textproduct: Pendleton

KEY MESSAGES

- Atmospheric river This Week bringing mountain rains will keep rivers running elevated with a few rivers possible returning to flood. - Much warmer than average temperatures this week

- Windy conditions across the Yakima and Simcoe Highlands Thursday

DISCUSSION

A continuing atmospheric river will be found across Washington for much of the coming week, bringing light to at times moderate rain to the Washington Cascades. The NBM mean would produce around 2.5 to 3 inches of total QPF in this all-rain warm AR, where snow levels average around 6 to 8k ft AGL through much of the week, and certainly Tuesday - Thursday. Each 6 hour period will only range up to a quarter inch of rainfall, hence rates will not be high, but the duration on the snowpack will cause considerable runoff/exacerbate the melting for area rivers, including the Yakima and Naches and Walla Walla.

Positively anomalous high and low temperatures are anticipated as a strong upper high builds over the western U.S. This shows up in the ESAT values ranging from around .82 to .86 relative to the model climatology broadly and a few spots like central Oregon and the Columbia Basin/Wallowas that can see higher shift of tails near .90 to .95 for MaxT and MinT. Wednesday and Thursday look to be the hottest days of the week where temperatures even by the mean NBM temperatures can reach 80 degrees in the John Day Basin and the other deeper river valleys like Deschutes.

By and large, the period does not look windy, however ridgetop winds can be elevated across the Simcoe Highlands and Lower Slopes of the Eastern Washington Cascade Crest (40 to 55 mph gusts) Tuesday and Wednesday. A look at Tuesdays box and whiskers spread shows a reasonable expectation of wind gusts between 30 and 40 mph however, on Thursday, that kicks up to 35 to 50 mph across the Simcoe Highlands with gusts of 60 mph along the ridge tops.

AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/

VFR conditions currently at all sites, which will stay the course through the period. Ceilings are expected to drop to around 10kft for the majority of sites late Tuesday morning associated with a frontal system well to our north. This feature will also enhance winds slightly across KPSC/KALW/KPDT/KDLS with winds between 10-15kts likely. 75

Preliminary Point Temps/PoPs

PDT 66 43 66 44 / 40 0 10 10 ALW 61 48 65 49 / 50 10 20 20 PSC 64 46 69 47 / 30 10 10 10 YKM 62 41 67 44 / 20 10 20 20 HRI 65 45 68 44 / 30 0 10 10 ELN 54 38 59 43 / 30 20 30 40 RDM 72 38 72 39 / 10 0 0 0 LGD 62 41 67 43 / 50 0 10 10 GCD 66 41 70 43 / 20 0 0 0 DLS 67 45 64 44 / 10 0 20 10

PDT WATCHES/WARNINGS/ADVISORIES

WA...None. OR...None.