Wednesday, September 22, 2010

Happy Autumn!

Today is the first day of fall/autumn in the Northern Hemisphere.  This will be signified by the Autumnal Equinox, which takes place later this evening and tonight.  This is a scientific term used to describe the process where the Earth's axis is tilted away from the sun for a longer period of time.  This results in longer nights and shorter days as we progress through winter, as well as gradually cooler temperatures as the sun bakes us for shorter periods of time each day (as shown in the image below).

So what does the fall and winter season look like for this year?  Below are the latest forecast maps showing the outlook from the National Weather Service:

In general, "above normal" temperatures are forecast from the southwest and southcentral U.S. into the Great Lakes region.  "Below normal" temperatures are forecast along the Pacific Coast.  Precipitation-wise, "below normal" values are forecast across the southern tier of states, with "above normal" rainfall forecast for the Pacific Northwest.

The above maps cover the period October-December.  We'll continue to monitor long-term trends and post updates throughout the season.

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