Area Forecast Discussion
Issued by NWS Portland, OR

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248 FXUS66 KPQR 122208 AFDPQR Area Forecast Discussion National Weather Service Portland OR 308 PM PDT Sat Jul 12 2025 .SYNOPSIS...
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High pressure maintains warm and dry conditions this weekend, with a Heat Advisory on Sunday for most interior valleys. Expect sunny skies across the area with morning marine stratus/fog along the coast. Temperatures cool slightly on Monday, but still remain warm and dry. An Extreme Heat Watch continues for some interior valley locations from Tuesday to Wednesday, as afternoon temperatures between 90 to 100 degrees and low temperatures between 65 and 70 degrees are possible.
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&& .SHORT TERM...
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Tonight through Monday night...A broad upper level ridge of high pressure remains over the western US through the weekend. This will maintain our summer weather pattern of hot and dry conditions through Sunday. 850 mb temps rise to around 20-22 C on Sunday, allowing temperatures for Sunday afternoon across the lowland valleys to warm into the 90s, likely around 5 degrees F warmer than today`s (Saturday) highs. Hottest temps into the upper 90s likely through the southern and central Willamette Valley, where there is a 20-30% chance of reaching 100 degrees. Therefore, the Heat Advisory remains in effect from 11 AM to 10 PM Sunday for the Willamette Valley, Portland/Vancouver metro, Columbia Gorge and Upper Hood River Valley, as well as the lower Columbia-Cowlitz County lowlands. Onshore northwest to northerly winds will again increase Sunday afternoon as surface high pressure offshore and low pressure east of the Cascades increases the pressure gradient. Expect wind gusts up to 25-30 mph inland, while gusts up to 35 mph will be possible along the central Oregon coast. The upper ridge axis retrogrades over the Pacific as an upper level trough drops out of British Columbia into Washington on Monday. This will likely push 850 mb temps back down into the mid-teens, resulting in surface temperatures cooling around 10 degrees, toward near normal values for July. Could also deepen the marine layer along the coast enough to push up the lower Columbia into the Portland metro by Monday morning. /DH .LONG TERM...Tuesday through Saturday...Temperatures are expected to trend warmer Tuesday and Wednesday next week, with Wednesday likely being the warmest day. There is still a bit of model spread in the temperature outlook for Tuesday, though narrowing in on highs in the upper 80s to mid 90s. High temperatures on Wednesday are more likely to warm into the mid-90s, with around a 30-50% chance of reaching 100 degrees across the Willamette Valley. Will continue the Extreme Heat Watch for now, though NWS HeatRisk continues to trend toward widespread Moderate Risk rather than Major Risk. Should also see morning temperatures remain somewhat elevated Tuesday night, especially around the urban areas, as a surface thermal trough develops, bringing light offshore flow through the Columbia Gorge and downsloping across the Cascades. But, the probability that overnight temperatures don`t drop below 70 degrees remains at around 10%. More uncertainy arises in the forecast Thursday and Friday of next week. Ensembles continue to struggle with the overall pattern, as guidance shows a bimodal solution of either cooler weather and upper level troughing, or high pressure ridging and continued heat, with nearly a 50/50 split. Guidance does show higher confidence of temperatures trending into the mid-80s by next Saturday with dry conditions persisting. /DH
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&& .AVIATION...
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High pressure with increasing daytime heating. Overnight expect conditions inland to remain VFR over the next 24 hours. Upwelling continues along the coast which will promote cooler temperatures along the immediate terminals. Overnight, there is around a 50% chance of fog returning from KTMK southward, however, given the persistent pattern leaning towards another IFR night along the main coastal airports. VFR elsewhere. Gusty north winds this afternoon will ease overnight before increasing once again in the afternoon. Probability for gusts greater than 25 kt is around 25-30% in the Willamette Valley and greater than 60% along the coast. PDX AND APPROACHES...VFR CIGs and VIS. Northerly winds. Generally northerly winds aloft up to 30 kt between 02-10Z Sunday at 2000 ft. For higher approaches around FL040 northeast gusts up to 35 kt during that time. There is a chance (around 30% chance) that these winds mix down. -Muessle
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&& .MARINE...
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Strong high pressure over the waters for the next week or so. Tonight, there is around a 25% chance of dense fog for the inner waters due to upwelling along the shore. Due to drier conditions today, confidence is low as to whether or not it will develop. Therefore have not issued any dense fog products. Slight fluctuations in small scale features will cause increased wind speeds through early next week. Tomorrow (Sunday) winds will increase higher than previously thought due to a strengthening thermal trough. Gusts up to 30 kt possible, though higher probability between 25-30 kt. These conditions will likely last through Monday, and even through Tuesday in some locations. Seas will increase slightly but remain in the 7-9 ft at 10 seconds range. However, on Tuesday, with an increased wind wave, seas will rise closer to 10 ft. -Muessle
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&& .PQR WATCHES/WARNINGS/ADVISORIES...
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OR...Heat Advisory from 11 AM to 10 PM PDT Sunday for ORZ108-109-111- 112-114>118-120>122. Extreme Heat Watch from Tuesday afternoon through Wednesday evening for ORZ108>115-119>122. WA...Heat Advisory from 11 AM to 10 PM PDT Sunday for WAZ204>207-209- 210. Extreme Heat Watch from Tuesday afternoon through Wednesday evening for WAZ204>207-209-210. PZ...Small Craft Advisory from 11 PM this evening to 5 AM PDT Monday for PZZ251-271. Small Craft Advisory until 5 PM PDT Sunday for PZZ252-253-272- 273.
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