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.
Unsettled weather will stretch across the United Kingdom on 27th November as millions set out in search of the best Black Friday deals on offer.
Compared to Thanksgiving Day in 2014, this Thanksgiving will be substantially warmer in the Northeast.
Hurricane Sandra, located hundreds of miles southwest of Mexico, is becoming better organized and will likely track northward through the rest of the week.
A few days of drier weather is expected across southern India before downpours return this weekend.
An expanding area of snow, rain, wind and cold will hamper Thanksgiving travel in the West, while most areas east of the Rockies can expect no major weather-related problems during the early to middle part of this week.
A major Thanksgiving Day storm threatens to ruin holiday events across the Central states with flooding rain, snow, a glaze of ice and fog.
Wilkes-Barre/ Scranton (1971)
Heavy snowfall in the Wilkes-Barre/Scranton area. It started to snow the night before, and by about noon Thanksgiving Day 11/25/71, 20.5 inches of snow was reported on the ground at the Avoca, PA airport. Some of the surrounding areas had even more snow. Dallas, PA, had 27 inches and parts of the Poconos had as much as 30 inches. Barn roofs collapsed, power lines were downed, and tree branches were broken. The majority of the snow fell within 12 hours.
A dozen tornadoes across these states.
Astoria, Or (1998)
5.56 inches of rain fell, setting a new all-time record. the previous rainfall record was 4.53 inches from January 9, 1966.