textproduct: Portland

SYNOPSIS

Dry and warm weather is expected across the region through the weekend with high pressure over the NE Pacific spreading east over the Pacific NW. Rain, cooler temperatures, and slightly elevated winds return to the area late Sunday into early next week, which could impact any outdoor Memorial Day plans.

DISCUSSION...Today through Wednesday

There has been very little change in the forecast since the previous package. Today is still shaping up to be the warmest day of the week. Temperature observations at noon were around 70-74 degrees for most interior lowland locations, which is right on track for high temperatures to peak in the low to mid 80s. The daily normal temperature for today is around 69-71 degrees across the Willamette Valley, so today's high temperatures are forecast to be around 10-15 degrees warmer than normal. However, no record high temperatures are expected to break as record high temperatures are generally in the upper 80s to mid-90s through the Memorial Day Weekend. Temperatures at noon along the immediate coast were much cooler, in the mid 50s to low 60s due to lingering marine stratus. As that dissipates through the early afternoon, coastal temperatures are expected to peak in the mid to upper 60s.

Conditions are expected to remain dry through the end of the week and into the weekend as high pressure continues across the region. High temperatures on Friday will be just a few degrees cooler than today, generally right around 80 degrees for the inland valleys. The broad upper level ridging on Friday becomes more zonal aloft Saturday into Sunday. Expect a slight cooling trend in temperatures through the weekend, but still likely to remain above seasonable averages in the mid to upper 70s.

There remains good agreement that Sunday will remain mainly dry and warm, though could begin to see increasing cloud cover ahead of an approaching weather system. There high confidence in the ensemble members that a frontal system will push into the PacNW sometime late Sunday night into Monday, with chances of rain increasing for Monday, followed by showers into Tuesday. Some uncertainty still remains in the general timing of rain as well as rain totals, but latest consensus is that rain will hold off until at least late Sunday night along the far N OR and SW WA coast, then spread southeast Monday morning. Confidence is high that this will be non-impactful rain. When looking at the probability of reaching or exceeding 0.5 inch for 48 hour rain totals through 5 AM Wednesday, there's a 10-20% chance for the Willamette Valley, 20-40% for the Portland and Vancouver metro area and SW WA lowlands, 45-65% for the coast and Coast Range, and 50-70% for the Cascades. However, some elevated winds are possible on Monday as the front sweeps through the area. There's a 60-80% chance of peak gusts of at least 25 mph and about a 20-40% chance of peak gusts of at least 30 mph. These aren't high enough gusts for any wind advisory concerns, but they could cause impacts to any tents that might be in place for outdoor holiday activities.

Temperatures will also drop substantially Monday and Tuesday with high temperatures in the lower to mid 60s for the interior lowlands. Conditions are likely to rebound back to seasonable normals by the middle of next week, though some uncertainty remains due to continued low chances of precipitation. -03/DH

AVIATION

Latest satellite imagery depicts regions of low marine stratus beginning to redevelop along the coast, while largely clear skies otherwise remain in place. Inland, clear skies and VFR flying conditions will prevail through the period with diurnal winds rising to 5-10 kt out of the north to northwest by 17-19z Fri. Patchy low stratus will initially result in intermittent VFR/IFR flying conditions along the coast through 09z Fri, when coverage is expected to increase, pushing chances for IFR/LIFR to 50-80%, with highest chances along the central Oregon coast at KONP. Cigs will most likely lift to low- end MVFR after 18z Fri, however there are 20-50% chances IFR cigs persist through much of the day. Any improvement will be temporary as cigs are again favored to fall below IFR threshold by 03z Sat. Gusty diurnal winds continue, with north to northwest flow easing to around 5 kt through the 12z Fri, then rising to 10-15 kt with gusts reaching 20-25 kt after 18z Fri.

KPDX AND APPROACHES...VFR conditions continue through the period with only a 15-20% chance of low marine stratus reaching far enough inland along the Columbia to yield MVFR cigs. Any low clouds will quickly mix out by 16-18z Fri. Diurnal northwest winds will ease below 5 kt by 09z Fri, then rise to 5-10 kt by 18z Fri. -36

MARINE

High pressure offshore will maintain breezy northerly winds through the end of the week. The strongest winds are expected during the afternoon and evening periods as the surface thermal trough strengthens over the northern CA/southern OR coast. Small Craft Advisories for northerly wind gusts up to 25-30 kt remain in effect for the waters south of Cape Falcon through 11 PM Friday, and through 5 AM Friday for the waters north of Cape Falcon and beyond 10 NM offshore. Seas 6 to 9 feet are expected across all waters through this weekend. The summer-like pattern is expected to break down Sunday night as a front approaches the waters. This system will return breezy southwesterly winds and a westerly swell that will likely (60-80% chance) build seas above 10 ft by Monday. -10/DH

PQR WATCHES/WARNINGS/ADVISORIES

OR...None.

WA...None.

PZ...Small Craft Advisory until 11 PM PDT Friday for PZZ252-253-272- 273.

Small Craft Advisory until 5 AM PDT Friday for PZZ271.