Meteorologists on the long-range forecasting team forecast trends in the weather over the next several months. Our mets and writers get a lot of questions about how long-range forecasting even possible. AccuWeather.com meteorologist Jack Boston answers some of the most-asked questions.
How detailed can you get with your forecasts so far ahead of time?
In long-range forecasting, we don't actually predict what's it going to be like every day. In other words, I can't sit here and say, "Well, on October 10th, it's going to be 60 degrees and party cloudy with showers in the afternoon." We don't do that. What we do is we look at a trend. "Overall, the month of October's going to be dry. Over all, the month of October's going to be colder than normal." Temperature forecasting might be a little bit easier than forecasting rainfall or snowfall
How far out do you forecast?
We have most of our confidence in the season that's coming up. We issue that forecast somewhere around two months ahead of time. There are some clients that are actually interested in next year, in next spring, in next summer. In fact, we actually look out a year and sometimes more than a year.
What factors do you look at when you're forecasting for a whole season?
We look at a number of things, but three majors factors we use in our season forecasts are ENSO, NAO, and analog years.
ENSO, or the El Niño-Southern Oscillation, is the La Niña and El Niño. What it basically is, when you take a long-term average, is if the sea surface temperatures in the Equatorial Pacific Ocean are above normal or below normal. If those temperatures are above normal, warmer than normal, we call that an El Niño. If those temperatures are below normal, we call it a La Niña. And that has a great affect on the type of weather in North America.
The NAO, or the North Atlantic Oscillation, is a relationship in temperature between the far-north Atlantic as compared to the temperature down near the Azores, off the coast of Spain. If it is warmer than normal up around Greenland, and colder than normal down around the Azores, that is what we call the negative NAO. That is what tends to cause blocking. If there is blocking in the Atlantic Ocean, weather systems coming across North America get forced down into the eastern United States, instead of just heading out into the North Atlantic. If that happens, that's how we get lots of cold air masses to come straight down into the Eastern United States, from Canada.
Analog years are past years that we see that have had similar precipitation and temperature patterns. We put them into our thinking as far what might happen this year might be similar to what happened in those years.
With so much uncertainty, why make a long-range forecast?
All I can say is that a [long-range forecasting] gives you an opportunity to plan. If it's going to be a snowy and cold winter, maybe you want to make sure your boots are in good shape. It's also very important to the energy industry because they have an opportunity to find out how much heating oil is going to be needed during the winter. They can plan that and buy a certain amount and make sure they keep a certain amount in supply.
A cooldown with clouds, showers and thunderstorms is in store for Southern California and much of the Southwest following recent heat and sunshine.
A dominant storm track featuring storms moving west to east across Europe will result in a stark contrast between cold air building across Scandinavia and milder air masses entrenched near the Mediterranean.
After waves of cool air progress through the Midwest and Northeast this week, some areas will be cold enough for the first snow showers of the season by this weekend.
An effort is underway to fill a radar hole in Charlotte, North Carolina, and similarly populated areas in the United States to better detect and protect the public from severe weather.
Unmanned aerial vehicles (UAVs) interfered with containment efforts in the West on at least 25 occasions in 2015.
Newly formed Tropical Storm Koppu is on track to threaten the Philippines this weekend. Those in Taiwan and Japan should also monitor the storm for potential impacts next week.
New England (1990)
Remains of Tropical Storms Klaus and Marco brought torrential rains and flooding. Parts of Connecticut had 6 inches of rain or more. Stafford, CT, had 4.20 inches.
East Coast (1846)
Great Hurricane of 1846. Track: Cuba, Key West, FL; GA; Carolinas; Chesapeake Bay; PA - major damage all areas (Similar to Hazel in 1954). Lashed the Delaware River "into a perfect fury and its roar would have drowned out the thunder of the Niagara.
Layton, NJ (1906)
11 degrees - record early season cold snap.