textproduct: Portland

SYNOPSIS

Warm and dry conditions expected through much of the week with morning clouds and afternoon clearing. Daytime highs are expected to be in the 80s through the week. Winds generally out of the west to northwest, strongest in the afternoon and along the Central Columbia River Gorge and Upper Hood River Valley. Next chances for light showers arrive Friday into next weekend.

DISCUSSION...Tonight through Saturday

Minimal changes to the forecast as dry and warm conditions continue through the week with minimal weather impacts. The large-scale pattern remains stagnant through the period as a cul looks to persist off of the OR/WA coast within the upper levels of the atmosphere. This is resulting in relatively calm winds and stagnant conditions. However, this pattern is at least maintaining northerly surface winds which will keep daytime highs near seasonal normals as well as cool and moist air infiltrating into the region each night. So, expect marine stratus to develop along the coast, as well as filter into the Willamette Valley each evening before mostly clear skies return by the afternoon through the upcoming week. Expect light west to northwest winds, peaking each afternoon. The strongest winds are likely to be along the Central Columbia River Gorge and Hood River Valley, but impacts are not anticipated.

As the week progresses, a majority of ensemble members are in agreement that upper-level ridging over the Rockies and the Great Basin will build late in the workweek, which would favor a brief warm-up on Thursday. However, that warm up will likely be short lived as ensemble guidance also shows an upper-level trough over the northeast Pacific shifting onshore Friday into the weekend, resulting in slightly cooler temperatures and winds coming from the south/southwest. Chances for showers also increase to 10-25% across the region during this time, with the highest chances over the Coast Range and Cascades. However, there is still high uncertainty in the timing and potential rain amounts. A weak front at the end of the week would have a hard time counteracting the dry airmass in place, making accumulating rainfall unlikely and keeping most places dry. It should also be noted that with southerly flow into the region the potential for thunderstorms also comes into the forecast. Now, while the pattern is favorable model soundings are suggesting that nocturnal thunderstorms could develop with ensembles suggesting around a 5-10% probability at this time. /42-10

AVIATION...Through 00z Wednesday

VFR conditions with high clouds across all terminals with a few lingering strands of stratus along the coast. Marine stratus quickly becomes widespread again along the coast after 00-03z Tue, returning IFR/MVFR CIGs (>80% chance). There's a 20-40% chance of MVFR stratus pushing east along the Columbia River and forming in the northern Willamette Valley after 12z Tue, including KPDX, KTTD, and KUAO. There's a 10-25% chance of MVFR cigs forming at KSLE and KEUG, as well. Any MVFR conditions at inland terminals should improve to VFR by 18-20z Tue. Northerly to northwesterly winds today 10-15 kt with gusts up to 20 kt along the coast, and 5-10 kt across the Valley. Winds will be strongest in the afternoon and evening, then weaken overnight.

KPDX AND APPROACHES...VFR conditions with high clouds. There's a 25-40% chance of MVFR CIGS returning after 12z Tue. Northwesterly winds 3-7 kt, strongest in the afternoon and evening, decreasing overnight. -03

MARINE

A largely stagnant pattern continues through much of the week with high pressure offshore supporting northerly to northwesterly winds of 8-15 kt and afternoon gusts up to 20 kt. Weak low pressure moving over the northeast Pacific Friday into the weekend will shift winds out of the south to southwest across the waters, but chances for gusts exceeding 21 kt remain low, only 10-20%. Seas of 3-6 ft persist through the period. Increasing periods of 12-14 sec on Tuesday-Wednesday may result in a moderate risk for sneaker waves along the coast. Caution should be used when in or near the water.

PQR WATCHES/WARNINGS/ADVISORIES

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