Marine Weather and Tide Forecast for Springfield, OR

DISCUSSION
Now through Monday Night...A positively-tilted upper-level shortwave ridge axis currently extending across Vancouver Island into interior western Canada will continue to slide eastward, passing overhead and deamplifying through Thursday. Meanwhile, weak surface troughing along the coast will support offshore easterly to northeasterly flow and persistent clear skies with dry weather. As diurnal winds ease tonight, these ideal conditions for efficient radiative cooling will see temperatures fall to overnight lows largely in the 30s to low 40s. The warmest lows in the low to mid 40s are expected along the coast, where the Pacific will moderate temperatures, and through the Columbia River Gorge, where a continued easterly breeze will stymie surface cooling.

The coldest locale is likely to be the Upper Hood River Valley, where a Freeze Warning is now in effect from 1 AM through 9 AM PDT Wednesday. Areas including Odell and Parkdale have a 65-85% chance seeing temperatures at or below freezing, and a 30-60% chance of falling into the upper 20s by sunrise. In both cases, those chances are higher farther up the valley and lower toward Hood River proper. Other places the most likely to fall into the low to mid 30s and see areas of frost are the Cowlitz/Lewis River Valleys, the central and southern Willamette Valley, and wind-sheltered locales in the northern Oregon Coast Range, especially the Nehalem Valley including Vernonia and Pittsburg.
Frost Advisories have also been issued for these areas from 1 AM to 9 AM PDT Wednesday; those with agricultural interests or other outdoor plants which may be harmed by cold temperatures should take preventative measures.

More seasonable onshore northwesterly flow returns Wednesday afternoon with increased cloud cover. A weak trough and frontal system passing well to the north may yield a few rain showers early Thursday through Friday morning, most likely along the coast and across the higher terrain of the Coast Range, Willapa Hills, and Cascades. The immediate shorelines of Willapa Bay, Long Beach Peninsula, and coastal Clatsop County, as well as upstream in the Columbia Estuary to Cathlamet/Wauna, may see a 25-50% chance of 0.25" of rain or more, while chances of a wetting rain elsewhere and inland are generally 15% or less.

Toward the weekend, there is good consensus that a trough will dig over the Northeastern Pacific, bringing a return to wetter weather across the Pacific Northwest. At this lead time, there is high confidence in the occurrence of rain while the main mode of uncertainty is the amplitude of the trough. Around 45% of global ensemble members favor a deeper trough and a resultant wetter outcome, while another 30% favor a weaker trough and a drier scenario. There is also some uncertainty around how progressive the pattern is, and therefore the timing of precipitation onset. There is also a high likelihood in below normal temperatures from Sunday into early next week as the upper trough moves overhead. -36

AVIATION
An upper level ridge just offshore will maintain northeasterly winds aloft through tonight. VFR conditions with mostly clear skies persists as high pressure builds over the region. Offshore east to northeast winds remain gusty through this afternoon with gusts up to 20-25 kt. Winds expected to ease later this evening.

KPDX AND APPROACHES...VFR with mostly clear skies through the TAF period. East winds with gusts up to 25 kt expected through 02-03z this evening. /02

MARINE
High pressure remains offshore while an inverted trough of surface low pressure along the Oregon coast maintains breezy north to northeast winds, before weakening overnight. Strongest winds expected across the outer coastal waters south of Cape Falcon with gusts up to 25 kt through this evening. Winds ease as pressure gradients decrease across the coastal water through Wednesday, becoming northwesterly around 10 kt or less. Relatively tranquil conditions continue into Thursday, with light onshore winds and seas lingering around 4 to 6 ft.

A weak front will approach the waters late Thursday into Friday, followed by the return of high pressure, with minimal concerns.
A longer period northwest swell arrives later Friday, building seas to around 10 ft late Friday night into Saturday morning. A stronger frontal system is very likely to bring increasing southerly winds and higher seas during the weekend. Uncertainty remains with timing and strength of the system, but guidance does suggest there is around a 40-50% chance of gale force winds gusts late Saturday, especially across the northern inner waters. This front will likely be followed by a westerly swell building seas into the lower to mid teens on Sunday, with a 10% chance of significant wave heights exceeding 20 ft. /02

PQR WATCHES/WARNINGS/ADVISORIES

OR...Frost Advisory from 1 AM to 9 AM PDT Wednesday for ORZ104- 115>118.

Freeze Warning from 1 AM to 9 AM PDT Wednesday for ORZ121.

WA...Frost Advisory from 1 AM to 9 AM PDT Wednesday for WAZ204.

PZ...Small Craft Advisory until midnight tonight for PZZ272-273.