textproduct: Portland

SYNOPSIS

Onshore flow continues as a series of short wave, upper level troughs move over the area tonight through Friday. This will increase mixing and bring some moist air into the region. As a result of this pattern there is a slight chance (15-20%) of rain showers late tonight through Friday afternoon along the Cascades. Could see isolated thunderstorms over the ridges through the same time period. Warming and drying trends return for the weekend and persist through at least the middle of the upcoming week.

LONG TERM...Saturday through Wednesday

For the start of the weekend, warmer and drier conditions return. The upper level pattern starts to shift into a Rex like, blocking pattern. The cut-off low of this rex-like pattern looks to hover just off the northern coast of California and a more zonal-ish flow pattern for OR and WA. With this pattern over the Pacific, a surface low over the Great Basin will enable warm and dry air to re-enter the region. As a result, longer range models have 850 mb temperatures warming towards 18C to 20C, which will bring daytime highs into the upper 80s to low 90s for the weekend and continue to warm through Wednesday. At this time, the warmest days looks to be Monday and Tuesday. As Wednesday approaches, the aforementioned low looks to be pulled northward. This will bring about a slight cooling trend for the middle of the week. /42

AVIATION

Marine stratus has cleared, and skies are generally clear with VFR conditions in place for all terminals. Diurnal winds as of 21z Thu have also picked up slightly, with gusts up to 15-18 kts from the northwest at all terminals. Gusts up to 20-25 kts will be possible at coastal terminals only while winds are elevated. Around 6z Fri, winds begin to come down and drop below 6 kts for all terminals. Another chance of marine stratus developing for all coastal terminals and the northern Willamette Valley terminals (KPDX, KHIO, KTTD, KUAO) around 15z Fri. 20-30% chance of MVFR cigs at that time, lasting through Friday morning.

PDX AND APPROACHES...Generally VFR conditions through the period, though a 25-30% chance of MVFR marine stratus developing again tonight around 15z Thu. Northwesterly wind gusts up to 15-18 kts possible, dropping below 6 kts again over Thursday night. /JLiu

MARINE

Persistent surface high pressure offshore will result in continued northerly to northwesterly winds across the waters. Diurnal gusts will reach 10-15 kt north of Cape Falcon and 15-20 kt from Cape Falcon to Florence each afternoon, easing to around 10 kt overnight. A locally tightened pressure gradient across the inner waters south of Cape Falcon may see occasional gusts above 20 kt the rest of this afternoon, but majority of gusts remain well below SCA criteria. Seas will continue at 3-6 ft through the weekend, before strengthening surface high pressure sees winds and seas build Sunday into next week. -Picard/JLiu

PQR WATCHES/WARNINGS/ADVISORIES

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