Area Forecast Discussion
Issued by NWS Portland, OR

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000 FXUS66 KPQR 232307 AFDPQR Area Forecast Discussion National Weather Service Portland OR 306 PM PST Wed Jan 23 2019 .SYNOPSIS...After some lingering light rain and drizzle today, high pressure building over the northeast Pacific will likely bring dry weather and mild temperatures into at least early next week. && .SHORT TERM...This afternoon through Saturday...Radar this afternoon shows some very light rain, or likely drizzle across the area. This precip should taper off for most areas by this evening as upper heights begin to increase with ridging moving into the area. With rain last night and somewhat continuing today and high pressure moving in, would generally expect fog tonight. However, models are fairly insistent on some lingering low clouds which could prevent fog formation. Have included patchy fog in the forecast nonetheless for the coast and interior lowlands with all of the surface moisture present. Models suggest a shortwave trough dropping southeastward across the Inland Northwest Thursday evening and overnight, likely bringing a brief increase in high clouds. There is an outside chance of light rain across our far northern zones, but not even a high enough chance to mention in the forecast. Upper ridging will then become more solidly entrenched across the Pacific Northwest Friday and Saturday. This should result in areas of valley morning fog and mild temperatures. Weak offshore flow on Saturday, especially at the coast, may result in the central Oregon coast and portions of the Coast Range and Cascade foothills warming well into the 60s on Saturday. Inland, temperatures will likely warm some, but not as much as at the coast, also limited by any lasting fog or low clouds which develop overnight. Bowen .LONG TERM...Saturday night through Wednesday...Models remain in good agreement that a large ridge of high pressure will linger over the northeast Pacific into early next week. This will allow the multi-day stretch of dry weather to continue, with mild temperatures and areas of late night and morning valley fog. There is still a chance that a weak shortwave dropping south out of British Columbia late Sunday into Monday will bring cooler air to the Columbia River Basin. This will allow offshore flow to strengthen on Monday and could produce a weak downslope wind event. Conditions may start to change towards the middle of next week as some models/ensemble members continue to show a series of weak disturbances moving across the forecast area. Will keep slight chance PoPs in the forecast for now, but there is still a lot of uncertainty. /64/Neuman && .AVIATION...Primarily VFR across SW WA/NW OR this afternoon, though a few showers and patchy MVFR/mountain obscurations persist. Coastal areas remain MVFR with a few patches of IFR. MVFR cigs are expected to redevelop overnight inland, with some areas of fog for the more fog-prone terminals such as KHIO and KEUG. Fog should also develop tonight for the coastal valleys and may impact KAST, KTMK, and KONP. With light winds and a stable air mass, expect conditions to be slow to improve Thursday with low cigs persisting well into the day. KPDX AND APPROACHES...Mixed VFR/MVFR conditions on KPDX approaches this afternoon and early evening. MVFR cigs likely to redevelop tonight, but if they do not develop, there may be some areas of fog Thu morning. Winds will generally remain below 10 kt through Thursday. Weagle && .MARINE...High pressure is building into the Pac NW and will likely dominate through the weekend. Late spring or early summer- like pattern develops Fri/Sat with thermal low pressure building northward along the coast and increasing N wind across the waters as a result. Westerly swell peaked this morning around 15 feet and has come down to 10-12 feet this afternoon. Expect seas to fall below 10 ft later tonight/early Thu morning, so current timing of SCA for seas to expire around 4 AM still looks good. Very strong ebb will result in very rough conditions on area bars this evening. Weagle && .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...Small Craft Advisory for hazardous seas until 4 AM PST Thursday for Coastal Waters from Cape Shoalwater WA to Florence OR out 60 NM. Small Craft Advisory for Rough Columbia River Bar until 10 AM PST Thursday. && $$ Interact with us via social media: www.facebook.com/NWSPortland www.twitter.com/NWSPortland This discussion is for Northwest Oregon and Southwest Washington from the Cascade crest to 60 nautical miles offshore. This area is commonly referred to as the forecast area.

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