


Area Forecast Discussion
Issued by NWS Portland, OR
Issued by NWS Portland, OR
765 FXUS66 KPQR 062118 AFDPQR Area Forecast Discussion National Weather Service Portland OR 218 PM PDT Sun Jul 6 2025 .SYNOPSIS...Weak high pressure aloft with onshore flow at the surface. Warming temperatures through Tuesday with Moderate HeatRisk in the inland lowlands Monday and Tuesday. Cooler on Wednesday and Thursday as a broad low aloft moves northward. For the latter part of the week warming return as high pressure also returns. && .SHORT TERM...Tonight through Tuesday night...Broad area of high pressure builds through the start of the week. At the same time, an upper level low will park over northern California through Tuesday. With ridge of high pressure pole-ward along with an undercutting low, this creates a Rex Blocking pattern. Now, this blocking pattern is very weak, given that the upper level ridge is not very robust. However, this pattern will bring about a warming and drying trend for the forecast area through Tuesday night. Daytime highs at this time are forecasted to be in the upper 80s to low 90s for inland locations and into the upper 60s to low 70s along the coast. Highest temperatures are expected on Monday. On Tuesday, the upper level low that is forming the Rex Block, will start to meander northward along the California Coast. As that upper level low moves northward, the Great Basin surface low will also result in a tightening of the pressure gradient along the Cascades and could see gusts up to 30 mph for the Central and Eastern parts of the Columbia River Gorge on Tuesday. Monday and Tuesday will also have Moderate HeatRisk for the Willamette Valley, Clark County lowlands and the Gorge. Those sensitive to heat should take precautions and everyone should remain hydrated. /42 .LONG TERM...Wednesday through Saturday...As Wednesday approaches, the Rex Block will continue to break down as both the upper level ridge becomes more zonal and the upper level low continues to push eastwards towards eastern Oregon. This pattern change will also bring about relatively cooler and moister air into the region. 850 mb temperatures will drop from 16-18 deg C on Tuesday toward 8-10 deg C on Wednesday and Thursday. One newer feature that hasn`t been realized yet in previous model runs is a weak meso-low and shortwave trough at the mid-levels forming over Washington. The added instability combined with moister air and cooling temperatures is bringing a slight chance (less than 25%) of very light precipitation to southwest Washington, and less than a 10% chance of isolated showers along the Central Oregon Cascades. Confidence is very low though as the pattern could easily shift if the low tracks a bit further north. Overall, most places should remain dry. With all that said, any precipitation that does fall will be light, brief and result in little to no accumulations. Thursday will be dry once again with near normal high temperatures in the 80s inland. As the latter part of the week and the weekend approaches, models are showing a broad, upper level ridge returning to the eastern Pacific. Some models are also showing a meso-low developing again near northern California. Either of these scenarios look to bring back a warming pattern for the region and could easily be a repeat (or very similar) of Monday and Tuesday. As a result, daytime highs could warm right back into the upper 80s to low 90s for inland locations, while the coast warms into the 70s. The forecast will continue to evolve through the week and will likely change as details become more clear. /42 && .AVIATION...Clear sky VFR conditions across the region today as high pressure builds overhead. Guidance depicts marine stratus returning to coastal terminals 04-08z Mon, with a 30-50% chance for MVFR conditions or lower at KAST a 50-70% chance along the immediate coastline including KONP. Increasing subsidence and the shallow nature of the marine layer suggest probable IFR cigs with the potential for some patches of LIFR fog along the central coast near KONP, breaking out towards VFR again 16-18z Mon. Otherwise, VFR will prevail through the period at the inland terminals. Winds will continue to follow a diurnal trend, with N-NW winds increasing to 10-15 kt with gusts to 20-25 kt 20-23z Sun. Winds will diminish back to around 5 kt after 06z Mon. PDX AND APPROACHES...VFR prevails through the period under clear skies. NW winds 10-12 kt with gusts to around 20 kt, easing to around 5 kt after 06z Mon. /CB && .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. Inland heating will drive a strengthening coastal pressure gradient through Monday, which is in line with current observations showing gusts increasing to 20-25 kt over the waters. Small Craft Advisories remain in effect through Monday evening as wind gusts increase a bit more to 25 to 30 kt later today into 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 && .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...Small Craft Advisory until 10 PM PDT Monday for PZZ251>253- 271>273. && $$ www.weather.gov/portland Interact with us via social media: www.facebook.com/NWSPortland x.com/NWSPortland