textproduct: Pendleton

KEY MESSAGES

- Above normal temperatures and dry conditions Today

- Return of showers and isolated thunderstorms to the eastern mountains Thursday, with breezy conditions in the lower elevations Thursday and Friday

- Moderate to High confidence (60-90%) in freezing morning temperatures Saturday

DISCUSSION

An upper low continues spinning off of the central CA coast, with ridging across the Interior Northwest. As a result, clouds remain high across the central and eastern Oregon counties, with more sun across the Washington zones. Today will be the warmest afternoon across the broader area, and for all elevations, reaching the mid/upper 60s again over the Columbia Basin and Kittitas/Yakima Valleys, to the low/mid 70s across central Oregon/Grande Ronde Valley/John Day Basin. Another day of light and diurnally and terrain driven winds for all zones.

The next weather system will impact the winds due to pressure gradients across the Cascade gaps/Columbia River Gorge. NBM ensemble members show a range of about 50 to 75 percent offering wind advisory level , 39 mph or higher gusts Thursday evening. More mid and high cloudiness will be spreading farther north into WA Tonight and though the morning on Thursday. REFs shows light precipitation associated with a weak orographic / deformation band spreading north (southwest to northeast orientation) off the Blue Mountains, and bringing measurable (less than wetting rains) precipitation across the foothills of the Blues and into the lower Columbia Basin/central Oregon though noon. Better forcing/moisture profiles develop later Thursday and Thursday night and cool air aloft acts to increase instability and bump 3-hr QPF means to the 0.10 and locally 0.25 amounts starting mid evening Thursday in the southern Blues, and ending across the Wallowas sometime mid Friday morning.

Following the exit of the amplified trough, colder air will give another opportunity for freezing temperatures over higher populated areas of the Lower Columbia, and Yakima/Kittitas Valley zones that have not had the season ending freeze just yet. This opportunity comes Saturday morning. Blue Mt Foothills and Kittitas valley, including Walla Walla, Pendleton/Ellensburg have around a 90% chance or higher based on NBM probabilities of sub freezing temps. A bit less certainty exists as Yakima to Sunnyside falls in at about a 50 to 60 percent chance for 32 degrees or colder Saturday morning.

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

VFR conditions to prevail through the period. At the very tail end of the period(16-18Z tomorrow), sites PDT/ALW/RDM/BDN may see light rain showers approach the sites. At this time, chances/confidence too low to include in TAF. Winds will be light, 12kts or less, through the period. Lawhorn/82

Preliminary Point Temps/PoPs

PDT 68 38 61 37 / 0 0 60 50 ALW 68 44 61 41 / 0 0 60 70 PSC 68 36 64 38 / 0 0 20 20 YKM 69 40 68 39 / 0 0 10 0 HRI 68 37 62 38 / 0 0 30 20 ELN 67 37 67 34 / 0 0 10 0 RDM 72 32 63 23 / 0 0 30 10 LGD 74 44 65 37 / 0 0 90 80 GCD 76 43 64 35 / 0 20 90 70 DLS 72 43 70 43 / 0 0 10 0

PDT WATCHES/WARNINGS/ADVISORIES

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