Area Forecast Discussion
Issued by NWS Portland, OR
Issued by NWS Portland, OR
511 FXUS66 KPQR 051739 AFDPQR Area Forecast Discussion National Weather Service Portland OR 1039 AM PDT Wed Jun 5 2024 && .SYNOPSIS... High pressure is bringing a gradual end to the cloudy and damp weather from the past several days. Morning clouds will eventually break up today, allowing temperatures to recover to seasonable levels. The warming trend will continue with no precipitation through Friday, though recent rain will add a touch of humidity to the air. Temperatures will be well above normal by Friday, especially inland. Above normal temperatures likely linger through the weekend, though onshore flow will begin to moderate temperatures over the weekend. && .SHORT TERM...Now through Thursday Night... Today through Friday...Rain has just about come to an end across the Pacific Northwest as high pressure strengthens over the region. Enough moisture lingers in the low levels for persistent clouds across the forecast area, but subsidence will eventually break up these clouds as this morning progresses. Assuming there is a good deal of sunshine this afternoon, highs should easily reach the 70s for the inland valleys. The warming trend continues through Thursday and Friday, with Salem 850 mb temps climbing to around +14 deg C Thursday afternoon and into the +17 to +20 deg C range Friday afternoon, based on 00z GEFS and EC ensemble data. This should support inland valley highs in the 80s Thursday and possibly near 90 for Friday. Coastal areas will also see plenty of sunshine Thursday and likely Friday, but midday and afternoon sea breezes should hold highs in the mid to upper 60s for the beaches and 70s for the coastal communities. Low clouds may increase along the coast as early as Friday as marine inversions strengthen, but this is not certain. Additionally, some forecast models suggest some weak shortwave energy will dribble into SW Oregon as early as Friday, potentially enhancing mid-level instability for the Lane County Cascades. For now, it appears the mid levels remain too dry for thunderstorms Friday, and a westerly component to the flow aloft would likely carry any showers/t-storms quickly east of the Cascade crest. Therefore we opted to keep thunder chances below 10% Friday afternoon, as the NBM did. Weagle .LONG TERM...Saturday through Tuesday...The more progressive solutions appear to have won out for the weekend, as the upper ridge axis is likely to move east of the Cascades Saturday. This will focus thermal low pressure over the Columbia Basin, allowing onshore flow to bring its moderating influence to temperatures as early as Saturday. Temperatures will still be above normal inland, as 500 mb heights remain well above normal, representing the warm air mass in place. But the onshore low-level flow and a weak shortwave will likely deepen the marine layer enough to keep temps in the 80s for the inland valleys Saturday afternoon. In fact, NBM probabilistic guidance only shows a 70% chance Eugene will reach 80 degrees Saturday afternoon, when they were suggesting 90s not too long ago. Models diverge somewhat on how the ridge evolves beyond Saturday as a trough approaches from the Pacific, with some solutions directing this energy north into Canada while others try to develop a split flow pattern and shunt some energy south towards CA as a cutoff low. In terms of sensible weather impacts, expect mostly dry conditions to persist across northwest Oregon and southwest Washington with temperatures on Sunday dropping a few degrees into the upper 70s or low 80s but generally remaining above seasonal norms. WPC ensemble clusters show general agreement on maintaining high pressure over the Pacific Northwest through early next week, while differing on precise magnitude and placement. Temperatures are therefore expected to remain above normal through the period, but with a wider range of outcomes. This is reflected by NBM probabilistic guidance which shows a 20-25 percent chance to reach 90 degrees and around a 10 percent chance to reach 95 degrees throughout the Willamette Valley next Tuesday. However, the 25th percentile solution would result in temperatures inly in the mid 70s on Tuesday. Generally speaking, the pattern favors a continuation of warm and dry weather through the extended, but with less confidence on where high temperatures will ultimately land. Weagle/CB && .AVIATION...High pressure building over the region today and will bring warmer temperatures and drying. Clouds have rapidly dissipated across much of the area, except for lingering scattered clouds across the Coast Range and southern Willamette Valley. VFR is expected to continue through early Thursday. Light winds will becoming northerly at the coast with gusts to 25 kt in the afternoon and evening. For inland areas expect afternoon north to northwest winds 6 to 10 kt in the afternoon and evening. PDX AND APPROACHES...VFR expect through the forecast period. Light winds turn northwest around 10 kt later this afternoon into the evening hours. -Batz/mh && .MARINE...High pressure builds over the waters today to bring summer type pattern with northerly winds across the waters. Expect wind gusts in the 20 to 30 kt range next couple of days. In addition to winds, seas will be rather steep. Seas today starting around 14 feet at 14-15 second period will gradually subside over the next several days to around 9 ft Thursday and perhaps to near 5 ft by the weekend. /mh && .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...Small Craft Advisory until 5 AM PDT Thursday for PZZ210-251- 271. Small Craft Advisory until 6 AM PDT Friday for PZZ252-253-272- 273. && $$ www.weather.gov/portland Interact with us via social media: www.facebook.com/NWSPortland www.twitter.com/NWSPortland