textproduct: Portland

SYNOPSIS

Broad high pressure over the region will maintain generally dry conditions through the next several days. An upper level low offshore will bring chances for elevated thunderstorms over the Cascades today, however, some of which may track toward the Willamette Valley this afternoon and evening. A warming trend will peak on Sunday with daily record high temperatures in the forecast for some inland areas. Temperatures will cool but remain above normal into the next workweek.

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 or early morning hours.

Late in the week, guidance favors a flattening of the upper ridge as shortwave impulses ride up and over its northern periphery. This pattern will favor temperatures cooling further toward seasonal norms, as well as supporting low (10-25%) chances for light rain across portions of the region. -36

AVIATION

Northerly flow at the surface continues to support a MVFR/IFR marine layer along the coast. Flight conditions along the coast are expected to become more IFR/LIFR from 07Z-10Z Saturday, with a higher probability of LIFR conditions for KAST. While northerly flow at the surface is present for inland terminals, there is southerly flow aloft (which can be observed via satellite). This pattern is maintaining high level clouds across the airspace above FL200-FL250. West to northwest winds at the surface 5-10 kt through the evening, becoming light and variable overnight. Expect slowly lowering CIGs down towards FL050-FL100 around through 10Z Sat.

Radar is also showing some showers along the Cascades and they are high based. There are some embedded thunderstorms within these showers and as the upper level flow slowly becomes more southeasterly through the TAF period, these shower could push further inland, resulting in brief periods of MVFR conditions. General instability will continue to decrease as surface conditions cool. Still, the location and timing of any showers is uncertain, with confidence in any impacts to terminals remaining very low.

KPDX AND APPROACHES...VFR conditions beneath increasing high clouds expected through the period, with CIGs falling from FL200-FL250 towards FL100 through 08Z Saturday. Northwest winds to 5-10 kt easing below 5 kt around 06Z Saturday. /42

MARINE

Northerly winds continue through the weekend, rising to diurnal peaks in the afternoon and easing overnight. A steady slackening of the surface pressure gradient will favor lighter winds through the weekend. A Small Craft Advisory remains in effect beyond 10 NM south of Cape Falcon through only 8 AM today before gusts fall below 20 kt. Seas of 5-6 ft this morning will slowly increase to 6-8 ft as a long-period northwest swell arrives through today. A further Small Craft Advisory has been hoisted for 3-9 AM Sunday within the Columbia River Bar as a strong ebb current yields steep seas of 7-8 ft.

A wind reversal on Monday will see southerly to southwesterly flow continue through Tuesday night, with increased low marine stratus and overnight drizzle or light rain across nearshore areas. More seasonable northerly flow redevelops in the latter half of the week with persistent seas of 4-6 ft. -36

CLIMATE

Daily record high temperatures for Sunday, May 3

Location Forecast Record Year

Astoria 75 81 1992, 1944 Vancouver 89 84 1944 Portland Int'l 91 89 1992 Hillsboro 89 82 2017 McMinnville 86 87 1992 Salem 86 86 1992 Eugene 83 83 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 from 3 AM to 9 AM PDT Sunday for PZZ210.

Small Craft Advisory until 2 AM PDT early this morning for PZZ252-253-271.

Small Craft Advisory until 8 AM PDT this morning for PZZ272- 273.