textproduct: Pendleton

KEY MESSAGES

- Breezy to windy through the gaps today and Sunday

- Dry and warm conditions will persist through the week

- Uncertainty in a pattern shift for middle of next week

DISCUSSION

Tonight through Monday: A dry shortwave and surface cold front are moving across the inland PacNW this afternoon, with satellite imagery showing clearing behind the frontal boundary. Breezy west to northwest winds have developed this afternoon across much of the forecast area, with strongest winds occurring in the Kittitas valley at this time. Winds of 15-25 mph with gusts to around 40 mph will continue across much of the region, while winds of 25-35 mph and gusts to around 50 mph will continue to impact the Kittitas valley through this evening.

The aforementioned shortwave and cold front will exit the region early this evening, allowing a persistent upper level ridge to rebound overhead tonight. The upper ridge has kept conditions fairly dry while temperatures have remained around 5 to 15 degrees above normal across the much of the region. These conditions will continue through Monday as the upper ridge continues to influence the region. While winds will be light tomorrow and Monday, a shortwave passing through the ridge on Sunday will bring another round of widespread breezy conditions (15-25mph with gusts 25-40mph). Once again there is growing concern of stronger winds through the Kittitas valley, with moderate-high confidence (70-85%) that wind gusts of 45-50 mph will develop Sunday afternoon in the valley.

Tuesday through Thursday: Most recent run of the cluster ensemble solutions (12Z GEFS, 00Z ENS, and 12Z GEPS) indicate better agreement in upper level ridging persisting across the PacNW, while a closed low begins to develop off the West Coast. This will place the forecast area under a south to southwest flow, promoting further warming into the upper 80s to lower 90s across the lower elevations. There is also a signal for a weak thermal trough to develop into eastern OR, helping with the warming trend at the surface but also introducing unstable conditions that may impact any fires on the landscape.

Tuesday night through Thursday, disagreement grows amongst ensemble guidance in the eventual breakdown of the ridge and upper low/trough passage through the midweek. Solutions range from a trough gliding across the area with showers Wednesday and/or Thursday, or upper level ridging persisting with increasing instability across elevated terrain in the afternoons Wednesday and/or Thursday. Overall forecast confidence in this period is low (20-25%). Lawhorn/82

AVIATION /00Z TAFS THROUGH 00Z SUNDAY/

A surface cold front approaching the region will influence weather from west to east Through Saturday afternoon. Most high clouds have been scoured out maintaining VFR conditions for all terminals. Increasing high pressure will promote loss of gusts this evening with the loss of heating. Russell/71

FIRE WEATHER

High pressure will remain over the region through early next week, promoting warming temperatures and dry conditions. Min relative humidities will generally be in the teens to mid 20s, with locally single digits in central OR. Breezy conditions will continue through today, and redevelop again Sunday. Breakdown in high pressure over the region Tuesday may result in an increasing unstable airmass across central OR and elevated terrain in the eastern Oregon mountains.

HYDROLOGY

Naches at Naches remains above action level and is expected to remain as such into the weekend. (75% confidence)

Preliminary Point Temps/PoPs

PDT 46 77 49 79 / 0 0 0 0 ALW 49 76 52 79 / 0 0 0 0 PSC 48 81 51 84 / 0 0 0 0 YKM 45 80 51 83 / 0 0 0 0 HRI 47 80 50 81 / 0 0 0 0 ELN 41 76 48 74 / 0 0 0 0 RDM 37 83 46 80 / 0 0 0 0 LGD 41 76 45 82 / 0 0 0 0 GCD 39 80 44 87 / 0 0 0 0 DLS 48 83 54 77 / 0 0 0 0

PDT WATCHES/WARNINGS/ADVISORIES

WA...Wind Advisory until 11 PM PDT this evening for WAZ026. OR...None.