT THIS EVENING THROUGH NOON MDT THURSDAY FOR ELEVATIONS ABOVE 4000 FEET. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.
5 winter storm. Local standard time, as filed.
Nine inches of snow fell at Jackson 14S (the Bloody Dick SNOTEL site - elevation 7549 feet). Seven inches of snow fell at Grant 5S.
Twenty-five inches of snow fell at Ennis 15NW (the Lower Twin SNOTEL site - elevation 7900 feet).
Six inches of snow fell at Ringling 4SE (the Frohner Maedow SNOTEL site - elevation 6480 feet). Six inches of snow also fell at Boulder 11NW (the Rocker Peak SNOTEL site - elevation 8000 feet).
Six inches of snow fell at Townsend 17NNW (the Tizer Basin SNOTEL site - elevation 6880 feet).
Eighteen inches of snow fell at Bozeman 14NE (the Brackett Creek SNOTEL site - elevation 7320 feet).
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2010Every state in 2010This day in weather historyWarnings in Montana, May 2010
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: 221856, 221858, 221860, 221861, 221862.