Powerful post frontal bora winds blasted along the Front Range Foothills and across Northeast and East-Central Colorado. The damaging wind gusts ranged from 60 to 90 mph.
Every event with a place to put it; 17 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.
Powerful post frontal bora winds blasted along the Front Range Foothills and across Northeast and East-Central Colorado. The damaging wind gusts ranged from 60 to 90 mph. A woman in Louisville died after she was struck by a falling tree branch. She stopped to rest under a tree when a large branch broke off and struck her in the head. The winds uprooted trees, shattered windows, sprayed roof shingles, tossed outdoor furniture like toys and knocked over semitrailer trucks. It also blew up dust and debris, limiting visibility for motorists. The intense winds caused extensive tree damage in and around Washington Park in Denver. The storm toppled trees onto homes and vehicles. A 70-foot spruce tree slammed into the roof of a residence and cut through the ceiling of the master bedroom. A 3-month-old infant was sleeping in the room but uninjured. Several trees were uprooted and destroyed. A streetlight came down on an SUV in Denver.
The gusty conditions forced officials to close a number of roadways or place high-wind restrictions. Around 64,000 Xcel Energy customers experienced some sort of outage related to near-hurricane force winds that toppled trees and power poles. Service was not restored for approximately 5,000 customers until the following day. At Denver International Airport, delays occurred as two runways were temporarily shut down and 25 flights were diverted. Late in the morning, strong winds fanned the flames of a house fire near Castle Rock. Two homes were destroyed by the fire and 5 others were damaged. The fire started in the garage of one residence then was fanned by strong winds that spread the fire from one house to the others.
Peak wind reports included: 89 mph in Louisville, 86 mph at Rocky Mountain Metropolitan Airport, 83 mph at the National Wind Technology Center, 81 mph near Eldorado Springs, 79 mph, 4 miles east of Buckeye; 78 mph near Gold Hill and Akron, 74 mph at Cheesman Reservoir, 73 mph, 7 miles east of Ponderosa Park; 72 mph near Longmont; 72 mph near Erie, 71 mph at Bennett, 70 mph at Denver International Airport, 69 mph at Keenesburg, 68 mph at Briggsdale, Limon Municipal Airport, Mead and Sterling; 67 mph near Brighton, Buckley AFB and Strasburg; 66 mph near Hygiene, 64 mph, 9 miles north of Manila Village; 63 mph near Woodlin School, 63 mph at Beverly Hills, 60 mph at Centennial Airport, Front Range Airport, Nunn; 58 mph at Agate.
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 17, 8:07 AM MST, 53 minutes earlier.
Area Forecast Discussion National Weather Service Denver/Boulder CO 907 AM MDT Tue Apr 17 2018 .UPDATE... Issued at 907 AM MDT Tue Apr 17 2018 Upgraded the High Wind Watch to a Warning over the far northeast corner of Colorado. Latest, GFS, RAP, and HRRR all support gusts to 60 mph after 00Z, behind the cold front. For the foothills and South Park, wind gusts to 60-70 mph are expected, which is slightly below the 75 mph High Wind threshold for these areas. If it appears winds will be slightly higher will need to issue a warning for these areas as well. It's been a warm start to the day with 9am temperatures in the lower to mid 60s across the Denver area. Good chance temperatures will be bumped up a little since the cooler air doesn't arrive until noon or slightly later. && .SHORT TERM...(Today and tonight) Issued at 421 AM MDT Tue Apr 17 2018 An upper level trough will move across the area mainly this aftn. There is stg QG ascent and decent lapse rates associated with this feature which will bring a quick burst of heavier snow to the mtns this aftn with some thunder possible along with gusty winds. Meanwhile, at lower elevations, sfc low pres will develop over nern CO thru early aftn and then move eastward by late aftn. Meanwhile a pacific/bora type fnt will blast across the area nern CO by early to mid aftn and exit the far nern corner by 00z. As this feature moves across stg downward descent will also develop behind the passage of the upper level trough. Thus I would expect stronger flow aloft to mix down to the sfc. 700 mb winds are fcst to be around 50 kts or so will be close to high wind criteria across most of the plains in the aftn. I would expect some gusts up to 60 mph in places so will issue a warning. Over the far nern corner confidence is not as high and time period for high winds would be fm late aftn into early evening so will leave a watch in place for now. Over the Palmer Divide high winds could develop by sunrise so will issue a warning starting at 12z. High wind threat over the Palmer Divide will likely end by late aftn so will not have warning going past 6 pm. Finally am a little concerned about South Park as some of the hi res data has gusts exceeding 70 mph. Thus will have to keep an eye on that area later this morning. In addition portions of the normal windy spots in the Foothills (Boulder and nrn Jefferson) may have a brief 2 to 3 hour window of strong winds late this aftn, however, overall coverage and duration could be limited so will not issue a warning at this time but it will need to be watched as well. As far as highs this aftn, temps early this morning were very mild along most of the front range due to SWLY downslope flow. With expected downslope component, thru at least early aftn, highs may rise more than previously thought so have raised readings over most of nern CO. For tonight snow will decrease in the mtns early this evening, however, enough moisture will linger for sct -shsn thru midnight. Across the plains the high wind threat should end by 02z in most areas except possibly over the far nern corner. .LONG TERM...(Wednesday through Monday) Issued at 421 AM MDT Tue Apr 17 2018 Weakening zonal flow aloft is indicated on Wednesday as an upper ridge moves across the CWA Wednesday night into Thursday morning. For the rest of Thursday and Thursday night southwesterly flow aloft moves in and increases in speed Thursday night. The QG Omega fields show subsidence for the CWA on Wednesday, with benign synoptic scale energy Wednesday night and the first half of Thursday. By Thursday afternoon, upward energy is moving into the CWA from the west. By 12Z Thursday morning, decent upward motion is over the western forecast area. The boundary layer winds are all northwesterly downsloping for the CWA on Wednesday. Late Wednesday afternoon and evening, there are east and northeasterly winds progged, then southeasterlies the rest of Wednesday night. Increasing south-southeasterly low level winds are in place Thursday and Thursday night. Looking at moisture, cross section show it to be dry Wednesday and Wednesday night. Upper level moisture increases on Thursday. By Thursday night moisture increases from west to east, with it deepening over the mountains by Friday morning. There is very little in the way of CAPE through Thursday morning, with just a tad late day Thursday over the foothills and immediate plains. The QPF fields have no measurable precipitation on them Wednesday through Thursday evening. There is some over the western and southern halves of the CWA after 06Z Thursday night. For pops will bring them in Thursday evening and night. For temperatures, Wednesday's highs are a bit cooler than today's highs. Thursday's highs warm up 3 to 7 C from Wednesday's. For the later days, Friday through Monday, the medium range models are showing an upper closed low over the Four Corners on Friday afternoon. The feature is centered somewhere from the Texas panhandle to southeastern New Mexico by Saturday afternoon depending on the model. The persistence in the medium range models for the last several runs showing this upper low is uncanny. So it still looks like a decent precipitation event for much of the CWA from Friday morning well into Saturday. The latest 00Z model runs now show it warmer for night Friday and Saturday than did previous model runs. The forecast builder produces little to no snow now for the plains of northeast Colorado Friday night into Saturday morning. We'll see and continue to monitor. There is weak upper ridging indicated for Sunday and Monday. && .AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon) Issued at 907 AM MDT Tue Apr 17 2018 Main weather concern is winds through this evening. Southwest winds gusting to 35 knots will become more WSW late this morning with gusts up to 40 knots. After 18Z, winds turn westerly and are expected to increase with gusts of 40 to 50 knots through 00Z. Due to the strong winds there is a potential for reductions in visibility due to blowing dust. Around sunset winds should gradually decrease to 15 to 30 knots and continue to slowly decrease overnight. && .FIRE WEATHER... Issued at 421 AM MDT Tue Apr 17 2018 Critical to extreme fire danger will exist across portions of the area later this morning into early this evening. After analyzing the latest updates from a few of the fire managers have decided to include the Denver metro area, South Park and the srn Foothills in a Red Flag Warning just to be on the safe side. Strong winds combined with low humidity values will be in place later this morning thru the afternoon hours so if a fire gets started it could spread very rapidly. There will be an elevated fire danger over Park, southern Lincoln and Elbert Counties Thursday afternoon. && .BOU WATCHES/WARNINGS/ADVISORIES... High Wind Warning from 3 PM this afternoon to 9 PM MDT this evening for COZ050-051. Red Flag Warning until 8 PM MDT this evening for COZ239>241- 245>247. High Wind Warning until 9 PM MDT this evening for COZ038-040- 042>049. Red Flag Warning until 6 PM MDT this evening for COZ214-216. High Wind Warning until 6 PM MDT this evening for COZ041. && UPDATE...Meier SHORT TERM.....RPK LONG TERM......RJK AVIATION...Meier FIRE WEATHER...RPK/RJK
Hazardous Weather Outlook National Weather Service Denver/Boulder CO 510 AM MDT Tue Apr 17 2018 COZ030>051-181115- 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- 510 AM MDT Tue Apr 17 2018 ...High Wind Warning for the Palmer Divide and adjacent Plains today through early this evening... ...Red Flag Warnings today through early this evening, Denver Metro area, Palmer Divide, South Park, southern Foothills and east central Plains... This hazardous weather outlook is for northeast and north central Colorado. .DAY ONE...Today and Tonight High winds are expected late this morning through the early evening hours across the Plains and over the Palmer Divide. Wind gusts from 60 to 65 mph will be possible. Critical to Extreme fire danger will be in place from late this morning through early this evening across the Denver metro area, Southern Foothills, South Park, Palmer Divide extending into Lincoln county and eastern portions of Adams and Arapahoe counties. Wind gusts to 60 mph will occur along with low humidity levels. Elsewhere an upper level disturbance will bring snow to the mountains this afternoon into the early evening hours with gusty winds at times. Accumulations of 2 to 4 inches will be possible. .DAYS TWO THROUGH SEVEN...Wednesday through Monday Wednesday and Thursday look dry with high pressure aloft. The next Spring storm will bring deepening moisture, cooler temperatures and widespread precipitation to all of the forecast area Friday well into Saturday. Significant snowfall may occur over mountains and foothills east of the divide. Stay tuned. Upper ridging returns on Sunday and Monday with dry weather returning. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed today or tonight.
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DENVER CO
638 AM MDT TUE APR 17 2018
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0315 AM NON-TSTM WND GST 3 NNW LOUVIERS 39.51N 105.02W
04/17/2018 M60 MPH DOUGLAS CO MESONET
MESONET STATION AT112, 3 NNW LOUVIERS.
0354 AM NON-TSTM WND GST CHATFIELD RESERVOIR 39.56N 105.08W
04/17/2018 M57 MPH JEFFERSON CO MESONET
MESONET STATION CO007, CHATFIELD RESERVOIR.
0441 AM NON-TSTM WND GST APPLEWOOD 39.76N 105.16W
04/17/2018 M56 MPH JEFFERSON CO MESONET
MESONET STATION E7094, APPLEWOOD.
0439 AM NON-TSTM WND GST 2 NW KEN CARYL 39.61N 105.13W
04/17/2018 M55 MPH JEFFERSON CO MESONET
MESONET STATION C5285, 2 NW KEN CARYL.
0347 AM NON-TSTM WND GST 1 NW GLEN HAVEN 40.47N 105.45W
04/17/2018 M53 MPH LARIMER CO MESONET
MESONET STATION E4490, 1 NW GLEN HAVEN.
0503 AM NON-TSTM WND GST 1 SSE ROCKY FLATS 39.87N 105.20W
04/17/2018 M53 MPH JEFFERSON CO MESONET
MESONET STATION F1909, 1 SSE ROCKY FLATS.
0240 AM HIGH SUST WINDS 2 NE WHITE RANCH OPEN S 39.85N 105.25W
04/17/2018 M51 MPH JEFFERSON CO MESONET
MESONET STATION UP709, 2 NE WHITE RANCH OPEN
S.
0320 AM NON-TSTM WND GST 1 SE KEN CARYL 39.56N 105.10W
04/17/2018 M51 MPH JEFFERSON CO MESONET
MESONET STATION C4784, 1 SE KEN CARYL.
0427 AM NON-TSTM WND GST 11 WSW TABERNASH 39.89N 106.04W
04/17/2018 M50 MPH GRAND CO MESONET
MESONET STATION KSEC2, 11 WSW TABERNASH.
&&PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DENVER CO
942 AM MDT TUE APR 17 2018
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0934 AM NON-TSTM WND GST 12 ENE KIOWA 39.41N 104.24W
04/17/2018 M62 MPH ELBERT CO MESONET
MESONET STATION AR864, 12 ENE KIOWA.
0926 AM NON-TSTM WND GST 5 NNW RAMAH 39.20N 104.19W
04/17/2018 M61 MPH ELBERT CO MESONET
MESONET STATION E7240, 5 NNW RAMAH.
0846 AM NON-TSTM WND GST 10 NNE KREMMLING 40.21N 106.33W
04/17/2018 M57 MPH GRAND CO MESONET
MESONET STATION GSPC2, 10 NNE KREMMLING.
0810 AM NON-TSTM WND GST CENTENNIAL AIRPORT 39.56N 104.85W
04/17/2018 M56 MPH DOUGLAS CO ASOS
ASOS STATION APA, CENTENNIAL AIRPORT.
0852 AM NON-TSTM WND GST BEVERLY HILLS 39.49N 104.87W
04/17/2018 M53 MPH DOUGLAS CO MESONET
MESONET STATION CO073, BEVERLY HILLS.
0903 AM NON-TSTM WND GST 1 NW SILVER HEIGHTS 39.42N 104.88W
04/17/2018 M52 MPH DOUGLAS CO MESONET
MESONET STATION CO075, 1 NW SILVER HEIGHTS.
0911 AM NON-TSTM WND GST 5 NNW RAMAH 39.20N 104.19W
04/17/2018 M51 MPH ELBERT CO MESONET
MESONET STATION E7240, 5 NNW RAMAH.
0915 AM NON-TSTM WND GST 7 NE PONDEROSA PARK 39.48N 104.56W
04/17/2018 M50 MPH ELBERT CO MESONET
MESONET STATION D7154, 7 NE PONDEROSA PARK.
0900 AM NON-TSTM WND GST 1 WNW LOVELAND PASS 39.67N 105.89W
04/17/2018 M50 MPH CLEAR CREEK CO MESONET
MESONET STATION CALVP, 1 WNW LOVELAND PASS.
&&The national radar mosaic for the moment the first event began.
16 high wind, 1 strong wind. Local standard time, as filed.
Strong winds helped spread a fire that was started in the garage of a residence. Two homes were destroyed by the blaze and 5 others were damaged.
As the offices recorded each death: direct deaths were caused by the weather itself, indirect ones by something it set in motion.
| Event | Date | Age | Sex | Where | Kind |
|---|---|---|---|---|---|
| High Wind, Ne Weld County | 2018-04-17 | Female | Under Tree | Direct | |
| High Wind, Boulder & Jefferson Counties Below 6000 Feet / W Broomfield County | 2018-04-17 | Female | Under Tree | Direct | |
| High Wind, Elbert / C & E Douglas Counties Above 6000 Feet | 2018-04-17 | Female | Under Tree | Direct | |
| High Wind, Morgan County | 2018-04-17 | Female | Under Tree | Direct | |
| High Wind, N Douglas County Below 6000 Feet / Denver / W Adams & Arapahoe Counties / E Broomfield County | 2018-04-17 | Female | Under Tree | Direct | |
| High Wind, C & S Weld County | 2018-04-17 | Female | Under Tree | Direct | |
| High Wind, Washington County | 2018-04-17 | Female | Under Tree | Direct | |
| High Wind, Logan County | 2018-04-17 | Female | Under Tree | Direct | |
| High Wind, N & Ne Elbert County Below 6000 Feet / N Lincoln County | 2018-04-17 | Female | Under Tree | Direct | |
| High Wind, C & E Adams & Arapahoe Counties | 2018-04-17 | Female | Under Tree | Direct | |
| High Wind, Phillips County | 2018-04-17 | Female | Under Tree | Direct |
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Colorado in 2018Every state in 2018This day in weather historyWarnings in Colorado, April 2018
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: 752047, 751917, 752015, 752005, 752016, 751916, 751926, 752007, 751925, 752006, 751913, 751915, 752011, 752010, 752009, 752008, 752012.