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SYNOPSIS

Overall expect the continuation of a progressive southwesterly flow pattern into early next week with weak weather disturbances arriving every ~24-48 hours. Due in-part to warmer than normal temperatures and the weak nature of these weather systems, limited weather related impacts are anticipated over the next 4-7 days. Starting Tuesday into the middle of next week confidence increases in the return of a drier weather pattern although there is some uncertainty as to just how long this change may last.

LONG TERM...Sunday night through Thursday

An upper-level shortwave and accompanying cold-frontal boundary will likely be moving across the Pacific Northwest Sunday evening to begin the extended period with deterministic and ensemble models quickly progressing it to our northwest. Model uncertainty grows starting on Monday in regards to another shortwave trough attempting to moving into the region. A more amplified shortwave feature would increase our precipitation chances locally but several solutions like what is shown in the 12z Canadian bounces it well to our north. Headed through the remainder of next week the latest ensemble cluster analysis indicates another large ridge of high pressure building over far western CONUS which would usher in dry conditions. While there is better agreement resolving the placement of this feature today compared to yesterday, there is still some variance in the exact location of the ridge axis. In any case confidence is growing for easterly winds to develop through the Cascades Gaps and Columbia River Gorge in the Wednesday/Thursday time period next week. The earliest ensembles hint at the return of some precipitation would be late next week into next weekend assuming the ridge builds overhead as expected. -99/19

AVIATION

Rain has ended across the area Friday evening as a warm front continues lifting northward into northwest WA. Cigs have also lifted to above 8-10 kft in most locations. However, scattered clouds around 200-300 ft have developed from KSLE to KEUG with surface visibilities lowering to around 1-3 SM as fog tries to develop. This is in response to a brief period of clearing that occurred Friday evening over southern portions of the Willamette Valley, coupled with light winds. KHIO is also observing occasional visibility reductions down to 1-3 SM. While visibilities as low as 1/2 SM cannot be ruled out at KSLE, KEUG, and KHIO, it appears visibilities should stay around or above 1 SM the majority of the time tonight. In addition, high clouds are expected to fill back in by 10-12z Friday over the southern valley, which will likely bring improving visibilities. Overall confidence in the exact timing visibilities will lift at KSLE, KEUG, and KHIO is low.

After 12-15z Friday, the next frontal system will approach the coast, bringing low-end VFR cigs and widespread rain. By 18z Friday, there is a 80% chance cigs will fall below 3000 ft along the south WA/north OR coast, and an 80% chance at KONP by 21z. While rain will also spread into the Willamette Valley after 18z Friday, VFR cigs will most likely continue for the inland terminals.

Winds are trending light and variable around 5 kt or less tonight, except from KPDX to KTTD where easterly to southeasterly winds continue, strongest at KTTD with gusts up to 25 kt. Will note that with the next frontal system, stronger southwest winds of 35-45 kt at 2 kft and lighter winds at the surface may result in low level wind shear. While speed shear will be the main concern for most terminals, KPDX and KTTD will see both speed shear and directional shear.

KPDX AND APPROACHES...Expect a break from rain tonight with VFR cigs. Southeasterly winds at the surface and southwest winds around 2 kft may result in low level wind shear beginning mid to late Friday morning as rain redevelops. -23/10

MARINE

Another frontal system will move through the waters tonight, maintaining breezy southerly winds. Buoy observations as of early Thursday afternoon show seas of 14-16 ft at 13-14 sec, with seas forecast to gradually subside this evening. Hazardous Seas Warnings remain in effect for all waters including the Columbia River Bar until 7 PM tonight.

As the front moves through tonight, expect southerly winds to peak around 20-25 kt with gusts up to 30 kt. Occasional gusts up to 35 kt are possible, mainly for the outer waters (10+ NM offshore). Chances for widespread and frequent Gale force wind gusts of 34 kt or stronger are only around 20-40%. Since confidence was not high enough, Gale Warnings were not issued for tonight's system. Instead, Small Craft Advisories are in effect from 7 PM this evening through 7 PM Friday. There is high confidence (>90% chance) for seas remaining above 10 ft through Friday night and a 50-80% chance for seas exceeding 13 ft, with the highest chances 20+ NM offshore.

Potential for small craft conditions continue through the weekend before more benign marine weather returns next week. -10

BEACH HAZARDS

A long period westerly swell of 14-16 ft at 14-15 seconds will result in a high threat for sneaker waves through this evening. Waves can run up significantly farther on a beach than normal, including over rocks and jetties. Sneaker waves can suddenly knock people off of their feet and quickly pull them into the frigid ocean which may lead to serious injury or drowning. Caution should be used when in or near the water, especially those who will be razor clamming this week. -10

PQR WATCHES/WARNINGS/ADVISORIES

OR...None. WA...None. PZ...Small Craft Advisory until 7 PM PST Friday for PZZ210-251>253- 271>273.