Even though average temperatures were below normal across much of western Colorado during the month of December, precipitation was still below normal. As a result, drought conditions persisted across the entirety of the western slope and remained unchanged from what was experienced in November through the end of the month.
Every event with a place to put it; 21 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.
Even though average temperatures were below normal across much of western Colorado during the month of December, precipitation was still below normal. As a result, drought conditions persisted across the entirety of the western slope and remained unchanged from what was experienced in November through the end of the month.
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 Nov 30, 10:36 PM MST, 1 hour 24 minutes earlier.
Area Forecast Discussion National Weather Service Grand Junction CO 1036 PM MST Mon Nov 30 2020 .SHORT TERM...(Tonight through Tuesday night) Issued at 228 PM MST Mon Nov 30 2020 Another bright and sunny day today will give way to a short stretch of unsettled weather in the next two days. Clouds will increase tonight ahead of the system currently moving onshore in the Pacific Northwest. This system is going to be quick mover for western Colorado and eastern Utah, with precipitation starting around sunrise Tuesday and coming to an end by Tuesday evening. Snow will begin across the north in the morning, before focusing mainly on the northern and central mountains by mid-day, and the San Juans may see a few showers in the evening as the system moves out. With this storm being such a quick mover, as well as the fact that the moisture will be extremely limited - increasing to about 0.2 inches of PWAT, which is about 25% of normal - accumulations will be limited. 1-3 inches for the northern and central mountains, with up to 4 inches at the highest elevations, and less than an inch in the mountain valleys. The bigger story with system is really the cold airmass moving in behind it. Temperatures at 700 hPa are sitting at about -4C today, and surface temperatures are right about normal. By tomorrow afternoon, the 700 hPa temperatures will have dropped to around -13C, and surface temperatures are expected to follow. Expect daytime highs to run 5-10F colder than average. Tuesday night's low are going to be 5-10F colder as well, but anywhere that skies are clear, the bottom could fall out and temperatures could get colder. .LONG TERM...(Wednesday through Monday) Issued at 228 PM MST Mon Nov 30 2020 A north to south oriented jet stream will support another trough/cold front at the surface that will move through the CWA Wednesday afternoon and evening. As the jet drops down, it will carve out an area of low pressure and even though instability and plenty of lift exists...there's just no moisture available. With that, we can expect some light snow/snowshowers along the Divide with minimal accumulations. Expect more of a nuisance type snow for Rabbit Ears and Vail Pass and other higher elevations. By Thursday morning, the low and accompanying cold front will have shifted to the south while easterly flow sets up across the region. Clouds will favor the mountains with less elsewhere and this coverage will decrease through the day Thursday. After that, models are all over the place but they all do stay dry through next Monday. As the second push of colder air moves in on Thursday, expect high temps to reach below normal though they should warm up heading into the weekend. Overnight lows will be noticeable both Friday and Saturday morning as the clear skies allow for efficient radiational cooling. && .AVIATION...(For the 06Z TAFS through 06Z Tuesday night) Issued at 1036 PM MST Mon Nov 30 2020 A weak and fast moving storm system will impact the area late tonight and Tuesday morning. This will result in a brief period of snow at KHDN, KEGE and KASE which will result in CIGS below ILS breakpoints and a slight chance for MVFR visibility. Expect winds to shift to the north as the cold front associated with this system moves through the region from 06Z to 18Z/Tues. Aside from those areas outlined previously, VFR conditions will prevail through the next 24 hours at the remaining TAF sites. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && SHORT TERM...BGB LONG TERM...TGR AVIATION...NL
Hazardous Weather Outlook National Weather Service Grand Junction CO 522 AM MST Mon Nov 30 2020 COZ001>014-017>023-UTZ022>025-027>029-011230- 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- 522 AM MST Mon Nov 30 2020 This hazardous weather outlook is for eastern Utah and western Colorado. .DAY ONE...Today and Tonight Light snow will develop over the northern mountains of Colorado and Utah late tonight with only light accumulations expected by sunrise. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday Light snow showers over the northern and central Colorado mountains continue at times Tuesday and Wednesday with generally 1 to 3 inches of snow expected over the highest elevations. Temperatures will cool down to several degrees below normal in the wake of this system before returning back to seasonal values by Saturday. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed.
The national radar mosaic for the moment the first event began.
21 drought. Local standard time, as filed.
The status of the drought remained unchanged through the month of December with extreme (D3) conditions across the eastern and central portions of the zone and the exceptional (D4) drought in the western portion of the zone.
The status of the drought remained unchanged through the month of December with exceptional (D4) conditions across all but the far northeast and southeast portions of the zone where the extreme (D3) drought continued.
The status of the drought remained unchanged through the month of December with extreme (D3) conditions across the eastern half of the zone and the exceptional (D4) category over the western half of the zone.
The status of the drought remained unchanged through the month of December with exceptional (D4) conditions across the entirety of the zone.
The status of the drought remained unchanged through the month of December with exceptional (D4) conditions across the entirety of the zone.
The status of the drought remained unchanged through the month of December with extreme (D3) conditions across the far eastern portion of the zone and the exceptional (D4) category elsewhere.
The status of the drought remained unchanged through the month of December with extreme (D3) conditions across the northwest portion of the zone and the exceptional (D4) category elsewhere.
The status of the drought remained unchanged through the month of December with exceptional (D4) conditions across all but the far western portion of the zone where the extreme (D3) drought continued.
The status of the drought remained unchanged through the month of December with exceptional (D4) conditions across all but the far northwest portion of the zone where the extreme (D3) drought continued.
The status of the drought remained unchanged through the month of December with extreme (D3) conditions across the entirety of the zone.
The status of the drought remained unchanged through the month of December with extreme (D3) conditions across all but the far southeast portion of the zone where the exceptional (D4) drought continued.
The status of the drought remained unchanged through the month of December with exceptional (D4) conditions across all but the far southwest portion of the zone where the extreme (D3) drought continued.
The status of the drought remained unchanged through the month of December with extreme (D3) conditions across all but the far northern portion of the zone where the exceptional (D4) drought continued.
The status of the drought remained unchanged through the month of December with exceptional (D4) conditions across the western and central portions of the zone and the extreme (D3) category elsewhere.
The status of the drought remained unchanged through the month of December with extreme (D3) conditions across the western portion of the zone and the exceptional (D4) drought over the eastern portion.
The status of the drought remained unchanged through the month of December with exceptional (D4) conditions over the entirety of the zone.
The status of the drought remained unchanged through the month of December with exceptional (D4) conditions over the northern and southern tiers of the zone and the extreme (D3) category elsewhere.
The status of the drought remained unchanged through the month of December with extreme (D3) conditions across all but the far northeast and southern portions of the zone where the exceptional (D4) category continued.
The status of the drought remained unchanged through the month of December with exceptional (D4) conditions across all but the far southeast and far southwest portions of the zone where the extreme (D3) category continued.
The status of the drought remained unchanged through the month of December with extreme (D3) conditions across all but the north-central portion of the zone where the exceptional (D4) category continued.
The status of the drought remained unchanged through the month of December with exceptional (D4) conditions across all but the far northeast portion of the zone where the extreme (D3) category continued.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Colorado in 2020Every state in 2020This day in weather historyWarnings in Colorado, December 2020
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: 928260, 928261, 928262, 928263, 928264, 928265, 928266, 928267, 928268, 928269, 928270, 928271, 928272, 928273, 928274, 928275, 928276, 928277, 928279, 928280, 928282.