textproduct: Pendleton

KEY MESSAGES

- Rain chances increase into the weekend with mainly highland and mountain thunderstorms in Oregon Friday into Saturday.

- Cooler, more seasonable temperatures Sunday into next week.

DISCUSSION

A dry and mild setup continues Today as high pressure dominates the sensible weather with warm temperatures once again in the 60s and 70s. Some of the warmer areas will again be the Grande Ronde, Yakima and Kittitas valleys, central Oregon and the Lower Columbia Basin where temperatures nearing or surpassing the 70 degree threshold will be likely based on the the bulk of the NBM MaxT members. Areas from Yakima to Toppenish and Sunnyside have a 60 to 70% chance of exceeding 70 degrees This Afternoon. Likewise the Tri-cities is most likely to be in the low 70s at 80% chances.

In addition to the warm conditions a general thunderstorms risk outlook shifts inland and northward over the next 2-3 days maximizing on Saturday with the highest risk for thunderstorm impacts over central Oregon and the eastern mountains. For This afternoon, increasing MUCAPEs and SBCAPEs of an average of 250 J/kg is limited in areal coverage to the central Oregon areas late in the day, and quickly diminishing with the loss of peak heating. In addition the shear is there for brief organization, at 200-300 m2/s2 0-3km SRH. As a low off the Pacific coast moves inland, Friday's MUCAPES increase and expand across a larger areas including the John Day Highlands and eastern Mountains, as HREF 4-hour based thunderstorms probabilities ramp up from 20 to 50% between about 1 and 6 pm in these areas. By Saturday morning, there is a 95% and 70% chances respectively for wetting rains (one tenth of and inch or more) across the Eastern Slopes of the Oregon Cascades, and the Ochoco/JohnDay Highlands with a 50% chance extending across the Blue Mountains as far north as the Tollgate area. By Sunday morning,the 48 hour based total mean rainfalls from the NBM are right about 0.4 to 0.5 inches across these mountains and highland areas, and at least wetting rains over the Basins and Valleys. By Sunday these thunderstorm probabilities are once again minimal (sub 10%) over the broader area, although some lingering 15-20% chances are forecast based on NBM ensembles across the northern Blue Mountains.

AVIATION /12Z TAFS THROUGH 12Z FRIDAY/

High pressure still influences the region as most sites have no low or even mid level cigs through the TAF and light surface winds. RDM and BDN has a 15-20% chance for showers later in the afternoon.

Preliminary Point Temps/PoPs

PDT 69 42 67 45 / 0 0 20 40 ALW 69 45 67 50 / 0 0 20 50 PSC 73 43 72 48 / 0 0 10 40 YKM 70 43 72 46 / 0 0 0 30 HRI 72 42 70 47 / 0 0 10 40 ELN 66 39 68 45 / 0 0 0 30 RDM 70 39 66 40 / 20 40 40 70 LGD 69 41 69 44 / 0 0 40 60 GCD 71 44 64 43 / 20 20 80 70 DLS 74 48 72 51 / 0 10 10 60

PDT WATCHES/WARNINGS/ADVISORIES

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