An upper-level short-wave trough from the west and moist surface winds from the southeast combined with an unstable atmosphere to allow severe thunderstorms to develop across most of eastern Montana.
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.
An upper-level short-wave trough from the west and moist surface winds from the southeast combined with an unstable atmosphere to allow severe thunderstorms to develop across most of eastern Montana.
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 Aug 3, 1:36 PM MST, 2 hours 4 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GLASGOW MT 236 PM MDT SAT AUG 3 2013 .SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH MONDAY... UPPER LEVEL SHORTWAVE TROUGH IS MOVING ACROSS CENTRAL MONTANA THIS AFTERNOON. THUNDERSTORMS...SOME SEVERE HAVE DEVELOP AHEAD OF THIS TROUGH. AIRMASS IN CENTRAL AND EASTERN MONTANA IS VERY UNSTABLE WITH LIFTED INDICIES NEAR -4 AND CAPE 1000 TO 1500 J/KG. THE WAVE AND STORMS WILL MOVE EAST INTO EASTERN MONTANA DURING THE LATE AFTERNOON AND EARLY EVENING. EXPECT SCATTERED TO NUMEROUS THUNDERSTORMS THIS EVENING EXTENDING INTO THE OVERNIGHT HOURS MAINLY IN THE EAST. THE WAVE WILL MOVE TO THE EAST OVERNIGHT AND SOMEWHAT DRIER AIRMASS WILL MOVE INTO THE AREA FOR SUNDAY. ENOUGH INSTABILITY LINGERS FOR A SLIGHT CHANCE OF THUNDERSTORMS. UPPER RIDGE BRIEFLY EXTENDS INTO THE NORTHERN ROCKIES SUNDAY NIGHT AND MONDAY BEFORE THE STRENGTHENING HUDSON BAY LOW COMES TO DOMINATE OVER CENTRAL CANADA AND THE NORTHERN PLAINS. COLD FRONT PRESSES SOUTH FROM CANADA IN THE AFTERNOON WITH A CHANCE OF THUNDERSTORMS. FORRESTER .LONG TERM...MONDAY NIGHT THROUGH SATURDAY... GIVEN THE RECENT WET MODEL BIAS...I FELT IT WAS PRUDENT TO CUT BACK POPS...ESPECIALLY WHERE RECENT MODEL RUNS HAVE SHOWN A DRY CONSENSUS. MOST OTHER ADJUSTMENTS MADE TO THE GRIDS WERE MINOR IN NATURE AND REFLECTED AN ALIGNMENT WITH RECENT MODEL RUNS...ETC. LATEST MODEL DEPICTIONS OF THE MID-WEEK ARCTIC LOW SHOW A MINIMAL IMPACT TO OUR CWA...POSSIBLY A WEAK COLD FRONT DROPPING TEMPERATURES BY 5 TO 10 DEGREES FOR TUESDAY AND WEDNESDAY. BMICKELSON PREVIOUS LONG TERM DISCUSSION...THE OVERALL SYNOPTIC PATTERN ACROSS THE CONUS CONSISTS BROADLY OF AN UPPER TROUGH ACROSS THE NORTHEAST...A RIDGE ACROSS THE SOUTHERN U.S. THAT OCCASIONALLY PUSHES NORTH INTO THE UPPER MIDWEST...AND ANOTHER LARGE UPPER TROUGH OVER THE PACIFIC. THIS PATTERN LOOKS TO REMAIN FAIRLY STATIC THROUGHOUT THE EXTENDED PERIOD STARTING MONDAY NIGHT ALL THE WAY INTO NEXT WEEKEND. TEMPERATURE TRENDS WILL DEPEND UPON MOVEMENT OF THESE OVERALL FEATURES. PRECIPITATION CHANGES WILL DEPEND UPON TRACK/TIMING OF SHORTWAVE FEATURES PROPAGATING THROUGH THE FLOW ALOFT. HAVING SAID ALL THAT...MONDAY NIGHT THROUGH TUESDAY NIGHT WILL PLACE NORTHEAST MONTANA IN NORTHWEST FLOW ALOFT WITH THE UPPER RIDGE TO THE WEST AND A CLOSED LOW TO THE NORTHEAST. THE 03/00Z MODEL SUITE CONTINUES TO EJECT SHORTWAVE ENERGY ACROSS THE CWA WITH A SURFACE COLD FRONT AND SO WILL INCREASE TO CHANCE POPS...ESPECIALLY IN THE NORTHERN ZONES WHERE BEST DYNAMIC SUPPORT WILL BE. WEDNESDAY THROUGH THURSDAY NIGHT...MODEL GUIDANCE CONTINUES TO KEEP NORTHEAST MONTANA ON THE COLDER SIDE OF A THERMAL BOUNDARY WITH 850MB TEMPERATURES COOLING INTO THE SINGLE DIGITS IN THE FAR NORTHEASTERN ZONES BY MIDWEEK. THIS IS SUPPORTIVE OF TEMPERATURES WELL BELOW SEASONAL NORMALS FOR EARLY AUGUST. MODELS SHOW DISAGREEMENT ON HANDLING OF WEAK DISTURBANCES IN THE NORTHWEST FLOW ALOFT BUT GIVEN A CONTINUATION OF AN ACTIVE PATTERN WILL MAINTAIN AT LEAST SLIGHT CHANCE POPS GOING ACROSS MUCH OF THE CWA. FRIDAY AND BEYOND...RIDGE AXIS ACROSS WESTERN/CENTRAL MONTANA MAY TRANSLATE EASTWARD AND OVER NORTHEAST MONTANA. THIS WOULD SUPPORT LARGE SCALE SUBSIDENCE OVER THE CWA AND WITH RISING HEIGHTS A GRADUAL WARMING TREND MAY INITIATE. AFTER A FEW MORE RUNS OF THE MODELS BETTER CONTINUITY SHOULD PROVIDE BETTER CONFIDENCE ON THIS AS IT GETS A BIT CLOSER IN TIME. FOR NOW DID ALLOW DAYTIME HIGHS ACROSS NORTHEAST MONTANA TO FINALLY REACH THE UPPER 70S TO LOWER 80S AGAIN IN MOST PLACES BY NEXT WEEKEND. MALIAWCO && .AVIATION... WHILE VFR CONDITIONS WILL PREVAIL FOR MOST OF THE TAF CYCLE FOR MOST OF THE TAF SITES TODAY...STRONG TO SEVERE THUNDERSTORMS WILL FORM AND SPREAD ACROSS THE REGION LATER THIS AFTERNOON AND EVENING. AT THIS TIME IT SEEMS KGDV WILL MOST LIKELY BE IMPACTED WITH STRONG WINDS AND VLIFR CONDITIONS SOMETIME BETWEEN 02Z AND 05Z TONIGHT. ALL REMAINING TAF SITES WILL LIKELY EXPERIENCE VCTS AND MAYBE MVFR CEILINGS FROM 23Z TO 05Z. AMENDMENTS WILL BE NECESSARY TONIGHT. VFR CONDITIONS WILL RETURN WITH SOME LINGERING SCT CLOUDS AROUND THE AREA TOWARD THE END OF THIS TAF PERIOD. BMICKELSON && .GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE. && WEATHER.GOV/GLASGOW
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE GLASGOW MT 338 AM MDT SAT AUG 3 2013 MTZ016>027-059>062-040945- CENTRAL AND SOUTHEAST PHILLIPS-CENTRAL AND SOUTHERN VALLEY- DANIELS-SHERIDAN-WESTERN ROOSEVELT-PETROLEUM-GARFIELD-MCCONE- RICHLAND-DAWSON-PRAIRIE-WIBAUX-NORTHERN PHILLIPS- SOUTHWEST PHILLIPS-NORTHERN VALLEY-EASTERN ROOSEVELT- 338 AM MDT SAT AUG 3 2013 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHEAST MONTANA. .DAY ONE...TODAY AND TONIGHT AN UPPER SYSTEM WILL MOVE ACROSS THE STATE TODAY...PRODUCING THUNDERSTORMS ACROSS NORTHEAST MONTANA IN THE AFTERNOON AND EVENING. SOME OF THESE STORMS MAY BECOME SEVERE WITH LARGE HAIL AND DAMAGING WINDS. HEAVY RAIN IS ALSO POSSIBLE. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.
The Billings radar (KBLX), 138 km away, was scanning. The volume nearest the first event began at 22:41 UTC.
8 hail, 3 thunderstorm wind. Local standard time, as filed.
Trained spotter reported tennis ball sized hail, broken windows and skylights, and 0.62 inches of rain.
Public reported hen egg sized hail.
Public reported tennis ball sized hail.
Public reported half dollars sized hail and wind gusts up to 50 mph.
Trained spotter reported 1.10 inches of rain in 10 minutes and quarter-sized hail.
Public reported half dollar sized hail at the Hell Creek Recreation Area.
Public estimated penny-sized hail resulting in total crop loss.
Public estimated wind gusts up to 60 mph.
Public reported wind gusts up to 60 mph.
Trained spotter reported wind gusts up to 60 mph.
Trained spotter reported 3 inches of rain in one hour and some nickel-sized hail.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2013Every state in 2013This day in weather historyWarnings in Montana, August 2013
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: 474493, 474494, 474495, 474496, 474498, 474497, 474500, 474501, 474499, 474502, 474504.