Higher Summits Anticipating Colder Conditions

2011-09-12 11:33:23.000 – Rick Giard,  Weather Observer / Education Specialist

Snow at Tip Top House October 2006

Last week continued the trend toward generally rainy, unsettled weather. During the previous week the major precipitation producer was Hurricane Irene. On the heels of Irene more moisture of tropical origin pelted the peaks, as the long-lasting remnants of Tropical Storm Lee lingered within a frontal system stalled along the Atlantic seaboard. This persistent pest instilled instability and induced a series of rainfall events distributed during Sunday through Thursday. The quantity of weekly wetness amounted to 3.99 inches to make the total 4.37 inches for this fledgling month.

With the fall equinox nearly upon us and days noticeably shortened, the temperature is trending inexorably toward cooler conditions. This foretells that ice accumulations and measureable frozen hydrometeor events will soon become a regular Rockpile occurrence. Last week’s only observed solid precipitation particles were Monday’s trace of graupel (a.k.a. hail) with convective origin.

However, the Bergeron cold-cloud process dictates that higher elevations should expect significant snowfall before month’s end. As we enter the cool season most precipitation, including liquid rainfall, forms in the frozen state within super-cooled clouds. Situated closer to the cold level, the summit typically receives its first significant snowfall in mid-September. By October, large snow accumulations are very common.

Current weather model guidance suggests much colder temperatures following the expected frontal passage on Thursday. We are keeping the winter gear close at hand!

Rick Giard,  Weather Observer / Education Specialist