textproduct: Portland

SYNOPSIS

Fairly seasonable early July conditions continue the rest of the week into the weekend. Expect a gradual cooling trend through Wednesday as an upper-level trough passes north of the region and increases onshore flow locally while allowing for more prolific morning low clouds, especially Wednesday morning. Temperatures remain fairly close to normal into the first half of the weekend before a ridge of high pressure amplifying to our east allows temperatures to trend warmer into early next week.

LONG TERM...Friday through Monday

As mentioned above, the Great Basin high is expected to strengthen while an additional trough slowly drops into the northeastern Pacific from the the Gulf of Alaska. This system looks to mitigate the Great Basin High, thus keeping a more zonal flow pattern in the forecast through the weekend. However, the exact strength and track of this low is resulting in a fair amount of uncertainty. Still, ensemble models are at least maintaining north/northwest flow at the surface. However, guidance is showing southwesterly flow aloft which is causing the warming trend seen within various models and their families. Still, overall daytime highs are looking to remain near normal or slightly warmer than normal for the latter part of this week and through the start of next week. /42

AVIATION

Onshore flow will maintain a typical summertime pattern across the region. MVFR to IFR marine stratus continues to persist along the coast which is impacting all coastal sites. This marine stratus is expected to infiltrate along the Columbia River as well as through the gaps and flows of the Coast Range, thus bringing MVFR conditions to KEUG around 12Z-14Z Tuesday and a 15-30% chance for low-end VFR/ high-end MVFR conditions at all other inland TAF sites. Any lowered flight conditions for inland locations should improve to VFR around 17Z-20Z Tuesday with coastal locations likely improving towards low-end VFR/ high-end MVFR around 20Z-23Z Tuesday. North/northwest winds 10-15 kt or less expected throughout the majority of the TAF period, across the airspace. However, could see gusts up to 25 kt along the coast from 18Z Tuesday through 03Z Wednesday as well as gusts up to 20 kt for inland locations through the same time period.

KPDX AND APPROACHES...Predominately VFR conditions expected through the TAF period. 15-20% chance of low-end VFR/ high-end MVFR conditions developing from 12Z-16Z Tuesday as marine stratus meanders down the Columbia River. Any lowered flight conditions should improve to VFR starting around 16Z Tuesday. North/northwest winds 10-15 kt or less expected throughout the majority TAF period. However, could see gusts up to 20 kt from 20Z Tuesday through 05Z Wednesday. /42

MARINE

A broad, upper level trough will slowly drop out of the Gulf of Alaska through Wednesday. This will maintain northerly winds generally 15 kt or less across all waters with seas of 5 to 7 ft. Winds briefly increase Wednesday and Thursday evenings, with gusts up to 20 kt, strongest across the coastal waters south of Cape Foulweather. Overall, relatively benign conditions expected to continue through the week and into the weekend. /42

PQR WATCHES/WARNINGS/ADVISORIES

OR...None. WA...None. PZ...None.