A University of Massachusetts Amherst analysis of climate data from the National Weather Service shows several Northeast communities experienced their driest autumn on record this year.
With little precipitation and an outbreak of wildfires in the Bay State, Massachusetts recorded its second-driest October. Connecticut experienced its driest October ever.
WAMC's Lucas Willard spoke with UMass Climate System Research Center's Dr. Michael Rawlins to learn more.
So when we look at the meteorological autumn or fall, which is the months of September, October and November, Amherst and Hartford both experienced the driest autumn on record. Worcester, Massachusetts, third driest, and several, quite a few climate sites along the Northeast, particularly closer you get toward the coast, were also record dry. For example, New York, Kennedy Airport, Newark, New Jersey, down south. The dryness was actually a bit more severe in New Jersey and Wilmington, Delaware, had a record dry up even up north into Bangor Maine. So it's quite, quite period of dryness. And that dry weather that we've seen recently was exacerbated, if you will, by the extremely dry weather in October. For October, Massachusetts had its second driest October on record, the two-month period September, October was really, really dry for central and western Massachusetts, really quite anomalous compared to what we've experienced in recent decades, which is actually a trend upward toward more wet fall in recent decades.
Now, what about the global weather picture is contributing to this dryness? Why has it been so dry with such a lack of precipitation?
Well, it's interesting. Typically, in this time of year, particularly in, let's say, September and into October, our region typically gets precipitation from weakening tropical systems that originate in the Gulf of Mexico and the western Atlantic that move up from the south and bring precipitation. These are low pressure systems of a tropical origin, as opposed to things like nor'easters. And we've really had an absence in recent months of those types of systems. It's almost been like a dry wind out of the west, if you will, off of the land that's been just…an absence of these weather systems that typically bring fall precipitation to the region. A few years ago, I recall there was a one period where we had from around July all the way through into December, where it was just rain after rain. And this was an interesting fall. Can't really say it's linked to any specific, large scale weather anomaly. It's just one of those years where we just had a bunch of dry weather stacked up upon, week upon week.
Now based on the autumn and how dry it has been, does that give you any indicators of what the winter and maybe into the spring will look like? Or is it impossible to predict?
Now, we really can't. The National Weather Service forecasters really don't…it's really difficult to go out beyond about a week or two. That said, the projections are for a slightly…NOAA, the National Oceanographic and Atmospheric Administration, does do seasonal forecast, they use things like actually soil moisture and large scale projections of things like the tropical Pacific Ocean. There's forecast to be a weak La Nina in the Pacific Ocean, and so they're forecasting slightly warmer than normal and equal chances of wetter and drier. Now, those forecasts, the skill level really is nothing compared to your typical seven or 10 day forecast, which is much more accurate. So, it's really kind of a toss-up of what we'll experience and the weather that has occurred over the last several weeks, couple months, doesn't really factor much into what we can expect as we go through winter.
So Michael, why do you think it's so important that we study this climate data, and why is this valuable to your research?
Well, one of the reasons why we want to understand and take a closer look at the depth, if you will, of the dryness is, for one thing, water resources. A lot of places, smaller reservoirs and lakes, particularly as I mentioned, to the south, like in New Jersey and into Delaware, groundwater levels even in Massachusetts and up further north, up in the up into New England, groundwater levels have dropped quite a bit. They're really particularly low right now. As I mentioned, smaller surface storages, like smaller lakes and ponds, reservoirs, the levels have dropped quite a bit over the past couple months, and one of the reasons for that is it was also warmer than normal. Both Hartford and Worcester had their second warmest autumn on record. So, with the warmer weather and the lack of precipitation, you get more evaporation from the surface. So, water at the surface evaporates, the atmosphere is more thirsty, if you will. So, we really want to understand how, actually, how dry it was, so we can better conserve water. So, a lot of agencies are encouraging folks to conserve right now. Don't wash your car quite as often, you know, check for leaks in your homes and try to do your best to conserve our resources, because we don't really don't know how much longer the dry weather will continue, we're running quite big deficits of precipitation right now, upwards for the year, up to places eight to 10 inches shy of what's normal. So that's why it's really important to understand how dry it's been and put that in a perspective of our water resources. Now, as I mentioned, we really don't expect, in years to come that this dryness will turn into long term trends like out in the western US, but it has been quite severe and the drought monitoring agencies like the US Department of Agriculture, lot of places in the region are running moderate to severe drought right now for the surface conditions,
When you speak about the precipitation deficits of eight to 10 inches, did the recent rain and snow that we've seen over the last week or so, did that make any dent into those deficits at all?
Actually, the recent precipitation amounts were not particularly large. You might refer to them as a drop in the bucket, if you will. Really hasn’t had much effect on the on the drought status. Places that got they got a little bit of snow. That's not a whole lot of water equivalent. So, now the drought may the areas of, let's say severe drought, may contract a little bit a little smaller area. Severe might go to a little bit more moderate drought, but it's really hasn't been much. We really need several weeks, a couple months of above normal precipitation, or at least normal precipitation, in December, January, February, to help get out of this drought. And of course, in the winter time, there's a lack of a connection between the surface and the deeper groundwater levels. And so, we're going to accumulate some snow coming up here. And so, hopefully this would be a great winter to get an above average snow pack and a bit of rain into the early spring, to kind of bump up these levels of the reservoirs and the ground water storages because continuation of below normal precipitation through winter and into spring, we could really be looking at some pretty severe water shortages as we get into the warm season in the spring.
