textproduct: Portland

SYNOPSIS

Expect a warm and dry 4th of July weekend across northwest Oregon and southwest Washington. Temperatures warm up slightly Sunday and Monday as high pressure builds, leading to localized Moderate HeatRisk. An upper-level trough moving into British Columbia Tuesday to Wednesday will cool temperatures a few degrees and bring chances for precipitation along the south Washington and north Oregon coast. Dry and warmer conditions return on Thursday, however persistent onshore flow will help to maintain near normal daytime highs across northwest Oregon and southwest Washington. Make sure to practice water safety when swimming in local rivers.

LONG TERM...Tuesday through Friday

Looking into the middle of next week and towards next weekend, the majority of ensemble members are showing an upper-level trough from the Gulf of Alaska moving down into British Columbia thus compressing The Great Basin upper level high. Given the more northern track of this trough, most places across the area is expected to be dry. An exception would be the south Washington and north Oregon coast where this system favors a 15-30% chance for light rain from Tuesday night to Wednesday, but it should be noted that current QPF totals are minimal at best. Despite the lack of widespread, if any precipitation, onshore flow will increase and support temperatures cooling a few degrees closer to seasonal normals for early July. West-northwesterly winds are generally expected to be light for most areas during this time. However, will see locally breezier along the central Columbia River Gorge and Upper Hood River Valley, where there is a 25-40% chance for at least isolated wind gusts exceeding 40 mph Tuesday and Wednesday. As for the end of next week, most ensemble members show the British Columbia trough weakening as it moves eastward. At the same time, The Great Basin high looks to re-establish itself. This will bring about a return of zonal flow for the Pac NW which will bring warm and dry conditions back into the forecast. /42-10

AVIATION

High pressure lingers over the area increasing daytime heating, and forming overnight inversions. Generally northwesterly flow through the forecast therefore have seen more pervasive MVFR CIGs than previous days. Because of this dense cloud deck, which via PIREPs is reported around 1700-3500 ft, it may be a bit more challenging to fully dissipate. However, the overall trend based on a more persistence forecast shows these CIGs improving around 20Z Sat. Afternoon diurnally driven northerly winds expected today with gusts up to 20 kt along the coast, and sustained 10-14 kt within the Willamette Valley - especially near KEUG.

Overnight is where the challenge comes in and whether or not we will see MVFR CIGs redevelop. Some positives is that there is a weak shortwave moving in which will increase winds earlier and thus mixing aloft. However, some models continue to show areas of MVFR CIGs in the interior valleys, with high probabilities along the coast.

KPDX AND APPROACHES...MVFR CIGs through the next several hours but could last as late as 22Z Sat. Northerly winds increase over the afternoon after 20Z Sat, but will be strongest after 00Z Sun. Around a 70% chance of MVFR CIGs redeveloping after 14Z Sun with some models suggesting similar probability for IFR CIGs. However, due to winds remaining elevated and drier air remaining, getting these levels will be more difficult. Cannot rule it out completely though. Winds will begin to increase late in the forecast as a weak disturbance passes through. -27

MARINE

High pressure over the region result in increasing winds and building seas through Monday. Northerly winds will slowly increase through this afternoon and will result in gusts up to 20 kt by this evening. Winds will continue to strengthen with gusts up to 30 kt by Sunday. Seas will also build from 4 to 6 ft towards 6 to 8 ft by Sunday. As a result, have maintained the current suite of Small Craft Advisories through at least Sunday night. High pressure will slowly become displaced towards the start of next week, thus easing overall conditions by Monday night/Tuesday which is expected to persist through the remainder of next week. -42

PQR WATCHES/WARNINGS/ADVISORIES

OR...None. WA...None. PZ...Small Craft Advisory from 11 PM this evening to 11 PM PDT Sunday for PZZ251-271.

Small Craft Advisory from 8 PM this evening to 11 PM PDT Sunday for PZZ252-272.

Small Craft Advisory from 2 PM this afternoon to 11 PM PDT Sunday for PZZ253-273.