A few weeks ago this page listed a month-by-month synopsis of typical sunlight, cloud and climate conditions for our region. I concluded by offering the National Climate Center’s long-range forecast for this winter. It gave a 55 to 60 percent probability of warmer-than-normal conditions for the mid-Hudson Valley.
Well, they just changed their mind. It wasn’t due to last week’s brutal snowstorm and Januarylike temperatures. Their latest midmonth models say that our region has equal chances for a cold versus a warm winter, and they also expect normal levels of precipitation. They now predict warmer-than-normal temps for us starting in March and continuing right through next fall – and give that a fairly high probability.
So, you might wonder, how can anyone look that far ahead? At the Old Farmer’s Almanac, where I have been astronomy editor the past 20 years, a complex formula is used to issue that venerable publication’s seasonal forecasts. I give those predictions little credence, though I can tell you that my colleagues there honestly believe in them.
The National Weather Service’s climate prediction center takes a very different route, of course, relying on nine separate long-term indicators. A very important one is the ENSO (El Niño Southern Oscillation), which is essentially whether or not an El Niño exists. Currently the Climate Prediction Center pegs the chance of an El Niño at 58 percent during these final weeks of the year. If it happens, such an increase in the surface temperatures of the North Pacific Ocean powerfully influences our weather.
Another factor is the position of the jet stream. Normally there is a northern and a southern branch of those super high-speed, high-altitude winds. If the northern branch stays north of us, our weather is much warmer than when we are trapped on the polar side of the northern stream.
Then there is the NAO, the North Atlantic Oscillation, which is the low pressure that almost permanently hovers over the dismally cloudy Iceland and Greenland regions, and a quasi-permanent high pressure off the sunny coast of Africa near the Canary Islands. The strength of those two pressure regions steers the wind patterns here in eastern North America, especially during winter.
Then too, local conditions such as excess soil dryness or lingering snowpack leave a “memory” that gets imprinted on any region’s longer-term weather patterns. Put it all together and it lets experts create about a 60 percent probability assessment of what any region’s climate is likely to be, months in advance.
Yet with all that, they rate our area’s coming winter as a coin toss. They see no tendency for either a warm or cold or snowy or dry season between now and March.
One thing you can count on this weekend is the Cold Moon: the informal name for early December’s Full Moon, coming up at sunset Saturday night. It will be the earliest-rising Full Moon in over a decade. Then on Sunday, December 7, we’ll see the darkest afternoon – meaning the year’s earliest sunset. You heard right: Starting next Monday, sunset starts happening later and afternoons get brighter.
It’s true, despite the fact that the shortest day is still two weeks away, and the darkest morning won’t arrive for another full month. For sun-lovers, the first good news arrives this weekend.