National Weather Service (2024)

Area Forecast Discussion
Issued by NWS Portland, OR

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-- Discussion containing changed information from previous version are highlighted. --467FXUS66 KPQR 270506AFDPQRArea Forecast DiscussionNational Weather Service Portland OR1006 PM PDT Wed Jun 26 2024.SYNOPSIS...Mother Nature not sure on pushing summer into ourregion, so she will give us alternating mix of warm summer daysand cooler showery spring days. Lots of clouds around overnightinto Thursday, along with a few showers as low pressure shiftsinland. High pressure will bring dry and bit warmer weather forFriday into Saturday. But, its back to clouds and some showerswith seasonal temperatures for Sunday into early next week. Dryand back to bit warmer weather as next week progresses.&&.SHORT TERM...Now through Saturday...Southwest flow aloft willcontinue overnight into Thu, as broad low pressure area sitsoffshore, centered just west of Vancouver Island. Meanwhile, aweak upper level disturbance off the south Oregon coast willshift inland across southwest Oregon tonight. Add to the mix aweak front that extends from the low near Vancouver Island backto the south roughly along long 127 (about 125 miles offshore).Together all these systems will provide ample lift, and withmoisture in place, will see scattered showers for just aboutanywhere for late this afternoon into Thursday morning. Doesappear best chance of showers will be focused over the higherterrain (Coast Range, Willapa Hills, and the Cascades/foothills)as the weak front comes onshore and across the regionovernight. Even so, any rainfall will remain on the lighterside, with 0.01" to 0.15" of rain, with 0.10" as much as 0.25"in the higher terrain. That said, could see few spots in thecoast mtns and the Cascades (north of Santiam Pass) 0.25" to0.50" with heavier prolonged showers.Not much change on Thursday, as will maintain moderate to strongonshore flow. As such, will be plenty of clouds in the morning, withclouds gradually breaking apart in the afternoon. Though showerpotential will be decreasing through the day, will maintain highchance of showers over the higher terrain.Once the upper trough shifts east of the Cascades, high pressure willbuild across the region. At same time, will see thermal trough overfar southwest Oregon strengthen. This will bring back a north tonorthwest flow in the lower to mid levels, which is a drying andwarming pattern. So, will see lot more sunshine across the region onFriday, as well as Saturday. Temperatures jump up well into the 60salong the coast, and 70s to near 80 across the interior. Suspect manyinland areas (from Portland/Vancouver metro southward through theWillamette Valley, and in the Gorge to Hood River Valley) will getback into the lower 80s on Friday, and again Saturday.But...changes arrive again, as another upper trough approaches. Willsee increasing onshore flow later Sat afternoon, with cloudsincreasing along the coast and over the Coast Range/Willapa Hills.Could even see a shower or two in those areas. /Rockey.LONG RANGE...Back to cooler temperatures and increased onshore flowas upper trough works its way inland over the Pac NW. Ensemblemembers suggest the potential for the return of scattered showers,40-60% for the coast and higher elevations and 15-35% for inlandvalleys according to the NBM. Again, amounts look very limited atthis time. Ensembles show bit more uncertainty in the pattern earlynext week, though in general the suggested patterns would bringcontinued mild weather. Temperatures look to remain in the 70s forinland valleys with mostly dry conditions, except for the potentialfor lingering scattered showers Monday. -HEC&&.AVIATION...
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Strong onshore flow across the region tonight, withwidespread VFR deck (mostly 3500 to 5000 ft) inland, though stillseeing IFR to MVFR CIGS along the coast mainly under and aroundshower activity. Generally, inland sites will remain VFR withbroken decks from 3500 to 6000 ft through the forecast periodalthough most guidance suggests a period of high end MVFR cigsbetween roughly 1500-2000 before rising back to VFR. 00z HREFsuggests the best chances for inland showers will be during theafternoon hours before they quickly taper off 00-03z.PDX AND APPROACHES...VFR deck overnight, with main deck at 4500to 5000 ft. Will see CIGS likely drop to 3000-3500ft Thursdaymorning around 1500-2000z. Showers remain largely in the vicinityof the site through the morning before increasing in coverageslightly Thursday afternoon. -Schuldt
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Broad low pressure offshore will maintain south tosouthwest flow on the coastal waters, with winds mostly 10 to 15 kt.Seas staying in the 4 to 6 ft range.High pressure offshore will return a bit for Thu night through earlySat. At same time, will see thermal low pressure over far southwestOregon into northwest California. As such, will get back into somenortherly winds, with gusts 20 kt in afternoons/evenings.But, yet another low pressure arrives later Sat, with winds flippingback to the west or southwest. Gradients weaker, so winds notexpected above 15 kt. Seas stay in the 4 to 6 ft range.
-- End Changed Discussion --&&.PQR WATCHES/WARNINGS/ADVISORIES...OR...None.WA...None.PZ...None.&&$$www.weather.gov/portlandInteract with us via social media:www.facebook.com/NWSPortlandwww.twitter.com/NWSPortland