April 24, 2020

Two Strong Fronts Are Approaching

For those those worried about dry conditions, additional relief is on the way.

Two strong fronts are approaching for this weekend.

The first arrives Saturday morning and it is interesting to watch it get modulated and weakened by our mountains..  Let me show the the 3-h precipitation predicted by the UW model.

For the period ending 8 AM Saturday, you can see the front making landfall, with the precipitation just reaching Puget Sound.


Three hours later is has reached the Cascades, with the mountains locally enhancing rainfall.

 But then dramatic change in the frontal rain is evident (2 PM shown): as the front descends the eastern side of the Cascades, the downslope flow greatly weakens the front and its associated rainfall.

And by 5 PM the frontal rain has reached the Rockies, where it is enhanced .  Note the residual showers on the western slopes of the Olympics and Cascades well behind the front.  Quite typical.

 The total precipitation for the entire frontal passage (through Sunday at 5 AM) shows the overall story, with up to around an inch in the Cascades, nearly nothing on the lower eastern slopes of the Cascades and modest amounts over the Rockies.   Classic.


And then we do it all again, late Sunday and Monday morning (see precipitation forecast for 2 AM Monday).


With these two fronts, April rainfall will have recovered to be in striking distance of normal. 

The first front will have a sharp wind shift and decent winds, particularly over the coast and Northwest Washington--the UW/Seattle Windwatch guidance shows the story at 6AM Saturday, with some gusts above 40 mph.
Enjoy the fronts....and Sunday looks like the best day to get out...or at least as out as you can be these days.

8 comments:

  1. Funny closing, Cliff!

    I'm glad there are fronts coming through Seattle. A rainy day can be so relaxing.

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  2. I'm thankful for all this rain. The pollen was horrible. And then the rain came and washed it all into puddles in the streets and sidewalks. There's an inch and a half of solid pollen in some places. I've never seen anything like it before. You can pick it up and mold it like clay.

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    Replies
    1. So with you on this!...the pollen really affects my breathing/wheezing, and with this coronavirus scare, I was beginning to think this old man's number might be up!...however, pollen has been flushed--and my lungs feel much better...problem is, after this tree pollen surge, will come the grasses surge....but comes August, I will no longer sound like a wheezebag!

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  3. 12:40 pm Saturday and the BOW, WA Rock-on-a-string weather reporter is getting pounded by heavy rain. 1:09 pm Saturday and the BOW, WA Rock-on-a-string weather reporter is being disinfected by bright sunlight.

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  4. Got zero measurable rain all day in Everett.

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  5. "For those those worried about dry conditions..."

    Haha that's funny Cliff. Anyone "worried about dry conditions" this year needs serious medication. Of course the same thing was true last year and the year before and the year before and we got fake droughts anyway so maybe you should change that to "Anyone worried about fake drought proclamations..." in which case I would be right on board with you.

    Today (4/25): set a record at Seatac for precip (.59" vs. .52" (last set 2011); for the water year we are at 102% precip and for the calendar year 118%.

    Snowpack at Stevens Pass currently est. >90" (5 yr avg 69" on May 1) with a prediction of snow tonight and Monday night. If we continue in the 30's at night and can keep the wind down we will have another late meltout, not surprising given the thirty year trend of later meltouts there.

    Snowpack statewide 102%/112%/118%/105% north to south in the west Cascades and that's based on today's USDA map which historically understates snowpack (which you have pointed out countless times). The rest of the state is similar and another year of >avg Cascade snowpack that no one will talk about.

    It's just always the same now. Already there has been an article over at KOMO stating "the region’s long-term drought conditions will persist". That is a blatant lie on multiple levels. I'm wondering: do actual statistics mean anything anymore? Does truth matter, at all?

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  6. Even though facts are objective, it is the human tendency to skew factual information that is the problem...subjective analysis seems to be rampant!

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  7. I'm always amazed that some people panic as they do when we have a few nice dry spells. The reality here in Glacier WA is that the current Rain Year to date (since Oct 1) is wetter than last year or the year before. And, as others have already noted, snowpack is heavy. In fact, for a couple of years I've observed that snow is building up on local ridges (like Cougar Ridge, here) over time - patches that don't melt during the summer are getting larger. That actually comports with the recorded trend downward in overnight lows. Just this morning the Mt Baker avalanche telemetry reported 3" new snow. The banana belt "coasters" who look to weather reports at SeaTac (and Bellingham airport) AND the 'river flow' analysis that doesn't factor freezing-to-streamflow make me think about the adage: "In the land of the blind, the one-eyed man is king."

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Please make sure your comments are civil. Name calling and personal attacks are not appropriate.

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