November 19, 2012

Heavy Precipitation

6:45 AM Monday Update:  Take a look at the radar....this is serious rain....yellow is moderate/heavy precipitation:

and here is the last 48-h precipitation from Seattle RainWatch. 1.5-2 inches over the city and 4-6 inches over parts of Kitsap/Hood Canal.

The latest 24-h precipitation amounts (ending 8 AM) show 5-6 inches over the SE side of the Olympics and over the mountains of SW Washington.  Lesser, but still heavy, amounts now falling over the western slopes of the Cascades.

The latest Northwest River Forecast Center update shows a number of rivers at flood stage...particularly over SW WA and NE Oregon....some at moderate flood. This is going to get worse before it gets better, since the latest run shift the precipitation more northward...which is confirmed by the Langley Hill radar.

Here is the latest storm total from Langley Hill.  Roughly 6 inches over the mountains of SW WA and heavy rains on the southern and western sides of the Olympics...the Chehalis will rise quickly with such input.

Here is the latest hydrograph (past and future flow levels) for the Chehalis at Ground Mound from the NW River Forecast Center.  They are going for 15.5 ft...substantially level than the all-time record (20.7 ft during the December 4, 2007 storm).  I assume they are looking carefully at the Langley radar and updating their inputs regularly to their hydrological models.  THIS is when the new radar will pay for itself.


  1. Just an inch in my gauge in Wedgwood, Cliff, in 24 hours. The 48 hour total is 1.45.

    I noticed from reviewing the rain shadow data that there are anamolies. For instance, on that map at least it was wet along Hood Canal, but across Puget Sound in Seattle, and east of it, there were areas that had very light totals.

    Not being a meteorologist I naively conjecture that such data indicates some relatively complex wind patterns when these storms are approaching from specific directions and interacting with the Cascades.

    Today doesn't appear to be one of those days. Is it because the airflow is more SSW than WSW or W?


  2. I recorded 2.1" overnight (@10:20a Monday) at Shoreline near Echo Lake. Looks like that rain total will well exceed the forecast 1.5-2". Minor flooding in the parking lot @ the Dale Turner YMCA.

  3. NWS is sticking to that 4500 ft snow level....but I came through Snoqualmie Pass this morning and had to sit for half an hour while semi-trucks took up both lanes to chain up....and the snow was coming down way before we got to the pass!

  4. I have the same question as Mr. McBride concerning the rain shadow,or lack thereof, here on Whidbey today. I thought it might be because the rain clouds are too high to be much effected by the mountains.

  5. NWS boeing field station shows 1.4" in the six hours ending at 9:53 this morning. that's big time.

  6. Here is an interesting comparison. According to an article in the Seattle Times yesterday, they plan to cut the rate of the Missouri River down to about 12,000 Cubic Feet per Second (CFS) y this Friday, down from its current 36,000 CFS. See

    In contrast some of the river flows in the Pacific NW are really picking up. The Nehalem in NW Oregon, which I monitor for various reasons, is running close to 25,000CFS and headed upwards. The Skagit at Mt. Vernon is running at 22,500. They will probably stay high if these storms continue all week.

    Thus for this week, our rivers will rival the Mighty Missouri in terms of stream flow.

  7. Current WA streamflow data:

  8. I'm thinking they unpredicted this one, for both rain and wind. It's crazy outside for the past few hours, windy, rainy, etc. It's really blowing outside!

  9. We are right in the middle of that weather system in the central valley. There is a LOT of wind. So much rain---even more than we Oregonians are used to having--this has been so for the past four winters.

    I am hoping for snow in our little neck of the woods. Even when everyone else gets snow--our weather bubble is different than anyone else's. (sigh)

    And I love snow.

    So, maybe this year, eh? Thank you for your post.

  10. 2:20 PM and the Mighty Nehalem in NW Oregon is approaching 30,000 CFS. And still headed up.

  11. A hair shy of 2.5" at Meadowbrook in NE SEA, down in the holler. Thornton Creek highest I've seen it since the Dec. 2007 gusher (it's in our backyard so a thing of profound fascination, sometimes fear).

  12. Cliff, any word on the possible Giant Weather Even you mentioned a couple of days ago? I had a morning of extreme intimacy w/sump pumps here, am wondering if we're in for a repeat?

  13. Around 7:10PM - Wow, that little red dot on the radar inbedded in that squall line just east of Kent was dumping rain into my tipping rain gauge at rate of 3.86 in/hr. I've never seen it that high here.

  14. Wow, Don's stats are 100 year rate if what I read is correct.

    Final tally here for yesterday was 2.8" after the last gasp ~4:30p


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

The Weather Regimes of Summer

 Weather patterns tend to get "stuck" for extended periods and we have certainly seen such persistent conditions this summer.    W...