A closed upper level low lifted northeast across eastern Montana on May 6th through the 9th. This low merged with a shortwave streaming from the Pacific Northwest.
Every event with a place to put it; 62 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 episode as NWS TFX wrote it up.
A closed upper level low lifted northeast across eastern Montana on May 6th through the 9th. This low merged with a shortwave streaming from the Pacific Northwest. This storm system brought strong winds across Central and North Central Montana with the highest wind gust measured near Whitlash where a mesonet station measured an 87 mph gust. Widespread wind gusts of 55 and 75 mph were measured. Most damage was limited to trees being uprooted and power outages, but an exterior barrier of a high school roof was torn off by the wind in Shelby. Additionally, ample precipitation was observed with this system. Precipitation was mostly rain at lower elevations and fell as heavy snow in the mountains. Blizzard conditions were observed in the Little Belts, where multiple feet of snow was observed.
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 6, 10:35 AM MST, 54 minutes earlier.
Area Forecast Discussion National Weather Service Great Falls MT 1135 AM MDT Mon May 6 2024 .SYNOPSIS... A Pacific weather system is on track to initially bring strong northwest winds to much of North Central, Central, and Southwest Montana with some areas of precipitation. While the strong winds will linger through Wednesday, the low elevation rain and mountain snow will increase and become heavier, especially over North Central and Central Montana. The system will then exit the area Wednesday night into Thursday, for decreasing winds and precipitation, and a period of drying and warming conditions into the weekend. && .UPDATE... Forecast appears to be mostly on track so far, so no major changes are planned until the afternoon forecast package aside from expiring the Winter Weather Advisory for Southwestern Montana. Ludwig && .AVIATION... 1105 AM MDT Mon May 6 2024 (06/18Z TAF Period) Light to moderate rain has overspread areas along and northeast of a KLWT, to KGTF, to KCTB line late this morning, with this area of precipitation expected to slowly lift north and east of a KLWT to KHVR line through 00-06z Tuesday. MVFR/low-VFR conditions will predominately prevail beneath and outside of this area precipitation through much of the TAF period, with CIGS falling to IFR/MVFR at the KCTB and KHVR terminals beyond 12z Tuesday as precipitation pivots back to the southwest from southern Canada. Mountains will be obscured over the next 24 hours. In addition to the lower ceilings throughout much of the TAF period, strong and gusty west to northwest winds will occur along and north of the I-90 corridor, particularly at the KHLN, KLWT, KHVR, and KCTB terminals where wind gusts in excess of 35kts are expected. Mountain wave turbulence and instances of low level wind shear will be a threat for the entire 0618/0718 TAF period. - Moldan Refer to weather.gov/zlc for more detailed regional aviation weather and hazard information. && .HYDROLOGY... A slow moving Pacific weather system will bring an extended period of lower elevation rain and mountain snow this week, with the heaviest precipitation falling Tuesday through early Thursday. NBM probabilistic guidance highlights the eastern portions of Central/North-central MT with the heaviest rainfall amounts for this period, largely supporting 1 to 3 inches of rainfall/snow melt liquid equivalent over locations east of a Great Falls to Shelby line Tuesday through Thursday. While flooding is generally not expected, some rivers, creeks, and streams along the Canadian border in Hill and Blaine Counties are expected to approach or reach action stage Wednesday and Thursday, mainly impacting unpopulated rural locations. Anyone near waterways should remain alert for changing conditions and be prepared to seek higher ground should water rises occur. - RCG && .PREV DISCUSSION... /ISSUED 1105 AM MDT Mon May 6 2024/ Key Points: - A significant spring storm remains on track to impact the Northern Rockies through the middle of this week; bringing strong winds, widespread low elevation rain, and heavy mountain snow. - Strong northwest winds of 30 to 45 mph gusting to 65 mph will develop today over much of North Central and Central Montana and continue at times through Wednesday. - The heaviest forecast rainfall amounts have spread west to include the plains for much of North Central and Central Montana. Amounts are mostly in the 1 to 2 inch range for this afternoon through Thursday, with up to 4 inches of rain/snow water equivalent possible in the mountains. - The heaviest mountain snowfall amounts have remained consistently in the 1 to 2 feet range for most areas Tuesday through Wednesday, but up to 3 feet of snow is possible in the Little Belt Mountains. Today through Tonight... A low pressure area aloft that is over the Utah/Idaho/Wyoming borders early this morning is forecast to be moved northeast across Wyoming today and into the Dakotas tonight. Moisture wrapping around this system will continue light to at times moderate snow with gusty southerly winds in the mountains of Southwest Montana, so the Winter Weather Advisory will remain in effect there until noon today. Precipitation will gradually shift northeast on the back side of the low pressure area, focusing over the area along and east of a Lewistown to Havre line this afternoon. The moisture axis is then forecast to move further to the northeast overnight as the low center lingers over North Dakota. However, strong (45 to 60 kt) low- to mid- level winds on the backside of the low will also combine with a strong surface pressure gradient to bring a 70 to 85 percent probability of strong northwest winds of 30 to 45 mph with gusts to 65 mph to much of North Central and Central Montana beginning this afternoon. Have therefore upgraded the High Wind Watch for much of North Central Montana to a Warning and expanded it to include much of Central Montana. This potential seems to be driven partially by areas of downsloping off the Sweetgrass Hills, Bears Paw Mountains, and the island mountains of Central Montana, as well as by the northwest winds blowing through northwest to southeast oriented valleys in Central Montana. This system will also begin the downward trend in temperatures, as they should fall closer to seasonal averages. Tuesday through Thursday... The low pressure center is then forecast to retrograde west into Eastern Montana Tuesday into Tuesday night as it merges with a large low pressure trough moving east across the Pacific Northwest. This shift west of the precipitation-laden system will spread moderate rainfall over much of North Central and Central Montana, which will persist into Wednesday night. Probabilistic guidance continues to give much of the area an 80+ percent chance for at least 1 inch of precipitation, with a 50 to 70 percent probability of 2+ inches east of Interstate 15. Temperatures cooling up to 15 degrees below normal will help lower snow levels to between 4000 and 5000 feet, resulting in at least a 50 percent chance of 12+ inches of snow for most mountain areas with a 70+ percent chance of at least 24 inches of snow in the Little Belt Mountains. Have therefore continued the Winter Storm Warning for the Little Belts and upgraded the Winter Storm Watches to Warnings for the East Glacier Park Region and for the remaining mountain areas of Central Montana. The approach of the low pressure center and its associated strong northwest flow mentioned earlier will continue the strong surface winds through Tuesday into Tuesday night, which will cause reduced visibility in the mountains due to wet blowing snow, and a few power outages are possible due to the winds blowing wet accumulated snow on some power lines. Winds should decrease through the day on Wednesday and the snow should taper off Wednesday night into Thursday as ensemble guidance members are in good agreement with moving a high pressure ridge southeast into Montana, forcing the weather system into the Central Rockies and High Plains. Friday through next Monday... Most of the ensemble guidance keeps at least a weak high pressure ridge over Montana through this period, which should keep the area mostly dry as temperatures warm to around 15 degrees above normal by Monday. However, the NBM brings some weak disturbances through the area Sunday and Monday, so there is a chance of mainly mountain precipitation for those days. -Coulston && .PRELIMINARY POINT TEMPS/POPS... GTF 56 39 47 36 / 40 20 60 90 CTB 54 37 45 35 / 20 30 70 90 HLN 55 38 49 39 / 30 10 50 80 BZN 53 31 48 32 / 70 20 50 80 WYS 44 26 40 26 / 60 50 80 80 DLN 50 29 45 32 / 40 40 40 60 HVR 56 38 48 37 / 80 80 90 100 LWT 47 34 42 31 / 80 40 70 90 && .TFX WATCHES/WARNINGS/ADVISORIES... High Wind Warning until 6 AM MDT Wednesday for Bears Paw Mountains and Southern Blaine-Eastern Toole and Liberty-Fergus County below 4500ft-Hill County-Judith Basin County and Judith Gap-Little Belt and Highwood Mountains-Northern Blaine County- Snowy and Judith Mountains-Western and Central Chouteau County. Winter Storm Warning from noon Tuesday to midnight MDT Wednesday night for Big Belt, Bridger and Castle Mountains-East Glacier Park Region-Little Belt and Highwood Mountains-Snowy and Judith Mountains. High Wind Warning until midnight MDT Tuesday night for Big Belt, Bridger and Castle Mountains-Canyon Ferry Area-Elkhorn and Boulder Mountains-Gates of the Mountains-Helena Valley-Meagher County Valleys-Upper Blackfoot and MacDonald Pass. High Wind Warning until 6 PM MDT Tuesday for East Glacier Park Region-Eastern Glacier, Western Toole, and Central Pondera- Northern High Plains-Southern High Plains-Southern Rocky Mountain Front. && http://www.weather.gov/greatfalls
Preliminary Local Storm Report
National Weather Service Great Falls MT
1106 AM MDT Mon May 6 2024
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1029 AM Non-Tstm Wnd Gst 11 WNW Augusta 47.55N 112.61W
05/06/2024 M47 MPH Lewis and Clark MT Mesonet
Mesonet station TR276 L-C Portable No. 1.
&&
MoldanPreliminary Local Storm Report
National Weather Service Great Falls MT
1155 AM MDT Mon May 6 2024
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1145 AM Non-Tstm Wnd Gst 6 ESE East Helena 46.56N 111.79W
05/06/2024 M51 MPH Jefferson MT Mesonet
Mesonet station MTSPK Spokane Creek Us-287
Mp 55.7.
&&
MoldanThe national radar mosaic for the moment the first event began.
51 high wind, 8 heavy snow, 3 flood, 2 winter weather, 1 blizzard. Local standard time, as filed.
RAWS station TR276 L-C Portable No. 1 measured many gusts in excess of 58 mph, including a peak gust of 69 mph.
Ambient station 'Howards Lodge' measured a 66 mph gust.
Ambient sensor 'LJ Johnson Farms' measured a 67 mph gust.
Ambient Sensor 'Red Barn' measured a 60 mph gust.
An Ambient sensor in Winifred measured a 61 mph gust.
Mesonet station MTM68 4.8 S Blossburg (MT-Meso) measured two gusts of 58 mph or greater, including a peak gust of 59 mph.
The N Bar Ranch AWOS (KMVH) measured many gusts in excess of 60 mph, including a peak gust of 72 mph.
AWOS station K1OM Oscar measured multiple gusts in excess of 60 mph, including a peak of 67 mph. Sustained high winds (40 mph) were also observed early morning 5/7.
Mesonet station GW3546 measured many gusts in excess of 58 mph, including a peak gust of 87 mph.
Mesonet station DELMT Dellwo (MCSCN) measured two gusts in excess of 58 mph including a peak of 60. High sustained winds of 41 mph, averaged over an hour, were also observed.
RAWS station JPKM8 Judith Peak measured multiple gusts into the 60s mph, including a peak gust of 67 mph.
Mesonet station FW9939 Chester measured multiple gusts in excess of 58 mph, including a peak of 71 mph.
RAWS station FBLM8 Fort Belknap RAWS measured multiple gusts in excess of 60 mph, including a peak of 65 mph.
ASOS station KHVR Havre Airport measured multiple gusts of 58 mph or greater, including a peak gust of 59 mph.
Mesonet station GW3478 TCTIBER measured multiple gusts in excess of 58 mph, including a peak gust of 70 mph.
Mesonet station MTM47 MDA - Benchland measured two gusts of 58 mph or greater, including a peak gust of 60 mph.
COOP observer reported 14 inches new snow over 24 hours. Verification time estimated.
Trained spotter reported 11 inches new snow overnight. Additionally, a COCORAHS observer measured 7.5 inches new snow over 24 hours.
AWOS station K1CM Charlie measured multiple gusts of 58 mph or greater, including a peak gust of 67 mph.
Mesonet station MTBZH Bozeman Pass measured sustained winds that averaged 42 mph over three hours.
Mesonet station MTM09 2.1 W Moccasin (MT-MESO) measured two gusts of 58 mph or greater, including a peak gust of 64 mph.
Snotel equipment at Mount Lockhart estimated 20 inches of new snow over 24 hours. Additionally, Snotel equipment at Dupuyer Creek estimated 13 inches new snow over the same timeframe.
The public reported 14 inches new snow 12 miles NNW of Canyon Creek. Additionally, Snotel equipment at Nevada Ridge estimated 12 inches new snow over 24 hours.
Three snotel sites estimated 9 inches or more of new snow. Lick Creek (14 in), Lone Mountain (13 in), and Clover Meadow (10 in) were the sites that saw the heavy snow. Lighter snow was observed at Albro Lake snotel (8 in).
Ambient Sensor 'Nob Hill' in Helena measured a 59 mph gust.
AWOS Station KSBX Shelby Airport measured sustained winds averaging 42 mph over multiple hours.
Hill County Department of Emergency Services and MT Department of Emergency Services reported flooding in and around the Bears Paw Mountains. Total damage done totaled $1,205,267. The main expenses were to roads & bridges ($368,000) and to parks, recreational, or other facilities ($836,000).
Mesonet station GW2412 Hill 2SW measured multiple gusts of 58 mph or greater, including a peak gust of 63 mph.
Mesonet station GW1987 Ethridge 3 SE measured many gusts in excess of 58 mph, including a peak of 72 mph.
MT DOT sensor at Monarch Canyon showed visibility at or below one-quarter mile for at least 7 hours (Power failed at that point). US-89 was closed from Armington Junction to White Sulphur Springs early morning May 8. The Onion Park Snotel estimated 28 inches new snow with rates of 2 inches per hour. Elsewhere, the Porphyry Peak RAWS reported sustained winds averaging 25 mph, with gusts into the 50's mph before the sensor failed at 1005 PM MDT May 7. A widespread power outage affected much of the zone through Wednesday morning. End time is estimated given lack of observations after late evening of the 7th. The Monarch Fire Department reported 48 inches storm total snow by noon Wednesday the 8th. They reported numerous trees down, trees were on houses, roadways, and in Belt Creek. Other snowfall estimates from snotels in the zone: 29 inches at Stringer Creek over 24 hours, 21 inches at Deadman Creek over 24 hours, and 16 inches of new snow at Spur Park over 24 hours. Around $114,000 in damages were done to utilities.
Many automated stations estimated snow in excess of 9 inches, including Bridger Alpine (20.4in), Bridger Top (19 in), Sacajawea Snotel (12 in), Brackett Creek Snotel (10 in), and Boulder Mtn Snotel (11 in).
Ambient station 'Cut Bank Resort' measured a 62 mph gust.
Mesonet station GW1986 Lothair 9 north measured multiple gusts in excess of 58 mph, including a peak gust of 65 mph.
Mesonet station EW1931 Rudyard measured multiple gusts of 58 mph or greater, including a peak gust of 69 mph.
Mesonet station GW0664 Shelby Airport measured two gusts of 58 mph or greater, including a 59 mph gust.
ASOS station KLWT Lewistown Airport measured a 58 mph gust.
Mesonet station GW4015 Chester 4 NE measured multiple gusts in excess of 58 mph, including a peak gust of 86 mph.
Mesonet stationMTM02 10.2 S Loma (MT-MESO) measured multiple gusts in excess of 60 mph, including a peak gust of 62 mph.
AWOS station K1DM 7 ENE Denton measured multiple gusts in excess of 60 mph, including a peak gust of 67 mph.
Mesonet station MTM73 Ledger N MDA measured multiple gusts in excess of 58 mph, including a peak gust of 63 mph.
Little Snowy RAWS (LSNM8) measured two gusts of 58 mph or greater, including a peak gust of 60 mph.
MT Department of Emergency services reported $1,071,000 in damages to roads and bridges from the combination of rain and snow melt on the Fort Belknap Reservation in Blaine County.
Mesonet station MTDEN Denton (MT DOT) measured two gusts in excess of 60 mph, including a peak gust of 64 mph.
Mesonet station MTM53 Oilmont measured a 63 mph gust.
Mesonet station MTLOM Loma (MT DOT) measured a lone 63 mph gust.
Snotel equipment at Badger Pass estimated 16 inches new snow. Verification time estimated.
Mesonet station GW3487 Tiber Dam six east measured a 58 mph gust.
Mesonet station MTSWT Sweetgrass MTDOT measured two gusts in excess of 58 mph, including a peak gust of 61 mph.
Mesonset station MTM05 ARC-Wtri Conrad measured a 66 mph gust.
Mesonet station MTM45 3,2 SW Loma (MT-MESO) measured a lone gust of 65 mph.
Mesonet station GW0719 Joplin 9 N measured two gusts in excess of 58 mph, including a peak gust of 66 mph.
Peak wind gust observed at the Fort Benton Airport AWOS (K79S).
Mesonet station MTINV Inverness (MT DOT) measured two gusts of 58 mph or greater, including a peak gust of 61 mph.
Mesonet station DW4821 14 NNW Joplin measured a 60 mph gust.
Mesonet station GW1952 Riverview Colony measured a 59 mph gust.
ASOS station KCTB Cut Bank Airport measured a 58 mph gust.
Fergus Electric COOP posted several photos on Facebook showing numerous power poles knocked over due to a combination of strong winds and ice building up on the lines. Areas hit hardest were in Judith Basin and Fergus counties. 164,000 in damages were done to utilities.
Fergus Electric COOP posted several photos on Facebook showing numerous power poles knocked over due to a combination of strong winds and ice building up on the lines. Areas hit hardest were in Judith Basin and Fergus counties. No snow observation reports were received for the lower elevations of Fergus county. $224,000 in damages were done to utilities.
AWOS station K1NM 5 NE Forestgrove measured a 58 mph gust.
Mesonet station GW4079 Inverness 10 S measured a 59 mph gust.
Trained spotter estimated 9 inches new snow overnight into the morning of the 8th.
Ambient weather sensor 'six spot' measured a single gust to 58 mph on the west side of Great Falls.
Mesonet station FW1843 Great Falls measured a single 59 mph gust.
MT Department of Emergency Services reported $177,000 worth of damages to roads and bridges near the Bears Paw Mountains. Additional damages to utilities totaled $17,000.
RAWS station GINM8 Ginger measured a lone gust to 58 mph.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2024Every state in 2024This day in weather historyWarnings in Montana, May 2024
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: 1176116, 1176095, 1176097, 1176110, 1176084, 1176118, 1176085, 1176086, 1176126, 1179980, 1176087, 1176129, 1176074, 1176104, 1177141, 1176112, 1179988, 1179992, 1176113, 1176094, 1176115, 1179990, 1179991, 1179994, 1176119, 1179983, 1184543, 1177142, 1179981, 1179986, 1179989, 1176098, 1177146, 1176106, 1179982, 1176088, 1177147, 1176080, 1176089, 1177152, and more.