textproduct: Portland

SYNOPSIS

Hot temperatures remain the main story today with Extreme Heat Warnings and Heat Advisories in effect through very late tonight. Conditions cool tomorrow as onshore flow returns, though inland areas will remain warmer than normal through the upcoming week.

DISCUSSION...Tonight through Sunday

Temperatures will remain elevated through the evening hours, with a gradual cool down expected tonight. So, while we are on the backside of this heat wave, remember to stay hydrated, limit strenuous afternoon activity, use air- conditioned spaces when possible, and check on vulnerable neighbors, family, and pets. Also remember rivers and lakes remain cold despite the hot weather, increasing the risk of cold-water shock for anyone seeking relief near the water.

As tonight/Tuesday morning approaches, a significant pattern change is expected as a shortwave trough sliding southward from western Canada, this will help to usher the upper level high pressure and associated thermally induced surface trough further eastward over the Cascades and into Central OR and WA. This pattern change will bring a return of onshore flow to the region and provide a brief respite from the extreme heat. However, daytime highs will still remain above normal (low 60s to mid 70s) for this time of year. Expect daytime highs along the coast in the mid to upper 60s, low to upper 80s inland and low 70s to low 80s for the Cascades on Tuesday and Wednesday. Probabilities for temperatures reaching 90 degrees Tuesday are now less than 15% and nearly zero for Wednesday.

Looking towards the latter part of the week, ensemble guidance remains in very good agreement that a weak, upper level transient high pressure system builds along the central coast of western CONUS. At the same time, very broad upper level troughing develops across western and central Canada. This synoptic formation looks to bring slightly warmer temperatures back into the forecast for the PacNW. Daytime highs on Thursday and Friday look to be in the mid 80s to low 90s for inland locations on Thursday and Friday. This while system looks to move eastward Friday into Saturday, with the Canadian trough developing a cut- off low that will overtake the eastern Pacific high, resulting in cooler temperatures for the weekend. Overall, there are no significant cool down or precipitation signals in the extended forecast at this time. /42-03

AVIATION

High pressure will maintain predominately VFR conditions through the TAF period with FEW/SCT high clouds across inland locations. Northwesterly winds weaken to around 5 kt or less overnight. After 12z Tue, there is high confidence (>90% chance) for marine stratus pushing onshore into the north Oregon coast, bringing MVFR CIGs at KAST. Limited mixing will maintain MVFR CIGs throughout the day along the north Oregon coast. There is some uncertainty whether or not marine stratus makes it down to the central Oregon coast, but there is a 40-60% chance for MVFR CIGs at KONP at any given hour between 12-21z Tue. Guidance suggests mixing occurs at KONP after 00-02z Wed, returning VFR conditions. Northwesterly winds gradually increase after 15-18z Tue as pressure gradients tighten with gusts up to 25 kt along the coast and up to 20 kt inland in the afternoon.

KPDX AND APPROACHES...VFR with FEW/SCT high clouds through the TAF period. Light northwesterly winds overnight will gradually increase after 18z Tue with gusts up to 20 kt from 21z Tue-06z Wed. -10

MARINE

High pressure offshore will maintain the summertime pattern through this week. Diurnally driven northerlies are expected to peak each afternoon and evening through next week. North winds will continue to increase this afternoon with gusts up to 25 kts south of Cape Falcon, then ease overnight into Tuesday morning. Winds then increase across all of the coastal waters later Tuesday afternoon and evening, with this pattern persisting through late in the week. Seas around 4 to 7 ft at 7-10 seconds are expected to persist through Tuesday, driven primarily by the northerly wind chop. Seas are expected to build to around 8 to 10 ft Wednesday into Friday as a fresh northwesterly swell builds across the waters. /DH

CLIMATE

Record high temperatures and warm low temperatures for Monday, June 15

High Temperatures: Warm Low Temperatures: Portland Int'l 95F (1966) 60F (1969) Vancouver, WA 95F (1930, 1966) 62F (1961) Hillsboro 99F (1961) 60F (1963) McMinnville 96F (1961) 59F (1936) Salem100F (1966) 59F (1931) Eugene 96F (1966) 60F (1961) Astoria 91F (1966) 58F (1997)

PQR WATCHES/WARNINGS/ADVISORIES

OR...None. WA...None. PZ...Small Craft Advisory from 4 AM to 8 AM PDT Tuesday for PZZ210.

Small Craft Advisory from 5 PM Tuesday to 5 AM PDT Wednesday for PZZ251-252-271-272.

Small Craft Advisory until 4 AM PDT Tuesday for PZZ252-272.

Small Craft Advisory until 5 AM PDT Wednesday for PZZ253-273.