An upper level trough tracked into northwest Montana by late afternoon on July 8th. The leading 50 knot mid-level southwest jet maximum moved towards the Bitterroot Valley by late morning helping to initiate a few hail producing supercell thunderstorms.
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 MSO wrote it up.
An upper level trough tracked into northwest Montana by late afternoon on July 8th. The leading 50 knot mid-level southwest jet maximum moved towards the Bitterroot Valley by late morning helping to initiate a few hail producing supercell thunderstorms. A second round of thunderstorms developed by the afternoon across northwest Montana producing more hail.
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 Missoula, MT wrote its last area forecast discussion before the first event at Jul 8, 3:05 AM MST, 7 hours 30 minutes earlier.
Area Forecast Discussion National Weather Service Missoula MT 405 AM MDT Mon Jul 8 2013 .DISCUSSION...A trof of low pressure in Washington state is approaching the Northern Rockies. Ahead of this quick moving short wave this early morning are a couple of lines of showers and thunderstorms in West Central Montana through Central Idaho. This activity will increase in coverage through the morning hours and encompass much of the region. Impacts from this activity will be brief heavy rain, gusty outflow winds and frequent lightning. A secondary burst of scattered showers and thunderstorms will redevelop this afternoon with the short wave nosing its way into northwest Montana. Similar impacts of gusty outflow winds, heavy rain and frequent lightning are once again expected. This system will quickly exit the region during the evening hours and a strong ridge of high pressure returns through much of Thursday. Warmer temperatures and dry weather will occur. Confidence is increasing a bit for a scenario of a weak trof of low pressure to brush through the region. The intensity of this low is uncertain. It appears now the best potential for convection may well be in southwest Montana and Lemhi county. The other impact late Thursday through Saturday may be moderate westerly winds. Models diverge in their solution Sunday through early next week. They are indicating either a continued windy westerly flow or a building strong ridge with much warmer temperatures. Confidence is very low on either solution at this time. && .AVIATION...Scattered showers and thunderstorms currently in central Idaho and west central Montana will impact terminal KMSO through 08/1200z. These storms will increase in coverage later this morning through mid Thursday evening. Terminals impacted will be KGPI, KMSO and KBTM. Any storm that will pass through these regions will impact terminals with brief heavy rain, frequent lightning and gusty outflow winds. This activity will quickly dissipate after 09/0300z. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...None. ID...None. && Follow us on Facebook and Twitter! https://www.facebook.com/US.NationalWeatherService.Missoula.gov https://www.twitter.com/NWSMissoula
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MISSOULA MT
714 AM MDT MON JUL 8 2013
MTZ007-043-081400-
BUTTE/BLACKFOOT REGION-POTOMAC/SEELEY LAKE REGION-
714 AM MDT MON JUL 8 2013
...SIGNIFICANT WEATHER ADVISORY FOR NORTHERN GRANITE...EASTERN
MISSOULA AND CENTRAL POWELL COUNTIES UNTIL 800 AM MDT...
AT 710 AM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING
STRONG THUNDERSTORMS ALONG A LINE EXTENDING FROM 10 MILES NORTHEAST
OF SEELEY LAKE TO 10 MILES NORTHWEST OF EDS GULCH IN DRUMMOND...AND
MOVING NORTHEAST AT 45 MPH.
HAIL UP TO ONE-HALF INCH IN DIAMETER AND WIND GUSTS UP TO 40 MPH ARE
EXPECTED WITH THESE STORMS...ALONG WITH HEAVY RAIN.
LOCATIONS NEAR THE PATH OF THESE STORMS INCLUDE...OVANDO AND
HELMVILLE.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
IF THREATENING WEATHER APPROACHES YOUR AREA...GO INDOORS AND STAY
AWAY FROM WINDOWS. IF YOU ARE CAUGHT OUTSIDE...MOVE TO A WELL
PROTECTED AREA.
&&
LAT...LON 4669 11332 4737 11347 4750 11309 4748 11305
4719 11304 4718 11281 4717 11279 4688 11279
TIME...MOT...LOC 1314Z 243DEG 38KT 4732 11332 4682 11322SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE MISSOULA MT 836 AM MDT MON JUL 8 2013 IDZ006>008-081515- LOWER HELLS CANYON/SALMON RIVER REGION-OROFINO/GRANGEVILLE REGION-SOUTHERN CLEARWATER MOUNTAINS- 736 AM PDT MON JUL 8 2013 ...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL IDAHO COUNTY UNTIL 815 AM PDT... AT 729 AM PDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM 5 MILES SOUTH OF GRANGEVILLE...MOVING NORTHEAST AT 45 MPH. HAIL UP TO ONE-HALF INCH IN DIAMETER IS EXPECTED WITH THIS STORM... ALONG WITH HEAVY RAIN AND FREQUENT DANGEROUS LIGHTNING. LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE...LOWELL...HARPSTER... CLEARWATER...NEWSOME AND SYRINGA. PRECAUTIONARY/PREPAREDNESS ACTIONS... IF THREATENING WEATHER APPROACHES YOUR AREA...GO INDOORS AND STAY AWAY FROM WINDOWS. IF YOU ARE CAUGHT OUTSIDE...MOVE TO A WELL PROTECTED AREA. IN ADDITION...THIS STORM MAY INTENSIFY...SO BE CERTAIN TO MONITOR LOCAL RADIO AND TV STATIONS...AS WELL AS LOCAL CABLE TV OUTLETS...FOR ADDITIONAL INFORMATION AND POSSIBLE WARNINGS FROM THE NATIONAL WEATHER SERVICE. && LAT...LON 4638 11551 4593 11513 4575 11613 4591 11626 TIME...MOT...LOC 1435Z 240DEG 38KT 4588 11606 DICKERSON
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE MISSOULA MT 1131 AM MDT MON JUL 8 2013 IDZ006-MTZ005>007-043-081800- SOUTHERN CLEARWATER MOUNTAINS- BITTERROOT/SAPPHIRE MOUNTAINS-BUTTE/BLACKFOOT REGION-MISSOULA/BITTERROOT VALLEYS-POTOMAC/SEELEY LAKE REGION- 1131 AM MDT MON JUL 8 2013 ...SIGNIFICANT WEATHER ADVISORY FOR NORTHERN RAVALLI...NORTHWESTERN GRANITE...SOUTHERN MISSOULA AND NORTHEASTERN IDAHO COUNTIES UNTIL NOON MDT/1100 AM PDT/... AT 1124 AM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM NEAR VICTOR...OR 12 MILES NORTH OF HAMILTON... MOVING EAST AT 40 MPH. HAIL UP TO THE SIZE OF PENNIES AND WIND GUSTS UP TO 50 MPH ARE EXPECTED WITH THIS STORM...ALONG WITH HEAVY RAIN AND FREQUENT DANGEROUS LIGHTNING. LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE...STEVENSVILLE...BELL CROSSING...QUIGLEY AND NIMROD. PRECAUTIONARY/PREPAREDNESS ACTIONS... IF THREATENING WEATHER APPROACHES YOUR AREA...GO INDOORS AND STAY AWAY FROM WINDOWS. IF YOU ARE CAUGHT OUTSIDE...MOVE TO A WELL PROTECTED AREA. IN ADDITION...THIS STORM MAY INTENSIFY...SO BE CERTAIN TO MONITOR LOCAL RADIO AND TV STATIONS...AS WELL AS LOCAL CABLE TV OUTLETS...FOR ADDITIONAL INFORMATION AND POSSIBLE WARNINGS FROM THE NATIONAL WEATHER SERVICE. && LAT...LON 4676 11341 4643 11328 4627 11437 4648 11443 TIME...MOT...LOC 1731Z 252DEG 36KT 4643 11416 DICKERSON
The Missoula radar (KMSX), 72 km away, was scanning. The volume nearest the first event began at 17:33 UTC.
3 hail. Local standard time, as filed.
A supercell enhanced by the Bitterroot Mountains tracked east-northeast at approximately 43 mph producing 1 inch hail in Victor.
A thunderstorm outflow boundary triggered another cell that grew in strength over higher terrain west of Moiese. This thunderstorm produced hail one inch in diameter, as reported by personnel at the National Bison Range.
A right-moving supercell thunderstorm tracked across the Mission Mountains moving east around 43 mph. A member from the public 9 miles south of Condon reported golf ball size hail that tore branches and leaves off trees and covered the ground.
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, July 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: 462085, 462086, 469360.