A storm system brought snow and blowing snow to the northern mountains, with strong post frontal bora winds to the Front Range Foothills, I-25 corridor and northeast plains. Peak wind gusts from 58 to 85 mph were recorded across the region.
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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 storm system brought snow and blowing snow to the northern mountains, with strong post frontal bora winds to the Front Range Foothills, I-25 corridor and northeast plains. Peak wind gusts from 58 to 85 mph were recorded across the region. A few trees were reportedly knocked down as well. In addition to the strong winds, storm totals in the mountains ranged from 3 to 9 inches.
In and near the Front Range mountains and foothills, the more impressive gusts included: 91 mph near Loveland Pass; 85 mph 3 miles south of Boulder, 80 mph, 3 miles northwest of Boulder; 79 mph near Marshall, 78 mph near Glen Haven and 75 mph near Rocky Flats. Across the northeast plains of Colorado, the stronger gusts included: 76 mph in Fort Morgan, 70 mph at Cedar Point; 69 mph at Akron; 68 mph, 11 miles northwest of Westplains, and 67 mph near Crook and 8 miles south of Holyoke.
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 Nov 13, 8:44 PM MST, 16 minutes earlier.
Area Forecast Discussion National Weather Service Denver/Boulder CO 844 PM MST Fri Nov 13 2020 .UPDATE... Issued at 842 PM MST Fri Nov 13 2020 Have adjusted PoPs slightly tomorrow morning to show a bit of a north to south movement of a band that would be responsible for any light precip over the urban corridor and adjacent plains, though still not expecting much. Winds have been trending stronger in the high mountains and foothills, and radar has been showing areas of reflectivity moving down the foothills denoting the mountain wave lowering in elevation. This matches up well with our beginning time of the High Wind Warning in the foothills, South Park and into the western suburbs. These will continue to strengthen through midnight and into the morning hours, where model cross sections show it peaking before sunrise. The winds look to decrease ever so slightly, before very strong subsidence on the backside of the passing upper trough will force the stronger winds aloft down. Forecasted snow amounts still look on track, so no need to adjust these. Forecast cross-sections are also hinting that after the bora type winds that spread across the entire forecast area tomorrow, another mountain-wave Chinook pattern will set up tomorrow night. Currently the High Wind Warnings go through 9pm, and we may end up needing to extend these, though this doesn't seem as strong as tonight's set up. && .SHORT TERM...(This evening through Saturday) Issued at 142 PM MST Fri Nov 13 2020 Short Term: Main concern will be potential for high winds over much of Northern Colorado for tonight and Saturday, and the combination of wind and snow impacts for the mountains. An upper level trof will be sweeping across Colorado tonight and Saturday along with approaching strong 120+kt jet streak. For the winds in the mountains and foothills tonight, look for increasing winds again this evening as cross barrier flow increases 50-75kt. Shear profile and stability are initially favorable for enhanced mountain wave after 03z this evening. As moisture depth increases in the mountains after midnight, we do loose the good stability profile after 09z so expect the stronger winds to retreat back up along the divide and higher foothills. Given increasing ascent with approaching storm this could also lead to another negative factor for high winds. Certainly not a slam dunk but enough parameters and brute force winds to justify going to a high wind warning in the foothills. Expect short duration for the high winds, mainly from 03-09z. The upper trof will rapidly sweep across the state on Saturday with increasing subsident flow from late morning through the afternoon across the northeast plains. QG fields showing strong +35 to +50mb/hr descent through this period and will help to bring the strong winds aloft to the surface. Cold advection will also result in well mixed airmass from surface to 550mb. MOS guidance from both NAM/GFS showing 35-40kt sustained winds across the plains which is pretty good indicator for strong winds and gusts up to 60 mph. High resolution models from HRRR/RAP also showing gusts 45-50kt across much of the plains, especially north and east of Denver. DIA will probably see high winds but could see a bit more sheltering right in Denver and places in southern sections of Denver. Won't nit pick overall highlights so will keep Denver, zone 40 in the warning but expect DIA to be the only station to verify. Given the strong and subsident flow expected, will upgrade the watch to a high wind warning for Saturday. As for the snow in the mountains, cross sections showing moisture depth deepening after 06z up to around 450 mph. Mountain top flow initially is sw-w and then turns west and northwest with trof axis and good cold advection. Decent orographic flow and lapse rates, but time length of only about 6-9 hours of good snowfall. Latest models and local snow model showing a general 3-6 inches, with a few local spots of 8-12 inches over higher areas of zone 31,33. Advisory still looks good along with quite a bit of blowing snow with the strong winds. Main change was to delay the start of the advisory until 06z and drop off the last few hours Sunday evening. .LONG TERM...(Saturday night through Friday) Issued at 142 PM MST Fri Nov 13 2020 Saturday night through Sunday a large upper level trough of low pressure will cover the Central and Eastern U.S with a moderate northwesterly flow aloft over Colorado. This pattern will produce breezy to windy conditions across the CWA with wind gusts to 55 mph over the higher mountains and foothills. In addition, there should be enough moisture caught up in the flow to produce isolated to scattered light snow showers over the northern mountains. Dry and warmer conditions and light winds are expected much of next week as upper level high pressure builds over the Rocky Mountain Region. However, the higher mountains and foothills may see breezy conditions from time to time. Temperatures are expected to climb into the lower 70s across the plains by mid-week. By Friday, the models diverge with the GFS showing an upper trough stretching from Southern California into the Northern Rockies, while the ECMWF still has a large upper level ridge of high pressure dominating the Western U.S. The GEM model lies between these two solutions with an upper trough over the west coast and a dry southwesterly flow aloft over Colorado. The GFS solution suggests the potential for snow in the high country with cooler temperatures and a chance of showers on the plains. On the other hand, the GEM and ECMWF solutions would lead to a continuation of warm and dry weather across north central and northeastern Colorado. With quite a bit of uncertainty and this being all the way out in day 8, have decided to keep the pops and temperature grids from Forecast Builder. && .AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon) Issued at 842 PM MST Fri Nov 13 2020 Southwesterly winds are trending slightly weaker now, and will trend slightly more southerly at DEN and APA. Winds expected to increase again later tonight and Saturday morning, especially at BJC with mountain wave conditions. Strong upper trof will sweep across Colorado during the day with gusts in the 35-50kt during the afternoon period, with strongest winds likely at KDEN. Could see a few rain/snow showers Saturday morning but they will be brief with no accumulation expected. Ceilings and visibility will remain VFR with ceilings remaining above 10kft. && .FIRE WEATHER... Issued at 142 PM MST Fri Nov 13 2020 Elevated fire danger for tonight and Saturday as strong system brings increasing west and northwest winds to the mountains and plains. Could see gusts up to 75 mph over the Mountains and foothills tonight and early Saturday and then spread over the plains by the afternoon with gusts up to 60 mph. Humidity levels generally above 15-20 percent so will not issue any Red Flag Warnings. Southern Lincoln County would be the most susceptible with humidity levels right around 15 percent for a couple of hours Saturday afternoon. && .BOU WATCHES/WARNINGS/ADVISORIES... High Wind Warning from 8 AM to 9 PM MST Saturday for COZ040>051. High Wind Warning until 9 PM MST Saturday for COZ035>039. Winter Weather Advisory until 6 PM MST Saturday for COZ031-033- 034. && UPDATE...Kriederman SHORT TERM...Entrekin LONG TERM...Kalina AVIATION...Kriederman FIRE WEATHER...Entrekin
Hazardous Weather Outlook National Weather Service Denver/Boulder CO 852 AM MST Fri Nov 13 2020 COZ030>051-141600- 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- 852 AM MST Fri Nov 13 2020 ...WINTER WEATHER ADVISORY NORTH CENTRAL MOUNTAINS TONIGHT AND SATURDAY... ...HIGH WIND WATCH FRONT RANGE FOOTHILLS, SOUTH PARK, URBAN CORRIDOR AND NORTHEAST PLAINS TONIGHT AND SATURDAY... This hazardous weather outlook is for northeast and north central Colorado. .DAY ONE...Today and Tonight Strong and gusty winds can be expected over the Front Range foothills and adjacent plains this morning with gusts up to 60 mph. The strongest winds will be from Boulder to Golden. Expect winds to decrease a little this afternoon before increasing tonight. A Pacific storm system will bring snow to the mountains late tonight and Saturday. The heaviest snow is expected to occur over the northern mountains. Roads will likely become snow covered and slippery, with poor visibilities from snow and blowing snow, especially through the mountain passes. This system will also bring strong winds to areas in and near the Front Range Foothills and South Park tonight, then the eastern plains on Saturday. .DAYS TWO THROUGH SEVEN...Saturday through Thursday Snow will continue in the mountains Saturday morning and then taper off Saturday afternoon. Additional snowfall amounts of 2 to 5 inches are expected for the mountains Saturday morning. In addition to the snow, strong west winds will continue to produce blowing and drifting snow. The strong winds will spread across the plains Saturday with wind gusts to 65 mph possible. .SPOTTER INFORMATION STATEMENT... Spotter reports will not be needed today or tonight, but snow and wind reports would be greatly appreciated.
The national radar mosaic for the moment the first event began.
14 high wind, 3 winter weather. Local standard time, as filed.
Storm totals ranged from 5 to 9 inches.
Storm totals ranged from 3 to 8 inches.
Storm totals ranged from 2 to 5 inches.
Peak wind gusts included: 85 mph, 3 miles south of Boulder; 75 mph at the CO93 and CO72 Junction; 58 mph at Rocky Mountain Metro Airport.
Peak wind gusts included: 80 mph, 3 miles northwest of Boulder; 79 mph, 3 miles northwest of Marshall with 78 mph near Glen Haven.
Peak wind gusts included: 65 mph in Westminster, 62 mph at Centennial Airport, 61 mph at Denver International Airport and 58 mph near Buckley AFB. The high winds downed a tree in Westminster, approximately one foot in diameter.
Peak wind gusts included 73 mph, 6 miles southwest of Carr; 65 mph, 2 miles north-northeast of Natural Fort; 61 mph, 7 miles north-northeast of Purcell and 7 miles north of Rockport.
Peak wind gusts included: 68 mph, 11 miles northwest of Westplains; 63 mph, 1 miles north-northwest of Briggsdale, 61 mph, 2 miles north-northwest of Briggsdale; and 59 mph, 8 miles south-southwest of Grover.
Peak wind gusts included 61 mph, 4 miles east-northeast of Severance.
Peak wind gusts included 64 mph, 1 mile south-southwest of Bennett and 58 mph, 10 miles east of Arapahoe Park.
Peak wind gusts included 60 mph, 2 miles southeast of Julesburg and 59 mph, 2 miles north-northeast of Iliff.
Peak wind gusts included 67 mph at Crook and 59 mph, 2 miles east-southeast of Sterling.
Peak wind gusts included 67 mph 8 miles south of Holyoke.
Peak wind gusts included: 76 mph in Fort Morgan, 62 mph at Fort Morgan Airport and 59 mph, 2 miles east-northeast of Wiggins.
Peak wind gusts included 69 mph at Akron-Washington County Airport.
Peak wind gusts included: 70 mph, 3 miles south of Cedar Point; 66 mph at Limon Municipal Airport and 62 mph at Hugo.
A peak wind gust to 91 mph was measured near Loveland Pass.
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, November 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: 930046, 930047, 930048, 927111, 927110, 927112, 930042, 930043, 930044, 930049, 930055, 930051, 930052, 930054, 930050, 930053, 930068.