Tuesday, March 22, 2005
From Variability to Consistency
Matt Ross @ 1:00 AM
The beginning of spring is still a time of great variability in sensible weather. Averages and Norms are truly that, as in reality we still are in a period of time when temperatures can go well above and well below average. However, as we proceed through Spring and into Summer, we gradually move toward a time when this variability is greatly diminished.
Forecast: No real changes from Jason's thoughts yesterday. Unfortunately our 1st week of spring will be a bit disappointing, highlighted by a cold rain overnight tonight into Wednesday when high temps will struggle to get out of the 40's. Next week presents our best opportunity for springlike daytime 60's to attempt to establish as we head into April. In less than two weeks we will have average highs in the low 60's with sunset nearing 8:00PM. Those folks who hate cold and snow will eventually be rewarded. Climatology guarantees it.
If we look at this issue from a monthly standpoint, it also shows that variability decreases as we head into summer and then gradually increases starting in August. The turning points are January and July. January exhibits DC's largest variance in record maximum and record minimum monthly temperatures. In 1918, DC's average January temperature was 23.7 degrees while in 1950, it was 48 degrees. A difference of 24.3 degrees. July, on the other hand, has the smallest difference between record minimum and record maximum monthly temperature. In 1891, the average July temperature was 72 degrees, while in 1993, it was 83.1 degrees, for a difference of only 11.1 degrees. While these are large scale singular examples, they are indicative of increased consistency as we march toward Summer. Unfortunately, as we all know, that consistency often results in persistent heat and humidity.
I noticed that Jason recently mentioned Kocin and Uccelini's phenomenal book on Northeast Snowstorms. I, also, cannot recommend it highly enough for snowlovers. In honor of our first severe weather of the season this past Sunday, I would like to recommend another excellent book, Jerrine and Arjen Verkaik's, Under the Whirlwind. It is a very enjoyable and fascinating look at tornadoes for people of all levels.
A goose hangs out near the Wilson Bridge on an early Spring Day, courtesy of Brett Roberts.
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