textproduct: Portland

SYNOPSIS

Onshore flow continues over the next week. Near zonal flow aloft today through Sunday will become southwesterly early next week, with surface high pressure building this weekend. This pattern will bring warmer temperatures and a good deal of sunshine during peak heating hours each day. Most inland valleys will warm into the low to mid 80s each day, except 70s today. Onshore flow will keep the coast cooler with highs in the 60s.

DISCUSSION...Now through Wednesday night

There has been minimal change to the forecast with this morning's update. Models and their ensembles remain in excellent agreement July 2-8, resulting in a high confidence short term and long term forecast. Cluster analysis for 500 mb heights and anomalies highlights this well, with all clusters suggesting zonal flow aloft today through Sunday before becoming southwesterly early next week. 500 mb heights are trending near normal to slightly above normal each day. At the surface, high pressure will be building into the upcoming holiday weekend with onshore flow remaining in place.

This pattern will bring a warming trend, with inland valleys warming into the 70s today and low to mid 80s Friday through early next week. The coast will remain cooler with highs in the 60s each day due to persistent onshore winds. These temperatures are near average for early July, resulting in only a minor HeatRisk. NBM probabilities for highs of 90 degrees or warmer are very low each day and range between 0-10%, except on Monday when probabilities briefly increase to around 5-15%. Given the dry weather in place, conditions will be ideal for outdoor recreation over the holiday weekend. However, it is important to remember that while things will be warming up, many of our lakes and rivers remain cold. Please practice water safety and note that rivers may have swift currents in some areas, which can quickly sweep you away. Wear life jackets, and visit with a buddy. It is also worth noting that northwest winds will become a bit breezy along the Columbia River, in the Gorge, and downwind of the Coast Range gaps each day during the afternoon and evening hours. Expect wind gusts upwards of 15-20 mph in these areas, except up to 25 mph in the Gorge. -23/27

AVIATION

At 13Z Thursday, MVFR ceilings were occurring along the coast and in southwest WA. Skies were mostly clear over most of the Willamette Valley aside from scattered high clouds above 15 kft, resulting in VFR conditions at KSLE and KEUG. However, cloud cover over the north Oregon Cascades has expanded far enough to reach KTTD and KPDX with ceilings near 2300-2500 feet. This cloud deck is only a few miles away from KHIO and KUAO, and there is a 20-25% chance it will expand over these two terminals for a brief period of time this morning. Expect these low clouds to scatter out and lift by 17-18Z Thursday and bring a return to VFR conditions at all terminals, except at KAST where MVFR ceilings are expected to continue throughout most of the TAF period.

KPDX AND APPROACHES...MVFR ceilings around 2300-2500 feet this morning should scatter out and lift by 17-18Z Thursday, bringing a return to VFR conditions. Expect scattered to broken high level clouds above 15 kft in the afternoon and evening. Similar to yesterday, light winds in the morning will become northwesterly around 8-10 kt by 01-02Z Friday with an incoming sea breeze. Occasional gusts up to 15 kt are expected between 01-06Z Friday. -23

MARINE

The forecast remains on track Thursday morning. Winds and seas have eased as expected, with buoy observations showing significant wave heights hovering between 3 to 5 ft along with weak winds around 5 to 10 kt. Expect these benign conditions to continue through Friday morning. Northerly winds will increase Friday afternoon and evening to around 10 to 15 kt, strongest to the south of Cape Foulweather where gusts up to 20 kt are expected late in the day. This will help increase seas by a foot or two, but conditions are expected to remain below small craft advisory criteria.

A thermally induced surface trough will build northward up the south Oregon coast over the weekend, bringing a more notable uptick in northerly winds with gusts increasing to 20-25 kt. As is often the case during this typical summertime pattern, wind speeds will be strongest during the afternoon and evening hours each day with daytime heating. Although significant wave heights are not expected to increase much, the increasing winds will result in choppier seas. Northerly winds gradually ease early next week. -23

PQR WATCHES/WARNINGS/ADVISORIES

OR...None. WA...None. PZ...None.