textproduct: Portland

SYNOPSIS

High pressure will form and persist over the area through at least Tuesday leading to an abnormally warm and dry weekend. Low probability of precipitation on Wednesday or Thursday.

LONG TERM...Tuesday through Friday

The long term forecast is highlighted by relatively cooler temperatures compared to the weekend with an 80-90% chance for continued dry conditions west of the Cascades. There is some uncertainty as to how much cooler conditions will become, as model spread suggests highs could range anywhere from the mid 50s to upper 60s per the NBM 10th-90th percentile. Most of this uncertainty stems from the exact track of a closed upper level low over the Pacific that will be slowly moving towards California, and how far south an upper level trough will dig over the Pacific Northwest along the northern periphery of this closed low.

In the current ensembles, models are pushing this low further south than previous days. This track will maintain drier and warmer air over the region with much lower probabilities of precipitation. On Tuesday night into Wednesday, there is less than a 20% chance of precipitation along the coast and the central Oregon Cascades, with probabilities rising to around 40% on Wednesday afternoon for the Willamette National Forest. Something to consider is the pervasive nature of the ridge and the surplus of dry air. This will combat some of that precipitation from reaching the ground. Unfortunately, no snow is expected.

Thursday dries out once again before some global models suggest another messy low pressure system drops down from the Gulf of Alaska. At this point, there is so much uncertainty and what the impacts will be will greatly depend upon the strength of the ridge from the previous days. -27/23

AVIATION

Widespread VFR with generally variable winds 6 kts or less for inland locations and northerly winds, less than 10 kt along the coast. Scattered high clouds continue to slowly lift northward out of the area through 00Z Saturday. The clearing skies could result in a return of patchy IFR/LIFR conditions (10-20% chance) within the Willamette Valley starting around 11Z-14Z Saturday. KPDX, KSLE and KEUG currently have the highest chance for these conditions to manifest as fog. Any IFR/LIFR conditions that do develop should scour out around 16Z-19Z Saturday, with VFR returning to the airspace afterwards.

KPDX AND APPROACHES...VFR flight conditions with slowly clearing skies and light winds. 10-20% chance of IFR/LIFR conditions developing at or near the terminal starting around 11Z Saturday. Any IFR/LIFR conditions that do develop should scour out around 16Z-19Z Saturday, with VFR returning afterwards. -42

MARINE

High pressure remains in place over the waters and is resulting rather benign conditions across all waters through the start of the weekend. Seas are currently around 5 to 7 feet and are expected to hold through at least the start of next week. Winds, on the other hand look to be a little bit more active come Saturday. Northerly winds are expected to increase and bring marginal small craft advisory gusts up to 25 kt across the outer waters. Therefore, have expanded the current Small Craft Advisory to now include zone PZZ271. Wind gusts will generally stay below 21 kt over the inner waters, but there could be isolated gusts up to 25 kt potentially beginning as early as late Saturday morning for the inner waters. Despite the uptick in winds, seas are not expected to respond much, likely staying below 8 ft. As the start of next week approaches, Winds become more northwesterly with seas remaining relatively low. -42

PQR WATCHES/WARNINGS/ADVISORIES

OR...None. WA...None. PZ...Small Craft Advisory from 11 AM Saturday to 5 AM PDT Sunday for PZZ271>273.