textproduct: Portland

SYNOPSIS

Monday will be a cool and rainy day as steady stratiform rain spreads over the area with an incoming surface low. Expect persistent rain from near sunrise to near sunset before stratiform rain transitions to off-and-on showers towards 8 PM Monday. Showers will then linger into Tuesday and Wednesday, maintaining cooler than normal temperatures. Breezy south to southwest winds will also occur Monday afternoon through Tuesday afternoon with wind gusts as high as 30-35 mph. High pressure arrives on Thursday, bringing dry weather with highs in the 70s, except 60s at the coast. Attention then turns to a multi-day heat wave beginning next weekend and extending into early next week. Highs in the 90s are likely (65-85% chance) for inland valleys during this heat event, with a 10-30% chance for highs at or above 100 degrees June 14-15 for inland valleys.

LONG TERM...Thursday through Saturday night

The long term forecast is highlighted by a prolonged stretch of dry conditions with a multi-day heat wave beginning next weekend. Before the heat kicks in, expect pleasant weather on Thursday with mostly sunny skies and high temperatures in the 70s, except 60s at the coast. From Friday onward into early next week, models and their ensembles show an upper level ridge amplifying over the far northeast Pacific, with some uncertainty regarding exactly how far east the ridge axis will move. Despite the uncertainty with the location of the ridge axis, confidence is high temperatures will be heating up significantly June 13-15. This is when the LREF mean shows 500 mb heights near the climatological 97-98th percentile and the NBM shows a 65-85% chance for high temperatures above 90 degrees for inland valleys and less than a 10% chance at the coast. In fact, there is a 10-30% chance for highs at or above 100 degrees June 14-15 for inland valleys, suggesting a major heat wave is within the realm of possibilities. In addition, overnight lows in the mid or even upper 60s will offer minimal overnight relief. As such, probabilities for a Moderate HeatRisk or higher peak near 75-90% June 14-15, with a 20-50% chance for a Major HeatRisk or higher. Note the highest probabilities are over the greater Portland/Vancouver metro. Anyone who is sensitive to heat or those who have outdoor plans should pay attention to the forecast over the coming days and be prepared for potential extreme heat. Those planning on swimming in rivers or lakes to cool off should be mindful of cold water temperatures and swift currents, which can become life threatening. -23

AVIATION

VFR flying conditions with high cloud coverage continuing to increase ahead of an approaching frontal system. Westerly winds aloft with generally light and variable winds at the surface overnight. Cigs trend lower tonight before rain arrives from the west by 10-15z Mon. Cigs lower to MVFR a few hours after rain begins, around 15-18z Mon along the coast and 17-20z Mon inland. Chances for IFR conditions increase along the coast after 20z Mon. Winds shift southerly ahead of the front and rise to 5-10 kt by 12-15z Mon. Winds then increase along the front to 12-15 kts and gusts up to 25-35 kts along the coast by 18-20z Mon and 25-30 kts inland by 00-03z Tue.

KPDX AND APPROACHES...VFR conditions. High cloud coverage will increase from the west overnight, followed by rain beginning by 13-15z Mon. Variable winds less than 5 kt overnight, shifting out of the south near 5 kt Monday morning ahead of the frontal boundary. Expect cigs to become MVFR by 16-18z Mon, continuing through the rest of the TAF period. South winds increase after 21z Mon - 00z Tue to 10-15 kt with gusts up to 25-30 kts. -03

MARINE

An active and progressive pattern continues with periods of rain and elevated wind through midweek. A first frontal system arrives tonight into Monday morning, bringing widespread rain and strengthening southerly winds. The strongest winds reach 20-25 kt with gusts as high as 30-32 kt through much of the day on Monday, with isolated gale-force gusts as high as 35 kt most likely between 1-6 PM PDT within 20 NM south of Cape Foulweather. Seas will build from 4-5 ft this afternoon to 7-9 ft at 8 seconds by Monday afternoon with a continued dominant westerly swell. Small Craft Advisories remain in effect beginning at 11 PM PDT this evening beyond 10 NM and at 5 AM PDT Monday within 10 NM, and continuing through at least Tuesday afternoon. While southerly winds will subside behind the frontal passage, west-northwesterly winds is its wake are also expected to gust near 20-25 kt while seas remain relatively steep, so Small Craft Advisories may need to be extended further.

West-northwest winds on Wednesday will steadily turn out of the north as high pressure builds offshore. Strengthening northerlies will see diurnal peaks in the afternoon each day Thursday through at least Saturday, periods which could necessitate additional Small Craft Advisories for gusts near 25 kt. Seas through this period look to remain near 5-7 ft with a west-northwest swell at 9-11 seconds. -36

PQR WATCHES/WARNINGS/ADVISORIES

OR...None. WA...None. PZ...Small Craft Advisory from 5 AM Monday to 2 PM PDT Tuesday for PZZ251>253. Small Craft Advisory until 2 PM PDT Tuesday for PZZ271>273.