The calendar says it’s spring and the sun is high in the sky, so why you say are 30s°F and 40s F in the forecast? No it’s (probably) not some cruel weather modification prank for campus preview weekend, but instead an inescapable characteristic of spring-time in coastal southern New England. After a long winter, water temperatures near Boston are still only in the upper 30s F (water has a high heat capacity). High pressure areas to our north (with clockwise wind circulation) or low pressure areas to our south (vice-versa) can both orient wind from the Atlantic which subsequently cools down all of New England. The latter is expected for this weekend, the low pressure also bringing rain and leaving the first two Sox-Yanks games in doubt.
A winter storm is fast approaching southern New England to finish the work week. Unlike nearly every storm to hit the area since late December, this one should remain mostly in the form of snow. Light snow should begin by noon and become steadier and heavier toward the evening. Expect a few inches on the ground by nightfall, which should feature a tough commute for anyone working until 5.
Arctic air will continue to be the rule for the next several days, making this the coldest week so far of the winter. Invasions of cold, dry air from the north are an inevitable result of the radiation deficit at high latitudes this time of year, but that doesn’t mean I have to like it. I find everything to be uncomfortable after an Arctic front blows through, whether I’m freezing outside or sitting in the extreme low humidity of a heated building. Thankfully the air masses don’t usually last more than a few days at our latitude, and the fresh batch of Arctic air late this week will be no different.
Now that Thanksgiving is in the rear view mirror, I have started wondering when that first accumulating snow of the season will arrive and really enhance the holiday feel. The first flakes of the season last week were somewhat of a surprise and also seemed sudden because of all the warm weather preceding it, but the average date for the first trace of snow in Boston is actually Nov. 4. For measurable snow, the average date for the first 0.5 inch is Dec. 5. I’m not sure if we will make it by that date this year, but the weather pattern looks to be favorable for chances of snow in the coming weeks. Until then, however, the forecast looks seasonally cool but not frigid.
Just when you thought fall had arrived in the form of cool daytime temperatures and downright chilly nights, the thermostat is getting bumped up again. To recap, this month started off very much above normal, followed by a period of nearly normal highs and lows. Now a second surge of warmth looks to cement October 2007 as quite an anomalously warm time in Boston. Specific to the next several days, a southerly wind flow will bring our weather from the warm southeast United States, an area that has been baked dry this year. Speaking generally though, there is just not much cool air available in any direction right now. Air coming straight from Canada the last week or so has only served to cool temperatures to climatologically average levels. Looking even farther north, temperatures are running about 10 degrees above average in regions like Alaska.