Last week’s rainfall didn’t do much to get us out of the drought
This week, temperatures are going to run five to 10 degrees above average, with highs getting near or exceeding 80 degrees for two of those days. The warm weather might make us nostalgic for summertime—and also remind us that our drought is very much still in play.
There’s been some improvement of the drought south of Boston, but most areas haven’t seen a big change.
We’ve seen some much-needed rain the past few weeks but, unfortunately, it’s done little to move the drought needle in most of New England. The image below shows that, in spite of the rain, most areas are running one to two inches under average rainfall since September.
Most of New England continues drier than average in spite of recent rainfall.
Drought in New England isn’t common. Typically, the fluctuation in precipitation doesn’t have nearly as large a range as that of snowfall. Since 1872, only 10 years have passed during which the total precipitation has been more than 10 inches below the long-term average of just over 41 inches of rainfall. This year, Boston has seen just over 24 inches of rainfall, which is 10 inches below where we would typically be by now.
To understand the drought, it’s worth widening the time period and looking at rainfall over the past three years. The map below shows just how far behind the area is with regard to precipitation. Notice that, during this period, some areas are 16 to 20 inches below average. This is as if it didn’t rain for four or five months!
Nearly all of southern New England is drier than average since 2013.
The big snows two years ago didn’t help the situation. The snow that winter was very light and contained less water than typical snow. The map below shows how much snow fell in relation to average for February. Boston and surrounding areas had around 45 inches more snow than the 10-14 inches usually expected. However, the amount of water in that snow was only significantly above average in a very small area from Boston to roughly 20 to 30 miles south and west of the city. The rest of the area had close to normal precipitation (melted snow), with the western part of the state seeing below average moisture.
Heavy snow doesn’t mean a lot of moisture
Notice the image below showing just how far below average rain was during the spring of 2015. The lack of rain combined with strong sunshine dried the ground out rapidly after snow had melted.
The spring following the big snow in 2014-2015 was very dry.
The chart illustrated shows how low precipitation has been in 2016 since meteorological spring began. Much of the region saw around half the normal rainfall during this period.
Dry weather has been continuing for since early spring
The main reason for the dry weather is a continued persistent ridge in the Atlantic. While this is a typical pattern for the core of summer, it’s more unusual for it to last for so long.
Before you make a leap to this being part of climate change, remember: New England has seen droughts before, and this is likely just part of a large cyclical pattern which will eventually swing back to a wetter period in the coming 12-24 months.
Persistent high pressure has kept much of the northeast dry this year.
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