Epi Week #36 - 2014 General Statements

Arbovirus activity rose this week, as it typically does in early September, but numbers of EEEv- and WNV-positive mosquito pools remain far below those in 2013 and 2012. The warm temperatures that were felt most of Epi Week 36 did come with increased mosquito activity for some parts of the state. Districts/Projects with arbovirus-positive mosquitoes have continued to implement standard control responses, including larviciding of catch basins and ULV truck spraying of adulticide in a wide area around positive finds. However, those activities are winding down for the season, with several Districts/Projects announcing that the treatments have ended this week except for emergency responses (and even those will be dependent on nighttime temperatures being high enough).

Weather

The first week of September ended with temperatures nearly 10◦F degrees above normal (those temperatures would have been considered substantially above normal even by late-July standards). The total number of “cooling degree days” (a way of relating the day’s temperature to the energy demands for air conditioning) for 2014 now stands at 729, which is 38 days above normal from the period of January 1 through September 8th.

The period was relatively dry as well, with the exception of localized storms that wreaked havoc on some parts of the state. Worcester experienced a tornado Sept. 1, and a cold front Sept. 6 brought a line of heavy rain across MA and NH, resulting in microbursts that cause downed trees and power lines in Franklin County (Leyden, Bernardston) and Essex County (Ipswich).