textproduct: Pendleton

KEY MESSAGES

- Lingering light precipitation Today over the Cascade Crest and Northern Blue Mountains.

- Precipitation returning across the mountain areas Monday Night and again by the weekend.

DISCUSSION

Strong gusty winds were noted across higher elevation area above 3500 ft in the Simcoe Highlands This Morning, and other than that, gusty winds in the Blue Mt foothills had subsided overnight. As a low/tough and mid level height gradient moves through BC/WA early this morning, a shortwave midlevel ridge will develop for this afternoon and evening across WA and OR. Cooler temperatures are expected Today in the post cold front air across most of the forecast area, with the exception of the Yakima valley where downsloping winds will have more of an impact on warming temps this afternoon. More broadly breezy winds are expected across the Columbia Basin of Washington This afternoon, with winds going light after sunset. Light rain and snow showers continue across the Cascade Crest Today as well as rain showers in the the Northern Blues amounting to less than a wetting rain.

Winds remain light over most lower elevations Monday afternoon with gusts reaching 20 to 30 mph range in the higher mountain zones. Being a progressive pattern. The next deep upper low rotates toward the BC/AK coast late Monday into Monday Night, dragging an elongated vorticity lobe/upper tough across into the PAC NW and across the Inland Northwest Monday Night through early Tuesday morning. The onset for precipitation will be gradually early to late Monday afternoon, and by mid evening Monday, the 6 hourly based REFS probability matched mean QPF would have wetting rains over the eastern slopes of the Cascades (WA and OR), as well as the northern Blue Mountains. This system again is followed by short timed upper ridging on Tuesday and increasingly southwest flow aloft developing though weekend as a deep eastern pacific trough is carved out by the ensembles. Plenty of agreement between the EC and GFS systems with respect to this synoptic pattern by the weekend, in the general placement of a deep cutoff low/trough off of he the PAC NW coast. How the mesoscale feature resolve into early next week is where a high amount of uncertainty lies in strength and timing of the the shortwaves and resultant precipitation. However from Friday onward into early next week does look to be a wet period, with widespread 20 to 40 percent chances for rains in the lower elevations, and higher probabilities for the mountain zones. Snow levels are generally above 5000 ft AGL for the Cascades and 7000 ft for the the Eastern Mountains.

AVIATION /18Z TAFS THROUGH 18Z MONDAY/

VFR conditions currently across all sites, which will stay the course through the period. Breezy winds at KPSC/KALW/KYKM with gusts of 20-25kts this afternoon, subsiding this evening. 5-7kft ceilings improve through the afternoon as a transient ridge of high pressure builds ahead of the next system. 75

Preliminary Point Temps/PoPs

PDT 58 39 59 43 / 60 0 10 60 ALW 57 43 57 46 / 60 0 10 90 PSC 62 38 57 38 / 10 0 10 50 YKM 58 36 55 36 / 0 0 40 40 HRI 60 39 58 39 / 20 0 10 50 ELN 49 29 50 31 / 40 0 30 70 RDM 54 31 59 37 / 10 0 60 30 LGD 50 37 58 39 / 60 10 10 70 GCD 53 36 60 38 / 20 10 10 60 DLS 57 42 56 43 / 30 0 60 90

PDT WATCHES/WARNINGS/ADVISORIES

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