One of the earliest snowstorms on record swept through parts of the United States, from Montana to New Mexico on September 8 and 9, 2020, bringing record-early snow and record-cold temperatures to much of the region. The weather system hit the region after record-breaking heat, producing a drastic 33 °C (60 °F) drop in temperatures within just 24 hours.
The slow-moving mid to upper level low that has been responsible for the early season winter storm through the Rockies and Central High Plains is winding down on Thursday, September 10.
"Winter weather will be confined to the Central Rockies tonight into Thursday where additional heavy snows are possible," NWS forecaster Oravec said.
The much below-average temperatures that this system has also been responsible for, from the Rockies into the Plains, will continue to moderate over the next two days.
Temperatures are expected to remain well below average Thursday and Friday, September 11 across much of the Central to Southern Rockies into the Central to Southern Plains but they are not expected to be as below average as in past days, according to Oravec.
The weather started shifting in Montana as early as Sunday, September 6. Before the event was over, the city of Red Lodge - a gateway to Yellowstone National Park -- received 266.7 mm (10.5 inches) of snow.
Some of the greatest snow totals were recorded in Wyoming, where up to 431.8 mm (17 inches) of snow fell just south of Casper, Natrona County.
Casper recorded 58.4 mm (2.3 inches) on snow on September 7, and 132 mm (5.2 inches) on September 8, breaking its previous earliest measurable snow by one day (September 8, 1962).
Rapid City, South Dakota recorded 25.4 mm (1 inch) on September 7, breaking its previous record early snow by 4 days (September 11, 2014).
On September 8, Cheyenne, Wyoming tied its earliest measurable snow with 27.9 mm (1.1 inches).
At least 50.8 mm (2 inches) fell on Ft. Collins, Colorado on September 8, breaking the city's previous record early measurable snow by 4 days.
Pueblo, Colorado also broke its record-earliest snowfall dating back to 1898 on September 9, 2020.
Earliest-snow records were also broken in North Platte, Nebraska; Goodland, Kansas; Yuma, Colorado; and Las Vegas, New Mexico.
Aside from the snow, this storm brought strong winds and very cold to record-breaking low temperatures throughout the region.
Denver, Colorado registered 25.4 mm (1 inch) of snow, just days after the city hit an all-time September high of 38.3 °C (101 °F) on September 5.
The city tied a record-low temperature of -0.5 °C (31 °F) on September 8 and 9. The last time it was this cold in the city on September 8 and 9 was in 1962.
Denver also experienced its largest 2 Calendar day drop, in temperature for September, of 34 °C (62 °F). The previous record was 32 °C (59 °F) set in September 1993.
Albuquerque, New Mexico registered 5.5 °C (42 °F) on September 8 and 4.4 °C (40 °F) on September 9, breaking its record low temperature for the day, set at 6.1 °C (43 °F) in 1915.
NWS Meteorologist Clay Anderson said the city experienced November weather in early September. The temperature drop is 'highly unusual,' because it comes after a Labor Day weekend with temperatures in the 90s [°F] – and on the heels of one of the hottest Augusts on record, Anderson said.
According to the NWS office in Amarillo, Texas, all three of their official climate sites in the Panhandles broke their record low temperatures on September 9 and 'crushed the record Coldest High Temperatures' for the day. "These record cold high temperatures probably won't be matched any time soon," the office said.
Amarillo ASOS registered 4.4 °C (40 °F) on September 8, setting the new record low for September 8. This is now the all-time earliest (on record) Amarillo has hit a low of 40 °F after summer. The previous record was set on September 10, 1898.
The same site registered 2.7 °C (37 °F) at 09:55 LT on September 9, breaking the old record for the date set at 6.6 C (44 °F) in 1941. It is also the all-time earliest on record Amarillo has dropped into the 30s °F, beating the old record by 2 days.
"Tomorrow [September 10] could very well be the third day in a row that record low has been broken this week," NWS Amarillo meteorologists said. "It's going to be close in some places, with the low tying the record in the morning. One more cold morning then warming to the 50s [°F] in the afternoon."
Damaging winds hit the region, from 96 km/h (60 mph) to as high as 156 km/h (97 mph), leaving hundreds of thousands without power. As of 10:00 UTC on September 10, about 67 000 customers are still without power in Utah.
Farmers are also reporting extensive crop damage after incredible temperature swing and snow.
In contrast, massive wildfires are raging throughout the West Coast, from Washington to California, producing extremely large smoke plume for the past 3 days.
The image below was captured at 23:00 UTC (16:00 PDT) on September 9:
Image credit: NOAA/GOES-17, RAMMB/CIRA. Acquired 23:00 UTC on September 9, 2020
Elevated fire weather threats remain for portions of the West Coast today, but as winds continue to decrease, these threats will also weaken.
The strong, gusty winds over the West are expected to weaken by the weekend, helping reduce the severity of the fire conditions. However, low humidity and warmer temperatures will be enough for elevated fire concerns to remain.
With the wind direction returning to a more westerly component, smoke from the wildfires may waft and settle inland.
Featured image credit: NOAA/GOES-17, RAMMB/CIRA. Acquired 23:00 UTC on September 9, 2020