Thursday, March 18, 2010

Snow on the First Day of Spring?

As the first day of Spring, March 20, draws closer, I've been watching the weather forecast (and forecast models) closely to see what the first day of Spring will be like. Right now, it appears that the weather will be winter weather. Snow is possible, and the wind chill will be in the low 20s or upper 10s. Not exactly a great start to Spring.
March 20, however, is astronomically the first day of Spring. It is the day of the vernal equinox. There will be 12 hours of light and 12 hours of darkness everywhere in the world. This event was chosen by scientists years ago to be the "official" start of Spring. The reality, however, depends on a myriad of local and climatological factors that the amount of daylight cannot affect. So, while the "official" first day of Spring may be on March 20, the true first day of Spring is going to be recognized only in hindsight: whatever day is the first of a sequence of days with "Spring-like" weather, define that how you will. (I suggest Spring be defined as a week in which 5 out of the 7 days have temperatures over 60 and whether the temperature never falls below 32.)
So, enjoy the nice the weather today (and possibly tomorrow), because winter is going to make one last gasp before bowing out to Spring.

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