by Donia Moore
What did Hurricane Harvey, Irma, and Maria have in common? Eighteen months ago, the “Almanac” predicted a minimum of three violent category-three hurricanes for this fall’s hurricane season. NASA and NOAA (the National Oceanic and Atmospheric Administration, parent to the U.S. Weather Service) scientists on the Almanac’s forecasting board backed it up with scientific data. However, none of the scientists anticipated the hurricanes making landfall in Texas or Louisiana - predictions were aimed from Florida to North Carolina.
San Clemente is part of the Pacific Southwest region for 2017 prediction purposes. The prediction was that summer would be hotter than normal, with above-normal rainfall. The hottest periods were to have been early and mid- to late July through mid-August. So far, so good.
For 226 years, The Old Farmer’s Almanac has been North America’s oldest continuously published periodical, featuring information for home, garden, history, food, and fun. Its famous traditional weather forecasts, predicted 12 to 18 months in advance of publication each year, claim to be 80% accurate for over 100 years. For generations, farmers and gardeners have been basing their seasonal chores on the predictions offered; and many
still do. Some people even look up the Almanac’s handy Best Day list to schedule everything from haircuts to farm animal castrations. It’s fun. It’s folksy. It’s followed by respected scientists.
How Do They Do That?
The Almanac’s weather forecasts involve a secret formula devised by the founder, Robert B. Thomas, in 1792. Thomas believed that weather on earth was influenced by sunspots, magnetic storms on the surface of the sun. Added to that were the observations of the phases of the moon and the height of the tides. The formula was so secret that it was, and remains, locked into a small black box in the Almanac’s offices in Dublin, New Hampshire. There have been instances when the predictions were extremely accurate, but maybe a day or two off. Still, a day or two is pretty amazing considering the overall weather picture.
Originally, people’s observations of the natural world through the years fueled the predictions. Persimmon seeds and wooly bear caterpillars were as likely to be consulted as the height of skunk cabbage. Almanac predictors have refined and enhanced the original formula with state-of-the-art technology and modern scientific calculations.
Currently, three scientific disciplines are used to make long-range predictions:
• solar science: the study of sunspots and other solar activity
• climatology: the study of prevailing weather patterns
• meteorology: the study of the atmosphere.
The Almanac’s predictions on weather trends and events are based on comparing solar patterns and historical weather conditions with current solar activity. Forecasts emphasize temperature and precipitation deviations from averages, or normals. These are based on 30-year statistical averages prepared by government meteorological agencies like NOAA, and updated every 10 years. The most recent tabulations span the period 1981 through 2010.
Colder winter in 2018?
Overall, the long-range winter forecast by the Almanac for 2017-2018 shows generally much colder temperatures than last winter for the U.S. and Canada but not colder than a typical winter, based on historical averages. Much of the northern United States will experience milder-than-average temperatures, while much of the South and West can expect to feel cooler than normal. Florida and the Southeast will feel milder-than-usual temperatures.
Precipitation will be at above-normal levels throughout the country, which means equally above-normal amounts of snowfall in parts of the northeast, central Great Lakes, central plains, intermountain region, and from eastern Tennessee through New Mexico. Notable exceptions to this wet winter are the Pacific Northwest and Upper Midwest, where less precipitation than usual is expected.
Predictors say there are currently no sunspots on the visible portion of the Sun, so solar activity is very quiet. Traditionally, this meant a cooling influence. So why isn’t it colder than average?
Some scientists support the theory that although the changes in magnitude of solar activity are small, there is a mechanism in the upper atmosphere that can amplify these changes, causing larger ripples in the lower portion of earth’s atmosphere, where weather occurs.
Scientists have been watching sunspot activity cycles from the mid 1700s to our current cycle that shows the data for the officially numbered sunspot cycles, from Cycle 1 in the mid-1700s to our current Cycle 24. The current cycle is comparable to the very low levels of solar activity that occurred in the early 1800s and 1900s, also a cool period. These periods have brought the lowest solar activity levels since the period from about 1645 to 1715, when solar cycles apparently stopped and sunspots were exceedingly rare.
Historically, all periods in the known sunspot record that had low activity have also had relatively cool temperatures, averaged across the globe. Scientists believe that with low solar activity continuing for at least the next 10 to 30 years, global temperatures will be cooler than they would otherwise be.
Despite recent low solar activity, the winter of 2015-16 was historically warm across much of the United States and Canada. And while winter 2016-17 was much colder than the previous winter in most locations, temperatures were still above normal in nearly all regions.
The eruption of Bali’s Mount Agung volcano, or others in the Ring of Fire, is another factor that atmospheric scientists suspect can make earth colder for a few years. An eruption spews ash into the middle and upper portions of the atmosphere. While this has not been a major factor in recent years, it could be in the future.
The most significant factor besides solar activity affecting our weather in recent years has been the increase in greenhouse gases. Most (but not all) atmospheric scientists believe these are making earth progressively warmer. Almanac predictors take these increases into consideration as a factor that will offset much of the cooling from our current period of low solar activity. In fact, despite the low solar activity, the first half of 2017 was 3.4 degrees F above average across the United States, the second warmest January to June period on record, behind only 2016. Amazingly, the last month in which the global average temperature was below its average for the 20th century was in February 1985; more than 30 years ago, according to NOAA.
On average, earth has been warming for decades, but not every place is or will be warmer than normal each season. Other factors are at play, including the normal variation in weather that occurs from day to day and year to year.
2017-2018 Winter Forecast
According to Almanac predictions, last winter’s weak La Niña will most likely be replaced by a weak El Niño this winter; cold air masses will slide into the intermountain region and western states but will not greatly affect the central and eastern states.
In California, winter will be cooler than normal, with rainfall above normal in the north and near normal in the south. The coldest periods will occur from late November into early December and in early February. Mountain snows will be above normal, with the stormiest periods in early to mid-November and early and late January. April and May will be slightly drier than normal. Temperatures will be below normal near the coast and above normal inland. Summer will be cooler than normal, with near-normal rainfall. The hottest periods will be from late May into early June and in mid-June and mid-July. September and October will have near-normal temperatures, with rainfall above normal in the north and below normal in the south.
Sounds about normal.