NBC10 First Alert Weather: Glenn’s Long-Range Summer Outlook

NBC10 First Alert Weather Chief meteorologist Glenn "Hurricane" Schwartz reveals his long-range summer outlook so that you can make your summer plans.

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Summer 2016 was exceptionally warm. In fact, it was one of the hottest summers ever recorded in our area. And we weren’t alone: nearly 50 U.S. cities had their hottest summers on record. Look at how widespread the heat was. In Philadelphia, we had 46 days when temperatures reached 90 degrees or higher. More than HALF of the days in July and August reached 90+. And we had a couple of unusually long heat waves during those months-a 7-day heat wave in July, and an 8-day heat wave in August. It was also a very dry summer. We had a drought in the spring, then one wet month (May), and then we had below normal rainfall every month from June to September. The total was more than FOUR inches below normal for the four month period. This summer will not be as hot-or as dry.
This spring was much wetter than last spring around here. But what stands out even more is how wet it’s been from the Great Lakes to the Plains. Above is a map of soil moisture, compared to normal. The greener, the wetter. There is a tendency for weather patterns to follow soil moisture, especially when it is extreme. This summer, we would expect more LOW pressure to develop in the abnormally wet region, with HIGH pressure affecting drought-stricken Florida. The winds that follow that pattern would lead to a main storm track west of us, bringing lots of moisture up from the Gulf States and the Atlantic Ocean.
And, speaking of the Atlantic Ocean, the above map shows how warm the ocean temperatures are, compared to normal, just off the coast of the Southeast U.S. This also helps HIGH pressure build in from the Central Atlantic (the “Bermuda High”), which also helps pump warm and moist air up the East Coast. This all adds up to a much wetter summer for us.
I’m predicting this summer to not be as hot as last summer. But I still expect it to be hotter than the “normal” from 1981-2010 (the standard measurement of “normals”). The period of normals shifts every 10 years. So, the next period will be 1991-2020. If we compared these recent summers with the average of the 20th century, for example, EVERY one would be well above normal. The “normal” keep moving higher, due to the significant warming that has taken place since around 1970.
Climate Central, based in Princeton, NJ, has made some nice, simple maps showing the overall warming. Of course, some summers are warmer than others, but the general trend is clearly upward. A trend of nearly one degree per decade is considered a dramatic rise when we’re talking about averages. So, get used to summers at least as hot as the coming one. And, in a few decades, we may be looking back on the super-hot summer of 2016 as “the good old mild summers” of history.
Last summer we saw 46 days that were 96 degrees or higher. This summer we should see 30 to 40 days of 90+ degree weather.
The hottest month this year should be August, the same as last year.
This summer, the amount of rainfall should be two inches above the average in comparison to four inches below last year. June should also be the wettest month this year. The wettest month last year was in July.
We should see severe storms this June.
We should also see rain from a tropical storm or hurricane.
We should also see more days with high humidity this summer.
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