textproduct: Portland

SYNOPSIS

The upper level ridge is building over the region which will lead to a few days of hot temperatures, warm overnight lows, low humidity, and breezy winds. Peak heating days will be Sunday and Monday with minimal overnight temperature relief. Extreme Heat Warning in effect for the Greater Portland-Vancouver Metro and Columbia River Gorge Sunday through Tuesday. Heat Advisory in effect elsewhere, with the coast only being on Sunday. Breezy easterly winds through the Columbia River Gorge on this afternoon and Sunday will ease on Monday. Warm conditions remain through the week though will be at least 10 degrees cooler for inland locations.

LONG TERM...Tuesday through Saturday

Models are coming into better agreement that the ridge will hold into Tuesday and the trough that was displayed earlier in the week is no longer going to have significant influence. It will still cause the ridge to flatten slightly, but we are not necessarily expecting straight zonal flow. Instead, we will see a slight northwesterly wind which will keep the northern portions of the area cooler than the southern areas. With this in mind though, heat remains a concern though the daytime highs continue to remain below critical levels. While the Extreme Heat Warning and Heat Advisories remain in effect through Tuesday, we will continue to evaluate on whether they remain a significant threat. An area that will maintain at least Moderate HeatRisk on Tuesday is the greater Portland-Vancouver Metro area and other urban centers. This is likely due to the urban heat island effect.

Come Wednesday we will have transitioned out of the heat wave but 500 mb ensemble models continue to show general ridging over the region. This means that we will continue to see dry, clear, and warm conditions. Overall, high temperatures will be in the 60s along the coast, in the 80s inland, and in the 60s-70s along the Cascades. The pattern remains fairly stable with minimal changes in the sensible weather. Ultimately it just comes down to the numbers and how much uncertainty we experience. As we move into later on the week (Thu-Fri), confidence decreases in exact temperature values. Right now there is anywhere from a 6-10 degree spread in potential high temperatures each day. Ultimately prepare for a week of dry and warm conditions. -27

AVIATION

l confidence in this pattern change is low at this time. -03

CLIMATE

High pressure will maintain VFR conditions with clear skies through the TAF period across all terminals. North to northeasterly winds expected, except northwesterly at the coast. Surface pressure gradients tighten this afternoon supporting gusty winds up to 20-25 kt at any given terminal. After 03-04z Sunday, winds should gradually weaken as pressure gradients ease and winds turn back offshore at the coast.

In addition, temperatures between 90 to 100 degrees are forecast across the Willamette Valley Saturday through Monday. Be aware of high density altitude which may reduce aircraft performance.

KPDX AND APPROACHES...VFR with clear skies through the TAF period. Northeasterly winds with gusts up to 20 kt are expected through the afternoon. Winds weaken later in the evening after 03-04z Sunday. -DH

MARINE

High pressure offshore will maintain the summertime pattern this weekend and through much of next week. A strengthening thermal trough along the coast will increase pressure gradients over the coastal waters today. As such, northerly winds will increase to around 15-25 kt with gusts up to 25-30 kt south of Cape Falcon, while gusts up to 25 kt will be possible northward toward Cape Disappointment. Winds ease by Sunday morning, but are expected to increase again as diurnally driven northerlies peak each afternoon and evening through next week. Seas around 4 to 8 ft at 7-10 seconds are expected to persist, driven primarily by the northerly wind chop. -DH

PQR WATCHES/WARNINGS/ADVISORIES

OR...Heat Advisory from 11 AM to 11 PM PDT Sunday for ORZ101>103. Heat Advisory from 11 AM Sunday to 11 PM PDT Tuesday for ORZ104>108-113>119-121>125. Extreme Heat Warning from 11 AM Sunday to 11 PM PDT Tuesday for ORZ109>112-120. WA...Heat Advisory from 11 AM to 11 PM PDT Sunday for WAZ201. Heat Advisory from 11 AM Sunday to 11 PM PDT Tuesday for WAZ202>205-208-210. Extreme Heat Warning from 11 AM Sunday to 11 PM PDT Tuesday for WAZ206-207-209. PZ...Small Craft Advisory until 2 AM PDT Sunday for PZZ251-271. Small Craft Advisory until 5 AM PDT Monday for PZZ252-253-272- 273.