textproduct: Portland

SYNOPSIS

Largely dry weather through Thursday night aside from a weak front bringing light rain Wednesday night into early Thursday. The pattern shifts wetter by the end of the workweek as a more potent system could bring more widespread lowland rain and mountain snow late this weekend or early next week.

LONG TERM...Friday through Monday

While another upper low dives southward into southern California, very low amplitude ridging will be centered over the Pacific Northwest. This will place the mid-latitude jet and resultant storm track pointed into Vancouver Island. As shortwave impulses approach the coast, this will keep persistent chances of rain in western Washington with lower chances extending south into western Oregon. Ensemble guidance is in fairly good agreement that the storm track will sag southward as the upper ridge axis shifts inland through the weekend, bringing increased chances for precipitation to the region especially through Sunday and Monday. As snow levels fall due to cold air within any troughing, impactful mountain snows remain possible by next Monday, with a 35-45% chance for 6" of snow at the Cascade passes through 4 AM Tuesday. -36

AVIATION

Largely VFR flying conditions are in place across the region as a weak frontal system nears the coast this morning. Clear skies earlier in the overnight period have allowed for areas of low stratus and fog to develop inland, most notably at KEUG, which will likely continue to see IFR or worse conditions within fog through 16-18z Tue. Other inland terminals may see brief vis restrictions or low cigs, however approaching low cloud coverage should limit additional radiative cooling and reduce those chances over the next 2-4 hours. Along the coast, scattered light rain showers are possible through this morning, ending from south to north by 00z Wed. Inland, rain shower coverage will likely be too low to mention in TAFs, before skies trend clearer at all terminals after 21-24z Tue. Winds will remain generally out of the north at around 5 kt through the period.

KPDX AND APPROACHES...Largely VFR conditions expected through the period. Areas of low clouds or mist are possible in the next 2-4 hours, which may briefly yield MVFR/IFR conditions, but chances those conditions persist is low, only about 15%. Especially following sunrise, cigs will lift to 4-5 kft. Light and variable winds will become northwesterly at 5 kt or less by 21z Tue. -36

MARINE

A brief reprieve from active weather is expected Tuesday and Wednesday as seas subside to 6-8 ft at 12-13 seconds. Winds will also ease while remaining out of the northwest through Tuesday evening, becoming northeasterly Tuesday night and then easterly for a brief period of time Wednesday morning as offshore flow develops. East winds should generally stay under 10 kt, but may be locally stronger downwind of coastal gaps.

Winds veer to the south on Wednesday as another frontal system approaches the waters, then increase with gusts up to 30 kt through Wednesday night, with the strongest gusts likely to remain beyond 10 NM offshore. Behind the passing front, winds become northwesterly and weaken through Thursday. A building westerly swell moving into the waters will most likely see seas become steep and hazardous by Thursday afternoon with wave heights of 14-16 ft and a dominant wave period of 14-15 seconds. While this is the most likely outcome, there remains notable uncertainty: there is a 10% chance that waves only reach 10-13 ft, and there is equally a 10% chance seas reach 18-19 ft by Thursday afternoon. Seas are then expected to slowly subside to 10-13 ft on Friday, then persisting through the weekend. -36/42

PQR WATCHES/WARNINGS/ADVISORIES

OR...None. WA...None. PZ...Small Craft Advisory until 7 AM PST early this morning for PZZ271>273.