textproduct: Pendleton

KEY MESSAGES

- Record or near record warm highs and lows

- Locally windy Thursday and beyond

- Big break from the unseasonably warm temperatures on Saturday with a cold front

DISCUSSION

Stationary/stalled atmospheric river up to 600 kg/ms magnitude will continue undergo orographic lift , bringing several inches of rain to the Washington Cascade Crest through the end of the week. This is of high confidence (90-95%) as snow levels now and for the next few days are averaging 7000 to 9000 feet AGL or higher. This will impact area rivers with runoff over snow and some melting as well. The last 24 hours have seen upwards of about 1 inch across this forecast zone. Most river forecast respond with within bank rises; going to near or above action stage however the Naches river at Naches does have a forecast hydrograph going into minor flood stage Saturday, cresting Friday afternoon through Saturday evening, at the low end of the minor range 17.8 feet. Breezy to Windy conditions return to the Yakima Valley and Simcoe Highlands on Thursday however those trends do not look quite as strong on the most recent runs. NBM range box and whisker plots show close to to just over advisory (low end with up to 45 mph gusts) on the 75th percentile across parts of these forecast zones. Windy conditions have the potential to trend upward through the 4-7 day period as 24 hr Max 10m Gusts increase to a more broad area covering more of the Columbia Basin and as far north as the Kittitas valley Friday into Saturday, when a cold front comes into play scouring out the hot air of the late week.

Record or near record highs and lows are possible given the latest trends of a large amplified western U.S ridge that will extend subsident warm air into Oregon through the week. The ESAT table and shift of tails continues to trend toward an extreme temperatures episode for Oregon with respect to model climatology. Expected temperatures from the NBM mean are in the low 70s across most of the lowlands.mid to upper 70s in central Oregon and hitting around 80 degrees through the lowest basins like John Day and the Deschutes/John Day river valleys. Based on the timing of the strongest winds in the highest elevations of Klickitat county the cold front pushes through around late Friday afternoon or Friday evening, driving mean high temps down 10 to 15 degrees on average between Friday and Saturday.

AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/

Westerly surface winds up to 12 knots across the area Today will broadly slacken overnight to generally light (under 5 knots) and south southwesterly. VFR category is anticipated for all terminals.

Preliminary Point Temps/PoPs

PDT 43 71 47 75 / 10 0 0 0 ALW 49 70 52 72 / 10 10 10 0 PSC 46 73 49 75 / 10 0 0 0 YKM 43 68 46 71 / 20 10 10 10 HRI 43 71 47 75 / 10 0 0 0 ELN 42 60 42 63 / 40 30 10 20 RDM 38 75 41 76 / 0 0 0 0 LGD 42 73 46 75 / 0 0 0 0 GCD 43 74 44 75 / 0 0 0 0 DLS 45 70 47 70 / 0 10 0 10

PDT WATCHES/WARNINGS/ADVISORIES

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