103 FXUS66 KPDT 160911 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 211 AM PDT Thu May 16 2024 .SHORT TERM... Today through Saturday night... High pressure off the coast will be suppressed to the southwest later today and tonight by a strong shortwave and upper level trough that will drop down from the northwest. This trough and shortwave will move across the area tonight into Friday morning before moving east of the region. Another shortwave will move across mainly eastern sections of the area on Friday. Dry northwesterly flow will return for Friday night into early Saturday before yet another trough and shortwave move southeastward across Washington during the day on Saturday into Saturday night. As the trough approaches, it will bring precipitation first to the Washington Cascade crest, then to the Oregon Cascade crest and Blue Mountains. QPF is expected to be light, only a few hundredths, with the exception of the Washington Cascades which could see over a tenth of an inch and possibly up to 0.20 inches. Snow levels will start off over 8000 feet, but by Friday morning will be around 3000 feet in the Washington Cascades and 4500 to 5000 feet elsewhere, so it is possible there could be some very light snow at or above these levels. The biggest concern continues to be gusty winds ahead of and with the passage of the trough. Based on the latest data, a wind advisory will be issued for the Kittitas Valley, Simcoe Highlands, Oregon Columbia Basin, Columbia Gorge, and Oregon Foothills of the Blue Mountains. Winds of 25 to 35 mph with gusts 40 to 50 mph are expected. NBM probabilities of wind gusts >= 39 mph are 90 to 100% in these areas today. NBM probabilities of wind gusts >= 47 mph range from 60 to 80% in these areas. The ECMWF EFI has these same areas generally in 0.6 to 0.7, with some embedded locations of 0.7 to 0.8. Breezy conditions are expected to continue behind the trough as well through much of Friday, and winds will increase with the approach of the next shortwave later Friday into Friday evening. Breezy to windy conditions will occur again on Saturday with the approach of the next trough on Saturday. Additional precipitation, mainly over the mountains is possible later Saturday into Saturday night, but QPF should be less than the event tonight into Friday. High temperatures will be about 10 degrees above normal today, but then will drop to near normal on Friday and Saturday. .LONG TERM... Sunday through Thursday...Models coming into better agreement on what looks to be a relatively active pattern through most of next week, filled with chances for showers and potentially mountain thunderstorms as a couple of upper-level lows look to impact the region. For Sunday, the forecast area will fall on the southern flank of an ongoing low situated over western Canada, inviting a band of amplified NW flow over the PacNW. Light orographic shower activity is possible across the crests of our mountain zones, however chances are on the lower end (20-30%) as the western Canada low will help usher in a pretty dry airmass overhead through much of the weekend, with PWATs reading in the 0.3 to 0.5 inch range. Such a pattern will invite breezy winds across the Cascade Gaps as well, namely through the Columbia River Gorge, Kittitas Valley, and Simcoe Highlands. Better chances for area-wide showers look to occur later in the work week as a well-developed upper-level low is shown dropping down into the forecast area from the Gulf of Alaska by around Tuesday. Given this system's northwesterly approach, not expecting particularly heavy rain, but lift will be much more supportive for shower activity Tuesday into Wednesday. Some of these showers may develop into thunderstorms across primarily the eastern mountains, should lift prove to be suitable enough, however the pattern thus far doesn't look to be conducive for particularly strong storms, as temps will be right at or just below seasonal averages under this NW pattern, which would mean generally 50s and 60s for daytime highs across the eastern mountains. QPF guidance isn't particularly precise this far out, but NBM does depict widespread PoPs in the 25- 50% range Tuesday into Wednesday, increasing across our mountain zones. Ensembles and deterministic guidance are a bit shaky beyond the midweek next week, as to be expected under a relatively progressive pattern, but ensemble clustering does hint at continued troughing across the PacNW. Expect a continuation of persistent shower chances, roughly seasonable temps, and breezy winds should these ensemble members verify. Evans/74 && .AVIATION... 12z TAFs...VFR conditions expected, with the main concern through the period being gusty winds across all sites. By the late morning, winds will pick up primarily out of the west, gusting up to and even over 30 kts at times, especially for DLS and PDT, where winds are expected to be the strongest. Skies will generally be clear outside of some high clouds. Gusty conditions are expected to carry over into the overnight hours and pick up once again heading into Friday. Evans/74 && .PRELIMINARY POINT TEMPS/POPS... PDT 77 44 65 40 / 0 10 0 0 ALW 80 48 68 45 / 0 20 0 0 PSC 85 50 72 45 / 0 10 0 0 YKM 80 39 70 39 / 0 0 0 0 HRI 82 47 70 44 / 0 10 0 0 ELN 72 40 63 42 / 10 10 0 0 RDM 78 42 65 34 / 0 0 0 0 LGD 77 45 60 36 / 0 10 0 0 GCD 79 46 62 36 / 0 0 0 0 DLS 74 49 67 45 / 0 0 0 0 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...Wind Advisory from 11 AM this morning to 11 PM PDT this evening for ORZ041-044-507. WA...Wind Advisory from 11 AM this morning to 11 PM PDT this evening for WAZ024-026-521. && $$ SHORT TERM...77 LONG TERM....74 AVIATION...74