


Area Forecast Discussion
Issued by NWS Portland, OR
Issued by NWS Portland, OR
232 FXUS66 KPQR 071808 AAA AFDPQR Area Forecast Discussion...UPDATED National Weather Service Portland OR 1108 AM PDT Mon Jul 7 2025 Updated aviation discussion. .SYNOPSIS...High pressure lingers through Tuesday with a low spinning over northern California aloft. Temperatures will be in the upper 80s to low 90s through Tuesday but will quickly cool on Wednesday as the low moves inland. Slight chance for showers on Wednesday in southwest Washington. Warmer temperatures return late in the week though confidence is quite low. && .SHORT TERM...Now through Wednesday Night...High pressure continues to build over the northeast Pacific which will keep conditions dry and cause temperatures to rise. Sunday highs ranged from the mid 80s within the Willamette Valley to 60-70 degrees F along the coast, and near 80 deg F within the Cascades and foothills. Keep these temperatures in mind as we dive into today`s forecast. This morning, low temperatures are around 5 degrees warmer than Sunday morning which means that we are already starting with a leg up for even warmer temperatures today. While higher resolution models are trending a little cooler than the NBM mean, these warmer temperatures overnight further support the warmer daytime temperatures of the NBM. Still will see Moderate HeatRisk for the inland valleys including the Gorge and valleys within the Cascade Foothills. With the thermal trough forming to the south, expecting northerly winds along the coast and the Willamette Valley. Gusts up to 20 mph are possible. Will note that humidity will be low (around 25-30% RH) within the Willamette Valley and along the Cascades. Minimal difference in the forecast for Tuesday in regards to temperature and impacts. In the evening, the ridge will begin to break down though as a low aloft that is sitting near northern California begins it`s inland trek. Winds aloft will shift to the northwest and usher in a moister airmass. Winds will become gusty along the Coast Range ridgetops, the gaps into the Willamette Valley and Gorge near Hood River. There is around a 30% chance of gusts greater than 30 mph in the Upper Hood River Valley and exposed terrain in the Gorge. Will note that as the low shifts inland, there are a few shortwaves forming in the mid-level flow. Some wrap around moisture is possible with the initial passage of the low, but confidence is very low on whether or not precipitation is possible along the Cascades. The NBM is showing around a 10% chance of very light showers over the Cascades Tuesday night. However, given the pattern, showers should remain east of the Cascades. Wednesday will see an increase in the onshore flow as a shortwave trough digging down over Washington from the north, and the low that sat over northern California advects eastward. This trough brings around a 20-40% chance of light showers to southwest Washington with most of northwest Oregon evading the rain. Temperatures will swing around 10 deg F cooler inland as the onshore flow increases. -Muessle .LONG TERM...Thursday through Sunday...Uncertainty increases considerably in the long term forecast. Global ensembles are in good agreement in a broad area of high pressure forms over the Pacific on Friday with a thermal trough at the surface. In this scenario, north-easterly winds will dominate aloft with 850 mb temperatures around 18 deg C. These warm temperatures will mix down to the surface bringing surface highs to similar values to what is expected Monday. With the dry air moving in, will see dropping daytime humidity and gusty winds from the north. On Saturday some of the global models are suggesting another shortwave trough forming over the Oregon/California border. This trough could shake up the forecast a bit if it were to manifest. For example, looking at the ensemble clusters, one ensemble cluster is showing a decrease in heights from the mean and thus, suggesting temperatures will be lower. Onshore flow is forecast to increase on Saturday and Sunday though so humidity should be higher, especially in the northern portions of the forecast area. Others pattern options though are continuing a warm pattern. The pattern over the weekend is chaotic so confidence is incredibly low. -Muessle && .AVIATION...Clear skies will maintain VFR flight conditions for all inland terminals through 18z Tuesday. Although the coast has cleared out as of 18z Monday, there is a 80-90% chance for LIFR cigs below 500 ft to redevelop around 07z Tuesday as a low marine stratus deck over the coastal waters pushes inland a bit. Surface visibilities are also likely to lower to 4-5 SM or less once the marine stratus deck pushes inland. For winds, expect a typical diurnal summer pattern with breezy north to northwest winds during the afternoon and evening hours today. Expect gusts up to 20-25 kt at the coast and up to 15-20 kt inland, strongest at KONP, KEUG, and KPDX. Winds will weaken significantly after 04-06z Tuesday as daytime heating wanes. PDX AND APPROACHES...Clear skies will maintain VFR flight conditions through 18z Tuesday. Breezy northwest winds with gusts up to 15-20 kt are expected between 21z Monday and 05z Tuesday. -TK && .MARINE...A typical summertime pattern persists through much of the coming week as surface high pressure offshore maintains north to northwest winds across the coastal waters. Relatively strong pressure gradient at the coast due to diurnal heating, and elevated winds remain in place for all coastal waters through Monday night. Small Craft Advisories remain in effect through Monday evening as wind gusts increase a bit more to 25 to 30 kt Monday. Expect the strongest gusts south of Cape Falcon, while conditions will be more marginal to the north across the mouth of the Columbia River and the south Washington coastal waters. Seas will remain in the 4-6 ft range, comprised mainly of short period wind- driven waves and a modest, mid-period westerly swell. -CB/JLiu && .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...Small Craft Advisory until 10 PM PDT this evening for PZZ251>253-271>273. && $$ www.weather.gov/portland Interact with us via social media: www.facebook.com/NWSPortland x.com/NWSPortland