Sunrise 5:35 AM   Sunset 8:36 PM Moonrise 11:38 AM   Moonset 1:38 AM

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FXUS66 KPQR 160442 AFDPQR

Area Forecast Discussion National Weather Service Portland OR 942 PM PDT Wed May 15 2024

Updated aviation discussion.

SYNOPSIS
High pressure is beginning to break down as a weak trough begins to ascend from the Gulf of Alaska on Thursday.
While a pattern shift is in store, precipitation will be minimal. Zonal flow follows which will keep the weather mild and dry.

SHORT TERM
Now through Friday...Marine stratus is has burned off for the most part, with the exception of some areas near the central coast. Winds remain breezy at the coast, with NW gusts up to 25-30 mph, but all inland areas are seeing fairly light winds. High pressure continues, but is in the process of moving out of the area. The rest of the week sees slowly cooling temperatures, with some very insubstantial showers possible in SW Washington and the northernmost parts of Oregon as a trough slowly descends from Vancouver Island. Highs today will be around the low 80s in the Willamette Valley, but these drop closer to 70 on Thursday as the trough begins to impact the area.

Thursday sees more of a shift to onshore flow, further supporting cooler temperatures. Any showers accompanying the trough will be very light and insubstantial, and most areas should still just remain dry.
With the switch to onshore flow, winds will increase through the Gorge as west winds pick up. By Thursday evening, wind gusts along I-84 will gust up to around 40 mph, with exposed areas at higher elevation could reach closer to 50 mph. These will begin to calm by late morning Friday. Friday's temperatures will be a few degrees cooler than Thursday, and there is around a 15% chance of some light rain showers in SW Washington only as the trough continues to approach. /JLiu

LONG TERM
Saturday through Tuesday...Zonal flow begins to settle in, ahead of the next trough that looks to arrive by Sunday.
Temperatures will settle out and stay fairly consistent through Saturday, maybe a degree or two cooler each day. Another low pressure system will move over Canada extending a trough over the west. This trough will bring another round of precipitation and a gradual cool down. The ridging to the east though will cause winds to amplify. Through the Columbia River Gorge we could see some gustier winds on Saturday.

NBM ensemble guidance is beginning to skew more towards the trough beginning to enter the area on Sunday, though uncertainty remains as to how long it will last. However, 75th percentile temperatures from Sunday through Tuesday have lowered to around 65-70 degrees. WPC Cluster guidance shows 60% chance of relatively stronger ridging remaining in the area through Tuesday, while the remaining 40% show a return to more zonal flow. Seems slightly more like that we skew towards a slightly more active pattern through mid next week. /JLiu

AVIATION
Marine stratus is forecast to impact the coast through the forecast period, though there will likely be a brief break for the central Oregon Coast from 18Z Thu through 03Z Fri. LIFR to IFR marine stratus will clinging to the beaches through around 18z Thu before lifting to MVFR conditions. Will see stratus push into the west slopes of the Coast Range after 06Z Thu with IFR conditions continuing through Thursday morning. North to northwest wind, generally less than 10 kts.

For inland areas, predominately VFR conditions expected through the TAF period. However, with onshore flow, expect to see MVFR cigs moving up the lower Columbia River into southwest WA and the north Willamette Valley after 10Z Thu. This pattern of northwest winds in the low level suggest a stratus deck could back build from near the west end of the Gorge into the Portland Metro area.
Could also see MVFR stratus build in portions of the rest of the Willamette Valley. Details on flight conditions for PDX below, but for the rest of the Willamette Valley, there is 40-50% chance for MVFR 12-18Z Thu reaching KUAO, and a 30-45% chance for MVFR 14-18Z in the KSLE and KEUG area.

PDX AND APPROACHES...Predominately VFR flight conditions to continue over the next 24 hours. That being said, there is a 50-80% chance for MVFR cigs 11-18Z Thu and a 20-30% chance for IFR cigs 11-16Z Thu in the PDX area. For KTTD, probabilities are 70-85% for MVFR conditions and 30-50% for IFR conditions 10-20Z Thu. VFR expected to prevail after 18-19Z Thu. Expect north to northwest winds less than 10 kts. -mh/HEC

MARINE
High pressure continues over the waters today, resulting in a typical summertime northerly wind regime. Similar to yesterday, northerly winds will peak in strength during the afternoon and evening hours with gusts to around 25 kt to the north of Cape Foulweather and gusts to 30 kt to the south. The Small Craft Advisory for all marine zones to continue through the afternoon for the northern waters, through the evening for the central waters, and through tonight for the southern waters.
Winds should temporarily fall below small craft criteria on Thursday as a weak cold front moves inland, but should increase behind the front Thursday evening with gusts to around 25 kt for the northern waters, so have issued a Small Craft Advisory there for Thursday afternoon and night.

Seas will generally remain between 5 to 9 feet over the next few days as a primary northwest swell continues along with northerly wind waves. /mh -TK

PQR WATCHES/WARNINGS/ADVISORIES
OR...None.
WA...None.
PZ...Small Craft Advisory from 2 PM Thursday to 11 AM PDT Friday for PZZ251-271.
Small Craft Advisory until 11 PM PDT this evening for PZZ252- 272.
Small Craft Advisory until 5 AM PDT Thursday for PZZ253-273.

Vancouver
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Wed -- 01:33 AM PDT     1.21 feet High Tide
Wed -- 02:41 AM PDT     Moonset
Wed -- 03:52 AM PDT     1.07 feet Low Tide
Wed -- 04:49 AM PDT     First Quarter
Wed -- 05:38 AM PDT     Sunrise
Wed -- 06:02 AM PDT     1.19 feet High Tide
Wed -- 09:24 AM PDT     0.68 feet Low Tide
Wed -- 12:40 PM PDT     Moonrise
Wed -- 01:06 PM PDT     1.45 feet High Tide
Wed -- 05:19 PM PDT     0.75 feet Low Tide
Wed -- 05:58 PM PDT     0.75 feet High Tide
Wed -- 08:35 PM PDT     Sunset
Wed -- 09:53 PM PDT     0.09 feet Low Tide
Tide / Current data from XTide NOT FOR NAVIGATION

Vancouver, Columbia River, Washington (dubious accuracy), Tide feet

Knappa
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Wed -- 02:43 AM PDT     3.05 feet Low Tide
Wed -- 02:46 AM PDT     Moonset
Wed -- 04:49 AM PDT     First Quarter
Wed -- 05:40 AM PDT     Sunrise
Wed -- 07:42 AM PDT     6.41 feet High Tide
Wed -- 12:42 PM PDT     Moonrise
Wed -- 03:25 PM PDT     0.80 feet Low Tide
Wed -- 08:41 PM PDT     Sunset
Wed -- 09:42 PM PDT     6.62 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION

Knappa, Knappa Slough, Columbia River, Oregon, Tide feet

Full Color Weather Map

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