Cape Lookout to Florence OR between 60 and 150 NM Offshore Forecast
|Today...N Winds 15 To 20 Kt. Seas 4 To 6 Ft.|
|Tonight...N Winds 15 To 25 Kt. Seas 5 To 7 Ft.|
|Sun...N Winds 15 To 20 Kt. Seas 5 To 6 Ft.|
|Sun Night...N Winds 15 To 20 Kt. Seas 4 To 6 Ft.|
|Mon...N Winds 10 To 20 Kt. Seas 4 To 6 Ft.|
|Mon Night...N Winds 15 To 20 Kt. Seas 4 To 6 Ft.|
|Tue...N Winds 15 To 20 Kt, Diminishing To 10 To 15 Kt. Seas 4 To 5 Ft.|
|Tue Night...N Winds 10 To 15 Kt. Seas 3 To 5 Ft.|
|Wed...N Winds 10 To 20 Kt. Seas 3 To 5 Ft.|
|Wed Night...N Winds 15 To 25 Kt. Seas 3 To 6 Ft.|
| Area Forecast Discussion|
National Weather Service Portland OR
232pm PDT Sat July 24 2021
Expect above normal temperatures to continue through the end of July as an upper level high over the Great Basin gradually builds to the north and east. The hottest temperatures are expected late this week into the weekend. There is also a small but nonzero chance of showers and thunderstorms mid to late week over the Lane and Linn County Cascades.
Tonight through Monday night...Satellite observations from early Saturday afternoon showed marine stratus hugging the coastline, with clear skies elsewhere. The exception was over the Lane County Cascades where hazy skies were being observed due to upper level smoke coming from the Jack Fire and the Dixie Fire to the south. Expect the same general trend tomorrow afternoon, with morning marine stratus along the coast and through the Coast Range gaps burning off during the mid to late morning hours. Elsewhere, skies will most likely remain clear through the day. That said, the HREF ensemble mean for cloud cover does show a 10 to 30 percent chance of low clouds forming over the Corbett/Sandy/Estacada area around sunrise, potentially backbuilding into Troutdale and Gresham. Even if this outcome does occur, cloud cover would likely burn off by 9-10 AM PDT.
The synoptic scale pattern does not look to change much tonight through Monday, with an upper level high centered over the Great Basin and an upper level low centered over the Gulf of Alaska, bringing southwest flow aloft to the Pacific Northwest along with low-level onshore flow. As a result, temperatures tomorrow should be fairly similar to Saturday. The latest iteration of the NBM suggests high temperatures will most likely top out in the mid 80s to lower 90s for the interior lowlands, and mid 60s to lower 70s along and near the coast. The same can be said for Monday's high temperatures, albeit a degree or two cooler due to high clouds streaming into the region from the south. Aside from temperatures and sky cover, expect breezy north to northwest winds during the afternoon and evening hours on Sunday and Monday with wind gusts generally ranging between 15-20 mph by late afternoon. The breeziest conditions should occur over the southern Willamette Valley to the south of Salem. -TK
Tuesday through Saturday...The long term forecast is highlighted by gradually warming temperatures and increasing chances for convection over the Lane and Linn County Cascades. The WPC's cluster analysis for 500 mb heigheights depicts fairly little variance between models and their ensembles Tuesday through Saturday, showing an upper level ridge strengthening slightly while building northward into Idaho, Montana, and the Northern Plains. Although the ridge axis will be well to the east of Washington and Oregon, 500 mb heights will still be on the rise for the Pacific Northwest. At the same time, low-level onshore flow looks to weaken. In addition, the EURO ensemble mean shows 850 temperatures rising to around 22 degrees Celsius by Friday afternoon at Portland, while the control run is a degree or so warmer than that. There is also not much spread between the 25th and 75th percentile, which ranges between approximately 21 and 24 degrees Celsius. The GEFS plumes for 850 mb temperatures agrees quite well with the EURO. This means forecast confidence is high that temperatures will be on the increase mid to late week, peaking on Friday and Saturday. That said, confidence is only moderate when it comes to the exact high temperatures. The NBM 1D viewer shows a 25% chance of temperatures reaching 100 degrees or warmer on Friday with a similar probability on Saturday. These probabilities are even higher in the Salem area where there is a 30-40% chance of temperatures hitting 100 degrees or warmer. Probabilities for the Eugene area are very similar to Portland's probabilities. Overall, it is very likely that high temperatures will be at least in the mid 90s across the interior lowlands Thursday through Saturday, and possibly on Wednesday as well. Despite the hot temperatures in the forecast, it is worth noting that this heat event looks much less significant than the historic heat wave that occurred in June 2021 in regards to the duration and severity of the heat. In fact, the probability of high temperatures reaching 105 degrees or warmer is only around 3-10% over the Willamette Valley and even less than that elsewhere. Areas along and near the coast will escape the heat altogether as some degree of low-level onshore flow continues. At this time, it appears coastal locations will remain in the upper 60s to mid 70s for high temperatures Wednesday through Saturday.
Aside from the heat, there is also a nonzero chance of showers and thunderstorms over the Lane and Linn County Cascades Wednesday through Friday as upper level flow becomes more southerly and mid-level moisture begins to increase. At this time, the chance is very small, but nonzero. Models and their ensembles are currently not showing any signs of significant widespread convection, but the threat will need to be monitored closely over the next several days as the details become more clear. Decided to go with the NBM for the probability of precipitation forecast given the uncertainty involved this far out in time. -TK
No change in the weather pattern, as high pressure remains anchored offshore and thermal low pressure hugs far sw Oregon into nw California. This will maintain northerly pressure gradients through Mon, with breezy conditions with gusts 20 to 30 kt in the afternoons/evenings, with the higher gusts being south of Cascade Head. Have small craft advisory up on all waters through Sunday evening or later. For the northern waters, winds will slack out at times later tonight into Sunday am, especially closer to shore.
Underlying swell is westerly at 1 to 2 ft. But, seas stay at 3 to 5 ft through Sunday, owing to built up wind waves. With shorter wave periods, will likely see choppy seas at times, mainly in the afternoons and evenings.
Pressure gradients will ease a bit early next week, with winds dropping back a bit. Still, good bet that will have gusts 20 to 25 kt south of Cascade Head in afternoons/evenings. /Rockey
.PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...Small Craft Advisory through Sunday evening on all northern coastal waters, or from Cape Shoalwater to Cascade Head.
Small Craft Advisory through Sunday night on all southern coastal waters, or from Cascade Head to Florence.