textproduct: Portland

SYNOPSIS

Dry and benign weather is expected across the region through much of the next week as high pressure builds over the Northeast Pacific, bringing a warming trend. Weak systems aloft may bring enhanced cloud cover on some days, but rain chances are minimal.

DISCUSSION...Now through Sunday

A weak upper level disturbance passing over the region this morning will maintain high level clouds through late morning, before skies become mostly sunny this afternoon. Concerns for hazardous weather remain minimal through the next week. There is high confidence that upper-level ridging and surface high pressure will build over the Northeast Pacific, with increasing uncertainty in the amplitude and position of the upper ridge later in the forecast. Early in the period, while the ridge is centered well offshore, upper shortwaves within northwesterly flow aloft may produce increased cloud cover, but chances for rainfall remain 5% or less through the middle of the week. On clearer nights, areas of fog are most likely to develop within sheltered valleys. As the ridge axis shifts east, temperatures will trend upward through at least Thursday, reaching the 60s along the coast and upper 70s to around 80 degrees along the I-5 corridor. Later in the forecast period, uncertainty in the evolution and possible break-down of upper-level ridging introduces a similar uncertainty in forecast temperatures. Highs are most likely to continue in the 60s to mid 70s, but the spread of possible outcomes becomes wider: chances of reaching 80 degrees along the I-5 corridor are generally 15-45% Friday and Saturday, but there are also 10-25% chances of remaining below 70 degrees. The next opportunity for widespread rain holds off until late next weekend when there is greater consensus that the ridge breaks down. 36/DH

AVIATION

A weak upper level disturbance is pushing high clouds across the area this morning within the northwest flow aloft. Marine stratus with MVFR CIGs near KAST is expected to persist through 18z this morning. Elsewhere, predominately VFR conditions are expected through at least 03-06z Tuesday. Though, there remains low chances (10-20%) for MVFR stratus to back build off the Cascades toward inland terminals, except 20-30% at KTTD, between 12-18z this morning. Chances for MVFR stratus increase again near KAST after 03z Tue, and at northern inland terminals after 06z. Light north to northwesterly winds again expected to become breezy this afternoon.

KPDX AND APPROACHES...VFR conditions expected through at least 06z Tuesday, though there remains a 10-20% chance for MVFR stratus between 12-18z this morning. High clouds expected to clear out this afternoon. Light northwest winds expected to increase to 8-10 kt by 22z this afternoon. /DH

MARINE

Northerlies are expected to persist through much of the week as the summer-like pattern settles in. Strongest winds are expected during the afternoon and evening periods as a surface thermal trough strengthens over the southern Oregon coast. A Small Craft Advisory has been issued for the inner coastal waters south of Cape Foulweather later this afternoon into this evening for gusts up to 25 kt. Similar conditions are expected on Tuesday. Seas around 6 to 8 feet are expected through the week as well.

Small Craft Advisories are in place for the Columbia River Bar early this morning, and again early Tuesday morning, for strong ebb currents which will produce hazardous conditions to small craft. Strong ebb currents are possible during the morning hours each day this week. /DH

PQR WATCHES/WARNINGS/ADVISORIES

OR...None. WA...None. PZ...Small Craft Advisory until 8 AM PDT this morning for PZZ210.

Small Craft Advisory from 5 AM to 9 AM PDT Tuesday for PZZ210.

Small Craft Advisory from 2 PM this afternoon to 11 PM PDT this evening for PZZ253.