textproduct: Portland

SYNOPSIS

Active weather continues with valley rain and high mountain snow through the middle of next week. Our focus remains on a fairly robust frontal system and atmospheric river impacting the region today through Tuesday which is slated to bring additional widespread rainfall and low chances (5-10%) for river flooding. After lingering shower chances during the mid to late week period, the pattern trends drier towards next weekend.

LONG TERM...Wednesday through Saturday

As the trough finally ejects eastward by midweek, a more zonal pattern is favored to develop through the long term period. While the potential for a shortwave arriving from the northwest maintains moderate chances for rainfall at times (40-60%) through Thursday and Friday of next week, the trend among ensembles models systems is towards calmer/drier weather for the start of next weekend. During this mid to late week period, temperatures look to hold near seasonal norms for late February. Beyond Saturday model uncertainty begins to increase substantial in regards to the progression of the upper-level pattern. -99/36

AVIATION

Early this morning conditions are generally VFR as a frontal system begins to move into the region. While confidence is high these VFR flight conditions will persist initially, as the front moves overhead 15-18z CIGs begin to falling to low end VFR with a 40-60% chance for MVFR CIGs across the area. Moderate rain with the frontal band could briefly bring VIS down to 4-6 SM this morning as well. Around 18-22z today, stratiform rain transitions to post-frontal showers with a mix of VFR and MVFR CIGs the rest of the TAF period.

Regarding winds, breezy east-souteast winds persist through the Columbia Gorge and coast range/Cascade gaps but pressure gradients begin to slowly ease as the day progresses, so winds should begin to weaken and also turn more southerly at most sites. An exception is the far eastern Portland Metro Area where breezy east winds are expected to persist - gusts continue around 25-30 knots at KTTD.

KPDX AND APPROACHES...Currently sitting with VFR CIGs/VIS as of 12z although there'll be increasing chances (40-50%) for MVFR CIGs by 17-18z Sun - similar probabilities last through the end of the TAF period. Any heavier rainfall associated with the frontal band this morning could briefly drag VIS down to 5-6SM as well. Easterly winds with gusts to 20-25 kt continue this morning before gradually easing after 18-21z Sun but they won't completely go away. -99

MARINE

Seas are expected to peak with morning with Buoy 29 and Buoy 50 reporting wave heights in the 17-20ft range at 12-13 seconds, although seas will likely be higher the further into the outer waters you go (up to 21-25ft). At least winds have begun to trend lower with southerly gusts generally in the 35-50 knot range, again higher winds the further you go from shore. Once we get into the midday and afternoon hours today, confidence is high conditions will begin to improve albeit slowly when it comes to wave heights. The current Gale and Storm Warnings across the outer waters transitions to a hazardous seas warning at 10am today with the latter hazard product continuing into early Monday morning after which point we'll likely need to transition to a Small Craft Advisory. Conditions continue to improve headed into the middle of the week with a fairly benign upper-level pattern allowing seas bottom out around 5-7 feet Wednesday into Thursday. Then on Friday the arrival of a WSW swell may push seas above 10-12 feet. -99

PQR WATCHES/WARNINGS/ADVISORIES

OR...None. WA...None. PZ...Hazardous Seas Warning until 4 AM PST Monday for PZZ210- 251>253. Gale Warning until 10 AM PST this morning for PZZ271. Hazardous Seas Warning from 10 AM this morning to 4 AM PST Monday for PZZ271>273. Storm Warning until 10 AM PST this morning for PZZ272-273.