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 Saturday night

Concerns for hazardous weather are 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 enhanced 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

AVIATION

Mainly VFR conditions expected across the airspace through the TAF period. Fair weather cumulus developing along northerly flow have settled around 3500-5000 ft, maintaining low end VFR CIGs for most terminals. Expecting more clearing through the evening as conditions continue to dry and daytime surface heating reduces. Chances for marine stratus pushing onshore this evening increase to over 50% by 04-06z Monday at KAST, lower at 20% around KONP.

KPDX AND APPROACHES...Predominately VFR expected through the period. North to northwest winds 5-8 kt expected, becoming light and variable overnight. Could see some low stratus develop over the eastern metro, mainly KTTD and KPDX, between 10-14z with a 20-40% chance of MVFR CIGs. -19

MARINE

High pressure offshore will shift back over the coastal waters returning north to northwesterly winds today. Northerlies are expected to persist through much of next 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 is in effect for the coastal waters south of Cape Foulweather through the early evening hours for gusts up to 25 kt. Similar conditions are expected on Monday. A series of upper level disturbances are expected to move over the region during the middle of the week, supporting chances for stronger winds for all marine zones. Seas around 6-9 feet are expected into the middle of the work week.

A Small Craft Advisory has been issued for the Columbia River Bar in effect between 4 and 8 AM Monday 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. -19/DH

PQR WATCHES/WARNINGS/ADVISORIES

OR...None.

WA...None.

PZ...Small Craft Advisory from 4 AM to 8 AM PDT Monday for PZZ210.

Small Craft Advisory until 9 PM PDT this evening for PZZ253- 273.