Summer Forecast 2017

This weekend marks the unofficial start to summer, and for many of you, it can’t get here fast enough.  The nearly 100 inches of snow this winter is still fresh in the minds of many, and up to last week, spring hasn’t been kind to  us either. The anticipation of warm summer days , and visits to the beach or lake may have you wondering if Vacationland will live up to it’s name in summer 2017.

The months of June, July, and August are expected to be warmer than normal, but likely not as hot as last summer. There’s a higher than average probability we’ll receive at least one heat wave this summer. That means three consecutive days of 90 degrees or higher.

There were a number of factors that went into this temperature forecast. First, a weak El Nino is expected to form this summer.  El Nino has a bigger effect during the winter months here in New England. Regardless, I took a look at weak June through August El Nino’s (0.5 to 1.0) that occurred over the past 30 years.  They are 2009, 2006, 2004, 2002, and 1991. The US temperature anomaly for those years during the summer months look like this.

There’s a clear signal for cool Midwest to Western Great Lakes. The eastern half of the US is either normal or warmer than normal for those years selected.  Next, I looked at the model forecasts. Here’s the May run of the Japanese Model valid June-August. It’s warm for the US.

The US CFS (often the less reliable) model is suggesting a warm summer in the east for June, July, August.

The current sea surface temperature anomalies are not exactly warm near New England , Gulf of Mexico, or the West Coast.

Models are seeing a reversal of this during the summer months.

Last year’s extreme drought in Maine was the worst in fourteen years. Over three feet of rain and melted snow fell since autumn, and groundwater  has returned to normal levels.

Confidence is high the extreme drought of 2016 will not return this summer. Rainfall is expected to be normal or slightly above normal this summer in Maine.

The same El Nino (0.5-1.0) years above were analyzed and looked like this. See the clear dry signal in the Great Lakes and Mid-West.  The east coast was wet though.

Modeling isn’t nearly as robust as analog years, and the primary reason for keeping the summer forecast average to slightly above average in rainfall here in New England. Here are the JMA and CFS models.

Summer rain is by far the most difficult to forecast . As we all know, thunderstorms may dump several inches on one community, while others see nothing more than a sprinkle.  Tropical storms and hurricanes are of course another threat.

As mentioned above, a weak El Nino is expected to form this summer.

Simply put, that means the ocean is expected to be warmer than normal in the Eastern Pacific.  Here’s an image from the last El Nino in 2015.

The ocean temperature in that region has an effect on the position and intensity of the jet stream, and in turn, our weather in the United States.  A stronger jet stream suggests the number of hurricanes will be lower than normal in 2017. Number of storms in the Tropical Atlantic might just be the biggest effect El Nino has on our potential weather here in the Northeast during the summer months.

Experts at Colorado State University are thinking the same thing, projecting 11 named storms. Four expected to become hurricanes with two becoming major hurricanes.

Here in New England the probability of a named storm making landfall is almost 5%. The chance of one impacting Maine is slightly over 3%.

Thanks Adam Epstein for the info fresh back from the National Hurricane Conference in South Padre Island ( I know, tough assignment, right… )

A lower than average hurricane season in numbers does not mean we’re out of the woods here in New England. In fact, some may argue the opposite. The last hurricane to strike New England 26 years ago was the 2nd named storm that year, and occurred in an El Nino summer just like this one.

Thanks for taking the time to read this blog. Have a great summer. You can also find daily weather updates via my WGME CBS 13 social media pages here.



Charlie Lopresti

About Charlie Lopresti

Charlie makes up the "Weather Part" of CBS News 13s evening edition. A native New Englander, he grew up enjoying the area's exciting and sometimes wild weather.