textproduct: Pendleton

DISCUSSION

Key Points:

1. High Pressure over the region through Saturday.

2. A system will bring precipitation, mainly to the Washington Cascades early next week. Very warm temperatures also early next week.

3. High Pressure re-establishes itself for the remainder of the week.

High Pressure will remain in place over the western CONUS through Saturday. This high will bring dry weather to the region. By Sunday, the ridge will flatten as a weather system moves mainly over the Washington Cascades and will bring precipitation. The precipitation will continue into Monday, before ending on Tuesday.

Snow levels will initially be in the 3000-4000 foot range early Sunday, but they will rise to over 6000 feet by Monday and continue to rise to over 8000 feet by Tuesday. As a result, mostly rain is expected with this event. Over 1 inch, and even close to 1.5 inches of QPF is possible along the crest of the Washington Cascades through Tuesday with lesser amounts further down. This rain, which is picked up by the ECMWF EFI would be in the 70th to 80th percentile during this time. QPF did come up a bit with the 12Z run, so will continue to monitor. The Naches River at Cliffdell is expected to get just above Action Stage by early next week and the Naches River near Naches gets close to Action Stage. These forecasts will also be monitored. Current forecasts along the Yakima River keep them all below Action Stage, though they all rise.

Southerly winds will also become gusty Saturday and Sunday across the Grande Ronde Valley, mainly in the 25 to 30 mph range, but at this point, wind advisories do not look to become necessary.

After Tuesday, a large and strong area of high pressure sets up through at least the end of the week. This will continue dry weather over the region. Depending on the location of the high and if cold air is trapped beneath it, there could end up being fog/stratus/air stagnation issues in the long term.

High temperatures Monday through Wednesday will be in the 50s in many lower elevation areas Monday and Tuesday and may push 60 degrees in central Oregon. These temperatures would be 10 to 15 degrees above normal and could be as much as 20 degrees above normal in some locations.

The ECMWF EFI has most of Oregon and Washington in 0.8 to 0.9 anomalies for high temperatures Tuesday and Wednesday, with some embedded areas of 0.9 to 0.95. On Monday the area is focused mainly across the Columbia Basin, and by later in the week, the areal coverage shrinks, but still exists across portions of central and eastern Oregon.

AVIATION

00z TAFs...VFR conditions expected through the period. Winds will be light and terrain-driven, with sct-bkn mid-level cigs during the evening becoming more ovc overnight. 74

PRELIMINARY POINT TEMPS/POPS

PDT 30 49 30 49 / 0 0 0 0 ALW 34 48 33 47 / 0 0 0 0 PSC 29 45 29 44 / 0 0 0 0 YKM 30 43 30 44 / 0 0 0 10 HRI 30 45 29 46 / 0 0 0 0 ELN 26 39 29 40 / 0 0 10 30 RDM 26 50 26 52 / 0 0 0 0 LGD 27 42 30 43 / 0 0 0 0 GCD 27 47 28 49 / 0 0 0 0 DLS 33 45 33 46 / 0 0 0 10

PDT WATCHES/WARNINGS/ADVISORIES

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