textproduct: Pendleton

KEY MESSAGES

- Showers will continue to diminish west to east through this evening as an upper low departs the region

- Breezy winds will develop through the Cascade gaps and Lower Columbia Basin today

- Drying and warming trend through the week will be followed by a potential return to unsettled weather in the mountains over the weekend (confidence 30-40%)

DISCUSSION

Satellite imagery tonight shows an upper level low swinging into ID, with clear skies developing across the western third of the forecast area. Meanwhile, regional radar shows a line of isolated showers from La Grande due north into the WA Columbia Basin and lighter showers over Wallowa county.

Today, the upper low will continue to swing east into the northern Rockies, with showers and cloud cover continuing to diminish west to east across the forecast area. Shower activity will mainly be focused across Wallowa County through this afternoon with a brief renewal in shower development tonight as a secondary low quickly swings across the area.

Tuesday into Wednesday, the forecast area will mostly be under a split flow aloft that'll become zonal ahead of an approaching trough. A drying and warming trend will develop, with afternoon temperatures warming back into the 80s by Wednesday (confidence 65-80%). Thursday, breezy winds will return to the forecast area as an upper trough approaches the region from the north. Winds will generally be 15-25mph with strongest gusts up to 40 mph. Relative humidities will also be low but above critical thresholds across the Columbia Basin and Cascade Gaps during this time, leading to elevated fire weather concerns for Thursday (confidence 55-75%).

Friday into the weekend, ensemble guidance is in good agreement of the upper trough slowly passing over the PacNW, with over 80% of ensemble members (from ECMWF, GFS, Canadian) favoring Saturday for light rain in the lower elevations and light to moderate precipitation in the mountains. That said, disagreement in timing of the trough exit is growing, with 22% of members favoring dry conditions returning by Saturday night, whereas 66% of members favor mountain showers continuing into Sunday. While confidence is moderate (40-55%) in shower activity over the weekend, confidence is low (20-25%) in timing and extent. Otherwise, there is moderate confidence (50-60%) that the upper trough passage will bring cooler conditions to the forecast area. Lawhorn/82

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/

VFR conditions prevail with dry conditions through the TAF period. May get some passing SCT to BKN clouds in PSC/ALW/PDT but not expecting MVFR or below conditions. Otherwise, breezy winds in DLS and PDT through the afternoon hours with winds decreasing by the evening hours.

Preliminary Point Temps/PoPs

PDT 71 44 77 46 / 0 0 0 0 ALW 73 51 78 52 / 20 0 0 0 PSC 76 48 80 49 / 0 0 0 0 YKM 76 51 79 52 / 0 0 0 0 HRI 74 47 80 48 / 0 0 0 0 ELN 71 46 77 48 / 0 0 0 0 RDM 68 38 76 41 / 0 0 0 0 LGD 68 43 75 46 / 20 10 0 0 GCD 67 43 77 46 / 10 0 0 0 DLS 74 52 81 55 / 0 0 0 0

PDT WATCHES/WARNINGS/ADVISORIES

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