Area Forecast Discussion
Issued by NWS Portland, OR
Issued by NWS Portland, OR
673 FXUS66 KPQR 110336 AAA AFDPQR Area Forecast Discussion...UPDATED National Weather Service Portland OR 835 PM PDT Fri May 10 2024 Updated Aviation Discussion .SYNOPSIS...A ridge of high pressure will remain overhead through early this weekend, bringing dry weather and rapidly warming temperatures. Inland valley temperatures are expected to reach the upper 80s to low 90s today and Saturday - could see some record breaking highs in urban areas. Saturday night into Sunday, winds throughout the region will shift to onshore flow, bringing cool yet still above seasonal normal temperatures into early next week. && .SHORT TERM...Now through Sunday...A positively tilted ridge will stay overhead early into this weekend. The ridge axis, running southwest to northeast into southern British Columbia, will shift south into WA/OR through today as a trough moves eastward across the Gulf of Alaska. Currently offshore winds across the Coast Range and Cascades, and northerly winds through the interior valley. With the combination of the ridge moving directly overhead and the thermal trough peaking this afternoon, expect today`s highs to be warmer than yesterday. There is a 50-80% and a 30-60% chance for temperatures to exceed 90 degrees today and Saturday, respectively, however it looks to be mostly focused on the Portland/Vancouver Metro due to warm easterly winds from the Gorge. Other inland urban areas, such as Salem/Corvallis/Eugene, have a 10-20% chance to exceed 90 degrees today and Saturday. Offshore coastal winds will shift to a northwesterly onshore flow during the evening as the ridge axis moves past the Coast Range into the Willamette Valley. This onshore flow could bring stratus to the coast Saturday morning, thus moderating and cooling temperatures into Saturday afternoon. With this in mind, expect coastal temps in the upper 70s to low 80s today with a 50-70% chance to exceed 80 degrees F, decreasing to upper 60s to low 70s on Saturday. Widespread cooling is expected Sunday as the upper-level shortwave trough moves towards the coast, weakening the ridge overhead and pushing it eastward. With such unseasonably warm temperatures for early Spring and coming out of cold weather, there is no doubt people will visit rivers, lakes, and the ocean for SW Washington and NW Oregon this weekend. It is important to remember that rivers and lakes remain dangerously cold with water temperatures mainly in the 40s. Such temperatures can easily cause cold water shock for those without proper cold water gear, resulting in an involuntary gasp of air that can lead to drowning. Be sure to bring a life vest and be extremely cautious around rivers, especially with snowmelt causing cold and swift currents! -JH .LONG TERM...Monday through Friday...The trough will continue eastward over the Cascades through early Monday morning. This will support continued westerly onshore flow, dropping temperatures across the interior valley into the low 70s, and upper 50s to low 60s along the coast. The marine layer will likely remain too shallow for much in the way of morning cloudiness inland through Sunday, but the upper ridge may weaken enough for some low clouds to push into the inland valleys for a few hours Monday morning. WPC cluster analysis has moved more towards a solution favoring ridging re-developing by the middle of next week. Nearly all ensemble members display relatively strong and broad ridging by Wednesday next week, allowing temperatures to climb to the upper 70s in the latter half of the week. Wednesday has good agreement with this broad ridge remaining over the region, however agreement lessens Thursday into Friday as there is a 20% chance of a trough developing and pushing south into the region. This trough would bring more seasonable temperatures and light rain showers back to the area, but there is still not enough model convergence to be certain. -JH/Batz && .AVIATION...High pressure and dry northeasterly flow aloft will maintain VFR conditions through most of the TAF period. Along the coast, onshore north/northwest winds increasing to around 10 kt. Light northerly winds expected through the Willamette Valley. By early Saturday morning, marine stratus begins to push toward the coast. This is resulting in around a 25% probability for IFR to LIFR conditions starting around 13Z-15Z Saturday. MVFR conditions along the coast likely along the coast starting around 18Z Saturday. PDX AND APPROACHES...VFR as high pressure with clear skies persists. Generally northwest winds. /42 && .MARINE...High pressure still anchored well offshore. Meanwhile, thermal trough is gradually shifting farther inland. The pressure gradient across the coastal waters will stay somewhat weak. So, will maintain north winds on the waters tonight and Sat, mostly at 10 to 15 kt, with gusts to 20 kt. Seas stay in the 5 to 7 ft range. Little change for Sunday into early next week, as high pressure remains anchored well offshore, and lower pressure well inland. As such, will maintain north to northwest winds on the coastal waters. Could see gusts 20 to 25 kt at times in afternoons and evenings. Seas remain mostly at 5 to 7 ft. && .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