THE VERMONT WEATHER BOOK by David Ludlum (Vermont Historical Society, 1996)
CONTINUED from PAGE 1:
The main Pacific jet stream follows about the same path as in November, except over the eastern states it continues directly eastward from the Ohio Valley and passes well south of Vermont. An additional jet stream pursues a path over the southern United States, then sweeps northeast to the Carolina capes, and thence over offshore waters to join the northerly jet stream east of Cape Cod. The principal storm tracks from the west migrate south of their November positions, with some storm centers crossing the Green Mountain area. With increasing frequency, barometric depressions move along the Atlantic seaboard as coastal northeasters whose precipitation can encompass all of New England with heavy rain or snow.
Anticyclonic movement takes on a winter pattern. The main track from the Canadian Northwest continues to introduce arctic outbreaks of frigid air that ultimately reach Vermont in modified form, and a new secondary center of anticyclonic activity is found over the Province of Quebec. In conjunction with a center of minimum mean pressure off Cape Cod, an active air flow often crosses New England from northwest to southeast.
The decline in mean temperature is more evident from November to December than between any other months. The amount ranges from about 13 degrees in the southeast to about 15 degrees in the northeast. Newport returns a December mean of 19.4°, compared to Vernon’s 25.4° and Bennington’s 26.1°. Over recent years the absolute extremes in December have been from -50°, the all-time Vermont minimum recorded at Bloomfield in 1933, to 72° at Enosburg Falls in 1941. The range of temperature in December is the greatest for any month of the year.
Precipitation drops off from the high levels of November by almost 20 percent in the northeast and west and by 13 percent in the southeast. Amounts in the mountains about equal the summer high figures: Mays Mills averages 5.21 inches and Searsburg Station 5.11 inches in December. Valley weather stations record much less precipitation, as exemplified by Champlain Valley locations where Burlington’s average is only 2.43 inches, indicative of the predominance of dry westerly winds from the interior of the continent.
One expects winter to be in full swing by Christmastime, and Vermonters are seldom disappointed in this regard. The chance of having a white Christmas with one inch or more on the ground is 77 percent at Burlington in the Champlain Valley, and the figure rises to 93 percent at higher elevations in the northeast, and probably to 100 percent atop the peaks. On Christmas Day in the the past, Burlington has experienced temperatures as high as 62° in 1964 and as low as -25° in 1980. Few will forget that recent bitter holiday, when the maximum of -5° occurred just after midnight, and at 3:00 P.M. the thermometer stood at only -14°. Nor will memory fade of the great Day-after-Christmas Snowstorm in 1969 when a record 29.8 inches fell at Burlington and 45 inches at Waitsfield. So great was the problem of clearing the highways that Governor Deane C. Davis declared a state of emergency in order to obtain federal assistance in opening the roads for holiday travelers.
