Area Forecast Discussion
Issued by NWS Portland, OR
Issued by NWS Portland, OR
511 FXUS66 KPQR 270455 AAA AFDPQR Area Forecast Discussion...UPDATED National Weather Service Portland OR 955 PM PDT Wed Jun 26 2024 .SYNOPSIS...Mother Nature not sure on pushing summer into our region, so she will give us alternating mix of warm summer days and cooler showery spring days. Lots of clouds around overnight into Thursday, along with a few showers as low pressure shifts inland. High pressure will bring dry and bit warmer weather for Friday into Saturday. But, its back to clouds and some showers with seasonal temperatures for Sunday into early next week. Dry and back to bit warmer weather as next week progresses. && .SHORT TERM...Now through Saturday...Southwest flow aloft will continue overnight into Thu, as broad low pressure area sits offshore, centered just west of Vancouver Island. Meanwhile, a weak upper level disturbance off the south Oregon coast will shift inland across southwest Oregon tonight. Add to the mix a weak front that extends from the low near Vancouver Island back to the south roughly along long 127 (about 125 miles offshore). Together all these systems will provide ample lift, and with moisture in place, will see scattered showers for just about anywhere for late this afternoon into Thursday morning. Does appear best chance of showers will be focused over the higher terrain (Coast Range, Willapa Hills, and the Cascades/foothills) as the weak front comes onshore and across the region overnight. Even so, any rainfall will remain on the lighter side, 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 the coast mtns and the Cascades (north of Santiam Pass) 0.25" to 0.50" with heavier prolonged showers. Not much change on Thursday, as will maintain moderate to strong onshore flow. As such, will be plenty of clouds in the morning, with clouds gradually breaking apart in the afternoon. Though shower potential will be decreasing through the day, will maintain high chance of showers over the higher terrain. Once the upper trough shifts east of the Cascades, high pressure will build across the region. At same time, will see thermal trough over far southwest Oregon strengthen. This will bring back a north to northwest flow in the lower to mid levels, which is a drying and warming pattern. So, will see lot more sunshine across the region on Friday, as well as Saturday. Temperatures jump up well into the 60s along the coast, and 70s to near 80 across the interior. Suspect many inland areas (from Portland/Vancouver metro southward through the Willamette Valley, and in the Gorge to Hood River Valley) will get back into the lower 80s on Friday, and again Saturday. But...changes arrive again, as another upper trough approaches. Will see increasing onshore flow later Sat afternoon, with clouds increasing 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 flow as upper trough works its way inland over the Pac NW. Ensemble members suggest the potential for the return of scattered showers, 40-60% for the coast and higher elevations and 15-35% for inland valleys according to the NBM. Again, amounts look very limited at this time. Ensembles show bit more uncertainty in the pattern early next week, though in general the suggested patterns would bring continued mild weather. Temperatures look to remain in the 70s for inland valleys with mostly dry conditions, except for the potential for lingering scattered showers Monday. -HEC && .AVIATION...Strong onshore flow across the region this am, with widespread VFR deck (mostly 4500 to 5000 ft), though still have pockets of MVFR CIGS along the coast. Clouds will continue to gradually breaking apart through this evening. Air mass is slightly unstable, enough to get a few showers. Better chance of showers overnight as weak front (about 125 sm offshore as of 3 pm) shifts inland overnight. Generally, will remain VFR with broken decks from 3500 to 6000 ft tonight into Thu am. PDX AND APPROACHES...Onshore flow continues through Thu. VFR deck this afternoon and overnight, with main deck at 4500 to 5000 ft. Will see CIGS likely at 3500 to 4000 ft overnight and persist into Thu am. Will maintain a small chance (25% or less) for showers into this evening, with better chance overnight. /Rockey && .MARINE...Broad low pressure offshore will maintain south to southwest 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 early Sat. At same time, will see thermal low pressure over far southwest Oregon into northwest California. As such, will get back into some northerly winds, with gusts 20 kt in afternoons/evenings. But, yet another low pressure arrives later Sat, with winds flipping back to the west or southwest. Gradients weaker, so winds not expected above 15 kt. Seas stay in the 4 to 6 ft range. .LONG TERM...Saturday through Wednesday... && .AVIATION... && .MARINE... && .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...None. && $$ www.weather.gov/portland Interact with us via social media: www.facebook.com/NWSPortland www.twitter.com/NWSPortland