December 7, 2010

Cold, Cold, Cold...and did I say cold?

It appears that old man winter has finally gotten a really tight grip on the Mid-Atlantic region, for me that means my first semester studying Meteorology is coming to an end.  I've really picked up a lot of knew knowledge from this class, even if we didn't do the mathematics or science to back it up.  Today is our last class before the final and we are going to try an apply all the things we've learned during the fall and make a forecast.
A forecast is the one tangible thing that people get from a meteorologist, and most people have no idea how much effort forecasters put into their predictions.  Heck, I was one of those people back in September.  Now, I have a very limited knowledge of the art of forecasting, but I have gained a huge amount of respect for the folks that do it.  There are several popular ways to put together a forecast, so I'll share some of the highlights with you.

1. Now-casting. The art of relaying to the people what is happening right now where they are. Twitter is full of now-casts, just look up the Capital Weather Gang, or Accu-Weather, or The Weather Channel. They are constantly posting updates about current weather all across the country.
2. Persistence Forecasting: This is used when the weather pattern is the same, day after day after day.  Use the desert for example.  The forecast of Sunny, and hot is very reliable over a period of days.
3.Climate-Forecasting: This is the art of using the climate data collected for a given area to build a long term forecast.   These forecasts are usually pretty vague but try to give people an idea of what they can expect over a period of weeks or months. 
4.Computer Forecasting: Plugging data from points all over a given area into a computer, and letting the computer model out what it thinks is going to happen. This is how most of our local 72 hour, 5 day and 7 day forecasts are generated.  The computer will run several models with the data that is entered and the forecaster will apply climate data, and current data to try and get as close to the actual events as possible.

So the next logical question is 'What exactly is a good forecast?' The answer that is most popular is "One that is right.", but how do you gauge "right"?  If you got the temperature right, but it was raining and you forecasted sun, were you right?   The matter of being right is difficult to define, so we broke it down into categories that you can score:

1. Did you get the temperature right?  Were you within 3-4 degrees either way?
2. Did you get the conditions right?  You called for rain, did it?
3. Were you able to successfully prepare people for the conditions they will encounter during that day?

So that's the very basics of weather forecasting.  From time to time I'll try to throw a forecast out there, just to see how well I do.  The outlook this week is a simple persistence forecast:  Sunny and COLD for the DC area.  Highs around 35 degrees F all week. You can look at the current U.S. Radar composite and see, there isn't much out there that will impact our region....see for yourself here.  The wind will die down after today though.  So there it is, my 1st official weather forecast, let the criticism begin!

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