Cascade Head to Florence OR from 10 to 60 NM Marine Forecast
|Tonight...Nw Wind 5 To 10 Kt. Wind Waves Nw 1 Ft At 4 Seconds. Nw Swell 5 Ft At 9 Seconds.|
|Sun...N Wind 5 To 10 Kt With Gusts To 15 Kt, Rising To 15 To 20 Kt With Gusts To 25 Kt In The Afternoon. Wind Waves N 2 Ft At 5 Seconds. Nw Swell 5 Ft At 9 Seconds.|
|Sun Night...N Wind 15 To 20 Kt With Gusts To 25 Kt. Wind Waves N 3 Ft At 6 Seconds. Nw Swell 7 Ft At 11 Seconds.|
|Mon...N Wind 15 To 20 Kt. Gusts To 25 Kt In The Afternoon. Wind Waves N 3 Ft At 6 Seconds. Nw Swell 6 Ft At 11 Seconds.|
|Mon Night...N Wind 20 To 25 Kt, Easing To 15 To 20 Kt After Midnight. Wind Waves N 3 Ft At 7 Seconds. W Swell 5 Ft At 12 Seconds.|
|Tue...N Wind 15 To 20 Kt. Wind Waves 3 Ft. W Swell 4 Ft.|
|Tue Night...N Wind 15 To 20 Kt With Gusts To 25 Kt. Wind Waves 4 Ft. W Swell 4 Ft.|
|Wed...N Wind 15 To 20 Kt. Wind Waves 3 Ft. W Swell 3 Ft.|
|Thu...N Wind 15 Kt. Wind Waves 3 Ft. W Swell 3 Ft.|
| Area Forecast Discussion|
...UPDATE National Weather Service Portland OR
942am PDT Sat May 8 2021
Updated aviation discussion
A warm front will brush our northern zones with some light rain and drizzle Saturday, followed by a few showers lingering into Sunday. High pressure then shifts eastward across the Pacific Northwest and likely produces dry weather and a gradual warming trend through at least Wednesday or Thursday.
Today through Monday...Water vapor satellite imagery early this morning reveals a low amplitude shortwave ridge over the northeast Pacific with a downstream shortwave trough sliding eastward across the northern Rocky Mountain states. The combination of building 500mb heigheights over the region due to the departing shortwave trough and the loss of daytime heating has led to earlier showers dissipating overnight.
KLGX doppler radar does indicate light precipitation is beginning to develop off the Washington coast early this morning. This is in response to a warm front sliding eastward towards the region. Ensemble guidance suggests this will likely bring light rain to the coast later this morning before it tries to push inland this afternoon and evening. While the operational GFS and EC keep the Willamette Valley dry through this time, model soundings are surprisingly saturated throughout most of the atmospheric column late
this afternoon into this evening. As a result, did expand mentionable rain in the forecast for inland locations for late today.
It should be noted that a secondary front will slide southeastward towards the region later tonight into Sunday morning. This boundary will likely provide a focus for shower activity along the coast. Farther inland diurnal surface heating should create some shallow instability Sunday afternoon, which should manifest itself in the form of a few light showers/sprinkles bubbling up Sunday afternoon, particularly areas farther north.
Models and their ensembles are in reasonable agreement shortwave ridging will then push towards the region and result in rain chances dropping to near zero with temperatures climbing back up to near 70F Monday. /Neuman
Monday night through Saturday...Models and their ensembles remain in good agreement the aforementioned low amplitude shortwave ridge in the northeast Pacific will gradually shift over the Pacific Northwest next week. The will bring another multi-day stretch of dry weather with temperatures likely gradually warming each day through roughly Thursday of next week. Inland valley temperatures most likely to peak anywhere between the mid 70s to low 80s midweek. With that said, the surface high pressure ridge axis looks to generally shift from west-to-east orientation across the northeast Pacific extending into Washington to a more north-to-south orientation over the eastern Pacific. This should result in late night/morning marine cloud coverage expanding each day to include more of our coastline.
Finally, the GFS/EC ensemble mean suggests a shortwave trough will likely slide into the western US late next week. However, there is still considerable variation in model/ensemble guidance on the magnitude and position of this shortwave trough relative to the US West Coast late next week. For example, the mean of ~50% of the GEFS/EPS/CMCE ensemble guidance suggest the 5640m isohypse will reside over southwest British Columbia. Meanwhile, ~40% of ensemble guidance has the 5640m isohypse traversing Washington state. And ~10% of ensemble guidance has the 5640m isohypse nearly as far south as the Oregon/California border. The end result is that the majority of available ensemble guidance suggests just a weak passing shortwave trough late next week, which will likely keep the area dry, but be enough to cool temperatures. Nonetheless, there are still scenarios (~10-20% of available model/ensemble guidance) that result in some much needed rain developing late next week so have maintained slight chance Probability of Precipitation for portions of the CWA Friday into Saturday. /Neuman
Weak front well offshore will push across the coastal waters later this afternoon into early evening. Winds will turn west to northwest behind the front, but overall winds will stay in 10 to 15 kt range through tonight. Seas still holding at 6 to 8 ft, with higher seas farther offshore.
Then, return to typical late spring pattern, with high pressure offshore and northerly winds. Thermal trough over nw Calif and far south Oregon coast will build a bit Sunday into Mon. This will strengthen the north-south pressure gradients. As a result, will see northerly winds pick up Sunday afternoon, with 15 to 25 kt to south of Cascade Head, possibly even bit farther to the north. So, will likely need to issue Small Craft Advisory for the south coastal waters for Sunday afternoon/Sunday night. Gradients ease a bit on Mon, with winds a bit weaker. But, should still have gusty northerlies for MOn afternoon south of Cascade Head. Seas will subside back to 5 to 6 ft, but expect 7 to 8 ft on the south waters with the stronger north winds.
Pattern for the most part will repeat for good part of next week, with gusty north winds for coastal waters around/to the south of Cascade Head at times. /Rockey
.PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...Small Craft Advisory from noon Sunday to midnight PDT Monday night for coastal waters from Cascade Head OR to Florence OR out 60 NM.