Moisture increased across western Colorado ahead of the next Pacific system. This, paired with daytime heating, led to scattered showers and thunderstorms.
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The episode as NWS GJT wrote it up.
Moisture increased across western Colorado ahead of the next Pacific system. This, paired with daytime heating, led to scattered showers and thunderstorms. The stronger storms produced gusty winds in excess of 58 mph across the Grand Valley.
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 31, 2:09 PM MST, 46 minutes earlier.
Area Forecast Discussion National Weather Service Grand Junction CO 309 PM MDT Wed May 31 2023 .SHORT TERM...(Tonight through Thursday night) Issued at 300 PM MDT Wed May 31 2023 Showers and thunderstorms have fired this afternoon with plenty of coverage seen across the CWA. As expected, those drier subcloud layers have allowed some gusty outflow winds to materialize. A stronger cell near Durango caused a 50 mph gust at the airport but, by and large, most gusts have been spread between 35 to 45 mph. CAM guidance has picked up on the location and intensity of this convection fairly well and they show convection continuing through the early evening hours before subsiding. Of note, the NAMNEST is picking up on another line of showers moving from the Four Corners up into the Grand Valley around midnight while the HRRR does show some activity in the same area but nowhere near as robust. Might see a few showers, a rumble of thunder or two, or maybe just some clouds...it's that kind of environment. Thursday, look for more of the same as the low pressure will be over the Four Corners region. The added lift from the low will work on the available moisture and increased instability will further aid in convective development. Those areas not seeing convection will see plenty of cloud cover and thus, lower high temperatures. This trend will continue into the weekend. .LONG TERM...(Friday through Wednesday) Issued at 300 PM MDT Wed May 31 2023 Very little change noted from previous model runs with regards to the long term period. The closed low will open up as it moves across the CWA and eventually stalls on top of Colorado. Plenty of moisture and instability will allow showers and thunderstorms to form each afternoon and evening heading into the weekend. As previously mentioned, this area of low pressure will basically dissolve in place as a retrograding downstream high pressure cell creates a strong omega block over central NOAM by early next week. This extremely amplified pattern persists into the middle of next week and is so anomalous that the models are struggling to find agreement in many areas. The basic flavor of the forecast remains daily afternoon showers and thunderstorms becoming fairly widespread through the weekend with lingering isolated convection during the overnight hours. Monday onwards, there will be no focus, per se, for convection aside from lingering moisture and daytime heating. Even so, it will be enough for convection to fire though coverage should lessen some from what was seen over the weekend. As we've said for the last several days, the finer details are still just not there but there is high confidence in widespread showers and storms. As one would expect, high temps will run below normal thanks to increased cloud cover and the precip. Sure doesn't seem like June... && .AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon) Issued at 1133 AM MDT Wed May 31 2023 Scattered to broken skies will continue to stream across the area from south to north today in response to the approaching low pressure system to our southwest. Some showers have already formed bringing some sprinkles to KASE and KTEX. This trend will continue through the day with more widespread convection expected. Included VCTS for many TAF sites with tempo groups for storms on station at KMTJ, KTEX, KEGE, KASE, and KGUC. Brief drops in vis may occur but the bigger concern will be gusty outflow winds from any convection that forms. Do not expect ILS breakpoints to be reached though it might be close for KASE and KEGE. Clouds will likely linger overnight but flight conditions will remain VFR. && .HYDROLOGY... Issued at 300 PM MDT Wed May 31 2023 No major changes in terms of hydrologic conditions today. Warm temperatures the last several days have helped accelerate snowmelt across high elevations, and narrowed the extent of snow left over mid-elevation zones. In general, the season's daily peak in flow typically coincide when these two elevation zones dwindle in unison. However, the oscillating temperatures this spring have mitigated the rate of snowmelt across the board, so far this year. As a result, the originally expected peaks are trending down. Instead, prolong periods of high water and fast flow have been observed and are expected to continue across much of the West Slope. Weather shifts in the coming days, towards a cooler and wetter than normal pattern. In terms of temperature, the rate of snowmelt will slow, decreasing the risk of a high spike along rivers and streams. On top of that, cooler mountain peaks (mainly above 10,500 ft) could accumulate several new inches of snow in this moist regime, which would just add to the delayed mountain season. In contrast, precipitation in the form of rain (heavy rain) falling on snow would enhance snowmelt processes. So in summary, the variance in the weather over a given basin in the coming days translates to a level of uncertainty in river forecasts, as spring runoff is highly dependent on spring weather. In general, though, forecast hydrographs are trending down through the weekend, which would reflect a cool regime and reduced snowmelt. Though, the caveat, convective processes may not be captured. Training storms focused over one basin could lead to instantaneous spikes in flow, or end becoming the daily peak we've been anticipating. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && SHORT TERM...TGR LONG TERM...TGJT AVIATION...TGR HYDROLOGY...ERW
Hazardous Weather Outlook National Weather Service Grand Junction CO 325 AM MDT Wed May 31 2023 COZ001>014-017>023-UTZ022>025-027>029-010930- 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- 325 AM MDT Wed May 31 2023 This hazardous weather outlook is for eastern Utah and western Colorado. .DAY ONE...Today and Tonight Storms will increase a bit in coverage today with the higher terrain of western Colorado being favored. Some storms could drift into adjacent higher valleys late in the day, especially across northwest and central Colorado. Gusty outflow winds and lightning remain the primary concerns. Rivers and creeks will continue to run high due to snowmelt for much of the area. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday Showers and thunderstorms will become more widespread with a better chance of moderate to heavy rainfall Thursday through the weekend. Gusty outflow winds will still remain a threat as well. Unsettled weather with daily storm activity looks to remain in the picture at least into next week. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed.
Preliminary Local Storm Report
National Weather Service Grand Junction CO
126 PM MDT Wed May 31 2023
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1238 PM Tstm Wnd Gst 7 SSW Olathe 38.50N 108.01W
05/31/2023 M51 MPH Montrose CO Mesonet
Mesonet station FW3775 Montrose.
&&Preliminary Local Storm Report
National Weather Service Grand Junction CO
200 PM MDT Wed May 31 2023
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0112 PM Tstm Wnd Gst 3 SW Oxford 37.14N 107.76W
05/31/2023 M49 MPH La Plata CO ASOS
&&
NLPreliminary Local Storm Report
National Weather Service Grand Junction CO
229 PM MDT Wed May 31 2023
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0215 PM Non-Tstm Wnd Gst 4 ESE Steamboat Springs 40.46N 106.74W
05/31/2023 M45 MPH Routt CO Mesonet
Mesonet station STORM 4.3 E Steamboat
Springs (DRI).
&&The Grand Junction radar (KGJX), 27 km away, was scanning. The volume nearest the first event began at 21:53 UTC.
1 thunderstorm wind. Local standard time, as filed.
A peak wind gust of 61 MPH was measured by the automated weather station at the Grand Junction Regional Airport.
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: 1092215.