Sunrise 6:06 AM   Sunset 7:56 PM Moonrise 1:46 PM   Moonset 3:31 AM

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FXUS66 KPDT 190000 AFDPDT

Area Forecast Discussion National Weather Service Pendleton OR 500 PM PDT Thu Apr 18 2024

Updated Aviation Discussion

AVIATION
00Z TAFs...VFR conditions over the next 24 hours. SCT high clouds possible BDN/RDM, clear skies all other sites. Winds occasionally breezy this afternoon all sites, but dominant winds should be around 5-15 knots becoming less than 10 knots overnight, with gusts 15-20 knots tomorrow expected primarily at YKM.
Goatley/87

PREV DISCUSSION
/issued 158 PM PDT Thu Apr 18 2024/

SHORT TERM...
Tonight through Saturday night... Dry northwesterly flow will be in place tonight through Friday. A ridge will move over the Pacific Northwest Friday night and early Saturday before moving eastward later Saturday into Saturday night.

An upper level low will move to the north, generally over British Columbia and Northern Washington by Sunday morning. The flow will become more zonal or even slight troughing as a result, and the pressure gradient will tighten.

There will be some breezy conditions tomorrow mainly over the western sections of the Oregon Basin and then the Simcoe Highlands.
the NBM probabilities of winds gusting >=39 mph on Friday are 50 to 60% across the Simcoe Highlands and 30-50% across the western Columbia Basin of Oregon. Winds will increase again Saturday evening and continue into Saturday night, with wind gusts 30 to 40 mph mainly during this time across the Simcoe Highlands, Yakima Valley, Columbia Basin, and Foothills of the Blue Mountains. NBM wind gusts probabilities >=39 mph are 50-80% in the Simcoe Highlands, Yakima Valley and and 40 to 60% in the Columbia Basin and Blue Mountain Foothills. NBM wind gust probabilities >=47 mph drop to 40 to 50 % across the Simcoe Highlands and Yakima Valley and less than 20% most elsewhere.

Dry conditions are expected everywhere through later Saturday.
Then, some precipitation will impact the Cascades. Snow levels will initially be over 7000 feet in the Oregon Cascades and over 5000 feet in the Washington Cascades, so any precipitation will be all rain, except at the highest peaks of the Washington Cascades. However, snow levels will fall through Sunday morning and will be around 3000 feet, so there could be some very light accumulations (less than 1 inch) accumulations at pass level and perhaps a couple of inches at the higher elevations.

Elsewhere by Sunday morning, precip chances increase by Sunday morning. However, QPF values are fairly light generally only a few hundredths. It is also interesting that most of the deterministic NAM is quite dry, with the GFS and ECMWF wetter.

Temperatures will be cold again tonight but look warmer than last night. With that said, will hold off on any freeze warnings at this time as widespread freezing conditions do not appear likely at this time, except for the Kittitas Valley. There could be some spotty areas that reach below freezing and this will continue to be watched. The NBM probabilities for low temperatures <=32 degrees at Hermiston is about 25%, about 10% at Pendleton, about 30% at Yakima and upwards of 90% at Ellensburg.

Highs will be close to normal on Friday, then a few degrees above normal on Saturday. Overnight lows should begin to warm up a bit as well.

LONG TERM...
Sunday through Thursday...A shortwave passing along the Canadian border on Sunday will provide a few showers to the mountains but otherwise cool and dry with some breezy to windy westerly winds.
This will be followed by the rebuilding of an upper level ridge over the region providing dry seasonal conditions Monday and Tuesday. The ridge moves off to the east Tuesday night as an approaching upper level trough comes onshore. This trough will be splitting with some energy dropping south towards California. The northern portion will move inland along the Canadian border on Wednesday followed by a deepening upper level trough over the region on Thursday. This will increase the possibility of precipitation on these days but with snow levels remaining 5000 feet or higher.

PRELIMINARY POINT TEMPS/POPS
PDT 32 63 35 66 / 0 0 0 0 ALW 34 67 37 70 / 0 0 0 0 PSC 37 69 40 71 / 0 0 0 0 YKM 33 64 35 67 / 0 0 0 0 HRI 34 68 37 70 / 0 0 0 0 ELN 32 61 34 64 / 0 0 0 0 RDM 28 62 34 69 / 0 0 0 10 LGD 30 61 34 69 / 0 0 0 0 GCD 30 64 36 73 / 0 0 0 10 DLS 39 67 42 68 / 0 0 0 0

PDT WATCHES/WARNINGS/ADVISORIES
OR...None.
WA...Freeze Warning from 2 AM to 9 AM PDT Friday for WAZ026.

Ellsworth, Washington - IGNORE HEIGHTS, Tide feet

Vancouver, Washington - IGNORE HEIGHTS, Tide feet

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