Moderate to heavy snowfall occurred over mountains north of Interstate 70. Storm totals ranged from 5 to 10 inches.
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 BOU wrote it up.
Moderate to heavy snowfall occurred over mountains north of Interstate 70. Storm totals ranged from 5 to 10 inches.
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 Apr 9, 2:38 PM MST, 2 hours 22 minutes earlier.
Area Forecast Discussion National Weather Service Denver/Boulder CO 338 PM MDT Sun Apr 9 2017 .SHORT TERM...(This evening through Monday) Issued at 332 PM MDT Sun Apr 9 2017 The upper low over eastern WY this afternoon will move into north central Nebraska by 12z Monday with a ridge of high pressure moving into the state on Monday. Strong subsidence this aftn and early evening and a fairly decent sfc pressure gradient will allow for gusty winds to continue into the evening hours. Have decided to cancel the high wind warning for zone 35, the winds will be strong there but expected to be less than 75 mph. Lower criteria gusts to 60 mph still a possibility for zone 38 so will continue with the high wind warning for this zone through the evening. An area of light rain showers over the far northeast plains will exit the state by this evening. Gusty winds will linger later into the evening over the far northeast plains but should start to decrease from west to east across the rest of the plains this early this evening. High pressure and dry conditions will make for mostly sunny conditions on Monday. Temperatures will be close to normal for this time of year. Overall less wind aloft and at the surface so no significant issues to contend with on Monday. .LONG TERM...(Monday night through Sunday) Issued at 332 PM MDT Sun Apr 9 2017 A generally zonal flow combined with occasional upper level disturbances moving north of our CWA will result in above normal temperatures and mostly dry conditions through the period. Monday night and Tuesday look dry across the entire CWA...with possibly a few showers across the far northeastern plains early Wednesday morning ahead of a weak upper level trough. Upper level high pressure building over the Rocky Mountain Region should bring dry weather along with warmer temperatures to all of north central and northeastern Colorado Wednesday with max temperatures in the lower to mid 70s on the plains. On Thursday...the upper ridge shifts eastward over the central plains as an upper level trough of low pressure moves into the western U.S. Most of the moisture and lift from the trough should stay north of Colorado...however there could be just enough moisture to produce a few light rain and snow showers across the mountains...mainly over the higher peaks. Previous model runs were hinting at some convection across the far northeastern plains late Thursday afternoon and evening...however latest runs are now dry. In addition...Thursday looks to be the warmest day of the week with temperatures in the mid to upper 70s across the plains. Friday and Saturday look dry and warm as well as dry west to southwesterly flow aloft dominates the Rocky Mountain Region. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 332 PM MDT Sun Apr 9 2017 VFR conditions with limited upper level moisture over the area tonight and Monday. Strong northwest winds gusts 35 to 45 kts the rest of this afternoon, will decrease by 01z. Sfc pressure gradient will less this evening with lighter winds expected as the boundary layer winds decouple. Drainage overnight, except at KBJC where gusty wly winds may persist through the evening. Less wind on Monday, with drainage winds in the morning transitioning to an easterly wind by the afternoon. && .FIRE WEATHER... Issued at 332 PM MDT Sun Apr 9 2017 Strong winds and driest conditions off the Cheyenne Ridge this aftn so will continue with the Red Flag Warning for northeast Weld County, FWZ242. Rain showers from earlier today have lessened the fire danger over the rest of the northeast plains. As a result the Red Flag Warning has been cancelled for the rest of the northeast plains this aftn. && .BOU WATCHES/WARNINGS/ADVISORIES... Red Flag Warning until 6 PM MDT this evening for COZ242. High Wind Warning until midnight MDT tonight for COZ038. && SHORT TERM...Cooper LONG TERM...Kalina AVIATION...Cooper FIRE WEATHER...Cooper
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE DENVER/BOULDER CO 956 AM MDT Sun Apr 9 2017 COZ030>051-101600- 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- 956 AM MDT Sun Apr 9 2017 ...High Wind Warning in effect for the northern Front Range Foothills...eastern Larimer and northwest Weld Counties this afternoon through midnight tonight... ...Red Flag Warning for the far northeast plains this afternoon... THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHEAST AND NORTH CENTRAL COLORADO. .DAY ONE...TODAY AND TONIGHT A storm system will move across Wyoming today and into the central high plains by tonight. West winds will increase across the area through the day with speeds from 25 to 35 mph. Gusts of 45 to 55 mph will be possible over the plains with high fire danger over the far northeast areas. In addition, high winds are expected to develop in and near the northern foothills and along the Cheyenne Ridge. Wind gusts from 60 to 75 mph are expected across the higher terrain of Larimer and Boulder counties. In the mountains there will be snow showers this morning which will decrease in the afternoon. Additional accumulation of 1 to 3 inches will be possible over the higher west facing slopes. Winds will gust from 60 to 70 mph at times above timberline. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY It will be dry across the forecast area Monday through Thursday. There will be a slight chance of showers Thursday night through friday night, then Saturday will be dry. Temperatures will be above seasonal normals much of the time. .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. Local standard time, as filed.
At Tower, 10 inches of snowfall was recorded.
Storm totals included 10 inches at Never Summer and Phantom Valley, with 5 inches at Willow Creek.
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, April 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: 691450, 691451.