After yesterday’s (somewhat unexpected) high temperature of 60°F (+1.5 standard deviations from the norm), you knew this unseasonably warm air wouldn’t last long. After November’s below-average warmth, deep down you knew it’d be cold again. In this case, again starts Friday. After that, the jet stream is forecasted to dip southward, bringing the colder Canadian air into New England and persisting for more than a week. Likely as a result, the Climate Prediction Center (CPC) is predicting a moderate chance that this month’s average temperature over the eastern-half of the United States to be below normal. Furthermore, since the jet stream is a “highway” for low-pressure systems to travel on, storms will likely pass by Boston every three days or so. Likely as a result, the CPC is predicting above-normal precipitation for the next couple of weeks. So the upshot: there’ll be more than a handful of opportunities for you see snow this month.
Sunny for five days in a row — is that possible? Yes! New England is well known for its changing weather, so several consecutive days of sunny skies can seem implausible. According to the National Climate Data Center, Boston receives clear skies for 98 days out of an average year, with clear skies being defined as less than 30 percent cloud cover. (Meanwhile, if you are curious, the number one city for clear skies is Yuma, AZ, which enjoys a whopping 242 clear days in an average year.) So statistically, the odds are against a string of clear days in Boston.
This weekend’s snowfall was eight inches, but it could have been a lot more. With the air temperature close enough to freezing, most of the snowflakes were in the form of wet snow. With all the ice, sleet, and rain at the tail end of the storm, the snow to liquid ratio was only 4:1. On average, a winter storm’s ratio is 10:1 and when the temperature is around 20°F, the ratio can get up to 20:1. Thus, if we had gotten the “fluff” factor, Boston could have received 40 inches of snow! Nonetheless, the observed eight inches more than doubled the season’s low snow totals and cost us our chance at setting the lowest recorded snowfall total (9") ever in Boston.