textproduct: Portland

SYNOPSIS

Broad high pressure over the region will maintain generally dry conditions through the next several days. Temperatures are expected to peak today with daily record highs in the forecast for some inland areas. An upper level low offshore may bring isolated Cascade showers or thunderstorms this afternoon and evening. Temperatures will cool but remain above normal heading into the workweek.

LONG TERM...Monday through Saturday

The large-scale pattern will slowly slide eastward through the early portion of the workweek, with a southerly wind reversal and extensive marine stratus along the coast and renewed onshore flow inland acting to cool temperatures substantially on Monday and Tuesday. Forecast highs largely in the 60s along the coast and in high terrain and 70s within inland valleys will feel much cooler, but still remain above normal for early May. Ensemble guidance continues to favor largely dry conditions beneath the upper ridge, but there will still be low (10-20%) chances for isolated showers or thunderstorms over the Cascades of Lane and Linn Counties, as well as periods of drizzle within coastal marine stratus in the overnight or early morning hours each day.

By the middle to late portions of the workweek, long-range ensembles continue to favor a flattening of the longwave ridge which will otherwise persist over the West Coast. This deamplification of the pattern may allow shortwave troughs to traverse the apex of the ridge, yielding increased chances for cooler temperatures as well as low chances for light rain, particularly on Friday and Saturday. Nonetheless, current forecast high temperatures still remain 5-10 degrees above seasonal norms in the 60s along the coast and in high terrain, and in the 70s within inland valleys. -36

AVIATION

Largely VFR flying conditions continue across the region early this morning and are likely to prevail at most terminals throughout the period. A narrow tongue of marine stratus along the Oregon coast has begun to recede per latest satellite imagery as light offshore flow develops. Some more sheltered terminals (KTMK) continue to observe mist/fog beneath the low cloud deck, but chances for further restricted vis/cigs will steadily decline through the morning. Inland, areas of restricted vis within radiation fog have developed as high clouds have cleared, primarily in the southern Willamette Valley including KEUG/KCVO. Any low cloud will quickly mix out by 15-17z Sun as robust diurnal heating increases.

After 21z Sun, chances for showers and thunderstorms increase over the western slopes of the central Oregon Cascades, but confidence in terminal impacts remains very low, more likely convective outflow debris in the form of high cloud cover may develop in the late afternoon to early evening, after 00z Mon. Otherwise, continued VFR conditions is expected with northwesterly flow of 5-10 kt along the coast, northeasterly flow becoming northerly around 5 kt at Portland-area terminals, and northerly flow at 5-10 kt along the Willamette Valley.

Late in the period, after 03-06z Mon, a wind reversal will see low-level flow turn southerly across the region. At coastal terminals, a renewed push of marine stratus will most likely see a return to MVFR/IFR cigs, which may also reach inland to KEUG and the southern Willamette Valley.

KPDX AND APPROACHES...VFR conditions expected throughout the period beneath largely clear skies. Northeasterly flow around 5 kt early will turn northerly this evening, then ultimately out of the south overnight. Convective debris in the form of high cloud cover may increase this afternoon and evening, but no terminal impacts are anticipated. -36

MARINE

Northerly winds continue today, peaking in the afternoon and easing overnight. Seas of 5-6 ft this morning will slowly build towards 6-8 ft as a long-period northwest swell arrives. A Small Craft Advisory remains in effect through 9 AM this morning within the Columbia River Bar as a strong ebb current yields steep seas of 7-8 ft.

A southerly wind reversal is on Monday is expected to bring resurgent nearshore marine stratus through Tuesday night, as well as overnight or early morning drizzle or light rain. Northerly winds return towards the latter part of the week with persistent seas of 4-6 ft. -36/42

CLIMATE

Daily record high temperatures for Sunday, May 3

Location Forecast Record Year

Astoria 78 81 1992, 1944 Vancouver 90 84 1944 Portland Int'l 91 89 1992 Hillsboro 91 82 2017 McMinnville 86 87 1992 Salem 86 86 1992 Eugene 83 83 1944

PQR WATCHES/WARNINGS/ADVISORIES

OR...Heat Advisory from 8 AM this morning to 11 PM PDT this evening for ORZ108-109-111-112.

WA...Heat Advisory from 8 AM this morning to 11 PM PDT this evening for WAZ204>207.

PZ...Small Craft Advisory until 9 AM PDT this morning for PZZ210.