January 05, 2022

Heavy Rain and Potential Flooding

 The National Weather Service has flood watches (dark green) out for large portions of western Washington and western Oregon for a good reason:  the combination of heavy rain, radically warming temperatures, and melting low-level snow will throw a huge amount of water on the landscape.


The amount of precipitation predicted during the next 48 h is enormous, with rain dominating over the lowlands (see UW WRF forecast below).  You rarely see such heavy amounts over the entirety of SW Washington, with some values reaching 3-10 inches of liquid water.

Add to that, the substantial lowland snow that will be melting (see snow water analysis below).

The NW River Forecast Center in Portland is predicting moderate (red dot) to major (purple) floods, with the Chehalis River being a particular concern.


Regarding snow, many of you will see some snowflakes later this afternoon, but accumulations will be minor (no more than an inch for most), but this will be wet, rapidly melting snow that will be gone tomorrow morning as the warm air surges in. 

The big exception will be NW Washington and the northern Olympics, where the cold Fraser River outflow will allow more snow to pile up (see 24-h snowfall forecast ending 4 AM tomorrow).   Great snow event for the Cascades and eastern Washington.





8 comments:

  1. Great post as always! You might have answered this before, but I wonder how much is known about how a La Nina condition can be used to predict the likelihood of lowland snow in Puget Sound, and also what is the mechanism by which La Nina affects weather in the PNW. Maybe this is all in your book?

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  2. Cliff.. can ya tell me Anything about the Kitsap peninsula? I see a good majority of heavy purple and blues in the area Wich reading the model in ( inches) is 8 plus inches on the graph.. but you say.. ohhhh everyone is going to get 2 inches but the NW..are you including Kitsap as part of the NW area that is supposed to have heavy amounts or what? What gives? Keep us informed.. please reply..

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  3. Will be interesting to see which model verifies the best for snow in Bellingham.

    The UW model you shared has 5.5 inches of snowfall but the afternoon forecast discussion was going for 2-4 inches. The spaghetti plot has models showing snow depth at 6am tomorrow ranging from 3 inches to 8 inches. Guess we will soon find out!

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  4. Been snowing since 8am today and never stopped. Accumulations were light until late afternoon. Now it's a respectable proper type snow of 4" and counting. Hood Canal @500'

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  5. Since snow began yesterday about 4pm and up to 10 am this morning (Jan. 6) 24 inches of snow fell at my home near downtown Wenatchee. This is the greatest single storm total I have experienced in Wenatchee since moving here in 1964.

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  6. I live in Leavenworth, and we are somewhere in the 30s with regard to the 24 hour snowfall. More than predicted. However, the UW WRF/GFS 1-1/3K model did show Leavenworth to get more than 30 inches from this storm. I didn't believe it, but it nailed it.

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  7. Blame it on Lorraine or Covid. Instead of saying “because of Covid,” I propose we say because of our reaction to Covid.

    What do you think is the reason why so many Americans have fallen for a Covid and have given up their personal rights and responsibilities. Get vaccinated and we won’t have to wear masks anymore. Get vaccinated and stop the spread. Stand 6 feet away, wear mask and we still get sick. Yet, as Washingtonians, we seem to listen to foolish advice to a fault. Look at the south and free states, Florida, South Dakota, Montana, Texas, etc. these states are essentially mask free and they are actually doing better with Covid as they are actually letting some immunity build rather than hide from Covid for ever. Heck look at college, pro football games, full stadiums, no mandates. Nobody is keeling over, there are not mass deaths occuring there. Yet in Wa State, go to Hawks game and u have to wear mask. Have to show your “proof of vaccination” to some random unqualified qwest field employee. What is wrong with us. Watch 1984. It’s actually a bit scary.

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

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