The Weather Guys

Last week was an alarming week in weather and climate news.

Hurricane Sally bore down on the Gulf Coast with fury and flooding, while four other tropical storms churned away simultaneously in the Atlantic. This is only the second time ever, and first since 1971, when such prolific tropical storminess has characterized the Atlantic basin.

In the northeastern Arctic, a 42-square-mile section of the Greenland ice sheet broke off and was set adrift. Locally, our sunsets and sunrises have been substantially more orangey as a consequence of smoke in the skies from the record western wildfires that are raging nearly a full month before their usual annual peak. These fires, part of a prolonged hot and dry spell that has resulted in what might be the world’s highest recorded temperature ever — 130 degrees on Aug. 16 in Death Valley, California — and a record high of 121 degrees in Los Angeles on Sept. 6 are manifestations of the climate change about which we have been warned for several decades.

In the face of such devastating evidence, President Donald Trump asserted last week “it will start getting cooler” and, regarding climate change, “I don’t think science knows, actually.” Thousands of hard-working, intelligent and dedicated scientists do know, actually — the planet is warming and the consequences of that warming are increasingly becoming headline news with devastating effects to millions of people around the globe.

Disrespect for hard-fought scientific expertise costs lives — a lesson that our nation seems reluctant to acknowledge six months into an unending pandemic, even while other alarm bells loudly ring.

The Farmers’ Almanac recently published its 2020-2021 winter forecast. For the Midwest region, it predicts a cold winter with normal to below-normal temperatures.

But don’t count on its forecast, as there is no proven skill. The Farmers’ Almanac does not share how it makes its forecast, so it cannot be judged scientifically.

The Farmers’ Almanac also makes a weather forecast for specific time periods in a given season. Such detailed forecasts can be announced but are not trustworthy scientifically.

Seasonal weather forecasting is a science challenge. The National Oceanic and Atmospheric Administration’s Climate Prediction Center (CPC) also makes seasonal forecasts. It explains the underlying principles of its forecast and provides validation of its forecasts publicly (see www.cpc.ncep.noaa.gov/products/predictions/long_range/tools/briefing/seas_veri.grid.php).

These modern-day seasonal forecasts rely on known relationships between climate and some key forcing mechanisms, such as the El Niño. An El Niño is a periodic warming of the equatorial Pacific Ocean between South America and the Date Line. This warming is a natural variation of the ocean and is used to predict departures from average conditions rather than to make specific weather forecasts. For example, a year with a strong El Niño leads to less snow fall than average in Wisconsin. These seasonal forecasts also take into account the climatic impacts of other global oscillations uncovered by the research of atmospheric scientists.

There is about a 60% chance of a La Niña, a cooling of the equatorial Pacific Ocean between South America and the Date Line, developing during the Northern Hemisphere fall and continuing through winter 2020-21. This will influence global weather patterns. The CPC predicts there is an equal chance our wintertime temperatures will be above, below, or at average conditions. They are also calling for a 40% to 50% chance that our winter precipitation will be above normal.