Marine Weather Net

Cape Shoalwater WA to Cascade Head OR from 10 to 60 NM Marine Forecast


TODAY

S
WINDS
5 - 10
KNOTS

TONIGHT

S
WINDS
5 - 10
KNOTS

THU

S
WINDS
5 - 10
KNOTS

THU NIGHT

N
WINDS
TO 5
KNOTS

The Marine Weather Forecast In Detail:
PZZ270 Forecast Issued: 227 AM PDT Wed Jul 06 2022

Today...S Wind 5 To 10 Kt. Gusts To 15 Kt In The Morning. Wind Waves S 1 Ft At 4 Seconds. W Swell 3 Ft At 10 Seconds. Areas Of Fog.
Tonight...S Wind 5 To 10 Kt. Gusts To 15 Kt After Midnight. Wind Waves S 2 Ft At 4 Seconds. W Swell 3 Ft At 10 Seconds.
Thu...S Wind 5 To 10 Kt, Veering To Nw In The Afternoon. Wind Waves S 2 Ft At 4 Seconds, Shifting To The Nw At 4 Seconds In The Afternoon. W Swell 3 Ft At 10 Seconds.
Thu Night...N Wind To 5 Kt. Wind Waves N 1 Ft At 4 Seconds. W Swell 3 Ft At 10 Seconds.
Fri...N Wind To 5 Kt. Wind Waves N 1 Ft At 4 Seconds. W Swell 2 Ft At 10 Seconds.
Fri Night...N Wind 5 To 10 Kt. Wind Waves N 2 Ft At 4 Seconds. W Swell 2 Ft At 10 Seconds.
Sat...Nw Wind 5 To 10 Kt. Wind Waves 2 Ft. W Swell 2 Ft.
Sun...N Wind 10 To 15 Kt. Wind Waves 4 Ft. W Swell 3 Ft.
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Area Forecast Discussion
...UPDATED National Weather Service Portland OR
816am PDT Wednesday July 6 2022

Updated Short Term

Synopsis
An upper level trough off the Pac NW coast will maintain temperate yet unsettled weather across the region through at least Thursday. Scattered showers are expected to persist through this evening, then showers should decrease in coverage later tonight into Thursday. The upper trough will finally accelerate eastward Friday, bringing an end to the showers. Seasonably warm and dry weather is expected over the weekend. A warming trend is looking increasingly likely early next week, though it remains uncertain just how hot it will get.

.SHORT TERM...Today through Friday (8am UPDATE)...At 15Z KRTX doppler radar showed a line of showers extending from the south Washington Cascades to near Salem. There have been some embedded heavier showers within this line. Significantly raised POPS in the Clark County, the south Washington Cascades and foothills, western Gorge and north Willamette Valley for the 12Z-18Z time frame to account for the current activity. Weishaar

REMAINDER OF PREVIOUS SHORT TERMLLOWS: The overall setup has changed very little over the last 24 hours, as we remain under the eastern periphery of an upper level trough which continues to push weaker upper level shortwave disturbances N-NE across the forecast area. Each disturbance has resulted in a more organized batch of showers. The mechanism for this enhanced shower activity appears to be weak lift near a quasi-stationary 700-500 mb front as a weak, 60-70 kt jet stream max moves overhead. Overlaying 700-500 mb theta-e from the 08z HRRR (High-Resolution Rapid Refresh) shows a sharp theta-e gradient nearly perfectly parallel and just to the west of said line of showers. Suspect the line of showers will pulse up over the next 2-4 hours, similar to what most WRF-based CAMs suggest, as the jet max moves overhead. There may be a brief lull afterward, but the boundary will remain nearly stationary. The next 60-70 kt jet stream max moves overhead this afternoon and may enhance shower activity on top of the instability provided by diurnal heating. This may lead to some fairly vigorous showers this afternoon and perhaps a few thunderstorms. The air mass is pretty moist now with Total Precipitable Water (TPW) values around 1 inch and surface dewpoints in the lower 60s at many locations, so stronger showers should be capable of producing heavy rainfall rates. The good news from a hydro perspective is that any individual storms that develop will move along at a fairly good clip. With the theta-e boundary stalled overhead and winds fairly unidirectional above 850 mb, we'll need to watch for training of cells. This kind of training occurred at Wanderers Peak RAWS in the northern Oregon Cascades, and that station reported nearly 1 inch of rain in a two-hour period Tuesday afternoon. So the potential is certainly there for torrential rain rates which could locally overwhelm small streams and storm drainage systems, but we are not expecting any widespread hydro issues or flooding of mainstem rivers.

The 00z GFS shows the above-mentioned theta-e boundary creeping eastward tonight, which likely means any elevated instability will shift eastward as well. As a result, showers will likely focus more over the Cascades later tonight and Thursday. That said, diurnal heating and another weak shortwave could still yield surface-based convection and a few showers Thursday afternoon, but this would favor the higher terrain as well. By Friday, much of the forecast area will be dry.

Cloud cover will be fairly prolific across the forecast area through Thursday, but there will probably be sunbreaks as well. With overnight lows struggling to dip much below 60 degrees for the lowlands, temperatures should still approach seasonal normals - though they will probably fall a little short with inland valley highs mainly in the lower to mid 70s this afternoon and again Thursday afternoon. Increased sunshine due to higher pressure and confluent flow aloft on Friday should push inland valleys closer to 80 degrees Friday afternoon as our upper trough gradually weakens. The coast will be cooler, but should at least see some sunshine Friday as the upper trough drifts toward the coast and weakens marine inversions. Weagle

Long Term
Saturday through Tuesday
Saturday looks to be a mostly sunny and seasonable day, as the 00z WPC cluster analyses show good agreement that 500 mb heigheights rebound to near to slightly above normal. The warmer air mass should help re-establish marine inversions, so we may see a return to coastal stratus, especially as flow remains onshore Saturday. Most models suggest one last shortwave will move through the forecast area early Sunday, likely allowing for at least some inland penetration of the coastal stratus Sunday morning. Morning clouds should be short-lived though, as high pressure strengthens over WA/OR and a thermal trough of low pressure strengthens along the Oregon coast. This will induce an offshore component to the flow that will likely lead to a hot day Monday, at least for the coastal valleys and points inland. The coast stands a chance of seeing highs in the 70s/80s if the offshore flow becomes strong enough.

Confidence remains lower than usual for our temperature forecast early next week, even though confidence is high that a strong upper ridge will develop over the western United States. Most guidance appears to be backing off from the hotter scenarios, though it is notable that the 00z deterministic ECMWF (European Centre for Medium-Range Weather Forecasts) pushes 850 mb temps close to +24 deg C, which is around the threshold where we start considering temps at or above 100 deg F. However the WPC cluster analysis continues to shift the upper ridge axis eastward with each of the last few model cycles. This would open the door for a faster return to deeper onshore flow, a cooler air mass, and thus less extreme temperatures Monday and especially Tuesday. NBM probabilistic guidance is now down to a 40-60% chance of reaching 90 degrees in the Willamette Valley Monday, and a bit lower for Tuesday. The lower chances are south, with the highest chances being near the Portland metro, Columbia Gorge, and Hood River Valley. NBM probabilities of triple-digit heat in the Willamette Valley are back down to less than 10 percent. Overall though, this is looking more and more like a run-of-the-mill warm spell for SW Washington and NW Oregon, but this can still change. Weagle

Marine
A weak upper level low pressure offshore will continue to allow southerly winds and areas of fog to spread northward across the waters today. High pressure will slowly build into the region late in the work week and over the weekend. As thermally induced lower pressure strengthens over southern Oregon, expect northerly winds and choppier seas to increase across the waters Sunday into Monday. Small Craft Advisory level wind gusts of 25 kt could extend northward into the waters off the central coast of Oregon by Sunday with winds strengthening further and spreading into the waters off the north Oregon and south Washington coast Monday. There is a decent chance that seas will become particularly steep and hazardous across the waters off the central coast of Oregon on Monday. Significant wave heigheights appear likely to climb to around 7 ft with dominant periods lowering to near 6 seconds.

For information about upcoming marine zone changes, go online to: https://www.weather.gov/pqr/marinezone

NOAA Portland OR Office: Watches - Warnings - Advisories
OR...None. WA...None. PZ...None.