textproduct: Portland

SYNOPSIS

Temperatures increase today and tomorrow as an upper level ridge amplifies. Highs in the mid 80s to low 90s expected for the interior lowlands. The temperature and precipitation forecast becomes more uncertain late Wednesday into Thursday, however chances for rain showers during that time have increased with the latest forecast update. Trending warm and dry Friday and Saturday.

LONG TERM...Wednesday through Sunday night

Confidence has increased for temperatures on Wednesday with the closed low expected to remain offshore. This means the warmer solution is favored at this time with a much smaller range in 10th- 90th temperatures, now ranging from the low 80s to low 90s for the interior lowlands. This is still a decent spread but much better than a few days ago. Cluster analysis favors this solution with 50% of members keeping the low offshore, around 20% slightly closer to the WA/OR coast but not quite overhead, and the remaining 30% with the disturbance directly overhead but weaker. If the low takes the overhead route, expect temperatures to be on the cooler end of the spread. The bigger question has now shifted to Thursday regarding the progression of the upper low. Cluster analysis shows a majority, around 50% of members, depicting the low directly overhead. Around 30% of members show the wave moving toward the WA/OR coast and the remaining members actually have the upper low deepening but shifting farther southwest off the California coast. At this time, the favored solution is for Wednesday to be on the warmer side with interior highs in the mid to upper 80s and Thursday to be the coolest day of the week with highs in the low 80s. However, total model spread for high temperatures on Thursday remains large due to this uncertainty, with inland highs ranging anywhere from the low 70s to upper 90s per the NBM 10th-90th percentile. Given how the ensembles have struggled, this solution is far from set in stone.

Wednesday evening into Thursday could be showery as the upper level low moves over the region. The latest NBM guidance reflects this well and has increased PoPs to 20-40% Wednesday night into Thursday. Chances for at least 0.25 inches of rain or more range between 10- 20% across all of northwest OR and southwest WA from the coast to the Cascade crest, with the highest probabilities over southwest WA, the north OR coast/Coast Range, lower Columbia, and Portland metro. There is a 1-10% chance for 0.50 inches of rain or more over the southwest WA Cascades and Coast Range, which represents the wettest model solutions.

Confidence in the forecast actually increases a bit Friday and into the weekend. Ensemble guidance is in good agreement for dry and warm conditions, with high temperatures somewhere in the 80s or 90s for inland valleys. Chances for highs of 90 degrees or warmer peak on Sunday at 50-60% across the Willamette Valley, Portland metro, Columbia River Gorge, and Upper Hood River Valley. Chances for highs above 100 degrees are around 5-15%, suggesting extreme heat and significant heat-related impacts are unlikely to occur next weekend. Beyond the 7 day forecast, it is possible the warm and dry conditions persist into next week. -19/23

AVIATION

VFR conditions are expected for a majority of the TAF period. Light north to northwest winds 5-10 kt expected through the day. Guidance suggests a 20-30% chance of sub-VFR CIGs along the coast through 17Z but current satellite imagery shows little to no stratus offshore. Chances for stratus development along the coast are a bit better tonight at 30-40% after 6Z.

KPDX AND APPROACHES...VFR with northwesterly winds around 5 kt. -19

MARINE

Benign conditions with a typical summertime pattern expected through the week. Northerly winds 10-15 kt expected with afternoon gusts reaching to around 20 kt each day. Seas could be choppy at times with heights mainly in the 4-6 foot range but could see some 7 foot seas at 8-10 seconds. Isolated steep and hazardous seas but not enough to issue a Small Craft Advisory (SCA).

A SCA is in effect until 7AM for the Columbia River Bar for rough seas in due to a strong ebb and seas of 7 ft. Another SCA will be in effect from 2AM to 9AM for another very strong ebb current Tuesday morning -19

PQR WATCHES/WARNINGS/ADVISORIES

OR...None.

WA...None.

PZ...Small Craft Advisory until 7 AM PDT this morning for PZZ210.

Small Craft Advisory from 2 AM to 9 AM PDT Tuesday for PZZ210.