Thunderstorms that developed in a very moist atmosphere caused local heavy rainfall amounts over portions of Grant, Union and Wallowa counties.
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The episode as NWS PDT wrote it up.
Thunderstorms that developed in a very moist atmosphere caused local heavy rainfall amounts over portions of Grant, Union and Wallowa counties.
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 Pendleton, OR wrote its last area forecast discussion before the first event at May 22, 1:04 PM PST, 1 hour 26 minutes earlier.
Area Forecast Discussion National Weather Service Pendleton OR 204 PM PDT Tue May 22 2018 .SHORT TERM...Tonight through Friday. Visible imagery show cumulus developing over the mountains with weak instability associated with an upper low to the south. Expect this to continue and will likely have scattered showers and thunderstorms late afternoon and evening. Flow aloft is fairly weak and indicates that storms will be slow moving. Mainly from northeast to southwest. So brief heavy rain is possible. Activity will decrease after sunset with partly cloudy skies overnight. For the remainder of the forecast area partly cloudy skies through mid evening then clear overnight. Lows mostly in the 50s. On Wednesday an upper low moving toward the coast will turn the flow aloft to the southwest. This will increase the instability over the region and expect another day of scattered showers and thunderstorms in the afternoon and evening. The upper low moves toward northern California Thursday and inland on Friday. This places the forecast area in a favorable location for continued showers and thunderstorms each day. Models continue to show potential for some decent rainfall especially over southern and central Oregon with short waves rotating around the upper low. Temperatures remain fairly warm through Thursday with a cooling trend Friday into the weekend. 94 .LONG TERM...Friday night through Tuesday...Models in good agreement in continuing widespread convection across our southern CWA into early Saturday morning. The system responsible for this unsettled weather will continue to move farther south and be in southern Nevada by late Saturday. ECMWF is a little more broad with the position of the low Saturday so will continue afternoon and evening showers/thunderstorms over Oregon. The convection is expected to end Saturday night as weak upper level high pressure builds in the wake of the exiting low. Overall, the area should remain dry through the rest of the extended period as the upper level ridge remains over the area. However, lingering instability and daytime heating will result in a slight chance of afternoon/evening showers and thunderstorms over the mountains of eastern Oregon. Daytime highs will be near to slightly above normal through the period. Earle && .AVIATION...Previous discussion...18Z TAFs...VFR conditions will prevail through the period. Upper level high pressure will keep the weather dry at all TAF locations. A few afternoon and evening showers and possibly a thunderstorm will develop over the mountains, but should not affect any TAF sites. Winds will generally be less than 10 kts. Earle && .PRELIMINARY POINT TEMPS/POPS... PDT 56 85 60 84 / 10 10 40 30 ALW 58 86 62 85 / 10 10 40 30 PSC 58 90 63 87 / 0 10 30 30 YKM 56 89 60 87 / 0 10 30 20 HRI 57 90 63 88 / 10 10 30 30 ELN 53 86 57 85 / 0 10 30 20 RDM 50 80 52 79 / 10 40 60 40 LGD 50 77 54 77 / 30 40 40 40 GCD 50 77 54 78 / 30 40 50 40 DLS 58 86 60 84 / 0 20 40 20 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. && 94/81/81
The national radar mosaic for the moment the first event began.
1 heavy rain. Local standard time, as filed.
A thunderstorm produced heavy rain in and around Cove, in Union county. One half inch to one inch of rain fell on this area over approximately a one and half hour period.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Oregon in 2018Every state in 2018This day in weather historyWarnings in Oregon, 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: 754840.