A period of moderate to heavy snowfall occurred in the northern mountains. Storm totals ranged from 6 to 15 inches, heaviest in the Park Range.
Every event with a place to put it; 3 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 BOU wrote it up.
A period of moderate to heavy snowfall occurred in the northern mountains. Storm totals ranged from 6 to 15 inches, heaviest in the Park Range. In addition, a peak wind gust to 78 mph was recorded near Winter Park.
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 Jan 9, 5:07 AM MST, 2 hours 53 minutes earlier. Its key messages:
Area Forecast Discussion National Weather Service Denver/Boulder CO 507 AM MST Tue Jan 9 2024 .KEY MESSAGES... - Windy in the mountains and in/near foothills today through Wednesday, windiest today but spreads over the plains Wednesday. - Snow, blowing snow, and hazardous travel in the mountains this afternoon through Wednesday morning. - Another round of light snow Wednesday night to Thursday, along with a shot of cold. - Arctic cold almost certain (>80%) and periods of light snow possible Saturday through Monday for the Urban Corridor and eastern plains. - Long duration and potentially heavy snow for the mountains begins sometime Friday and continues through the weekend, possibly into Monday. && .SHORT TERM...(Today and tonight) Issued at 343 AM MST Tue Jan 9 2024 Mid-level water vapor satellite imagery currently shows Colorado in between systems with Monday's system exited to the east and the next shortwave pushing into the Pacific NW. Northeast Colorado stays under the influence of subsident flow through the late morning hours resulting in dry conditions. Strong NW winds are expected aloft with about 45-55 kts at ridgetop. Model cross sections indicate the presence of a stable layer as well which combined with enhanced winds aloft will support high winds in the mountains and foothills. Gusts will range 55-65 mph for periods throughout the day. There is uncertainty in the eastward extent of the winds, but generally the stable layer isn't all too impressive limiting the eastward extend. Gusty winds may bleed onto the adjacent plains including windy spots along CO-93, 287 to I-25 in northern Larimer County. Temperatures will be warmer today with warmer temperatures aloft and downslope flow. Expect highs in the low 40s across the I-25 corridor and central plains and 30s for the east plains and Palmer Divide. Despite highs in the teens for most of the high country, it will feel colder than that with winds keeping wind chills in the negative single digits to single digits. By the afternoon, the incoming shortwave trough approaches closer from the east with synoptic ascent increasing as a jet axis shifts closer. Cross-sections show deepening moisture, cold air aloft, and development of unstable lapse rates across the high country. This will support the next round of orographically enhanced mountain snow starting the afternoon, extending through Wednesday. For snowfall, the heaviest is favoring in the mountains north of I-70 which is covered by a Winter Weather Advisory for 5-10 inches of snow and blowing snow. As the jet sinks further south, snow increases across the I-70 corridor overnight. 3-7 inches with the addition of blowing snow from gusty winds have warranted the addition of another Winter Weather Advisory for the I-70 mountains starting this evening. Blowing snow will result in hazaradous travel in the mountains through Wednesday. There is a low chance (< 20%) for a few spill over light snow showers onto the adjacent plains after midnight. This evening, cross-sections and high resolution guidance hint at the potential for the gusty winds to spread onto the adjacent plains with gusts up to 40 mph possible. The most likely timeframe for this is late evening to around midnight. .LONG TERM...(Wednesday through Monday) Issued at 343 AM MST Tue Jan 9 2024 ...A LOT GOING ON THIS FORECAST PERIOD... We'll tackle this one event at a time. We start Wednesday with strong west/northwest flow aloft and an ongoing Winter Weather Advisory in the mountains. The main shot of snow will be sliding southward through the I-70 mountain corridor and Summit County very early Wednesday morning with the strongest thermal gradient, orographics, and instability. Then we'll see a noted decrease probably not long after sunrise Wednesday with stronger subsidence and drying noted. That subsidence will mean sunshine returning for the plains, but also a gusty downslope west/northwest wind for most of the day. The airmass will become well mixed due to both sunshine, moderate to strong low level gradients, and subsidence. Thus, we'll see gusty winds spread out across the plains. Maximum winds in the mixed layer are near 35 knots, so gusts near 40 mph seems reasonable for most of the plains. That will lead to elevated fire weather conditions over our northern plains including Larimer, Weld, Morgan, and northeast Boulder Counties where we haven't see recent snowfall. Winds start to decrease late Wednesday afternoon and then quickly subside by Wednesday evening as we lose our mixing and winds aloft slacken. That decrease aloft occurs ahead of the next fast moving disturbance (get used to them this week!) that arrives in our mountains Wednesday night and then moves across the plains through Thursday. Light snow will start in the mountains through the evening hours as deeper lift and moisture arrive, but orographics aren't quite as favorable for most of our mountains as flow aloft is more west/southwest. That could still favor the Park/northern Gore Ranges, however, so another Winter Weather Advisory may be needed there tomorrow night and Thursday. On the plains, we expect at least areas of light snow to develop by Thursday as we'll see a combination of upper level support/QG forcing and a developing upslope component behind the first surge of colder air to arrive from the north. That front will just be a mild taste of what's likely to come toward the weekend. Any snow that falls on the plains should be light with a few locations potentially seeing 1-2", but even light amounts could have some travel impacts due to colder temperatures (highs most likely in the 20s). That system moves out moves out Thursday evening. Onward we go to the next weather system(s) Friday through Monday, and Arctic cold. This is where more uncertainty starts to enter the picture as we'll be dealing with fast moving shortwaves in very strong west/northwest flow aloft and embedded 130-150 kt jet cores. That said, we are quite confident that at some point the arctic air lurking to our north will make a plunge southward and spread across the Northern and Central High Plains, including eastern Colorado. There's still reasonable confidence that Friday will still see a little rebound in temperatures and possibly windy conditions ahead of the next disturbance. That said, the arctic front could lurk/surge dangerously close to our area by late in the day. It's more likely, however, to arrive by Saturday once we get the passage of the next disturbance. While it's hard to time these arctic airmasses, they do have a way of oozing southward across the high plains behind any passing shortwaves. Therefore, while we don't have complete certainty on timing, we'll paint colder temperatures arriving by Saturday, and then the coldest day toward Sunday as arctic air should be more firmly entrenched. From a probability perspective, it was interesting to still see the uncertainty in the ensemble data yet, with a few outliers still showing highs near 50 for Denver on Saturday, but the vast majority (>75%) had highs below 20 and a few at/near zero! The National Blend of Models (NBM) is on the warmer end of guidance (due to bias correction and lag), so we've largely discounted that and moved the deterministic forecast to the colder side of guidance, or at least the midpoint. Given the current temperatures in the source region of the Northwest Territories in the -20s to -40s, we would expect (>70% confidence) to see below zero readings down here for lows, and even single digit highs. It should be noted there's even a small chance (10-20%) that highs stay at/below zero. With regard to snow chances for this period Friday through Monday. We'll likely see an increase in mountain snow sometime Friday depending on the exact speed of the next shortwave. Then potentially heavy mountain snow Friday night into Saturday or even Sunday depending on evolution of the upper trough and infusion of Pacific moisture. Right now, it does look favorable for a period of significant snowfall although details will certainly need to be worked out in the coming days. As stated in the Area Forecast Discussion yesterday, we'd have potential for significant mountain snows of 1-3 feet, which would certainly help reduce our snowpack deficit this season. Meanwhile, any embedded waves will also bring a chance of snow down onto the plains, so we'll have an extended duration of snow chances in the lower elevations. However, the risk of any heavier snowfall for the lower elevations looks limited at this time. && .AVIATION...(For the 12Z TAFS through 12Z Wednesday morning) Issued at 506 AM MST Tue Jan 9 2024 VFR conditions expected at the terminals for the TAF period. Winds are already proving to be a challenge this morning and will continue to be the element of lower confidence for the TAF today. Winds at DEN this morning have settled SE as opposed to SSW early this morning, likely an effect of the mountain wave to the west. There is some uncertainty in when the winds shift more SW this morning, but they should by mid morning as winds mix out. Common with this type of pattern, there is lower confidence in if the gusty winds reach east enough to DEN. If they do, gusts up to 25 kts are possible. For BJC there is higher confidence in gusts today (up to 25-35 kts). Overnight, in the 06-09z timeframe there is potential for gusty winds to spill out into the terminals with gusts 20-30 kts. && .BOU WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from 2 PM this afternoon to 11 AM MST Wednesday for COZ031-033. Winter Weather Advisory from 5 PM this afternoon to 11 AM MST Wednesday for COZ034. && SHORT TERM...Mensch LONG TERM...Barjenbruch AVIATION...Mensch
Hazardous Weather Outlook National Weather Service Denver/Boulder CO 516 AM MST Tue Jan 9 2024 COZ030>051-101230- 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- 516 AM MST Tue Jan 9 2024 ...WINTER WEATHER ADVISORY NORTHERN MOUNTAINS LATE THIS AFTERNOON THROUGH WEDNESDAY MORNING... This hazardous weather outlook is for northeast and north central Colorado. .DAY ONE...Today and Tonight Strong winds are expected in the mountains and foothills today. Snow increases across the high country this afternoon, continuing through the evening. Strong winds and snow will result in areas of blowing snow and hazardous travel conditions in the mountains. .DAYS TWO THROUGH SEVEN...Wednesday through Monday Strong winds, snow, and areas of blowing snow will make for hazardous travel conditions in the northern mountains into early Wednesday morning. The gusty winds will also spread across the plains Wednesday, with gusts around 40 mph fairly common. That will lead to elevated fire weather conditions in the lower elevations where recent snowfall has been scarce, mainly in areas north of Denver. Arctic cold will likely spread across the plains and foothills by this weekend. This is expected to bring the coldest air of the season, with low temperatures possibly dropping below zero Saturday night and Sunday night. Periods of snow can be expected in the mountains Wednesday night through early next week, with a round of potentially heavy snow sometime this coming weekend. Mainly light snow will be possible over the plains from time to time starting Thursday. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed today or tonight.
The national radar mosaic for the moment the first event began.
2 winter weather, 1 winter storm. Local standard time, as filed.
Storm totals included 15 inches, 4 miles southeast of Mount Zirkel, with 13.5 inches near Rabbit Ears Pass.
Storm totals included: 10.5 inches near Cameron Pass and 9 miles south-southeast of Spicer; 7.5 inches, 6 miles west of Arapahoe Peak; with 6 inches, 9 miles east of Glendevey.
Storm totals included: 10.5 inches near Berthoud Pass and 10 miles north-northeast of Silverthorne, 7.5 inches near Copper Mountain, Green Mountain Reservoir and Loveland Pass; with 6 inches near Brainard Lake.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Colorado in 2024Every state in 2024This day in weather historyWarnings in Colorado, January 2024
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: 1154280, 1154281, 1154283.