An upper level system and favored southwesterly to westerly upper flow generated up to eight inches of snow across higher terrain locations as well as areas of blowing snow. Eight inches of snow was noted near Wolf Creek Pass in Mineral county.
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The episode as NWS PUB wrote it up.
An upper level system and favored southwesterly to westerly upper flow generated up to eight inches of snow across higher terrain locations as well as areas of blowing snow. Eight inches of snow was noted near Wolf Creek Pass in Mineral county.
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 Pueblo, CO wrote its last area forecast discussion before the first event at Dec 20, 11:56 PM MST, 4 hours 4 minutes earlier.
Area Forecast Discussion National Weather Service Pueblo CO 1156 PM MST Wed Dec 20 2017 .UPDATE... Issued at 1149 PM MST Wed Dec 20 2017 Updated to adjust temperatures for the overnight period into Thursday morning. Westerly winds have kept the lower slopes of the Eastern Mountains, east into the I-25 corridor warm so far tonight. Temperatures will remain in the upper 30s to upper 40s where the wind remain elevated from the west. Mozley && .SHORT TERM...(This evening through Thursday) Issued at 348 PM MST Wed Dec 20 2017 Upper trough dropping into the Great Basin this afternoon with very warm and dry southwest flow ahead of it over all of srn CO. Have seen some near critical fire weather conditions develop this afternoon along the I-25 corridor where humidity has fallen below 15 percent, though for the most part winds have held just under the required 25 mph threshold. Tonight, trough digs southward toward the four corners, with mid level low closing off over srn UT by early Thu morning. Cold front drops south through the plains toward sunrise, then banks up against the eastern mountains by midday Thu. Snow showers will break out along the Continental Divide after midnight, then spread eastward over most higher terrain locations by late morning Thu as upper level lift increases. Greatest accumulation overnight will occur over the swrn mtns, where favorable 20-30 kts sw flow develops as mid level low closes off, while remaining mountain locations see lighter snow through sunrise. Overnight mins will run on the mild side as clouds and winds increase. On Thu, upper low moves slowly eastward into CO, with system weakening and taking on a more positive tilt by late afternoon as it tracks along the CO/NM border. Models have continued to back off on snow amounts over the ern mountains and I-25 corridor, as vertical motion diminishes and upslope flow remains very shallow. Continental Divide zones should do best with snowfall, and current advisory looks ok, with amounts in the 4-8 inch range likely over the peaks. Highest peaks of the eastern mountains will see 2-4 inches, with spotty 1-3 amounts over lower slopes and interior valleys. I-25 corridor amounts in general look spotty and light, with perhaps an inch or 2 along the Palmer Divide and across the higher terrain south of Pueblo. Window for heaviest snow will be from mid morning through mid to late afternoon, with snowfall staying mainly along/west of I-25. Max temps will run some 30 degf colder than Wed over the plains, while mountains and interior valleys cool 10-20f. .LONG TERM...(Thursday night through next Wednesday) Issued at 348 PM MST Wed Dec 20 2017 Primary meteorological concerns during the longer term include but are not limited to temperatures, pops, and gusty winds at times. Recent forecast model soundings, computer simulations and PV/Precipitable Water analysis indicate that unsettled and cold conditions will continue into Thursday evening as weakening upper disturbance swings south of the forecast district. Drier conditions in combination with below seasonal temperatures are then anticipated over the majority of the forecast district(outside of the central mountains, where light snow will be noted at times) from later Thursday night into Saturday as drier northwesterly upper flow develops over southern Colorado. Next upper disturbance(primarily passing to the north of the CWA) in combination with another north-northeasterly surface surge will impact the CWA from later Saturday into Sunday, although highest potential of generally light accumulating precipitation should be noted near to just north of the forecast district during this time-frame. Then, drier and and warmer conditions are anticipated from Christmas Day(Monday) into next Wednesday morning as zonal to southwesterly upper flow develops over the forecast district. The highest potential for gusty winds over the forecast district during the longer term should be experienced from later Friday night into Saturday evening and then again from later Tuesday into Wednesday night. Finally, below seasonal temperatures should be realized over the majority of the forecast district from Thursday night into Christmas weekend, while near to above seasonal temperatures are anticipated from Christmas Day into Tuesday night. && .AVIATION...(For the 06Z TAFS through 06Z Thursday night) Issued at 1023 PM MST Wed Dec 20 2017 A winter storm system will spread across the flight area late tonight and Thursday. Areas of MVFR to LIFR CIGS/VSBYS will develop first beginning in the mountains after midnight and then spreading to the plains on Thursday. A strong cold front will move south through the plains, beginning along the Palmer Divide after midnight and crossing into New Mexico by early Thursday morning. Gusty north to east winds will drop south behind the front, through the plains, late tonight and Thursday. The KCOS, KPUB and KALS terminals will all likely see VFR through early Thursday with increasing odds for reduced conditions after about 15z. The cold front will probably begin to move through KCOS around 10-11z and then KPUB around 11-12z. Gusty north to east winds expected following FROPA. The front is not currently expected to make it over the Sangre De Cristo Mountains into the San Luis Valley. Thus, just gusty SW breezes expected there. && .PUB WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from 3 AM Thursday to midnight MST Thursday night for COZ058-060-068. && UPDATE...MOZLEY AVIATION...LW
Hazardous Weather Outlook National Weather Service Pueblo CO 543 PM MST Wed Dec 20 2017 COZ058>089-093>099-220045- Western Mosquito Range/East Lake County Above 11000 Feet- Leadville Vicinity/Lake County Below 11000 Feet- Eastern Sawatch Mountains Above 11000 Feet- Western Chaffee County Between 9000 and 11000 Feet- Central Chaffee County Below 9000 Feet- Western Mosquito Range/East Chaffee County Above 9000 Feet- Saguache County West of Continental Divide Below 10000 Feet- Saguache County East of Continental Divide Below 10000 Feet- La Garita Mountains Above 10000 Feet- Upper Rio Grande Valley/Eastern San Juan Mountains Below 10000 Feet-Eastern San Juan Mountains Above 10000 Feet- Del Norte Vicinity/Northern San Luis Valley Below 8500 Feet- Alamosa Vicinity/Central San Luis Valley Below 8500 Feet- Southern San Luis Valley- Northern Sangre de Cristo Mountains Between 8500 And 11000 Feet- Northern Sangre de Cristo Mountains Above 11000 Feet- Southern Sangre de Cristo Mountains Between 7500 and 11000 Feet- Southern Sangre de Cristo Mountains Above 11000 Feet- Northwestern Fremont County Above 8500 Feet- Western/Central Fremont County Below 8500 Feet- Wet Mountain Valley Below 8500 Feet- Wet Mountains between 6300 and 10000 Feet- Wet Mountains Above 10000 Feet- Teller County/Rampart Range Above 7500 Feet/Pikes Peak Between 7500 And 11000 Feet-Pikes Peak Above 11000 Feet- Canon City Vicinity/Eastern Fremont County- Northern El Paso County/Monument Ridge/Rampart Range Below 7500 Feet- Colorado Springs Vicinity/Southern El Paso County/Rampart Range Below 7400 Feet-Pueblo Vicinity/Pueblo County Below 6300 Feet- Walsenburg Vicinity/Upper Huerfano River Basin Below 7500 Feet- Trinidad Vicinity/Western Las Animas County Below 7500 Feet- Crowley County-La Junta Vicinity/Otero County- Eastern Las Animas County-Western Kiowa County- Eastern Kiowa County-Las Animas Vicinity/Bent County- Lamar Vicinity/Prowers County-Springfield Vicinity/Baca County- 543 PM MST Wed Dec 20 2017 This hazardous weather outlook is for portions of central...east central...south central and southeast Colorado. .DAY ONE...Tonight By late tonight, snow is expected to develop along portions of the Continental Divide, with localized snow accumulations of one to three inches anticipated over favored higher terrain locations by sunrise Thursday. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday A few to several inches of snow can be expected over the mountain areas on Thursday. Lower elevation locations in Chaffee and Fremont counties, may see 1 to around 3 inches of accumulations. Areas of the southern I-25 corridor, south of Pueblo, could see 1 to 2 inches of snow on Thursday. The next chance for snow will come on Saturday as a weather system moves into the area and brings cold air to the area. The Sawatch and Mosquito ranges, Pikes Peak and Teller county, the Wet mountains, the northern Sangre de Cristo mountains and the eastern plains are expected to have the best chances for accumulating snow, but at this time snow amounts look light. There could be another chance for snow on Wednesday, but there is still a lot of uncertainty at this time. .SPOTTER INFORMATION STATEMENT... Weather conditions that meet reporting criteria for spotters will be possible over the higher elevations along the Continental Divide by later tonight.
The national radar mosaic for the moment the first event began.
1 winter weather. Local standard time, as filed.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Colorado in 2017Every state in 2017This day in weather historyWarnings in Colorado, December 2017
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: 730575.