Wednesday, January 30, 2013

How are climate forecasts made and why is it warm again in Girdwood?

This is Girdwood today, overcast, grey, raining, quiet. The temperature at the T is 35°, snow is sliding off the metal roofs. Snow is sloughing off the trees that surround my house.  A magpie stopped by to rest on a bare cottonwood. Yesterday I saw a moth flying around. I imagine the magpie and other feathered creatures are happy about all the spring seasons we have had this “winter”. What is this now, the fourth spring of the 2012 - 2013 winter? From the news reports, it seems the northeast United States received winter this year as opposed to south central Alaska. Ce la vie, we had it last year. Is this another outcome of climate change? My second postulation: different regions of the country receive winter in rotating years.  

NOAA creates these three-month weather pattern predictions at the Climate Prediction Center. Currently, their projection is for warmer than normal temperatures and lower than normal precipitation in the south and southwestern United States. The NOAA extended climatological prediction for south central Alaska is for colder than normal temperatures. The colder temperatures could not arrive soon enough, but when? How does NOAA generate these predictions? Basically they generate statistical models. The main data is pulled from global ocean temperature data with no fluctuating adjustments. Forecasters also look at the position of the jet stream. The jet streams are affected by the Earth’s surface air temperature which is related to the ocean temperature. By looking at historical and current data of both temperature and jet stream, a climate prediction can be made. This is a basic review of a huge amount of study that goes into making climate predictions and by no means should be considered easy. 

This month, January 2013, the polar jet stream is at a higher latitude over Alaska because the stream is being pushed up by warm air and temperatures from the tropics. In the lower 48 United States, the polar jet stream is making a long dive south in the midwest bringing cold air to that region and the south. This link goes to a great website at San Francisco State University with maps of the jet stream.

Humans may heavily influence the weather by various means of altering environments or emitting concentrated amounts of gasses into the atmosphere. But I doubt humans will be able to fully control the climate of the Earth. The only place right now where you can control your environment is inside your home. This is where the joy of caring for and growing house plants comes in handy. You can turn lights on and off for your plants, and you provide the water and nutrients for your plants. Actually, this seems like a good outlet for Type A personalities that need to control events. So, while the ever changing outside weather is tempting and reminding us not to plant out there yet, go buy another plant to bring some green into your house!

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