West Coast Weather "Prediction"

Posted by: OregonMouse

West Coast Weather "Prediction" - 02/08/14 09:04 PM

We've had a perfect example this week of why weather prediction is a most inexact science here on the West Coast.

We were supposed to have cold weather all this week, with an "event" (possible ice storm) coming in late today, but with no significant accumulation.

It wasn't until early Thursday morning that the National Weather Service models picked up a series of snow storms coming in Thursday and Friday. EDit, later--actually they started hinting at it Wednesday evening, so I was able to stock up on food and firewood. I now have a 2 1/2 foot snowdrift covering my driveway, and there's no sense in shoveling it because the driveway will be drifted full again in an hour. By later tonight or tomorrow the freezing rain is supposed to get here, so I may as well wait until it melts!

For the reason the NWS was so late in picking up these storms, Dr. Cliff Mass of the University of Washington Atmospheric Sciences Department explains why. His post explains graphically why we can't rely on weather forecasting out here.

An hour later: the freezing rain is here! At least that has been in the forecast all week!

And I'm not complaining--we need every drop!
Posted by: intrek38

Re: West Coast Weather "Prediction" - 02/09/14 07:40 PM

Congrats to you and everyone else that received snow. Down here in this so calif desert, the temps today was in the low 70's and the low tonight around 45. As if someone is telling me get out and start gardening. Whatever the forecast, The opposite usually happens. Yes, I am complaining and I want snow or rain NOW!!!
Sorry, done with venting for now..
Posted by: OregonMouse

Re: West Coast Weather "Prediction" - 02/11/14 12:23 AM

Another article today, pointing out the complete failure to forecast snow in Seattle Saturday evening.
Posted by: billstephenson

Re: West Coast Weather "Prediction" - 02/11/14 01:50 PM

Originally Posted By OregonMouse
Another article today, pointing out the complete failure to forecast snow in Seattle Saturday evening.
Originally Posted By Cliff Mass
On Thursday, Portland was hit hard even though the forecast a day before called for a 20% chance of snow showers.


The things that stuck out at me when reading Cliff's blog was this:

Originally Posted By Cliff Mass
Why do weather forecast models fail?

There are at least three reasons:

The description of the atmosphere, the starting point of the simulation called the initialization, is flawed.

The physics of the model, how basic processes like radiation, clouds and precipitation are described, are flawed.

The forecasting problem is not possible considering the inherent uncertainties of atmospheric flows and the tendency for errors to grow in time.


And this:

Originally Posted By Cliff Mass
These disturbances were small in scale, fast moving, and developing offshore where data was sparse.


I do like the way Cliff describes the tools used and how they all work together. He does a great job of explaining how much we don't know about how the weather works, whereas too much of what we hear is how awesome the advanced technology they have is. As consumers of the products these weathermen create we like to think that all that techie stuff they use produces perfect output.

I'll offer that there was not really a "complete failure to forecast snow in Seattle" and instead that it was "not possible" to forecast the weather in Seattle. The two are not exactly the same if you consider that there were certainly not many meteorologist that were unaware of the lack of ability to produce an accurate forecast.

Originally Posted By Donald Rumsfeld
"Now what is the message there? The message is that there are no "knowns." There are things we know that we know. There are known unknowns. That is to say there are things that we now know we don't know. But there are also unknown unknowns. There are things we do not know we don't know. "


Well, something like that anyway grin
Posted by: aimless

Re: West Coast Weather "Prediction" - 02/11/14 01:59 PM

Originally Posted By: Donald Rumsfeld

goodjob
Posted by: OregonMouse

Re: West Coast Weather "Prediction" - 02/11/14 05:41 PM

Well, the Seattle city fathers called it a "complete failure." So would anyone who headed for the mountains relying on the forecast that it wouldn't snow that far north! Which is why I don't rely on the forecasts!
Posted by: billstephenson

Re: West Coast Weather "Prediction" - 02/11/14 09:21 PM

Originally Posted By OregonMouse
Well, the Seattle city fathers called it a "complete failure." So would anyone who headed for the mountains relying on the forecast that it wouldn't snow that far north!


To be fair, Seattle's city fathers and those who headed for the mountains completely failed to predict it too, and NOAA makes the data they gather publicly available.

I recall being advised to always take tire chains with me if I were driving above 5000ft in the winter in So Cal because "You never know when it might snow", so I did.

Originally Posted By OregonMouse
Which is why I don't rely on the forecasts!


Forecasts are made to help inform a decision. That's all.

If I lived there I would have still brought my tire chains if I were driving up into the mountains, but if they predicted it would almost certainly dump snow I probably would not have gone.
Posted by: OregonMouse

Re: West Coast Weather "Prediction" - 02/18/14 03:15 PM

Just as a followup--we've had a week of rain and snow in the Cascades that has brought us up to about 100% of average precipitation for this time of year. Fortunately, with not much snowpack previously, we are not yet getting severe flooding. Of course with many feet of fresh snow on top of an icy base, avalanche danger is extreme in the Cascades!

Since these were big storms, they were quite accurately forecast. It's the smaller ones, where ocean conditions and/or high mountains make their own weather, that are a problem. Of course those smaller ones can be equally severe in a local area!
Posted by: Heather-ak

Re: West Coast Weather "Prediction" - 02/18/14 04:25 PM

One week brought you up to "normal" average precipitation?! Criminy, that was one heck of a week.
Posted by: OregonMouse

Re: West Coast Weather "Prediction" - 02/18/14 05:16 PM

And it's pouring outside right now, also very windy.

As I mentioned, it's a good thing we didn't have enough snowpack to add to the flooding from the rain!
Posted by: rockchucker22

Re: West Coast Weather "Prediction" - 02/18/14 07:58 PM

Please send some down south of you a bit!