Granger, WA 98932 Weather

.Updated Aviation Discussion.

Key messages

- Near- to below-normal temperatures through the weekend.

- Periodic showers through the week, then medium-high (40-80%) chance of precipitation for central/eastern Oregon and southeast Washington over the weekend.

Discussion

An upper low off the Washington coast continues to be the source of scattered rain and snow showers across the Washington Cascades Today. Radar reflectivity has been relegated to areas along the Upper Slopes of the WA Cascades and the Crest as well as light showers exiting the Lower Columbia Basin into northeast WA. Trends will continue to be downward through the afternoon. Meanwhile, satellite had been indicating low stratus and fog along the Eastern Columbia River Gorge and the Kittitas valley where METARs reported dense freezing fog through the entire morning. By 1PM the stratus and vsby began showing signs of improving beyond one quarter mile.

The main challenge Tonight will be if fog redevelops across the Kittitas valley and to what extent. Recent runs of the LAMP guidance have shown extended low visibility for not just Tonight but through the day on Friday. A glance a the raw vs bias corrected min temps are different enough that the cold tail of the raw output is overlapping the expected 25th to 75th of the bias corrected). Went away form NBM temperatures for Tonights forecast in favor of the HRRR for potentially a much better overnight temperature forecast.

Freezing temperatures in the the Eastern Columbia River Gorge are are not showing a strong signal for a season ending freeze as NBM 6 AM Saturday QMD Temps range form 32 to 36 degrees on the 25th to 75th percent box and whiskers. Trends also show increasing cloud cover, and adjusting this, would put a freeze/subfreezing event at best less than 50% probability needed for a freeze watch, especially given the previous concerns with bis corrections in the NBM.

The next appreciable period of precipitation returns centered on Saturday Night and Sunday Morning across the eastern mountains, with averaging precipitation amounts less than a wetting rain in the valley floors and higher one to three tenths of an inch in the highest elevations. Some of this will be light snow accums above 5500 ft AGL.

Aviation

VFR conditions currently across all sites, which will stay the course through the period. Ceilings will drop tonight for KDLS and KYKM, with KDLS dropping to just above MVFR criteria. Winds will stay light and below 10kts for all terminal through Friday afternoon. 75

.Preliminary Point Temps/PoPs: PDT 35 49 30 49 / 0 0 10 10 ALW 37 50 34 49 / 0 0 10 10 PSC 38 54 29 53 / 0 0 0 0 YKM 37 53 28 53 / 10 30 0 10 HRI 38 52 28 50 / 0 0 0 0 ELN 34 48 22 48 / 10 40 0 10 RDM 28 50 20 46 / 0 0 0 20 LGD 36 58 30 54 / 0 0 10 30 GCD 35 57 32 55 / 0 0 0 20 DLS 45 55 32 54 / 0 20 0 10

Watches, warnings and advisories

WA: None. OR: None.