Friday, July 06, 2007

Forecast for the trip, version 1.0

Here's the start of it. I'll use available models and indicate which model is indicating which target.

GEM = the Global Environmental Multiscale--Canadian model. Out to 48 hours it runs in a "regional" configuration where it focuses on North America. Its usefulness after 48 hours drops rapidly because the outer boundaries of the domain start to have an influence after that time. Its weakness, I think, is that its convective feedback tends to be too strong. That is, sometimes it'll deepen or move lows too quickly because of latent heat release it sees but is not actually there.

GFS = Global Forecast System--American model. It forecasts on a global domain out to 16 days into the future. Its usefulness is primarily in forecasting long-range patterns. It tends not to have too much in the way of convective feedback, but once in a while...

NAM = North American Mesoscale--American model. It forecasts on the domain of North America and environs. It seems to have the worst convective problems out there. American forecasters often discount its output as farcical, especially over the past year.

UKMET = United Kingdon METeorological--British model (obviously). It has numerous domains, one of the North America. It's used often in a "let's have a look" way. I don't know too much about it, as I rarely look at its output.

ECMWF = European Centre for Medium-range Weather Forecasts, out of England. It is one of the stand-outs in terms of getting good verification on its long-range forecasts.

RUC = Rapid Update Cycle--American model. This model is on a small domain and runs out to as long as 24 hours. It ingests all kinds of surface data and is run hourly. It's okay, but I find people put too much emphasis on it and not enough on real-time weather information for their short-term forecasts.

NAEFS = North American Ensemble Forecast System--a joint venture among Canada, the US, and Mexico (although so far as I know, Mexico doesn't yet run a model to be input into the system). A bunch of perturbed runs of the GFS and the GEM are fed together and statistics are calculated on it--the mean, standard deviation, and so on. The true weather tends toward the ensemble mean, but by definition an ensemble system is horrible at predicting extreme events. This does not too badly at forecasting the upper flow, although it tends toward a humdrum solution after about day 5.

There are other models--NOGAPS, COAMPS, NGM (aka No Good Model), and many others I'm not mentioning. They, and ALL models, all have one main weakness: they're not as good as human forecasters.

Obviously, I have limited model access, so I will use synoptic setups as my pointers to severe weather locations.

July 15: Kindersley, SK (GEM), Yorkton, SK (GFS) or Melfort, SK (NAEFS).
July 16: Rapid City, SD (GFS) or repositioning (NAEFS).
July 17: Vegreville, AB (GFS) (with the giant pysanka!) or Calgary, AB (NAEFS).
July 18: Regina, SK (GFS) or Calgary, AB (NAEFS).
July 19: Regina, SK (GFS) or Calgary, AB (NAEFS).

So what this is suggesting is west of here. Pat and I were talking this week and he seems to think that this makes sense in a climatological sense, in that Alberta hasn't yet gotten their fair share of severe storms yet this year--that they're due. He also does a model-blend forecast (secret herbs and spices) he calls Pat's Ensemble (PE) and for the 5 days it says that west is the place to go, young man.

The models seem to want (at this time) to establish a southwest flow over the continent--what I call a storm chaser's flow. We'll see what tomorrow's runs bring...


At 12:15 PM, Anonymous Anonymous said...

...Go West life is peaceful there
Go West in the open air
Go West where the skies are blue
Go West this is what we're gonna do
Go West, this is what we're gonna do, Go West...

The blue sky part is not ideal, but you get the picture!


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