textproduct: Portland

SYNOPSIS

High pressure over the region will maintain generally dry conditions through the next several days. An upper level low though will increase instability and add moisture to the environment bringing chances for elevated thunderstorms over the Cascades on Saturday. Temperatures continue to rise through the weekend with Sunday being the warmest with record breaking highs in the forecast. Slightly cooler in the long-term forecast but overall, fairly typical spring time conditions.

LONG TERM...Monday through Friday

By the beginning of the workweek, ensemble guidance continues to favor moderating temperatures as the upper ridge axis moves inland. A southerly wind reversal will increase marine stratus coverage along the coast, with broader onshore flow cooling inland areas as well. There is general consensus in dry conditions across most of the region, however a minority of ensemble members depict very light rain or drizzle within the shallow marine layer, most likely in the overnight hours.

On Friday an upper level longwave trough will begin to advance towards the region which will begin to disrupt the overall pattern. Will see the ridge begin to flatten and temperatures lower even further to much more seasonable highs in the 70s. -27/36

AVIATION

Northwest flow continues to support marine layer clouds along the coast with MVFR CIGs between 1-1.5 kft. Could see a pullback in cloud cover this afternoon between 21z Fri through 2z Saturday as clouds shift just offshore. For the most part, MVFR or lower CIGs expected with northwest winds gusting to 20 kt this afternoon and evening.

Inland terminals can expect mainly VFR conditions. High level clouds around 20-25 kft will continue to stream in from the southwest. West to northwest winds 5-10 kt through the evening, becoming light and variable overnight. Expect slowly lowering CIGs down to 6-10 kft by 00-06z Sat, with 25-30% chances for showers or possibly thunderstorms late in the period. These showers or storms are most likely to develop over the Cascades and track northward, resulting in increasing chances heading east from the Willamette River. The location and timing of any showers is uncertain, and impacts to terminals remain very low confidence.

KPDX AND APPROACHES...VFR flying conditions beneath increasing high clouds expected through the period, with CIGs falling from 20-25 kft to near 10 kft by this evening. Chances for rain showers increase to 15-20% late in the period, after 06z Sat, with very low confidence in any terminal impacts. Northwest winds to 5-10 kt this afternoon before easing below 5 kt again this evening. -19/36

MARINE

High pressure will support northerly winds through the weekend, peaking this evening. Wind gusts of 20-25 kt are most likely for all waters south of Cape Falcon and north of Cape Falcon beyond 25-30 NM A Small Craft Advisory is in effect for these zones through 2 AM Saturday with wind gusts easing below 20 kt after that time. A wind gusts around 20 kt is still possible over the waters within 25-30 NM north of Cape Falcon but the frequency is expected to be much less compared to the rest of the waters. Seas remain around 6-8 feet through the weekend though the period will increase from around 11-12 seconds to around 16-17 seconds Saturday as a long period northwest swell moves in. A wind reversal on Monday will see southerly to southwesterly flow develop early next week with increased low marine stratus and overnight drizzle or light rain. More seasonable northerly flow redevelops in the latter half of the week with persistent seas of 4-7 ft. -19/36

CLIMATE

Daily record high temperatures for Sunday, May 3:

LocationForecastRecord (Year)

Astoria7581 (1992, 1944) Vancouver8984 (1944) Portland Int'l9289 (1992) Hillsboro9082 (2017) McMinnville8787 (1992) Salem8986 (1992) Eugene8583 (1944)

PQR WATCHES/WARNINGS/ADVISORIES

OR...Heat Advisory from 8 AM to 11 PM PDT Sunday for ORZ108-109-111- 112. WA...Heat Advisory from 8 AM to 11 PM PDT Sunday for WAZ204>207. PZ...Small Craft Advisory until 2 AM PDT Saturday for PZZ252-253- 271. Small Craft Advisory until 8 AM PDT Saturday for PZZ272-273.