Temperatures were above normal and precipitation was below normal across much of eastern Utah during the month of May. As a result, drought conditions in southeast Utah either persisted or worsened.
Every event with a place to put it; 4 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 GJT wrote it up.
Temperatures were above normal and precipitation was below normal across much of eastern Utah during the month of May. As a result, drought conditions in southeast Utah either persisted or worsened.
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 Apr 30, 9:59 PM MST, 2 hours 1 minute earlier.
Area Forecast Discussion National Weather Service Grand Junction CO 1059 PM MDT Mon Apr 30 2018 .SHORT TERM...(Tonight through Tuesday night) Issued at 353 PM MDT Mon Apr 30 2018 GOES water vapor channel is showing the dry slot spread across our cwa but another round of upstream moisture is knocking the door. There area some sprinkles and light rain showers around due to increasing instability and forcing from a surface front across NW Colorado which will linger into the evening hours. The first challenge with this forecast arrives on the nose of the jet max rotating northward across the 4 Corners overnight. Will there be sufficient lift to help tighten a mid level fronto band and use incoming moisture to form a well defined precipitation band? The one model hinting at this is now backing off and the newest runs of the hires suites say the same. Trended pops up to account for the possibility but confidence is not really there so this move may bust. No worries better chances come later. The jet core axis will be lifting north on Tuesday as the flow becomes more southerly aloft. This leaves the best chances for scattered convection across the northern CWA. Ascent once again increases along the CO/UT border early Wednesday as the upstream system approaches the 4 Corners. Models suggest a warm front lifting across the southern mountains in the predawn hours. Theta surfaces show a tap of Pacific moisture riding over this front and leading to some heavier precipitation over the southern mountains. This front is tied to a surface low over E.Utah which is stacked with an H7 circulation and this also helps to focus some heavier precipitation back to the West. Snow is likely to be falling close to the southern mountain bases but best accumulations will be closer to the 9000 foot mark and higher. Impacts to roadways are possible but with recent warm temperatures not clear on impacts attm. .LONG TERM...(Wednesday through Monday) Issued at 353 PM MDT Mon Apr 30 2018 The main portion of the system will move across the 4 Corners region to the Eastern Plains Wednesday through early Thursday. This will be the most active period of the storm with as precipitation is the most widespread. Time of year will play a big role on impacts as snow falling on high mountain roadways should be melting after the mid morning hours on Wednesday. Convection will play a role and produce some heavier areas of precipitation and some high roadways may accumulate some temporary slush. As temperatures cool Wednesday evening there will be window for some decent high mountain accumulations before the focus shifts east of the divide and upslope flow. Some of the high peaks and SNOTELS should record some decent snow amounts at higher elevations and winter highlights probably warranted at some point with this Spring storm. Instability showers linger Thursday on the back side of the storm is cool NW flow. Warmer and drier conditions move in for Friday into the weekend as ridging moves back over the Rockies ahead of the next upstream trough. && .AVIATION...(For the 06Z TAFS through 06Z Tuesday night) Issued at 1059 PM MDT Mon Apr 30 2018 Moist southwest flow aloft will bring scattered showers to the area through Wednesday. The best chance for rain/snow showers tonight and Tuesday will be across east-central Utah and west- central to northwest Colorado. The potential for precipitation will then shift south over the San Juan Mountains and adjacent southern valleys into southeast Utah Tuesday night and Wednesday. Expect occasional ILS CIGS with areas of MVFR/IFR conds as showers increase in coverage and intensity. Mountains will be obscured at times. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && SHORT TERM...GJT LONG TERM...GJT AVIATION...JDC
Hazardous Weather Outlook National Weather Service Grand Junction CO 514 AM MDT Mon Apr 30 2018 COZ001>014-017>023-UTZ022>025-027>029-011115- 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- 514 AM MDT Mon Apr 30 2018 This hazardous weather outlook is for eastern Utah and western Colorado. .DAY ONE...Today and Tonight Southwest winds can be expected again today ahead of an approaching disturbance, with gusts of 25 to 35 mph in many areas. Scattered showers and a few thunderstorms can be expected to spread across northeast Utah and northwest Colorado today. Snow is likely over the higher elevations of the eastern Uinta Mountains with 1 to 4 inches expected. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday Colder and more widespread shower activity is expected Tuesday into Thursday with snow showers in the mountains and rain showers for the lower elevations. Storm total snowfall amounts of 1 to 4 inches are possible in the mountains. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed today. However, reports of peak wind speeds would be appreciated.
The national radar mosaic for the moment the first event began.
4 drought. Local standard time, as filed.
Exceptional (D4) drought conditions persisted through the end of the month for all but the far western portion of the zone where extreme (D3) drought conditions remained.
Extreme (D3) drought conditions persisted through the end of the month for the majority of the zone, with the exception of exceptional (D4) drought conditions which slowly expanded further north into the zone in mid May.
Extreme (D3) drought conditions persisted across much of the zone through the end of the month while exceptional (D4) drought conditions remained in the southeast portion of the zone.
Extreme (D3) drought conditions persisted across the far west-central portion of the zone through the month.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Utah in 2018Every state in 2018This day in weather historyWarnings in Utah, May 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: 748138, 748139, 748140, 757877.