During the evening of October 12th a line of showers and thunderstorms produced damaging local outflow winds near the town of Diamond Lake in the northeast mountains of Washington.
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The episode as NWS OTX wrote it up.
During the evening of October 12th a line of showers and thunderstorms produced damaging local outflow winds near the town of Diamond Lake in the northeast mountains of Washington.
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 Spokane, WA wrote its last area forecast discussion before the first event at Oct 12, 3:44 AM PST, 3 hours 6 minutes earlier.
Area Forecast Discussion National Weather Service Spokane WA 444 AM PDT Fri Oct 12 2018 .SYNOPSIS... A dry cold front will arrive tonight producing breezy north winds across central Washington into Saturday. Next week will feature a prolonged period of dry and mild weather. Look for chilly overnight temperatures and mild mainly sunny days through the end of next week. && .DISCUSSION... Today through Saturday Night: Some high clouds are moving in from the north this morning ahead of the next front. The clouds will be fairly thin with a mostly sunny day expected. As the cold front approaches from the north we will see an increase in winds this afternoon. Winds will become breezy down the Okanogan Valley starting late this afternoon and continuing through Saturday. North winds 10-20 mph with gusts up to 30 mph is expected tonight. The winds will funnel down into portions of the Waterville Plateau and western Columbia Basin, but should be less than areas to the north. The strongest winds aloft are during the overnight and early morning hours Saturday when they are less likely to reach the surface. But the mountains of Okanogan and Ferry counties could see wind gusts up towards 50 mph. Then Saturday as we get a punch of dry canadian air, the winds will continue and increase in many areas. Okanogan valley winds will be 15 to 25 mph with gusts up to 40 mph. These winds will funnel into the Basin with the strongest winds occurring in the afternoon. Winds will begin to decrease by early evening. Relative humidities Saturday will be quite low, but the locations with near critical values will not be where the strongest winds will occur, so no highlights are expected. /Nisbet Sunday through Friday: The medium range models continue to forecast a prolonged period of high pressure next week. Confidence remains high that our region will experience a week without precipitation, relatively light winds, and mainly clear skies. The shot of dry north winds we experience with the Fri/Sat dry cold front will leave a very dry low level air mass behind. You will want to double up on the Chapstick early in the week with dewpoints in the 20s Sunday, Monday, and Tuesday. Dryness combined with light winds and mainly clear skies will promote efficient radiational cooling for chilly overnight lows. Morning lows Sun and Mon will likely be the coolest with widespread 30s and pockets of mid to upper 20s in our typically chilly valleys north and east of the Spokane metro. As high pressure builds inland Tuesday and beyond, look for a gradual modification of the air mass with improvements in humidity through the end of the week. Daytime and overnight temperatures should also respond to warming aloft with a trend toward slightly above average temperatures by mid to late week. /GKoch && .AVIATION... 12Z TAFS: Cold front approaching the region from the north. However it will produce little in the way of impactful cloud cover or precipitation chances as it moves in after 00Z. Increased winds will be the main notable impact with some gusts near 15-25 kts in the afternoon. Some stronger winds are possible down the Okanogan valley. Surface speeds start to abate at TAF sites after 01-03Z. && .PRELIMINARY POINT TEMPS/POPS... Spokane 61 38 56 32 57 33 / 0 0 0 0 0 0 Coeur d'Alene 59 34 54 31 56 32 / 0 0 0 0 0 0 Pullman 62 35 55 30 55 31 / 0 0 0 0 0 0 Lewiston 69 41 60 34 59 34 / 0 0 0 0 0 0 Colville 60 34 58 29 59 32 / 0 0 0 0 0 0 Sandpoint 58 33 53 29 55 30 / 0 0 0 0 0 0 Kellogg 58 32 50 28 53 30 / 0 0 0 0 0 0 Moses Lake 66 36 63 31 61 31 / 0 0 0 0 0 0 Wenatchee 65 42 61 36 60 39 / 0 0 0 0 0 0 Omak 64 40 61 34 61 35 / 0 0 0 0 0 0 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...None. &&
Hazardous Weather Outlook National Weather Service Spokane WA 500 AM PDT Fri Oct 12 2018 IDZ001>004-026-027-WAZ031>038-041>044-131200- Northern Panhandle-Coeur d'Alene Area-Idaho Palouse- Central Panhandle Mountains-Lewiston Area- Lewis and Southern Nez Perce Counties-Northeast Blue Mountains- Lower Garfield and Asotin Counties-Washington Palouse- Moses Lake Area-Upper Columbia Basin-Spokane Area- Northeast Mountains-Okanogan Highlands-Wenatchee Area- East Slopes Northern Cascades-Okanogan Valley-Waterville Plateau- 500 AM PDT Fri Oct 12 2018 This Hazardous Weather Outlook is for portions of North Idaho... North Central Idaho...Central Washington...East Central Washington...North Central Washington...Northeast Washington and Southeast Washington. .DAY ONE...TODAY AND TONIGHT No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY No hazardous weather is expected at this time.
The Spokane radar (KOTX), 63 km away, was scanning. The volume nearest the first event began at 14:49 UTC.
1 thunderstorm wind. Local standard time, as filed.
A spotter reported 4 trees uprooted and a few power poles snapped with power outages as a result of strong local outflow winds from a nearby thunderstorm. Time is estimated from radar data.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Washington in 2018Every state in 2018This day in weather historyWarnings in Washington, October 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: 784425.