A compact upper level closed low moved southeastward through Montana during the early morning hours of Thursday May 7th. Most lower elevation locations reported moderate to heavy rainfall with this system, though the combination H700 temperatures around -5C and diabatic cooling brought a period of accumulating snow to Fergus and Judith Basin County locations at and below 4000 ft.
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 compact upper level closed low moved southeastward through Montana during the early morning hours of Thursday May 7th. Most lower elevation locations reported moderate to heavy rainfall with this system, though the combination H700 temperatures around -5C and diabatic cooling brought a period of accumulating snow to Fergus and Judith Basin County locations at and below 4000 ft. The greatest impacts were exerted on area power infrastructure.
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 7, 4:38 AM MST, 2 hours 22 minutes earlier.
Area Forecast Discussion National Weather Service Great Falls MT 538 AM MDT Thu May 7 2020 ...Update to Aviation... .SYNOPSIS... Rain and snow over North-Central Montana will diminish and move out of the area by this evening. Most lower elevation locations will see high temperatures in the 50s and 60s for today. Another clipper system passes through the region on Friday and will bring another chance for showers. Cool temperatures and unsettled conditions continue into next week but the next chance for widespread precipitation will likely hold off until next Tuesday and Wednesday. && .DISCUSSION... Today and tonight...vigorous/compact upper level trough is progressing southeastward through Montana this morning, resulting in a continued area of rain and snow over Central/North-Central locations. The heaviest precipitation is generally occurring along and southeast of a Fort Benton to Great Falls line. Snow is also falling over mountain areas and portions of Judith Basin and Fergus Counties. A Special Weather Statement was sent out to address reduced visibilities and for the possible of slippery roads in these areas. The Winter Weather Advisories for the Little Belt Mountains and the Northern Rocky Mountain Front were left as is since conditions still warrant them, particularly the one for the Little Belts. There were some concerns that the rain would change to snow in the Great Falls area but current thinking is that some warm air advection from the northern side of the storm system will prevent this from occurring. Conditions will continue to be monitored should the situation change. As the system departs the area later today, the general rains and snows will become more scattered in nature and will end by this evening. Temperatures will rebound into the 50s and 60s for most lower elevation locations. Partial clearing takes place tonight with low temperatures mostly in the 30s and 20s over mountain areas and the cooler valleys of the southwest. There will be a possibility of patchy fog development, mostly for those areas that have received heavy rainfall tonight. Friday through Next Thursday...A clipper system will quickly move through the region on Friday, which will bring another chance for rain showers and perhaps some light mountain snow. Liquid precipitation amounts should range from trace amounts to about 2 tenths of an inch for most areas. This system will also bring breezy northwesterly winds and will keep temperatures slightly below the seasonal average. A general northwesterly flow aloft will maintain cool and unsettled conditions for the weekend. Most locations will remain dry but a day to day slight chance for showers is expected. There may be a brief period of ridging on Monday before southwesterly flow develops ahead of a Pacific Northwest trough that sends a weak disturbance along with shower chances to the southwest Monday night. The next chance for widespread precipitation will come Tuesday and Wednesday as this system moves in the region. && .AVIATION... Updated 538 AM MDT Thu May 7 2020 (07/12Z TAF Period) Areas of rain and snow will linger across Central Montana through 18Z with conditions varying from low VFR to IFR. Remainder of the forecast area will see cloudy skies and VFR conditions. Mountain obscurations prevail through much of the forecast period. Storm system moves eastward overnight leaving variable low- and mid-level clouds with VFR conditions expected to prevail. NOTE: Amendments not scheduled for Ennis (KEKS) due to ongoing runway closure. && .PRELIMINARY POINT TEMPS/POPS... GTF 57 35 59 35 / 80 10 40 40 CTB 60 38 57 35 / 30 10 40 20 HLN 58 34 62 37 / 30 0 30 20 BZN 55 31 62 34 / 40 0 20 20 WYS 51 23 56 24 / 20 0 20 10 DLN 55 32 62 35 / 10 0 10 10 HVR 66 39 64 35 / 10 10 40 20 LWT 51 31 55 32 / 80 0 50 50 && .TFX WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until noon MDT today above 5500 feet for Cascade...Judith Basin...Meagher. Winter Weather Advisory until 9 AM MDT this morning above 5000 feet for Northern Rocky Mountain Front. && http://www.weather.gov/greatfalls
Special Weather Statement
National Weather Service Great Falls MT
346 AM MDT Thu May 7 2020
MTZ050-051-071215-
Fergus-Judith Basin-
346 AM MDT Thu May 7 2020
...LIGHT TO MODERATE SNOW CONTINUES TO AFFECT MUCH OF JUDITH BASIN
AND FERGUS COUNTIES...
At 319 AM MDT, light to moderate snowfall continues to affect
portions of Judith Basin and Fergus Counties. Visibilities in this
area range from less than one mile up to 5 miles and could drop as
low as one quarter to one half mile early this morning. Snow
accumulations of a Trace up to 3 inches are expected by 9 AM MDT.
Icy roads are possible as the snow melts on the roads then quickly
refreezes.
Conditions can deteriorate rapidly in winter weather situations. Be
prepared for snow or ice covered roads. Slow down and allow extra
time when traveling.
LAT...LON 4727 10872 4710 10874 4708 10860 4675 10864
4675 10938 4669 10945 4675 11005 4668 11046
4678 11064 4709 11065 4710 11077 4735 11077
4748 10999 4755 10984 4772 10982 4772 10943
4781 10898 4765 10877 4758 10831 4732 10831
TIME...MOT...LOC 0919Z 010DEG 0KT 4727 10931
mpj2 winter storm, 1 heavy snow. Local standard time, as filed.
Power outages were reported near Geyser and Judith Gap due to heavy wet snow weighing transmission lines down. Report was relayed by Fergus Electric Cooperative via facebook.
Power outages were reported throughout Fergus County due to heavy wet snow weighing down transmission lines. Report was relayed by Fergus Power Cooperative via facebook.
Snowfall estimated from 8 inch snow depth and after the snow ended. Some melting and compaction was taken in account.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2020Every state in 2020This day in weather historyWarnings in Montana, May 2020
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: 894140, 894141, 894139.