Cape Shoalwater WA to Cape Lookout OR between 150 and 250 NM Offshore Forecast
|Tonight...N Winds 10 To 20 Kt. Seas 5 To 7 Ft.|
|Wed...N Winds 10 To 20 Kt, Becoming 10 To 15 Kt. Seas 4 To 6 Ft.|
|Wed Night...N Winds 10 To 20 Kt, Becoming 10 To 15 Kt. Seas 4 To 6 Ft.|
|Thu...N Winds 15 To 20 Kt, Diminishing To 10 To 15 Kt. Seas 5 To 6 Ft.|
|Thu Night...N Winds 10 To 15 Kt, Diminishing To 5 To 10 Kt. Seas 5 To 6 Ft.|
|Fri...N Winds 5 To 10 Kt. Seas 5 To 6 Ft.|
|Fri Night...N Winds 10 To 15 Kt, Becoming Ne 5 To 15 Kt. Seas 5 To 7 Ft.|
|Sat...E To Ne Winds Less Than 10 Kt, Becoming Variable. Seas 5 To 6 Ft.|
|Sat Night...Variable Winds Less Than 10 Kt, Becoming S To Sw. Seas 4 To 5 Ft.|
|Sun...S To Sw Winds 5 To 10 Kt, Becoming Variable. Seas 4 To 5 Ft.|
|Sun Night...Variable Winds Less Than 5 Kt. Seas 4 To 5 Ft.|
| Area Forecast Discussion|
...UPDATED National Weather Service Portland OR
747pm PDT Tuesday April 13 2021
Updated Aviation and Marine Discussion
High pressure over the region will maintain clear skies and dry weather through the coming week, and begin to warm as the weekend nears. North to northeasterly winds will be elevated through Wednesday morning before they begin to lower in the afternoon.
Tonight through Thursday night...Synoptically a fairly subdued system comprised of high pressure east of the Cascades and a thermally induced trough to the west. Several weak shortwave disturbances are passing through the overall flow which is helping to amplify the winds, especially through the Columbia River Gorge. An interesting about these winds is that many of the traditional traits that would initiate an event like this are not present. Commonly with an easterly wind flow like the one occurring are associated with a intensified pressure gradient. An example is the pressure gradient often seen through the Columbia River Gorge between Troutdale and the Dalles. When wind like this is occurring, a pressure change of around -4 mb is common; but today, the gradient is only -0.4 mb. This means that these winds are synoptically driven and leaning on the unusual side of conditions. The north to northeast flow will last through Wednesday early afternoon when they will weaken in the lowlands. Expect gust 20-25 kt through the northern Willamette Valley/Columbia River Gorge through tonight, and even higher at elevated and exposed terrain.
With the combination of gusty winds and clear skies, relative humidity (RH) values are lowering pretty drastically. RHs lower than 25% are observed throughout much of the forecast area, with some locations seeing RHs in the teens. Expecting drying conditions through the short term forecast. Temperatures will slowly climb over the next few days as the thermally induced trough expands, reaching the 70s inland with some potential 70 degree spikes along the coast in some downslope areas. Overnight tonight will be pretty spotty in regards to temperatures as the elevated winds will likely keep some areas (the windiest ones) warmer than calmer locations.
One thing to note is that the combination of gusty winds and several days of low RHs may create hazardous burning conditions. Fire danger will continue to be high for this time of year so be sure to seek local guidance on any burn restrictions in the area. -Muessle
Friday through Monday
Continued dry and warm conditions expected through the weekend into early next week. The high pressure/thermal trough combination will remain anchored in place with more offshore flow. By Friday, temperatures will climb into the mid 70s through most locations. By Saturday and Sunday, high temperatures will flirt with 80 degrees. One challenge in the long term is the temperature forecast. The NBM is trending a bit warmer (80-85 degrees) than other long term ensembles (75-80 degrees). Decided to split the difference given the time frame and the uncertainty with coastal areas in the low to mid 70s Friday through Sunday, and inland areas closer to 80 degrees. Less wind and clear skies will keep nighttime temperatures cool. -Muessle
Gusty northeast wind to continue over the waters through Wednesday morning. Observations and guidance are showing the wind speeds diminishing faster than expected. Therefore, have adjusted the current advisories to reflect current guidance. Expect conditions to fall below advisory conditions for zone PZZ270 by tonight with PZZ275 persisting through Wednesday evening.
The pressure gradient weakens Wednesday night and Thu, with a trend toward northwest to north wind. Do not foresee wind speeds exceeding 20 kt Wednesday night through early Fri. The NAM shows a return to east wind late Thu night and continuing through early Fri afternoon, with potential 20-25 kt gusts over the outer waters. The GFS maintains weaker north boundary layer flow. The latest models continue to show a southerly wind reversal to the waters this weekend.
Wave heigheights to hover in the 4-6 ft range for the next few days. There will be a 2-3 ft longer period main swell, but the prime contributor will be shorter period wind waves/fresh swell. Weishaar/42
.PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...Small Craft Advisory until 2am PDT Wednesday for Waters from Cape Shoalwater WA to Cascade Head OR from 10 to 60 NM.
Small Craft Advisory until 11pm PDT Wednesday for Waters from Cascade Head to Florence OR from 10 to 60 NM.
Small Craft Advisory until 11pm PDT this evening for Coastal waters from Cascade Head to Florence OR out 10 NM.