textproduct: Pendleton

DISCUSSION

Current radar shows some returns over the Cascades primarily focused along the WA. Cascades. Some lingering returns over the Northern Blues as well. Ground observations show light precipitation amounts have fallen over the last three hours of 0.01. Webcams do show wet roads along Snoqualmie Pass and the 84 corridor, but cannot distinguish and precipitation falling in the camera footage along the 90. However, cameras in the Tollgate and Spot Springs area show precipitation still falling. Models show that the mountain snow will continue through the early morning with raw ensembles showing a 40-60% probability of up to another 3 inches falling by 7 AM through the WA Cascades and the Northern BLues below 4500 ft. Winds will also remain a bit on the breezier side through the early hours as well with some areas seeing sustained winds between 10-15 mph with gusts of 25-30 mph.

Once the remnants of the system move to the east, models show the leading edge of an upper level ridge moving into the region. Models show some lingering mountain showers will persist Saturday with the majority of the precipitation over the OR Cascades, eastern mountains and the Blues with 80-90% of the raw ensembles in agreement that snow accumulations of 1-1.5 inches of snow will accumulate Saturday. By Saturday night and into Sunday, models show the ridge to be pushing in with the axis just off the coast a models show it to continue to remain overhead through Thursday night. With the cold air that came into the region the last few days coupled with the incoming high pressure, pattern recognition of the area lets us know that the biggest weather concern while under the high pressure will be fog. Looking at raw ensemble visibilities, they already show the effects of the system with lower visibilities could plague the region as soon as Sunday (20-30% confidence). Dense fog and freezing fog will be the primary concern through mid-week (50-60% confidence).

Thursday models show the ridge to begin to break down as an upper level begins to dig in from the northwest. Clusters show that there is a difference in the model solutions mainly with the timing and amount of precipitation this next event will bring. Regardless of those solutions, models are in agreement that there will be a change in the weather pattern as the weekend approaches. 90

AVIATION...12Z TAFs

VFR conditions ill prevail through the forecast period. The main concern will be with the winds as they continue to be breezy at most TAF sites. DLS/PDT/RDM/ALW/PSC are all seeing winds between 10-15 kts with PDT and DLS seeing gusts nearing 30 kts. Models show these winds to remain through 14-16Z or later. Winds in the aforementioned sites will remain near 10 kts even after 16Z. PSC will see a decrease to below 10 kts after 16Z while YKM is the only site seeing winds below 5kts and models show the site to remain calm through the period. 90

PRELIMINARY POINT TEMPS/POPS

PDT 40 25 38 23 / 30 10 0 0 ALW 38 26 37 25 / 50 10 0 0 PSC 43 22 37 22 / 0 0 0 0 YKM 40 21 36 21 / 0 10 0 0 HRI 43 24 38 23 / 10 0 0 0 ELN 35 19 32 21 / 0 10 0 0 RDM 39 19 39 20 / 0 10 0 0 LGD 33 23 35 22 / 60 0 0 0 GCD 34 22 38 22 / 30 0 0 0 DLS 45 30 40 28 / 10 10 0 0

PDT WATCHES/WARNINGS/ADVISORIES

OR...Winter Weather Advisory until 7 AM PST this morning for ORZ502- 509.

WA...Winter Weather Advisory until 7 AM PST this morning for WAZ030- 522.