Huge amounts of rain dumped onto Connecticut in the month of August, and the results will affect the state into next year and beyond.
Rain in August measured at the Connecticut Agricultural Experiment Station property, Lockwood Farm, in Hamden, totaled more than 14 inches. The official government rain tally for all of Connecticut was just over 11 inches. (Rainfall totals can differ depending on where they’re taken and how many measurements scientists average out.)
These records placed August 2011 as the second-wettest August in Connecticut in 117 years of record-keeping. Connecticut’s ground was saturated even before Tropical Storm Irene blew through at the end of the month.
The most immediate effect, everyone who walks outside at dusk will notice. An exploded population of disease-carrying mosquitoes will thrive into next year, scientists say.
“We have tremendous numbers of aggressive, human-biting mosquitoes pretty much statewide,” said Theodore Andreadis, chief medical entomologist and head of the New Haven-based agricultural experiment station’s entomology department.
Mosquito numbers roughly tripled after all the rain, and Andreadis said the insects will thrive until a hard freeze late in the fall. Between now and next spring, the chances of your being bitten and catching two serious viruses mosquitoes carry have gone up.
West Nile virus and Eastern Equine Encephalitis are rare, but officials consider them serious public health threats.
Potentially deadly infections
EEE, known in these parts since 1996, kills 30 percent of those infected by mosquito bites. West Nile virus, which showed up in New York 12 years ago, infects more often and kills 5 percent of the infected. And so, while known infections number only a relative handful in the Northeast in the last half-century, these diseases worry public-health officials.
Andreadis said that four people in Connecticut were diagnosed with West Nile virus this year. The most recent confirmed diagnosis was a Southington person over age 70. The others lived in New Haven, Bridgeport, and Stamford. All four people got sick the week of Aug. 17, but the diagnoses weren’t all complete at the same time, he said. No people have come down with EEE.
Both viruses live in birds and pass to mosquitoes that bite them. Research has shown that both viruses live through the winter: West Nile stays in mosquitoes and passes to their eggs, giving birth to entire crops of infected insects. How EEE makes it through the cold months isn’t clear.
The good news is that Tropical Storm Irene’s force flushed out the storm drains and pipes where the mosquito species most likely to carry West Nile virus (Culex pipiens) tend to breed. “We’re not completely out of the woods, because we know from past history that we’ve had human cases (of West Nile virus) that come on the first week of November,” Andreadis said.
But the bad news is that water levels are up everywhere else, especially in swampy areas, where those mosquito species that tend to carry EEE (Culiseta melanura) thrive.
The Connecticut Agricultural Experiment Station tests mosquitoes each week at traps all over the state. West Nile virus was found in the general region of these human cases -although not necessarily in the towns where the people lived - by mid-August, he said. “We had all the indicators that we knew human cases were imminent,” he said.
The new normal
The definition of “normal” rain and snowfall in Connecticut has changed in the past several years. The climate of Connecticut is getting wetter.
The Northeast Regional Climate Center at Cornell University has calculated that yearly precipitation averages for most of southern New England - which they tally by looking at a period of many years and averaging the actual rainfall - is now higher than it used to be. They conclude this by comparing the period 1971-2000 to the earlier range once used, 1961-1990. See http://www.nrcc.cornell.edu/page_differences.html. Most of this is in the form of rain; snowfall is going down because of rising average temperatures.
Irene alone dumped almost 8 inches on some areas of western Connecticut, and the earlier part of August brought several storms that saturated the ground and led to flooding even before the storm.
The August tally will contribute to data that shows rainfall trending upward. Year to year, the totals jump high and retreat, but the overall trend for a century has been increased rain. See the National Oceanographic and Atmospheric Administration chart here: http://www.ncdc.noaa.gov/temp-and-precip/time-series/index.php?parameter=pcp&month=8&year=2011&filter=1&state=6&div=0