An intense winter storm produced a large amount of high density snowfall which resulted in an unstable snowpack over portions of the San Juan Mountains. The Red Mountain Pass area received 18 inches of the high density snow within a 26 hour period that preceded an avalanche which came down onto Highway 550 on March 26th.
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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 GJT wrote it up.
An intense winter storm produced a large amount of high density snowfall which resulted in an unstable snowpack over portions of the San Juan Mountains. The Red Mountain Pass area received 18 inches of the high density snow within a 26 hour period that preceded an avalanche which came down onto Highway 550 on March 26th.
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 Mar 26, 11:16 AM MST, 1 hour 14 minutes earlier.
Area Forecast Discussion National Weather Service Grand Junction CO 1216 PM MDT Sun Mar 26 2017 .UPDATE... Issued at 905 AM MDT Sun Mar 26 2017 Snow was winding down in the mountains this morning, becoming more scattered in coverage. Expect additional accumulations will be light, therefore allowed the Winter Weather Advisory for the San Juan Mountains above 9500 feet expire. && .SHORT TERM...(Today through Monday) Issued at 500 AM MDT Sun Mar 26 2017 Upper air hand analysis at 500mb show a fairly blocky flow pattern across the lower 48. Ensembles suggests the heights along the mid-Atlantic coast to Great Lakes are slightly anomalous. This ridge is helping to keep a closed low over the MS valley which is holding back low pressure over our area from sweeping eastward at a faster pace. Radar mosaic had cooled off late last evening but through the early morning hours has blossomed. This is mainly due to convection as the cold core of the trough is slowly translating across western Colorado ahead of the back edge of the upper level channelized vorticity. The echos on radar also show northerly flow in place with cold air advection now favoring north facing slopes. Places like Telluride...and the Highway 550 corridor from Ridgway to Silverton will be favored. Snotels show mainly 3 to 6 inch totals with a few outliers in the 8 to 10 inch range so advisory is well on track. Snow is down to at least the 7000 foot mark and there will be some impacts to roadways in the south including Highway 160 between Durango and Cortez and 550 as mentioned above. Satellite imagery suggest this system will be focusing east of the divide by sunrise as the cyclonic jet slides into SE Colorado and lowers heights aloft and forces cyclogenesis at the surface. Drying of the dendritic layer and increasing mid level instability through the afternoon should leave mainly isolated showers in place favoring the higher divide mountains to the eastern San Juans. Transitory ridging overnight means dry conditions overnight which will preclude decent WAA tomorrow morning in the mid levels. This WAA will be evident by the increasing mid level cloud deck from SW to NE across the CWA from sunrise onward Monday morning. Felt the chances of precipitation in the lower elevations were a bit too optimistic as the lower portion of the the sounding will be quite dry. Virga seems more likely through the late morning into early afternoon in most elevations below 7000 feet. Elevated stability decreases and ascent increases with the arrival of the next cyclonic jet by mid afternoon and showers will be expanding across the region. Snow levels start around 9000 feet through influenced by convection could be as low as 7500 feet. Temperatures a bit tricky on Monday with thicker mid level cloud cover being replaced by more patchy convective clouds in the afternoon. There is a 13 degree spread in the Max numbers just at GJT as a result and will not make a big swing either way attm. .LONG TERM...(Monday night through Saturday) Issued at 500 AM MDT Sun Mar 26 2017 The pattern across the mid latitudes again favor the early week system to close off to our west Monday night and dig southeast on Tuesday before swinging east Tuesday night. Ensembles show this storm picking a decent amount of Pacific moisture out West but it will really tap the Gulf as it slides south of the 4 Corners on Tuesday. This storm will bring widespread precipitation much of it in the form of snow above 8000 feet. Convection will again play a big role with steep lapse rates leading to afternoon thunderstorms in many areas on Tuesday. Model spread still interesting with the H5 low tracks spread from northeast to south-central New Mexico Tuesday afternoon. Snow is excess of 6 inches again probable over many mountain locations above 8500 feet by Wednesday morning. The southern mountains would have to be favored due the proximity of the low and upper jet. Confidence in the speed of the potentially cut-off upper level low over northern NM moving east is moderate as most such lows move out slower than models predict. However, the GFS and ECMWF do agree on moving it east into the Central Plains Wednesday and a brief building an upper level ridge over the region Wed night and Thursday. There may still be some remnant scattered showers over the higher terrain Wednesday on the backside of departing low pressure. Thursday should be dry and warmer. Then yet another vigorous upper level trough, which is handled very similarly in the long range models, will drop southeast over the Great Basin Thursday, cut off Friday and settle south over Arizona into early next weekend. Sensible weather affects over eastern UT and western CO are of moderate confidence due to the nature of cut-off lows despite good agreement in the models. With such a dynamic system and strong upper level divergence on its east side as it drops south, would expect a high probability of precipitation Thursday night and Friday. However, will remain cautious with precipitation chances and realize that any deviation in the path or intensity of this system will result in significant changes one way or the other. A more eastward path over UT/CO will mean colder with snow at lower levels. A more westward path leaves our area warmer and drier. && .AVIATION...(For the 18Z TAFS through 18Z Monday afternoon) Issued at 1216 AM MDT Sun Mar 26 2017 Impacts from the last night's storm continued over eastern Utah and western Colorado through the early part of day. Showers were more limited and confined to the higher terrain. This trend will continue through the afternoon so do not expect showers to occur over TAF sites. However, residual low level moisture and instability is expected to keep CIGS below ILS breakpoints for much of the afternoon over KEGE and KASE. Clouds will be diminishing this evening as the atmosphere stabilizes so expect TAF sites will see a return to VFR conditions region wide. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && UPDATE...NL SHORT TERM...15 LONG TERM...15/BM AVIATION...NL
Hazardous Weather Outlook National Weather Service Grand Junction CO 506 AM MDT Sun Mar 26 2017 COZ001>014-017>023-UTZ022>025-027>029-271115- 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- 506 AM MDT Sun Mar 26 2017 This hazardous weather outlook is for eastern Utah and western Colorado. .DAY ONE...Today and Tonight Snow showers in the Colorado mountains and high valleys will gradually decrease in coverage and intensity through the mid morning hours. Travel may be impacted over the southwest Colorado roadways through sunrise due to icy and snow packed conditions. .DAYS TWO THROUGH SEVEN...Monday through Saturday Monday through Friday...Another series of Pacific storm systems will move through the area bringing a continued potential for more winter weather and hazardous driving conditions over the mountain passes with mountain snow and valley rain. Isolated thunderstorms are also anticipated Monday and Tuesday afternoons. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected today or tonight, however spotters are encouraged to report snowfall amounts to the National Weather Service in Grand Junction.
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
957 AM MDT SUN MAR 26 2017
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0855 AM SNOW MOLAS PASS 37.74N 107.70W
03/26/2017 M3.0 INCH SAN JUAN CO DEPT OF HIGHWAYS
REPORTED AT MOLAS PASS BY CAIC.
&&
NLPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
959 AM MDT SUN MAR 26 2017
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0855 AM SNOW COAL BANK PASS 37.70N 107.78W
03/26/2017 M3.0 INCH SAN JUAN CO PUBLIC
REPORTED AT COAL BANK PASS BY CAIC.
&&
NLPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1016 AM MDT SUN MAR 26 2017
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0855 AM HEAVY SNOW 4 E CAMP BIRD 37.97N 107.66W
03/26/2017 M11.0 INCH OURAY CO DEPT OF HIGHWAYS
REPORTED AT MONUMENT ON HWY 550 AT MM 88
SOUTH OF OURAY BY CAIC.
&&
NLPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1020 AM MDT SUN MAR 26 2017
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0800 AM SNOW 8 SW MAHER 38.56N 107.69W
03/26/2017 U1.4 INCH MONTROSE CO CO-OP OBSERVER
.
&&
NLPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1043 AM MDT SUN MAR 26 2017
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1040 AM HEAVY SNOW 7 NE SAWPIT 38.06N 107.91W
03/26/2017 M11.9 INCH SAN MIGUEL CO TRAINED SPOTTER
.
&&
NLPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1058 AM MDT SUN MAR 26 2017
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0820 AM SNOW 1 SW RIDGWAY 38.15N 107.76W
03/26/2017 M3.5 INCH OURAY CO CO-OP OBSERVER
.
&&
NLThe national radar mosaic for the moment the first event began.
1 avalanche. Local standard time, as filed.
An avalanche came down onto Highway 550 and covered the road up to three feet deep. The highway was closed at that location for several hours as road crews cleared snow off the highway.
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, March 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: 706433.