March 11, 2025

A Very Wet Period Ahead

Atmospheric rivers can be things of beauty, and the atmospheric river coming in on Sunday will turn heads.

The map below shows the total amount of water in a column of air (the precipitable water) at that time and you can see a "river" of higher amounts of water content streaming northeastward towards the Oregon/Washington border (greens and yellows are the highest amounts).

This is an atmospheric river, and since it starts just north of Hawaii, you might even call it a Pineapple Express.

This particular river is associated with strong southwesterly winds between a low over the Gulf of Alaska and a high off over California.  The typical setup for such moist plumes.



The total precipitation predicted through Monday morning is impressive, with nearly 3 inches in Seattle and twice that in the mountains to the south.  Most of the precipitation will fall on Sunday as the atmospheric river reaches our region.


Several of you have emailed me asking about snow.   Well, I have some good news!  Up to two YARDS of snow are predicted in some of our regional mountains  during this event (see below).


It is also important to keep in mind that rain and snow in mid-March is golden.... much more valuable than early in the season.    

All this water will be stored in reservoirs (no need to worry about leaving space for later flood control) and snowpack, and this water will moisten the soil immediately before we start to dry out in spring.

Seattle's reservoir storage is actually above normal now (see below), and the heavy rain is well-positioned to help boost the Yakima drainage.



All in all, an encouraging trend.

Also encouraging is the substantial rehiring of many of the probationary staff at NOAA.  Critical buildings will not be sold.  There will be more on this in a future blog.

Not so encouraging.   Will you be able to see the total lunar eclipse on Thursday night (around 10 PM)?

 Here is the cloud prediction for 11 PM on Thursday.  

Better go to eastern WA if you want a sure view!  NW Washington a possibility.




15 comments:

  1. Not very warm though, for a Pineapple Express, temp prediction is around 50 degrees...

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  2. If one was trying to time a ski visit to Stevens Pass, would you go for Monday or Tuesday? Most of the precip would fall on Sunday it sounds like?

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  3. Models seem to be over initializing these systems making them stronger than they pan out to be. Trend has been for weaker systems, and continuing the trend of pushing the bulk of forcing and dynamics to our south. Appears to be split flow of sorts with even negatively tilted fronts. Not ideal for building mountain snowpack, but better than nothing at all.

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  4. Why is this atmospheric river more conducive to mountain snow? I typically associate these events with warm air and high snow levels.

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  5. VERY glad to hear of the rehiring of many of the probationary staff at NOAA. 👏

    ReplyDelete
    Replies
    1. What should the government do to lower the deficit and live within their budget?

      Delete
  6. You’re obviously in command of the data, but my frequent attention to snowpack inclines me to posit that our snowpack/water equivalent is, with a few exceptions, significantly lower than average, but not dangerously so. We get water, but this winter has seen a notable percentage of it become runoff. Having the remaining storms add to our snowpack would be a positive outcome.
    https://nwcc-apps.sc.egov.usda.gov/imap/#version=169&elements=&networks=!MSNT&states=!&basins=!&hucs=&minElevation=&maxElevation=&elementSelectType=any&activeOnly=true&activeForecastPointsOnly=false&hucLabels=true&hucIdLabels=false&hucParameterLabels=true&stationLabels=&overlays=&hucOverlays=state&basinOpacity=75&basinNoDataOpacity=0&basemapOpacity=100&maskOpacity=100&mode=data&openSections=dataElement,parameter,date,basin,options,elements,location,networks,baseMaps,overlays,labels&controlsOpen=true&popup=&popupMulti=&popupBasin=&base=esriWsr&displayType=basin&basinType=wa_8&dataElement=WTEQ&depth=-8&parameter=PCTMED&frequency=DAILY&duration=I&customDuration=&dayPart=E&monthPart=B&forecastPubDay=1&forecastExceedance=50&useMixedPast=true&seqColor=1&divColor=7&scaleType=D&scaleMin=&scaleMax=&referencePeriodType=fixed&referenceBegin=1991&referenceEnd=2020&minimumYears=20&hucAssociations=true&relativeDate=-1&lat=48.124&lon=-120.914&zoom=6.9&autoExport=full,pdf,2,2,L,BL,Washington%20SNOTEL,49.4893,44.9175,-114.8615,-125.2705

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  7. What happened to this predicted onslaught of monsoon rain? It didn't happen -- only seem to have been scattered showers with minimal rain. Your prediction seems way off the mark from what actually occurred....

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    Replies
    1. Some parts of southern Oregon got 3-5 inches. You want more?

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    2. I'm not in southern Oregon. Like a reservoir manager I drew down my garden pond 2 inches in anticipation of copious rain in Bothell. So far about half an inch. I am still waiting. An I being rain shadowed?

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  8. No, I want an accurate forecast for around here (Puget Sound region)....that's the main reason that I follow your posts.

    ReplyDelete

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