textproduct: Pendleton

KEY MESSAGES

- Cooler, breezy, and showery weather is likely (99 percent confidence) Today into the weekend

- Chance (25-40 percent) of thunderstorms for the Blue Mountains after 2 PM Today, with a very low chance (5-14 percent) to slight chance (15-24 percent) elsewhere

DISCUSSION

A compact shortwave will slide down the backside of a larger scale upper low over the Columbia Basin through Sunday, carving a deeper trough into the Northern Rockies by Sunday Night. This will bring a 22 deg C pool of 500 mb level air across the area over the weekend. Based on NBM members afternoon highs will be limited to the 60s and low 70s from central Oregon though the Columbia River Gorge and the Lower Basin. The instability induced by the cold air aloft will limited to under a couple of hundred joules/kg across the eastern mountains This Afternoon, but still be adequate for HREF Thunder probabilities to print 10 to 40% chances on a 1 hourly basis from about 2 to 6 pm.

Cold advection and orographic lift induced from surface westerly flow will lead to mountains rains (wetting rains) on the order of one to three tenths of an inch along the Cascades Crease and Upper Eastern slopes Today and Tonight. The eastern Mountains can see a quarter of an inch as more of a lower bound with potential for one half to one inch near Wallowa National Forest/Summits Ridge/Hells Canyon. Showers will linger Saturday and Sunday as the upper cold pool moves east of the region by Monday resulting in decreased clouds, more sun and rebounding temperatures back into the 80s.

Although breezy to marginally windy conditions will be expected each day though the gaps, valleys and lower elevations, Sunday looks to be potentially the windiest day with potential for widespread 40 to 50 mph gusts across the Oregon Columbia Basin/Eastern River Gorge, Simcoe Highlands and Kittitas Valley, as wind pattern that could be repeated into early next week.

Longer range ensemble members have a general agreement moving into the first few days of July with the redevelopment of a trough alone the PAC NW, with clustering differences between a closed low Near NW WA or higher heights (warmer and slightly more sharp trough as in cluster # 2. Largest difference are between clusters 2 and 4 by Day 8 that can be the differences between widespread wetting rains across the Cascades to a warmer a dry pattern for the entire region. Russell/71

AVIATION /18Z TAFS THROUGH 18Z SATURDAY/

MVFR to VFR conditions expected through the period. Showers will continue to impact site PDT through the next hour, with showers ending at site ALW around 20Z. Prevailing showers will return to site PDT late this afternoon around 23Z, and persist through 3Z. There is a 10-20% chance of thunder embedded in these showers. Otherwise, A 30% chance of showers have been included at sites RDM/BDN/ALW for late this afternoon. Breezy winds will develop at all sites this afternoon, becoming light late this evening and overnight, except at site PDT where breezy winds will continue overnight. Expect breezy winds to redevelop mid to late morning tomorrow at sites DLS/RDM. Lawhorn/82

FIRE WEATHER

Fire risk is being suppressed by cooler temperatures rendering high overall relative humidity as well as wetting rains across the higher elevations. The biggest risk will be lighting this afternoon across the Blue Mountains from about 2 pm though 6 pm. Wetting rains are expected to be associated with these shower an and storms. Limiting the fire risk, with an average of one quarter inch to as much as one inch on a 24 hour basis ending This Evening. We will still see breezy to windy conditions across the gaps and lower elevations over the next several days. Russell/71

Preliminary Point Temps/PoPs

PDT 74 47 69 46 / 80 50 0 10 ALW 75 53 71 51 / 60 30 10 10 PSC 80 52 75 50 / 40 0 0 0 YKM 79 50 74 50 / 10 0 0 0 HRI 78 50 73 48 / 50 10 0 0 ELN 71 46 67 46 / 30 0 0 10 RDM 70 40 62 35 / 30 10 20 10 LGD 69 47 63 44 / 100 90 30 30 GCD 71 43 62 39 / 100 90 70 40 DLS 75 53 70 52 / 20 10 10 10

PDT WATCHES/WARNINGS/ADVISORIES

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