textproduct: Portland

SYNOPSIS

Temperatures cool off tonight after a hot spring day. The upper level pattern shifts east tonight and supporting cooler but still above average temperatures to the area through the week. Uncertainty increases late in the week with the ridge pattern possibly breaking down toward the weekend.

DISCUSSION...Tonight through Sunday

Temperatures are expected to moderate back into the 60s along the coast and in the higher terrain and 70s elsewhere on Monday and through much of the workweek as the ridge axis shifts inland. Highs will still run 5-10 degrees above normal for this time of year. Winds turn southerly with the ridge shifting eastward which will help support chances for marine stratus to develop along the coast. Ensembles show a strong consensus for dry conditions through the workweek for much of the area. However, there is a low (10-20%) chance for a pop-up shower or thunderstorm over the Lane and Linn county cascades both Monday and Tuesday afternoon. Could also see some light drizzle along the coast if the marine stratus is thick enough.

Cluster analysis favors the ridge flattening out toward the end of the week as a shortwave rides over the ridge. This could lead to a pattern shift back to cooler temperatures and low chances for light rain. The current forecast maintains temperatures slightly above normal next weekend, however, there is a decent amount of uncertainty in the forecast. -19

AVIATION

Current observations show VFR conditions for inland areas with IFR/LIFR marine stratus moving northward along the coast and infiltrating around the southern Coastal Range and through the gaps and flows. Overnight, a wind reversal will see southerly flow develop along the coast with a slight delay for inland locations. Southerly winds will persist through the TAF period. This wind reversal will also support the IFR/LIFR marine stratus mentioned previously and help to spread the marine stratus northward along the coast through 12Z Sunday. Current observations already show KONP being impacted with KTMK, likely see impacts around KTMK by 05Z Sunday and the marine stratus reaching KAST around 10Z Sunday. Additionally, there's a 50-75% chance MVFR cigs reach KEUG around 11Z Sunday, a 30-50% chance the MVFR cigs reach KSLE and a 15-20% chance they reach. KUAO, KPDX and surrounding terminals. If lowered flight conditions develop, inland locations expected to improve to VFR around 18Z-21Z Monday. Coastal locations will likely stay IFR/LIFR through the TAF period.

KPDX AND APPROACHES...VFR conditions expected throughout the period. Southerly will develop though 12Z Monday. There's a 15-20% chance of marine stratus with MVFR conditions impacting KPDX and surrounding terminals after 12Z Monday. If lowered flight conditions develop, expected improvement to VFR around 18Z-21Z Monday. /42

MARINE

A southerly wind reversal begins this evening south of Cape Foulweather, with the wind transition spreading from the southern waters to the northern waters overnight. A period of elevated south winds form along the inner waters late tonight through Monday morning with gusts up to 18-20 kts. South winds continue into Tuesday and will bring a resurgence of marine stratus tonight through Tuesday night which could result in overnight or early morning drizzle or light rain. Seas around 6-8 feet through Monday, falling to 4-5 feet on Tuesday. Northerly winds return towards the latter part of the week with persistent seas of 4-6 ft. -03

PQR WATCHES/WARNINGS/ADVISORIES

OR...Heat Advisory until 11 PM PDT this evening for ORZ108-109-111- 112.

WA...Heat Advisory until 11 PM PDT this evening for WAZ204>207.

PZ...None.