Thursday, March4, 2021
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Marine Weather and Tides
Cascade Locks, OR

Version 3.4
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1/26/2021 -- The West Coast Satellite images havd been updated. They now use GEOS-17.
1/1/2021 -- The 7 day forecast are now working well. Thank you NOAA for your support.

Sunrise 6:39AMSunset 6:02PM Thursday March 4, 2021 1:33 PM PST (21:33 UTC) Moonrise 12:00AMMoonset 9:39AM Illumination 64% Phase: Waning Gibbous; Moon at 21 days in cycle
NOTE: Some of the data on this page has not been verified and should be used with that in mind. It may and occasionally will, be wrong. The tide reports are by xtide and are NOT FOR NAVIGATION.
Marine Forecasts
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7 Day Forecast for Marine Location Near Cascade Locks, OR
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location: 45.68, -121.87     debug


Area Discussion for - Portland, OR
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FXUS66 KPQR 041841 AAC AFDPQR

Area Forecast Discussion . UPDATED National Weather Service Portland OR 1041 AM PST Thu Mar 4 2021

Updated aviation discussion.

SYNOPSIS. Mild dry Spring-like weather will continue through Thursday for much of the region. A front will become stalled along the coast today then slowly move inland Friday as it weakens. Another front arrives Sunday, also weakening as it comes onshore. Generally speaking, the coast will receive the bulk of precipitation while the Cascades received far less. Low pressure slowly slides south while centered well offshore to bring some form of rain and snow for much of next week.

SHORT TERM. Today through Saturday night . Thursday morning update . High resolution models as well as satellite and radar observations show the the approaching frontal system and atmospheric river slowing down and having a slightly more east/west orientation this morning. As a result of the system taking a more east/west orientation this morning then slowly becoming a south/north orientation through the late afternoon and evening have backed PoPs off for inland locations. /42

No changes . Previous discussion follows . Satellite and surface analyses show a complex upper pattern along the NoAm west coast. There is a large parent low centered off the Alaskan panhandle near 140W with multiple embedded lows. The most significant low near our area is developing from a shortwave moving north along a slow moving frontal boundary extending off the parent low. That low center is about 300 miles off Florence and is now showing a fairly mature baroclinic leaf. Additionally, there are signs of deep convection and lightning in the southeast quadrant per GOES lightning mapper data.

Models seem to have a good handle on this feature taking it and it's heavy rain band north into British Columbia by 00Z today. The broader frontal boundary will move close to the coast this morning and then begin to stall out becoming quasi-stationary Thursday night and Friday. Additionally, a somewhat robust sub-tropical moisture feed will bring notable moisture transport to the area. Most of this time, steering flow to the moisture will remain fairly southerly, thus not overly conducive to orographic enhancement. It looks to be classified as an atmospheric river nonetheless. Although the southerly winds and relatively low atmospheric moisture content is low on the AR scale, the event duration 24-36 hours will carry this event into a moderate atmospheric river classification. Given fairly consistent intra and inter model agreement with this feature over the last several days, and feeling confident there will be a rather strong gradient to the QPF amounts from west to east ending Friday afternoon. Am expecting 2.50-3.00" of rain on the south slopes of the terrain along the coast and west side of the coast range. This quickly tapers off to 0.25=0.30" along the I-5 corridor, and areas along the Cascade crest struggling to reach 0.25" by 4 PM Friday/00Z Saturday.

Main concern during all of this will be what kind of response is seen on the coastal rivers. 00Z-06Z (4-10pm) tonight appear to have the best potential for rain over a short period across the northern tier. Even then, am only expecting upwards of an inch in those 6 hours on the high end. The previous 6 hours will have only received around 0.33" which has itself been preceded by several days of minimal rainfall. The following two 6 hour periods will receive around 0.40-0.50" each. As such, don't currently expect there to be and significant threat of flooding for areas rivers, especially the Grays. However, will advise the NW River Forecast Center when they arrive this morning to ensure they are also in agreement. The central coast also appears it will receive a similar burst of rain, but later in the AR event Friday afternoon. Again, am not seeing any significant flooding threats there either.

Snow levels during this time largely hover between 4000 and 5000 feet so also do not foresee unusual impacts on the passes from a couple inches of snow at best. Also given the slow advance of the front, inland temperatures will remain rather mild today after some lower morning get pushed off. Coastal areas will be mild and windy with gusts mainly 35-40 mph along the exposed beaches, headlands, and ridges with perhaps a brief gust pushing 50 mph as the afternoon and evening wears on.

Another shortwave rotates around the south end of the trough late Friday and develops into a closed low. This will mainly serve to sever the moisture tap and then push the stalled front inland. By this time much of the QPF potential has been lost, especially across the Cascades where another less few inches of accumulation will potentially occur as snow levels lower to between 2500 and 3500 feet. Another facet of this shortwave transition was potential for thunderstorms put into the forecast by previous shifts. It appears that threat has now diminished as model sounding analysis with support from SPC outlooks indicates potential for modest showers at best. It seems the colder air aloft will remain too far offshore to justify keeping the thunderstorm threat mention in the forecast.

Expect a generally hybrid stratiform rain/embedded shower regime will be in place Saturday as the aforementioned, and now weakening, second low works it way across the region. Temperatures will be a few degrees below the 1980-2010 normal but still in the lower 50s for the Willamette Valley. /JBonk

Update: Later this morning and through Friday increasing westerly with a period of 15 to 17 seconds will reach the coast. This will result in elevated chances for sneaker waves at the beaches.

LONG TERM. Sunday through Wednesday . Another upper low will drop south from the Bering Sea and eventually drag another cold front across the region beginning early Sunday. This front will be rather stretched out and likely splitting so am questioning just how much QPF will actually occur and how soon models further back off on the already somewhat light QPF amounts.

There is surprisingly good agreement among the models, especially given the shoulder season, keeping the low center a modest distance offshore. They then slide it south of our area towards the middle of next week. This minimizes just how much precipitation will fall over the region. Cannot say that any upcoming day will definitively be dry across the board. NBM PoPs are struggling, however, to show much above 40% for any given location. Areas across the north keep the better possibility of comparatively dry weather versus west central Oregon areas which will remain closer to the passing low. Temperatures stay on the cooler side of normal but still appear not exactly cold either. /JBonk

AVIATION. Satellite imagery shows a swatch of marine stratus off shore as a weak atmospheric river advances towards the area, while inland areas are clear or mostly clear this morning. As the front pushes inland, the flow will become southerly and winds will begin to intensify. Along the coast skies will lower first from VFR to MVFR after 22Z Thu and offshore winds will turn southerly. Expecting increased winds along coastal terminals between 22Z-04Z Fri with highest gusts south of KTMK. Could see gusts nearing 40 kt around KONP this afternoon. At the initial onset of the system, may experience some slight wind shear with southwesterly winds aloft around 40 kt at 2000 ft; does not meet current criteria so left out of the TAF. Inland locations will see some slightly lowered cigs to around 5000 ft, but should still remain VFR through the first system passage. Could see some periodic gusts but not expecting to be widespread.

A brief break in both rain and winds is expected between 04Z-15Z Fri before yet another round of rain kicks in. Cigs should lift up to VFR everywhere during that break into the next period of rain but could see slightly lower cigs along the coast. More variability and uncertainty after 14Z Fri.

For detailed regional Pac NW aviation weather information, go online to: https://weather.gov/zse

KPDX AND APPROACHES . VFR through the next 24 hours with periods of rain. A southerly wind shift expected after 22Z Fri but not expected to exceed 15 kt. Could see a period of LLWS between 12Z-16Z Fri at 2000 ft but it is marginal. LLWS will likely depend on the timing of the front so have decided to leave out of the TAF for now. -Muessle

MARINE. Wind and seas on the uptick as next front approaches. Still looking for southerly gales to develop this morning over the outer waters, then for the near shore waters in the afternoon. It may be harder for the immediate coastline to reach gale force wind since the tighter pressure gradients remain offshore. But still, it will be close to gales. On the flip side, the tighter pressure gradients offshore may briefly bring gusts to 50 kt about 30-60 nm west of Florence to Cascade Head this morning.

Seas will be on the increase, but likely to see more increase in choppy chaotic wind waves during the day. Larger fetch of fresh swell will arrive this evening, with combined seas pushing 18 to 22 ft through the night. There is some differences in the models, and the resulting forecast is some where in between. The 00Z ECMWF wave indicating seas 22-24 ft late tonight, and the ENP closer to 20 ft.

Unsettled weather continues through the weekend with possible gale force winds at times for Fri and Fri night, and again Sat night. Weishaar

PQR WATCHES/WARNINGS/ADVISORIES. OR . None. WA . None. PZ . Small Craft Advisory until 7 AM PST this morning for coastal waters from Cape Shoalwater WA to Florence OR from 10 to 60 NM.

Gale Warning from 7 AM this morning to 6 AM PST Friday for coastal waters from Cape Shoalwater WA to Florence OR from 10 to 60 NM.

Small Craft Advisory until noon PST today for coastal waters from Cape Shoalwater WA to Florence OR out 10 NM.

Gale Warning from noon today to midnight PST tonight for coastal waters from Cape Shoalwater WA to Florence OR out 10 NM.

Small Craft Advisory until 10 PM PST this evening for Columbia River Bar.



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Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
LOPW1 - 9440422 - Longview, WA 65 mi45 min 44°F1016.4 hPa

Wind History for Longview, WA
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure

Link to 5 minute data for KCZK

Wind History from CZK (wind in knots)
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Last 24hr24------------------------SW12
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1 day ago53------------------------322SW632SE2E21S2
2 days ago----------------------------1214334434

Tide / Current Tables for Vancouver, Columbia River, Washington (dubious accuracy)
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Vancouver
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Thu -- 06:13 AM PST     0.43 feet Low Tide
Thu -- 06:43 AM PST     Sunrise
Thu -- 09:42 AM PST     Moonset
Thu -- 10:54 AM PST     2.03 feet High Tide
Thu -- 06:02 PM PST     Sunset
Thu -- 07:09 PM PST     0.08 feet Low Tide
Thu -- 11:35 PM PST     1.45 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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1.410.80.70.60.50.40.50.91.41.921.81.410.70.60.40.20.10.20.61.11.4

Tide / Current Tables for Knappa, Knappa Slough, Columbia River, Oregon
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Knappa
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Thu -- 05:07 AM PST     8.92 feet High Tide
Thu -- 06:47 AM PST     Sunrise
Thu -- 09:44 AM PST     Moonset
Thu -- 12:28 PM PST     0.29 feet Low Tide
Thu -- 06:05 PM PST     Sunset
Thu -- 06:13 PM PST     6.62 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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1.32.54.56.68.28.98.67.55.83.92.310.40.41.434.766.66.45.64.43.22.3

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NOTE: This section has been updated as of 1/26/2021. If the image you are expecting is not showing, please let me know. You may use the EDIT function to update your location.
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