textproduct: Portland

SYNOPSIS

A bit more of a dynamic weather pattern over the next several days as high pressure gives way to a longwave trough over the area. Rain chances increase for Wednesday night into Thursday with a slight chance (10-20%) for thunderstorms into Thursday morning. Rain accumulation will generally be orographically driven. Drying occurs starting Friday through the weekend as temperatures heat up once again. Moderate HeatRisk forecast for urban areas on Sunday and Monday.

LONG TERM...Friday through Tuesday

Conditions will begin to settle on Friday, though expect temperatures to remain seasonable or just slightly above normal. Once challenge on Friday is what ends up happening with the low aloft. Some models suggest that the low will stay more northerly, while others want to keep it further south. The overall Grand Ensemble shows the low center tracking p and over Vancouver Island on Friday which will allow for drier and warmer air to move in. This will set the stage for the weekend as conditions become increasingly hotter and drier. In this pattern, marine stratus is likely, especially along the coast though it could transition down the Columbia River into the interior lowlands. If cloud cover becomes pervasive, it will have an impact on high temperatures and minimum humidity.

As we move into the weekend, high pressure builds once again which will cause temperatures to rise. This ridge amplifies through Monday which will bring even warmer temperatures. Looking at Moderate HeatRisk for urban areas around the greater Portland-Vancouver metro area, the Columbia River Gorge, and the Upper Hood River Valley on both Sunday and Monday. There is around a 10% chance of highs hitting 100 degrees or more on both Monday and Tuesday and that is mainly within the inland valleys. Note that one trend that has been observed is that the highest temperature forecasts have been pushed off one day at a time as models come in. Therefore, the exact dates may be a bit more up in the air as we near - especially as the ridge remains anchored in place.-27

AVIATION

Southerly flow aloft will continue as an upper level low spins offshore. Mid-to high level clouds will stream over the forecast area tonight but skies are expected to become mostly clear again by Wednesday morning as VFR conditions are expected to continue for all inland locations through at least 06z Thu. Conditions along the coast are expected to deteriorate as marine stratus moves onshore with at least a 60% chance of MVFR CIGs after 06z Wed. There is around a 50% chance for IFR conditions to develop overnight into Wed morning at both KAST and KONP through 16-18z Wed. Conditions are likely to improve toward VFR after 18-19z Wed, especially near KAST, while MVFR probs near KONP persist at around 40-50% through Wed afternoon.

KPDX AND APPROACHES...VFR expected to continue through the period with variable mid to high level clouds tonight becoming mostly clear by Wed morning. Northwest winds become light overnight. /DH

MARINE

Benign conditions with a typical summertime pattern expected to persist through the week. Northerly winds 10-15 kt expected with intermittent afternoon gusts up to 20 kt each day. Seas 4-6 feet at 8-10 seconds.

A Small Craft Advisory is in effect from 3AM to 9AM Wednesday morning for the Columbia River Bar for rough seas due to a very strong ebb current leading to seas of 6 to 7 ft. /42

PQR WATCHES/WARNINGS/ADVISORIES

OR...None. WA...None. PZ...Small Craft Advisory from 3 AM to 9 AM PDT Wednesday for PZZ210.