A low-amplitude shortwave trough moved across northwest Colorado and, when combined with increased moisture and favorable orographics, produced moderate snow over the northern mountains. Winds gusted up to 50 mph at times.
Every event with a place to put it; 2 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 GJT wrote it up.
A low-amplitude shortwave trough moved across northwest Colorado and, when combined with increased moisture and favorable orographics, produced moderate snow over the northern mountains. Winds gusted up to 50 mph at times.
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 Grand Junction, CO wrote its last area forecast discussion before the first event at Feb 9, 10:46 AM MST, 14 minutes earlier.
Area Forecast Discussion National Weather Service Grand Junction CO 1046 AM MST Tue Feb 9 2021 .SHORT TERM...(Today through Wednesday) Issued at 501 AM MST Tue Feb 9 2021 Really anomalous H500 hand analysis map drawn at 00Z with 558dam Atlantic ridge nosing westward across Greenland and 558dam Pacific ridge arched into southern AK. This means lower than normal heights across the interior of NOAM where the polar vortex has settled. There is a double branched Polar Jet aloft...one branch separating the true arctic plunge from the polar air. The other branch extends around a digging trough off the Cali coast and merges with the northern branch over the Intermountain West. This southern branch is associated with moisture which will be severely needed as the 00Z KGJT RAOB only had 0.13 PWAT in the column. The interaction of the jets will help provide ascent for synoptic scale lift across our CWA which begins over the North this morning and drops southward over the next 36 hours or so. QG forcing overall is fairly week with this jet which doesn't bode well for top down saturation to the lower elevations. Luckily we have the highest terrain around which will help capture the moisture aloft and bring snow down to much of the Colorado mountain bases. There is a hint of mid level forcing over the southern 1/3 of the CWA tonight as the southern branch of this jet dips southward by the arrival of the upstream trough into the Southwest. This could bring some precipitation down to the lower elevations of southeast Utah and southwest Colorado...but measurable precipitation appears to be seen. Overall the precipitation trend is up a bit over the southern Colorado mountains and maybe just a bit less up north with the slow start to precipitation this morning. Advisories in the northern Colorado ranges will stand as is. Impacts expected at times over the I-70 corridor near Vail Pass with snow falling. The highest amounts however look to be over the higher peaks to the North and Southwest and have held off on an advisory for now. Some better amounts look to fall over high West Elks as well with lesser amounts over the bulk of the mid and lower elevations including the Gunny Basin. The San Juan look to see 2-5 inches with some locally high amounts on the northern high peaks as the event winds up late Wednesday. Temperatures will be impacted by the passing high clouds and precipitation the next few afternoon with milder temperatures at night as a result. Overall though it looks to remain seasonable. .LONG TERM...(Wednesday night through Monday) Issued at 501 AM MST Tue Feb 9 2021 The long term period continues to change from run to run with the biggest differences appearing with the latter half of the weekend. Until then, Wednesday and Thursday will see some snow showers along the Divide...mainly for the northern and central mountains...while the rest of the CWA will see times of sun and clouds. The action gets going early Friday morning as moisture overspreads the region and a series of disturbances provide plenty of lift for widespread precip. As mentioned, the evolution of these disturbances has changed from run to run with the GFS ensembles still trending wetter than the EC ensembles but there's still some decent precip in the drier solution. Look for light precip over the higher terrain starting by daybreak Friday morning. By noon, an approaching wave looks to cause a noticeable uptick in precip spreads and amounts. As this wave moves off, a secondary trough drops in from the northwest and keeps precip going through Saturday morning. The EC, and drier, model, doesn't like the idea of the deeper troughs moving through and so without the extra lift...QPF amounts are tempered down some. Interestingly, cluster maps aren't all 'that' different through Saturday so we'll see what the next few model runs bring. There is a HUGE discrepancy though with regards to temperatures on Saturday and Sunday. MEX guidance (GFS) suggesting high temps being about thirty..yes 30...degrees below normal Saturday with lows below zero across the region. The EC not showing anything near that. The GFS really wants to tap into the frigid air to our northeast and advect it across the Western Slope while the EC does not. Plenty of time to hammer this out... Yesterday, the models showed a second trough moving through the region on Sunday, keeping QPF in the picture. Latest guidance keeps the open wave in the forecast but it now gets shunted to AZ/NM where the heaviest precip falls. The EC keeps a more northerly track and so a bit more QPF across the region. These differences all deal with the deep low responsible for the bitterly cold air across the eastern half of the U.S. and it's evolution. Once models get a good handle on that, model solutions will come around and get in better agreement. Confidence is increasing for the Friday/Saturday system but after that, not so much. It's still only Monday so plenty of time for things to firm up. && .AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon) Issued at 1040 AM MST Tue Feb 9 2021 Widespread broken to overcast skies will continue for the next 24 hours with some scattered clouds for KDRO. Cloud bases, for the most part, hover between 5 to 7K and they will continue to lower through the day...especially towards the late afternoon and evening hours. Mountain TAF sites will likely start seeing some -SN from about 00Z onwards which will drop vis and cigs and will continue through the overnight though cigs and vis will vary as snow starts and stops during that time. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...Winter Weather Advisory until noon MST Wednesday for COZ004-013. UT...None. && SHORT TERM...15 LONG TERM...TGR AVIATION...TGR
Hazardous Weather Outlook National Weather Service Grand Junction CO 515 AM MST Tue Feb 9 2021 COZ001>014-017>023-UTZ022>025-027>029-101215- Lower Yampa River Basin-Central Yampa River Basin- Roan and Tavaputs Plateaus-Elkhead and Park Mountains- Upper Yampa River Basin-Grand Valley-Debeque to Silt Corridor- Central Colorado River Basin-Grand and Battlement Mesas- Gore and Elk Mountains/Central Mountain Valleys- Central Gunnison and Uncompahgre River Basin- West Elk and Sawatch Mountains-Flat Tops- Upper Gunnison River Valley-Uncompahgre Plateau and Dallas Divide- Northwest San Juan Mountains-Southwest San Juan Mountains- Paradox Valley/Lower Dolores River- Four Corners/Upper Dolores River-Animas River Basin- San Juan River Basin-Southeast Utah-Eastern Uinta Mountains- Eastern Uinta Basin-Tavaputs Plateau-Arches/Grand Flat- La Sal and Abajo Mountains-Canyonlands/Natural Bridges- 515 AM MST Tue Feb 9 2021 This hazardous weather outlook is for eastern Utah and western Colorado. .DAY ONE...Today and Tonight Snow will increase across the northern Colorado mountains through the morning hours...picking up across the central then southern mountains this afternoon and tonight. Impacts to travel over the higher mountain roadways and passes can be expected at times with blowing snow also a threat above timberline. .DAYS TWO THROUGH SEVEN...Wednesday through Monday Unsettled weather will continue through much of the forecast as a series of storms travel through the fast westerly flow aloft. The biggest unknown continues to be the threat of arctic air being pulled down the western side of the divide over the weekend. .SPOTTER INFORMATION STATEMENT... Spotter activation will not most likely not be needed but any snowfall reports would be welcome.
The national radar mosaic for the moment the first event began.
2 winter weather. Local standard time, as filed.
Generally 3 to 7 inches of snow fell across the area with locally higher amounts estimated at the Tower SNOTEL site. Winds gusted up to 50 mph at times.
Generally 3 to 10 inches of snow fell across the area.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Colorado in 2021Every state in 2021This day in weather historyWarnings in Colorado, February 2021
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: 932610, 932611.