textproduct: Portland

UPDATE

Overall the forecast remains on track this morning as lingering precipitation behind our latest warm-frontal boundary begins to wane. The Columbia River Gorge and northern portions of the Hood River Valley have risen above freezing with no further concerns for ice accumulation. However, portions the upper Hood River Valley near Parkdale have been slow to moderate late this morning (models typically struggle to mix out this area and warm conditions too fast) but temperatures are right around the 32-33 degree mark with only upwards to go the remainder of the day - further impacts appear extremely limited at this point. Otherwise another weather disturbance arrives late tonight into Saturday with active conditions expected through the week. The previous discussion remains below. -99

SYNOPSIS

Scattered showers continue this morning as a weak warm front exits the area. Freezing rain continues across the Upper Hood River Valley this morning. Showers briefly decrease this afternoon before returning overnight as an occluded front moves through. Breezier southerly winds return Saturday evening into early Sunday as a low pressure system approaches. Active weather continues next week with falling snow levels. There is potential for impactful snow through the Cascade passes mid- week.

LONG TERM...Monday through Thursday

Overall, ensemble guidance is pointing towards a fairly typical winter-time pattern for the Pacific Northwest early next week with snow levels remaining at pass-level - skiers/snowboarders rejoice. Monday will have a break in the rain and Cascade snow has weak ridging moves overhead in between systems. Tuesday to Wednesday, guidance suggests another system will move in from the north, bringing another round of lowland rain and Cascade snow. This time, it looks like the Cascades may get warning- level snow. Chances for 1 foot of snow or more in a 48 hour period from 4 AM Tuesday to 4 AM Thursday are around 55-65% for all our Cascade passes including Hwy 26 at Government Camp, Santiam Pass, and Willamette Pass. By the end of the week, most ensemble members suggest broad troughing continuing, however, 30-50% of ensemble members do also suggest upper level ridging building over the Pacific Northwest which would return drier conditions. -10

AVIATION

A low pressure system off the northern California coast will maintain moist southerly flow and periods of rain showers across the area through Saturday. A bit of a lull in shower activity expected through this afternoon. VFR conditions have generally returned to the coast, while IFR to LIFR CIGs are likely to persist inland through at least this morning. Conditions should improve this afternoon, trending toward a mix of MVFR and lower end VFR after 21z Friday.

After 06z Sat, another frontal band moves through the area from the south, returning showers and lower CIGs. By 08-10z Sat, there is a 40-50% chance for MVFR conditions, with the highest chances across the Willamette Valley. Offshore flow continues along the coast and eastern Portland Metro terminals, with gusts to 25 kt at KTTD. Elsewhere, winds remain light and variable, turning more southerly early Saturday morning with the next front.

KPDX AND APPROACHES...IFR CIGs expected to linger into early this afternoon. By 22z, chances increase for conditions improving to MVFR, with VFR likely by 04z Saturday. Rain showers increase again after 08z with conditions gradually trending back toward MVFR. ESE winds around 6-10 kt expected through the period. /DH

MARINE

Relatively benign marine conditions continue today before the next system arrives. Southerly winds turn more east- southeasterly with gusts up to 20 kt today as a low pressure system approaches from the south. Seas around 6-8 ft at 11-12 sec today. A Small Craft Advisory has been issued for the Columbia River Bar from 2-7 PM today for a very strong ebb current with seas around 8 ft.

Saturday, the aforementioned low pressure system will amplify southerly winds and introduce a southerly fresh swell. With swell heights as high as 13-15 ft at 12 seconds, the southerly swell will become dominate and, when combined with the southerly wind wave, could see significant wave heights around 16-18 ft. Maximum wave heights will occur late Saturday into Sunday morning where there is a 5-10% chance of seas of 20 ft or greater in the outer waters. Confidence is low though as there is still uncertainty with the exact track and strength of the low pressure system. If the low tracks right along the coast then winds will be higher than if it moves inland or further into the Pacific. Because of the uncertainty, the Gale Watch continues across all of the waters as there is around a 30-50% chance of frequent Gale force gusts of 34 kt or stronger. If Gales do not manifest, there is high confidence in hazardous seas on Saturday through early Sunday. -10/27

BEACH HAZARDS

Perigean Spring (King) tides are back this first week of January, which will result in the highest tides of the season. A Coastal Flood Advisory for minor tidal overflow has been issued from 9 AM to 2 PM Friday along the Clatsop and Tillamook Coast, and South Washington Coast. Minor flooding up to one foot above ground level during high tides is expected in the low lying areas near bays, sloughs, and the lower reaches of the coastal rivers. The tidal gauges at Toke Point and Astoria have forecast tides of up to 11.2 feet, while the tidal gauge at Garibaldi has a forecast tide up to 10.7 feet. Minor tidal overflow is expected to continue through the weekend during high tide. -10

PQR WATCHES/WARNINGS/ADVISORIES

OR...Coastal Flood Advisory until 2 PM PST this afternoon for ORZ101-102. WA...Coastal Flood Advisory until 2 PM PST this afternoon for WAZ201. PZ...Small Craft Advisory from 2 PM this afternoon to 7 PM PST this evening for PZZ210. Small Craft Advisory from 1 AM to 7 AM PST Saturday for PZZ210- 251>253. Gale Watch from Saturday morning through Sunday morning for PZZ251>253-271>273. Small Craft Advisory until 7 AM PST Saturday for PZZ271>273.