An upper level disturbance produced heavy snow across parts of the northern mountains. 5 inches, with the highest report 5 miles west of Green Mountain Reservoir.
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The episode as NWS BOU wrote it up.
An upper level disturbance produced heavy snow across parts of the northern mountains. Storm totals ranged from 10 to 17.5 inches, with the highest report 5 miles west of Green Mountain Reservoir.
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 Denver/Boulder, CO wrote its last area forecast discussion before the first event at Mar 21, 5:00 AM MST, 0 minutes earlier.
Area Forecast Discussion National Weather Service Denver/Boulder CO 600 AM MDT Tue Mar 21 2023 .SHORT TERM...(Today and tonight) Issued at 450 AM MDT Tue Mar 21 2023 Water vapor imagery shows a shortwave trough to the NW of Colorado moving to the north and east this morning with the remaining wrap around moisture moving across the central mountains. Radar shows light to moderate snow showers in the mountains. CDOT cameras show snow covered roads in the mountains, so take caution if driving up this morning. With weak lift still in place, this will keep showers going in the mountains early this morning. As the wave exits further east, subsidence works in by mid- morning decreasing shower coverage and bringing breezy conditions for mainly the mountains/foothills. Expect dry conditions on the plains today. Partial clearing may bring highs up a degree or two from yesterday, with highs in the 50s for the plains/urban corridor and 20s and 30s for the high country. During the day, the next system remains off to the west over the California coast with an accompanying rich atmospheric river. Flow becomes more zonal this afternoon as this system slowly makes its way east. There may be some scattered showers in the mountains late this afternoon; however, the best upper support doesn't arrive until later tonight. Tonight, the system approaches Colorado inducing SW flow aloft, synoptic ascent, and tapping more into remnants of the atmospheric river. This will increase snow showers over the high country overnight into early Wednesday. .LONG TERM...(Wednesday through Monday) Issued at 450 AM MDT Tue Mar 21 2023 An area of lift and instability will move across the area Wednesday. There will probably be a focused area that passes fairly quickly over the mountains in the morning and onto the plains in the midday or afternoon, with drying coming into the mountains behind it. But there is still shallow moisture and some instability to keep showers going in the afternoon. There will be strong west winds across areas south of Denver and Limon in the morning, with a shift to the northwest across all of the plains as cooler air rushes in during the afternoon. There's quite a range of high temperatures in the guidance depending on the frontal timing. We favor our going forecast with a midday high in the mid 50s across most of the area, but it could get near 70 in Lincoln county if the cooling comes a bit more slowly. The wind and warmth bring fire weather concerns...see more below. After the Wednesday system, there are a couple of weak shortwaves (roughly Thursday afternoon and Saturday) in an environment that never really dries out for long and remains only slightly stable. This will allow for occasional snow showers in the mountains and a few brief chances of rain showers on the plains. We'll probably have a little diurnal convection in between the batches of moisture as well. None of this looks particularly heavy, but it's a small step into spring. Wednesday will probably be a bit cooler, but this depends on the timing of the cooling associated with the weak shortwave Friday night or Saturday. There continues to be decent agreement on a large trough moving across the Rockies in the Sunday/Monday time frame. Details still vary a lot, but cooler temperatures, probably just cold enough for snow or rain changing to snow, and a period or two of lift and upslope look likely. If the trough comes through in pieces lift may not be very focused, but it should provide a couple days of light to moderate snow in the mountains and at least one showery period on the plains. PoPs are currently limited by timing uncertainty of when that is most likely. && .AVIATION...(For the 12Z TAFS through 12Z Wednesday morning) Issued at 600 AM MDT Tue Mar 21 2023 Winds have trended more W/NW this morning at DEN. Expect westerly component winds this morning and into the afternoon at 08-13 kts. BJC will continue to see a few gusts (20-25 kts) this morning. Clouds increase throughout the day as the next system approaches from the west with decks becoming BKN by late afternoon. Winds become light easterly late afternoon/early evening. && .FIRE WEATHER... Issued at 450 AM MDT Tue Mar 21 2023 It will be dry today; however, winds and relative humidity will remain below critical thresholds. May see some spotty areas of elevated conditions over the plains in the afternoon. Stronger west winds and lower humidity will produce conditions near Red Flag criteria on Wednesday. The worst conditions will be over southern Lincoln and southeast Elbert counties where a Fire Weather Watch has been issued. Further north humidities will be higher as cooler air moves in during the day, but dry conditions and gusty winds can be expected in all areas in the afternoon. && .BOU WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 8 AM MDT this morning for COZ031- 033. Winter Weather Advisory from 6 AM to 6 PM MDT Wednesday for COZ031-033-034. Fire Weather Watch from Wednesday morning through Wednesday afternoon for COZ247. && SHORT TERM...Mensch LONG TERM...Gimmestad AVIATION...Mensch FIRE WEATHER...Gimmestad/Mensch
Hazardous Weather Outlook National Weather Service Denver/Boulder CO 559 AM MDT Tue Mar 21 2023 COZ030>051-221200- Jackson County Below 9000 Feet- West Jackson and West Grand Counties Above 9000 Feet- Grand and Summit Counties Below 9000 Feet- South and East Jackson/Larimer/North and Northeast Grand/ Northwest Boulder Counties Above 9000 Feet- South and Southeast Grand/West Central and Southwest Boulder/ Gilpin/Clear Creek/Summit/North and West Park Counties Above 9000 Feet-Larimer and Boulder Counties Between 6000 and 9000 Feet- Jefferson and West Douglas Counties Above 6000 Feet/Gilpin/Clear Creek/Northeast Park Counties Below 9000 Feet- Central and Southeast Park County- Larimer County Below 6000 Feet/Northwest Weld County- Boulder And Jefferson Counties Below 6000 Feet/West Broomfield County- North Douglas County Below 6000 Feet/Denver/West Adams and Arapahoe Counties/East Broomfield County- Elbert/Central and East Douglas Counties Above 6000 Feet- Northeast Weld County-Central and South Weld County-Morgan County- Central and East Adams and Arapahoe Counties- North and Northeast Elbert County Below 6000 Feet/North Lincoln County- Southeast Elbert County Below 6000 Feet/South Lincoln County- Logan County-Washington County-Sedgwick County-Phillips County- 559 AM MDT Tue Mar 21 2023 ...MORE MOUNTAIN SNOW AND WINDY ON WEDNESDAY... This hazardous weather outlook is for northeast and north central Colorado. .DAY ONE...Today and Tonight Light to moderate snow showers continue in the mountains early this morning, decreasing in coverage and intensity mid-morning. Slick roads will result in minor travel impacts this morning in the mountains. After a brief lull, snow showers increase in the mountains from SW to NE late afternoon into this evening continuing overnight into Wednesday. Snow covered roads and patchy blowing snow will impact travel. .DAYS TWO THROUGH SEVEN...Wednesday through Monday Strong winds are expected over the mountains and on the plains south of Interstate 70 on Wednesday. Peak gusts of 40 to 55 mph are likely in these areas. Over northeastern Colorado winds will be lighter in the morning, but increase in the afternoon with gusts up to 40 mph. The winds and low humidity will create elevated fire weather conditions, especially south of a line from Colorado Springs to Limon. The mountains will have another batch of snow that will peak on Wednesday morning. Additional accumulations will be 4 to 10 inches over the higher mountains with the heaviest amounts around Rabbit Ears and Cameron passes. Valley areas will see 1 to 3 inches of snow. For Thursday through Saturday, an unsettled pattern will bring periods of mainly light snow showers to the mountains. The plains will mostly be dry though a few light rain showers are possible. A large weather system is expected to cross the Rockies on Sunday or Monday, likely bringing colder temperatures with mountain snow and a chance of rain and snow to lower elevations. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed today or tonight. Mensch/Gimmestad
The national radar mosaic for the moment the first event began.
3 winter storm. Local standard time, as filed.
Storm totals included 13.7 inches, 4 miles southeast of Mount Zirkel.
Storm totals included: 17.5 inches, 5 miles west of Green Mountain Reservoir; 10 inches, 6 miles southwest of Silverthorne and 6 miles east of Arapahoe Peak.
Storm totals included: 12.5 inches, 7 miles south-southeast of Cameron Pass and 5 miles southwest of Grand Lake; 11.2 inches at Mount Audubon and 4 miles northwest of Longs Peak; 10 inches, 3 miles south of Estes Park and 5 miles south-southwest of Glendevey.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Colorado in 2023Every state in 2023This day in weather historyWarnings in Colorado, March 2023
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: 1088380, 1088381, 1088382.