December 12, 2008

Major Change in the Forecast

UPDATE at 4 PM: The low center has moved north of us and wind have increased greatly...some locations are getting 40-50 mph gusts! No snow anywhere in the lowlands.

PS: Several people have asked me about how we can get snow in the lowlands...if you have my book I have whole chapter on it (chapter 3).


The bottom line: the low appears to be going further north than yesterday's model output suggested...making snow much less likely today and this evening. Cold is still coming tomorrow and Sunday. The National Weather Service (NWS) will have to amend their forecasts.

This is a perfect example of why we need a coastal weather radar. The big issue...where is the incoming low and how intense is it. This low only formed last night and was forecast to develop very, very rapidly. These are the circumstances that the models can make major errors...either in intensity of position. During the past few days the models have had varying solutions...and the location of landfall has varied. Two days ago it looked like it was going north...giving us strong winds and less lowland snow. Yesterday they went south...and the NWS went towards lowland snow. I hate to say it...but the new model runs, initialized with the latest data, and recent satellite pictures suggest the northern route will be it (see satellite picture--the low is in the center of the hooked shaped cloud). If we had a radar on the coast we would know without any doubt what would happen today and be able to provide you with an excellent and confident forecast...so tell you congressman and senators you want one (see my web site for
more info--http://www.atmos.washington.edu/~cliff/coastalradar.html)
The precipitation shield of the system is now upon us (see radar). Looking at the pressure changes along the coast...the greatest falls are on the north-central Olympic coast. The low should move over the N. Olympic Peninsula and be just north of us around 4 PM. Winds will pick up from the south this afternoon over Puget Sound...so be ready for 20-30 mph winds. Then a strong westerly surge will occur the Strait...that will effect Mukilteo, Everett, and Whidbey Island. (good night to have dinner at Ivars in Mukilteo for you storm watchers). Virtually no snow in the lowlands...but there could be some snow just to the SE of the Olympics (much less extensive than the earlier forecast).
Then as the low moves east, northernly winds down Georgia Strait will increase and then overnight strong winds will pour out of the Fraser River valley into Bellingham. There could be some upslope snow on the NE side of the Olympics Saturday morning.

A positive thing of this change is more snow in the WA Cascades...the skiing industry needs it.

And did I mention the strong southeasterlies over NW Washington this morning and afternoon and the very strong winds on the coast!

More later...

14 comments:

  1. Cliff,

    Is the "bomb" as intense (in millibars) as originally forcasted?

    More intense?

    I read 980 - 985 on KOMO4's weather blog...

    Any difference thus far?

    Joseph

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  2. But if we knew what was going to happen and could pinpoint exactly where snow would fall and how much, wouldn't all the mystery, excitement and fun of weather forecasting be taken away?

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  3. The NWS predicts some flooding at high tide this afternoon. The high tide on south Sound locations is predicted to peak at 3:37 pm today. To what extent will the Low moving through the north Sound still be a factor in increasing the height of the tide?

    The reason for my inquiry:
    My 91 yr. old friend lives in a cabin on pilings on Von Geldern Cove that has historically been awash at abnormal pressure/tide coincidences. We might need to roll up the rugs and put blocks under the furniture!

    And if the wind is out of the north at, too, it would be a BIG problem....

    Enjoy the weather action this weekend!

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  4. Yet another proto-typical, blown forecast. Cliff, you don’t need to blame the fact you don’t have a coastal radar on the poor modeling that led to another missed forecast. That just smacks of sour grapes. The models originally indicated that the low was heading farther north than yesterday’s runs and these subsequent runs since Wednesday led to the typical “snow euphoria” that seems to override objectivity and caution. Past history matters and clearly similar storm tracks from years past were ignored in favor of the new models that gave but a hope of a major snow event.

    It’s time for the NWS to step up and take ownership for the poor modeling and forecasting and to stop blaming it on equipment deficiencies – even if it is tough to predict snow events in the region.

    One more side note, this outcome is another perfect example that if we can’t get a 12 or 24 hour forecast right, how on earth is it that we triumphantly parade around thinking we know what the next 100 years will look like.

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  5. re: bhuston

    What? Do you have any proof that weather modeling can be improved without coastal radar? The thing is that Weather forecasting has never been precise and accurate, but I believe Cliff when he says that coastal radar can improve things. I don't understand your somewhat vitriolic skepticism. :)

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  6. To Jim:

    Someone should help out your friend. I'm on waterfront on Bainbridge. Tho we're still an hour from high tide, the tide appears higher than I would expect.

    Why? One of my tide calendars can explain it quicker than I can (from Evergreen Publishing): "Caution: Wind velocity, direction and low barometric pressure can have a decided effect on tidal predictions, especially for the inland waters of Puget Sound. ... Generally, prolonged onshore winds or a low barometric pressure can produce higher levels than predicted, while the opposite can result in lower levels than those predicted."

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  7. Bhuston,
    For the life of me, I can't figure out the logic of what you are saying. Forecasting is not based on historical tracks, but on direct modeling/simulation of the atmosphere. There was a great deal of uncertainty in this situation since 24h ago this low did not exist. And then it amplified in 12 hours into a major low. Anyway, I think you need to educate yourself about the forecast process before you sling accusations.
    Finally, the short-term forecasting problem is completely different than the climate prediction problem. I hear this over and over again... if you can't forecast 24h ahead, how can you forecast climate. Well you can. In one you are forecasting the exact position and magnitude of weather systems. In the other, you are forecasting the general climate over a season or year or decade.

    ...cliff mass

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  8. We up here on Whidbey Island are always amused by weather forecasts, as they are usually directed at larger population centers and only sometimes relate to us. I just drove from Coupeville (central Whidbey) to Freeland (south central Whidbey) in a very sloppy-snowy gale. So even though the prognosticators do their best to figure it out, there are so many variables that it is very hard.

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  9. Kitty...so it is snowing there? Anything accumulating?..cm

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  10. We've had a slushy mix up here in Sammamish in the heavier showers, enough to cover cars and the yard. Currently however, it is raining and 34 degrees.

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  11. 100% snow in Bridgeport, WA this morning at 1100. Along with freezing fog, and temps around 25-27 degrees. Beautiful but very difficult driving on unplowed roads and fog with visibility of less than 100ft.

    Just found your blog thanks to my dad.

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  12. Love the blog Cliff, your analysis is spot on. Don't pay attention to the trolls.

    Heavy wet snow here in Maple Valley at 34 degrees. It is sticking for now.

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  13. At 420 feet elevation in Renton it has been snowing for over two hours... still over 32 so no accumulation other than on metal vehicles, but getting heavier with larger flakes.

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  14. Sorry not to read your question till this morning, CM, but no, nothing stuck. It was just blustery and sloppy with half-formed flakes. This morning it's partly cloudy and about 38 degrees at my place in Freeland.

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