From 100-degree heat to snow. Colorado weather whiplash, one year later

If you person lived successful Denver oregon on the Front Range for a agelong time, you cognize however chaotic Colorado’s upwind tin beryllium and however rapidly it tin change.

One twelvemonth ago, betwixt Sept. 5-8, the Front Range of Colorado saw the latest readings ever of 100-degree vigor followed by the earliest accumulating snowfall successful astir 2 decades.

Satellite Imagery Showing the monolithic Cameron Peak Fire connected September 7, 2020

On Sept. 5, 2020, Denver acceptable its all-time grounds precocious for September, reaching 101 degrees that afternoon. This was besides the latest day a 100-degree speechmaking has ever been observed successful Denver.

Another regular grounds precocious was past tied connected Sept. 6 erstwhile Denver deed 97 degrees. Sept. 7 was the past time of vigor crossed the Eastern Plains of Colorado erstwhile Denver’s precocious somesthesia reached 93. That tied america for the grounds for the fig of 90-degree days for a twelvemonth (73) and was besides the warmest somesthesia ever recorded earlier a time of measurable snowfall. It was besides the day erstwhile ash was falling from the entity successful Fort Collins owed to the monolithic Cameron Peak wildfire.

Other cities on the Front Range besides felt this utmost September heat. Boulder, Fort Collins, and Colorado Springs were besides feeling grounds vigor starring up to the snow. One of the main factors that constricted immoderate Front Range cities from hitting the period people was the heavy fume blocking immoderate of the sun’s heat.

Water Vapor Satellite loop from GOES-16. Images from CIRA-CSU RAMMB-Slider September 7-10, 2020

On Monday, Sept. 7, 2020, a bid of acold fronts moved crossed the Denver area. This dropped temperatures from the 90s during the time into the 40s astatine night. Afternoon highs the pursuing time lone reached into the 40s for astir on the Front Range and a premix of rainfall and snowfall developed by that evening. Snow was falling crossed the higher elevations astir of Sept. 8 with accumulation stacking up on the Interstate 25 corridor from Tuesday nighttime to Wednesday morning.

This acold beforehand was 1 of the strongest acold fronts to deed the country successful September. Numerous records were acceptable during this event:

• Tied earliest frost connected grounds (Previously acceptable Sept. 8, 1962)
• Tied grounds debased connected Sept. 8 (31°F, past acceptable 1962)
• Tied grounds debased connected Sept. 9 (31°F, past acceptable 1962)
• Record coldest maximum somesthesia connected Sept. 9 (43°F). The erstwhile grounds was 53°F acceptable successful 1989.
• Tied grounds debased connected Sept. 10 (35°F, past acceptable 1898)
• Largest 2-calendar-day somesthesia driblet successful September (62°F drop). The erstwhile grounds was 59°F acceptable successful 1993.
• Warmest somesthesia ever recorded the time earlier a measurable snowfall (93°F connected Sept. 7). The erstwhile precocious was 92°F connected Sept. 12, 1993.
• Shortest fig of days betwixt a 100-degree time and measurable snowfall (3). The erstwhile grounds was 38 days successful 2019.
• Number of days (2) betwixt a grounds precocious and grounds debased successful Denver (Sept. 6 to Sept. 8).  Ties erstwhile grounds from Aug. 15 -17 successful 1960.

It was a chaotic upwind forecast and was a upwind lawsuit that volition beryllium remembered for years to come. The snowfall was highly notable and near cities buried nether inches of snow. Leading up to this event, the worst wildfires successful Colorado’s past were happening. Residents on the Front Range were taking pictures of ash covering cars, and drivers were utilizing headlights during the time due to the fact that of the acheronian owed to smoke. There was besides highly atrocious drought and the forecast of incoming acold and snowfall lone seemed fitting for the chaotic twelvemonth that was 2020.

Observed snowfall totals connected September 10, 2020

Numerous snowfall records were acceptable successful Colorado due to the fact that of this storm:

• Tied the 2nd earliest snowfall connected grounds for Denver (Sept. 8). The earliest snowfall connected grounds is 9/3/1961.
• Daily snowfall grounds acceptable for Sept. 8 (1.0 inch fell). The erstwhile grounds was 0.7 of an inch successful 1962.
• Daily snowfall grounds tied for Sept. 9 (Trace). The erstwhile grounds was a hint successful 1962.
• Snapped a streak of 19 consecutive years without September snowfall successful Denver.

Rocky Mountain National Park connected September 10, 2020 – RMNP

Total snowfall accumulations were 1 to 3 inches crossed overmuch of the Eastern Plains, 3 to 6 inches for cities on the mountains (including Boulder and the occidental portions of Fort Collins), and 4 to 10 inches for the mountains and foothills of the Front Range. A full of 5.6 inches of snowfall was measured astatine the NWS Boulder office, portion Denver officially measured a full of 1.0 inches. Parts of the Arkansas River Valley, the Sangre De Cristo Mountains, and the Pikes Peak Region saw much than a fractional of a ft of snowfall accumulate.