Why so warm?
An unprecedented heat wave has been underway over the past week. Really, since we entered daylight saving time back on March 11, temperatures have averaged out well above normal. This NASA image shows the surface temperature anomalies over the past week.
While we’ve seen some daytime highs in the 80s, temperatures approached 90 over parts of Northern Michigan Wednesday afternoon. Chicago has recorded more daytime highs in the 80s this month, than they’ve ever seen in the month of APRIL! The obvious question is: why?Well, the answer is two fold. One, there is virtually no snow east of the Rockies in the lower 48. Sure there is some snow on the Tug Hill Plateau, the Adirondacks, mountains of New England and Maine, but by and large, the area described above is snow-free. The following image is a comparison of last March snow cover on the 20th versus this year. Usually, early Spring warmth is wasted in melting existing snow cover, but that’s not the case this year. We’re getting all the heating we can from the strong mid-March sun right now, and consequently we’re seeing the incredible warmth.
The second conspirator in our summer-like warmth is the jet stream. For much of the winter, the jet stream has been located to our north, allowing our temperatures to be mild. Guess where the jet is now? You guessed it. Way to the north into Canada. The image below shows the general location of the jet stream.
Obviously, the pattern will change, but we still don’t see any switch to prolonged cold. Honestly, I don’t believe anything I’m seeing on the longer range computer models. I just don’t feel they have a good handle on things...at least in terms of surface temperatures. They’ve done well with the overall pattern, but they’ve just been too darn cold. With the lack of snow, any cold shot from Canada will lose its bite and the net effect on our weather won’t be too significant.
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