Accelerated snowmelt from a near-record snowpack due to above normal temperatures produced high and fast flow on drainages in several counties across the Western Slope. As a result, flooding compromised various low-lying roads and areas.
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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.
Accelerated snowmelt from a near-record snowpack due to above normal temperatures produced high and fast flow on drainages in several counties across the Western Slope. As a result, flooding compromised various low-lying roads and areas. This included some lanes along I-70 west of Fruita, Colorado.
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 May 15, 10:24 AM MST, 36 minutes earlier.
Area Forecast Discussion National Weather Service Grand Junction CO 1124 AM MDT Mon May 15 2023 .SHORT TERM...(Today through Tuesday night) Issued at 231 AM MDT Mon May 15 2023 Very little change to forecast thinking for the short term. The area of low pressure to our northwest has reached Oregon and it will remain over that general area through Tuesday. The location of this low and the notion of a weak area of high pressure setting up to our south will cause winds to become westerly this afternoon and effectively shut off the stream of moisture. However, with no real kicker to shift this moisture out of the area, we can expect daytime heating and weak disturbances to cause another day of convection. Once again, showers and storms will fire over the higher terrain before drifting into adjacent valleys. As mentioned, steering flow will become more westerly to northwesterly so expect storms to follow this general trajectory. CAPE will range from 500 to 800 J/kg with some pockets over the higher terrain reaching higher values than that. Lapse rates of 7 to 8C/km are co-located with these higher values of CAPE, as one would expect, so we can look for another day of hail, gusty winds, and heavy rain from the stronger cells that form. CAM guidance is also in good agreement with convection firing around noon and continuing through the afternoon before quickly dying down towards sunset. Will be very similar to yesterday. Tuesday, forecast PWATs start to drop and with no moisture tap to speak of, moisture will start becoming limited. NAM guidance is showing a marked downturn in convective activity while the GFS and HRRR are also showing a downturn just not 'that' much. The NBM is more in line with the HRRR/GFS with some shower/storms possible over much of the higher terrain but especially the eastern Uintas and the northern valleys. Looks reasonable as the NAM sometimes overdoes how fast moisture moves out of the CWA so the 30 to 40% chance PoPs for those mentioned areas will remain in the forecast. Outside of the convection look for near normal temps and Cu clouds increasing as the day progresses only to diminish overnight. .LONG TERM...(Wednesday through Sunday) Issued at 231 AM MDT Mon May 15 2023 The area of low pressure over Oregon will finally open up and get picked up by a cold front that will have its origins in Canada. The front will be draped from N. Dakota into Montana before losing consistency in Idaho, first thing Wednesday. As the front drops southward, the main impulse of energy will shift to the Front Range but enough will move through the CWA to cause some rather isolated convection to fire, best bet over the San Juans. Once the front has shifted well to the east, an upper level trough just to our north will start dropping down from the north. This disturbance will be the impetus for yet another round of convection though coverage will increase considerably across the CWA. In fact, this timeframe...Thursday through Sunday...looks to be quite active as rather robust shortwaves move across the CWA and cause afternoon and evening convection fairly consistently. As we've seen lately, look for some heavy rain, gusty winds, and small hail under the strongest cells. In fact, said convection may keep going through the start of the work week. Plenty of time for things to change though so we'll be keeping an eye on how things play out. The potential for heavy rain with this convection, each afternoon and evening, will likely lead to accelerated snowmelt or, at the very least, cause an uptick in flows for many rivers across the region increasing chances for river flooding. Something else we will also be monitoring. && .AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon) Issued at 1119 AM MDT Mon May 15 2023 A few convective storms have already began blossoming atop high terrain. Expect spatial coverage to expand this afternoon, maximized around 21Z. Storm initiation favors high terrain, but then will drift northeast over adjacent valleys. Stronger cells may be capable of producing periods of heavy rain, small hail, lightning and gusty outflow winds. Have included VCTS in most TAF sites through 00-02Z this evening, with gusts up to 20kts from nearby cells. Despite storm activity, VFR conditions prevail for the next 24 hours. && .HYDROLOGY... Issued at 353 AM MDT Mon May 15 2023 The Elk River near Milner has been reaching just above minor flood stage over the last few nights and tonight was no different. Snowmelt continues to keep the Elk River running high and this fluctuation between action stage and minor flood stage is expected to continue through the week. Rainfall from convection, which is possible over the coming days, will only exacerbate the situation. Issued a Flood Warning to account for this behavior. Will also need to keep an eye on the Yampa River further downstream as the forecast also calls for increased flows and heights, reaching action stage near Craig, Maybell, and Deerlodge Park later in the week. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && SHORT TERM...TGR LONG TERM...TGR AVIATION...ERW HYDROLOGY...TGR
Hazardous Weather Outlook National Weather Service Grand Junction CO 405 AM MDT Mon May 15 2023 COZ001>014-017>023-UTZ022>025-027>029-161200- 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- 405 AM MDT Mon May 15 2023 This hazardous weather outlook is for eastern Utah and western Colorado. .DAY ONE...Today and Tonight Showers and thunderstorms will fire, yet again, over the higher terrain this afternoon before drifting into adjacent valleys. Small hail, gusty outflow winds, and some heavy rain will be possible under and near the strongest cells. The Elk River near Milner has reached minor action stage early this morning and this trend looks to continue over the coming days so a Flood Warning has been issued for that area. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday A downtick in convection is expected Tuesday though some isolated showers and storms can't be ruled out. A slight uptick is expected Wednesday but from Thursday onwards, widespread convection each afternoon and evening through Sunday, and possibly beyond, is forecast. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed.
The national radar mosaic for the moment the first event began.
9 flood. Local standard time, as filed.
Closures were implemented on the outer lane of I-70 at Skipper Island west of Fruita in both directions as a result of flooding along the Colorado River. The closure was updated to only include the right lane of I-70 westbound several days later.
Flooding occurred at the Gypsum Valley Boat Launch as a result of increased snowmelt and flow along the Dolores River.
Seedhouse Road in Routt County northeast of Clark was closed between mile markers 3 and 5 as a result of flooding.
County Road 2 next to the USGS's Slater Fork gage south of the Wyoming/Colorado border had one lane closed due to flooding along Slater Creek.
The boat ramp at Bedrock along the Dolores River was inaccessible due to flooding on the river.
Increased snowmelt along the Dolores River led to the inundation of the campground and parking lot along the boat launch at the Bradfield Recreation Site outside Cahone. Some vehicles were stuck in the mud as a result.
An NWS employee riding on a bike trail outside Loma reported flooding along the trail near Reed Wash. The river was running incredibly high underneath the I-70 bridge.
Flooding along the Yampa River resulted in the closure of the Deerlodge Park Campground within Dinosaur National Monument.
Snowmelt produced a washout on National Forest System Road (NFSR) #525-Potter Basin road located at mile post 1.172 on the Ouray Ranger District, northeast of 25 Mesa Guard Station. The road was not passable and remained closed.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Colorado in 2023Every state in 2023This day in weather historyWarnings in Colorado, May 2023
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: 1088003, 1088030, 1088025, 1088010, 1088016, 1087999, 1088008, 1088055, 1088060.