Marine Weather and Tide Forecast for Kittitas, WA

FXUS66 KPDT 122337 AFDPDT

Area Forecast Discussion National Weather Service Pendleton OR 437 PM PDT Mon May 12 2025

Updated for Aviation

SHORT TERM
Today through Wednesday
Pocket of showers prevailing across the Southern and Northern Blue Mountains- Foothills of OR, and portions of the eastern mountains with some developing over the WA/OR Cascades, observed from current satellite and radar imagery. The upper level trough continues passing over the PacNW with the southwesterly flow aloft pushing the convective surge further to the eastern mountains. That, and with the combination of lift, instability and increased moisture will add more fuel to the isolated thunderstorms through this evening. This even resulted in warranting a Special Weather Statement earlier this afternoon for northeast of La Grande when a dime-sized hail was reported. However, the severity remains inhibited from the weak instability and with the SPC Outlook having only our northeast area in general risk.
PotThunder chances will be about 20-40% for the Blues and eastern mountains through evening. Widespread showers will also persist with QPF amounts up to 1 inch over the eastern mountains, 0.50 inches across the Blues and 0.10 inches over the upper parts of the Columbia Basin. The surface pressure gradients will continue strengthening from the southwest flow, producing gusty winds (25-35 mph) across the Cascade Gaps throughout today.

Tomorrow, the trough moves eastward as showers progress over the eastern mountains. Light QPF amounts will be at 0.10 inches across most of the forecast area, though may see 0.25 inches on the high end over portions of the Blues. The Wallowas could have isolated thunderstorms tomorrow afternoon (>60% chance) but, chances will remain low due to weak instability (CAPE values under 500 J/Kg) and decreasing moisture level. By Tuesday night onwards, precip activity gradually tampers off as the leading edge of the upper ridge builds over to the PacNW. Winds will start off as breezy at the Cascade Gaps tomorrow morning before becoming gusty in the afternoon through late evening.

Wednesday, showers may linger in the morning along the crest of the Cascades and the Wallowas (<30% chance), but will be mainly dry across the majority of the forecast area. Winds could also be gusty over the Cascades Gaps Wednesday morning, given the increased northwesterly flow. They should steadily decrease later in the evening to breezy conditions (15-25 mph). Feaster/97

LONG TERM
Thursday through Monday
The primary weather concerns in the long term will be the arrival of a shortwave Thursday night into Friday followed by an upper trough moving through the area Saturday and Sunday. The first system will only bring light rain to the mountains but the trough will have greater moisture and instability and this will develop a slight chance of thunderstorms Saturday afternoon and early evening. Model cluster analysis shows good agreement early on in the long term but by Saturday differences arise about the timing and strength of the trough and the location of a developing central low. These differences increase on Sunday which affects the end of precipitation and how soon an offshore ridge builds over the area. By Monday, 63 percent of model ensemble members have a ridge over the area though 31 percent of those members keep the closed low over eastern Nevada close enough to keep showers over Wallowa County. The other 37 percent have a flattened ridge with another shortwave moving into northern British Columbia giving us a zonal westerly flow. Overall, forecast confidence is good but becomes average over the weekend.

Thursday will see a ridge over the area flattening as a shortwave approaches the area. Precipitation will hold off until the evening when the Washington Cascades will have a chance of rain showers and overnight, the rest of the Cascades and the eastern mountains will have a slight chance of showers. Rain amounts will just be a few hundredths of an inch at most. Temperatures will drop a couple of degrees from Wednesday with highs in the mid 60s to lower 70s and in the mid 50s to mid 60s in the mountains. Winds will be fairly light though the Cascade gaps will have breezy west to northwest winds of 15 to 25 mph in the late afternoon.

Friday will see the shortwave move off to the east in the morning with very light showers lingering in the eastern mountains into the afternoon. Skies will be partly cloudy and this will allow for 3 to 5 degrees of warming to the upper 60s to mid 70s with upper 50s to mid 60s in the mountains.

Saturday the upper trough will move to the coast and a moist south to southwest flow will develop over the area. Models indicate decent instability and this will create a 30 to 50 percent chance of showers and a 15 to 25 percent chance of thunderstorms over much of the area, especially the eastern mountains, in the afternoon and early evening. the Washington Cascades and western portions of the Columbia Basin look like they will miss out on the thunderstorms.
Rain amounts are up to a quarter inch in the eastern mountains and Cascade crest and up to a tenth of an inch elsewhere. The cloud cover and rain will drop temperatures 2 to 4 degrees. The Cascade gaps will have west to northwest winds of 20 to 30 mph with gusts to 40 mph while other lower locations will reach 10 to 20 mph. The trough will split on Sunday as it moves east with a developing low to our south. Circulation around the low will keep a slight chance of showers in the eastern mountains tapering off in the afternoon.
Rain amounts will be less than a tenth of an inch. Temperatures and winds will be similar to Saturday.

Monday looks a little warmer as a ridge tries to build offshore and temperatures rise to the lower to mid 70s with 60s in the mountains.
Since some of the model ensemble members keep light showers circulating around the departing low into the eastern mountains, have a slight chance of very light rain showers in the northern Blue Mountains and Wallowa County. Breezy winds are anticipated in the afternoon. Perry/83

AVIATION...
00Z TAFS...Isolated SHRA with a few embedded TSRA continue across the region. The most likely locations to see SHRA for the remainder of the afternoon and evening are DLS/BDN/RDM, but SHRA remain possible everywhere.

Another round of SHRA are possible on Tuesday with the most likely areas (>60 percent) for PDT, ALW, BDN, RDM.

Otherwise gusty winds will remain at DLS through the evening with gusts 25 to 30 kts before decreasing to 10 kts or less. PSC will see gusts in the 20 to 25 kt range before decreasing. Winds will increase again on Tuesday at DLS, and gust to around 25 kts, PDT will gust to around 20 kts while other sites will generally be 10 kts or less.
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