September 14, 2019

Two Strong Fronts will Bring Unusual Amounts of September Rainfall

If the model forecasts are correct, this is going to be one of the wettest Septembers in recent memory.  And it is clear: wildfire season is over.

The first act starts tonight as a strong front moves in this evening.  The coastal radar is being overhauled--so I can't show you an ominous radar view.  But the latest infrared satellite image is impressive--particularly for September.

The UW high resolution WRF model 3-h precipitation forecast for 2 AM this morning show the front moving in.  And with the front, winds are going to pick up.

And then as a low pressure area moves towards us on Sunday, the precipitation will blossom, filling much of the state with moderate rain (see 3-h rain ending 2 PM Sunday).  This would be a lot for November.  And extremely wet for east of the Cascades.  

And then ANOTHER unusually strong front moves in on Tuesday (see below)

Now...are you ready to be meteorologically shocked?  Here is the accumulated precipitation total through 5 PM Tuesday.  Amazing.  Big areas of 2-5 inches.  Lots of rain in eastern Washington.

This September is already wetter than normal.   After the next week, the region will be thoroughly soaked.   A good time to plant grass seed or put in some bushes or other plants in the garden.


  1. As of this writing, I've measured 1.58" of precip for the month, thus far, in NW Bellingham. I measured 2.25" during September 2018 and 1.58" during September 2017.

  2. These early-season rains can create ideal conditions for chanterelles to pop up in the coming weeks.

  3. Cliff, It is good to know when the rain will arrive as we wind down the garden. We always rely on your forecasts. Lots of tomatoes and we're making sauce to can. The remainders likely won't ripen much, so green salsa may be in order next.

  4. Goodbye for another 9 months, warm sun. :/

  5. As of yesterday - 9/15 - I had measured 2.27"(in my COCORAHS rain gauge) for Sept. - in Greenbank - on Central Whidbey Island. So far, Cliff's 4KAST is spot-on !! :)

  6. How much mitigating effect are these early-season storms likely to have on the "mini-blob"?

  7. I was out in the sailboat on Saturday and the wind blew out a sail. Scary.

    I hope Tuesday's storm comes with lightning: I missed the one a week ago.

  8. As of yesterday evening, my gauge has recorded 3.30 inches of rain in central Bellingham so far this month. We're already over the average precip by quite a bit and have 1/2 of the month to go.

  9. I measured 1.06" of precip on Sunday in NW Bellingham with a maximum instantaneous rain rate of 2.1"/hr. I've now measured 2.65" for the month. This looks to be the wettest September in this area since 2013.

  10. question is will we get snow this winter do it early

  11. Some kind of rain
    Sets a new instantaneous discharge rate for Sep 18!
    Daily discharge, cubic feet per second -- statistics for Sep 18 based on 89 water years of record more
    (1951) 25th
    tile Median 75th
    tile Mean Max
    (1968) Most Recent
    Value Sep 18
    36.0 52 64 104 131 1210 1310,00065


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