textproduct: Portland

SYNOPSIS

A weak frontal system continues to slowly move eastward across the Cascades and out of the region. This is resulting in diminishing showers and snow showers to the mountains through this evening. A ridge of high pressure builds towards the end of Saturday and through Sunday. This will bring dry and cool conditions to the forecast area and this pattern is expected to persist through at least the middle of this week.

LONG TERM...Wednesday through Friday

Cold weather persists through at least Wednesday as high pressure lingers. As we move into Thursday, the forecast gets a bit more complicated. Models maintain an upper level ridge over the region, while some ensembles suggest a broad, long wave trough moving into the region that will bring precipitation and slightly warmer air. This particular set-up is resulting in a moderate PoP/low QPF scenario. It should be noted that confidence in the forecast is low with the variety of solutions being produced by the models and their ensembles. So, we will continue to monitor the situation and see what the first part of 2026 brings to the Pac NW. -42

AVIATION

Showery activity continues to weaken as high pressure slowly builds. A band of low-end VFR CIGs lingers over the area with the southern edge setting up around KEUG and KONP. Just to the south conditions are clearer with drier air. During periods of showers, periods of MVFR CIGs can be expected. VFR through much of the forecast. Climatologically one could expect lower CIGs overnight with fog developing but hi-res models are keeping many terminals fog/IFR stratus free. The area with the highest probabilities would be within the Willamette Valley where there is around a 40% chance of MVFR to IFR CIGs and reduced VIS. Will continue to monitor with later model runs. If it does form, it likely would be short lived except for within the southern Willamette Valley where a light north wind would encourage a more stubborn fog. Cannot rule out frost development tonight but temperatures do appear to hover just above freezing which would make it's development harder to form.

KPDX AND APPROACHES...Predominately VFR conditions with west- northwest winds around 5 to 10 kt through the TAF period. After 05Z Sunday, increasing probability of MVFR conditions though the dewpoint depression remains above 3 degrees which will limit saturation. Clearing skies, light winds and overnight lows are expected to fall at, near or just below freezing. This could result in frost development on elevated, metal surfaces starting around 10Z Sunday. -27

MARINE

A post frontal environment continues to develop over the waters. Seas 10 to 15 ft at 10 to 12 sec across all waters, highest north of Cascade Head. A Hazardous Seas Warning remains in effect for all outer water zones and a Small Craft Advisory for all inner waters and the Columbia River Bar through at least Saturday afternoon for a combination of winds and seas. Winds and seas slowly subside, with conditions falling below Hazardous Seas and Small Craft thresholds by late this afternoon. A ridge of high pressure builds overhead this evening into Sunday. Winds decrease to less than 15 kts by this evening along with seas settling towards to 4 to 6 ft range. These conditions are expected to persist to persist into next week as high pressure builds over the waters. -42

PQR WATCHES/WARNINGS/ADVISORIES

OR...Winter Weather Advisory until 4 PM PST this afternoon for ORZ126>128. WA...Winter Weather Advisory until 4 PM PST this afternoon for WAZ211. PZ...Small Craft Advisory until 4 PM PST this afternoon for PZZ210- 251>253. Hazardous Seas Warning until 4 PM PST this afternoon for PZZ271>273.