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General Statements from the State Reclamation & Mosquito Control Board – 2017


Epi week #36, September 3 – September 9, 2017

 

General Statement: Massachusetts has confirmed 262 WNV-positive mosquito pools so far this season, with WNV activity in every mainland county in the state. There are now a total of 155 towns and cities in 11 counties at MODERATE risk for WNV, more than 40% of the state. Since it is difficult to compare this year to past years, with new and high sampling levels in the Pioneer Valley area, the metric of towns per risk level category is useful. In comparison, at this time in 2016, there were only 55 municipalities at a MODERATE risk level; in 2015 there were 42 (and this did include some sampling in the Pioneer Valley area). Unseasonably warm temperatures will continue to contribute to mosquito activity, prolonging WNV activity statewide.

 

Weather:

Epi Week 36 was a wet week for most of the state, after a particularly dry August and September. Parts of Berkshire County, Northern Worcester County, Cape Cod and the Islands saw in excess of 3 inches and even 4 inches of precipitation:

 

 

Expect above-average temperatures to continue through at least the middle of Epi Week 37, at which point the southeastern part of the state will be dealing with a weakened Tropical Storm Jose that is expected to bring some wind and rain.

 

Epi week #35, August 27, 2017 – September 2, 2017

 

General Statement: Massachusetts has confirmed 228 WNV-positive mosquito pools so far this season, with WNV activity in every mainland county in the state. There are now a total of 140 towns and cities in 11 counties at MODERATE risk for WNV. We continue to see a high amount of WNV activity statewide, however, the state still remains without a confirmed human or animal case of WNV. EEEv activity remains low.

 

Weather:

There was limited precipitation across the state for Epi Week 35, except for the Cape and Islands. Bristol, Plymouth, most of Norfolk County, and the northwest tip of Essex County have actually re-entered drought conditions at the D0 level (Abnormally Dry). Anecdotal observations along I95 south of Boston indicate the vegetation is feeling this after a very dry August, with many roadside weeds seen with dying or yellowing leaves and some red maples already starting to show their fall colors.

 

 

As this report goes to press, we are ending Epi Week 36 with the first significant rain since July having come through at the start of the week. Nighttime temps remain cool. It is too soon to tell if Hurricane Irma will impact us during Epi Week 37.

 

Epi week #34, August 20 – August 26, 2017

 

General Statement: Massachusetts has confirmed 200 WNV-positive mosquito pools this season, with WNV activity in every single mainland county in the state. There are a total of 105 towns and cities in 11 counties at MODERATE risk for WNV. We continue to see a high amount of WNV activity statewide, even as we round out a dry August with cooler nighttime temperatures. EEEv activity remains low though Culiseta melanura numbers have recovered to pre-drought levels.

 

Weather:

There was limited precipitation in Berkshire County and in the north-central part of the state this past week, otherwise most of the state received little rain.

 

 

As this report goes to press, we are ending Epi Week 35 with little rain and cool nighttime temps. Expect remnants of Hurricane Harvey to pass by over Labor Day weekend, bringing showers to some parts of the state. Our weather expert is also keeping a wary eye on Hurricane Irma, but says it’s too soon to tell if it will impact us.

 

Epi week #33, August 13 – August 19, 2017

 

General Statement: We have now had 150 WNV-positive mosquito pools, with WNV activity in every single mainland county in the state. There are a total of 105 towns and cities in 11 counties at MODERATE risk for WNV. Though increased sampling in Franklin County bumped up the numbers higher than they would be normally, we are definitely seeing a high amount of WNV activity statewide. It remains to be seen whether a dry August and cooler nighttime temperatures give us a reprieve over the next week or two. EEEv activity remains low.

 

Weather:

Precipitation was limited again this past week, with most of the state receiving less than an inch of rain (with the exception northern Berkshire and western Franklin Counties, and a wallop of storm on Cape Cod that left in excess of 5 inches of rain in some towns).

 

 

As this report goes to press, we are ending another week of hot, sunny days that have been bookended by surprisingly cool nighttime temperatures. Expect almost fall-like temperatures for Epi Week 35, with nighttime cooldowns that will have some Projects thinking about the end of the spray season.

 

Epi week #32, August 6 – August 12, 2017

 

General Statement: We have now had 88 WNV-positive mosquito pools, with WNV activity in every single mainland county in the state. There are a total of 95 towns and cities in 10 counties at MODERATE risk for WNV. Given current trends in mosquito populations, temperature, and regular rain events, it is likely WNV levels will continue to build. In contrast, Culiseta melanura levels remain lower than average, and there have still been no EEV+ pools found.

 

Weather:

Precipitation was limited this past week, particularly in the eastern part of the state (with the exception of Cape Cod and the Islands (note that the map below is missing a lot of datapoints, so should only be used to interpret general trends). Compared to July, the first half of August has been notably drier, with near normal temperatures. Our weather experts notes that for the first time this summer, he is noticing minor water stress on non-irrigated lawns.

 

 

As this report goes to press, we are ending another week of hot, sunny days with a temporary cooldown accompanied by showers on Friday. Temperatures will quickly rebound for the weekend and into Epi Week 34, with humidity at typical August levels.

 

Epi week #31, July 30 – August 5, 2017

 

General Statement: We have now had 64 WNV-positive mosquito pools, with WNV activity in every single mainland county in the state. Given current trends in mosquito populations, temperature, and regular rain events, it is likely WNV levels will continue to build. In contrast, Culiseta melanura levels remain lower than average, and there have still been no EEV+ pools found.

 

Weather:

Rain was mainly limited to the middle of the state this past week, with hotspots of 3 inches or more in Worcester and Middlesex Counties:

 

 

As this report goes to press, we are ending a week of hot, sunny days and cool, almost crisp evenings, and heading into showers expected through the weekend. Expect above-average precipitation and average temperatures (possibly above-average on the coast) for Epi Week 32.

 

Epi week #30, July 23 – July 29, 2017

 

General Statement: We have now had 29 WNV-positive mosquito pools in in the state, including several in and around the Boston area, a region of the state known to be a hotspot for this virus. Given current trends in mosquito populations and regular rain events, it is likely WNV levels will continue to build. Culiseta melanura levels also remain lower than average, and there have been no EEV+ pools found. To put this into perspective, during this Epi Week in 2012 (the last time a wide-area aerial adulticide treatment was performed), there were already more than 55 EEEv+ pools confirmed in the state.

 

Weather:

Most of the state received at least one inch of rain this week, with the exception of the southeast and Cape Cod and the Islannds (and a tiny northwest portion of Berkshire County). Looks like South Suburban Boston received the bulk of the precipitation, topping out at 1.86 inches:

 

 

As this report goes to press, we are starting August with hot, humid weather punctuated by scattered thunderstorms. Expect higher than average temperatures and precipitation for Epi Week 32.

 

Epi week #29, July 16 – July 22, 2017

 

General Statement: We have now had 24 WNV-positive mosquito pools in in the state, including several in and around the Boston area, a region of the state known to be a hotspot for this virus. As noted in last week’s report, given current trends in mosquito populations and regular rain events, it is likely WNV levels will continue to build. Several Mosquito Control Districts have been increasing surveillance in these areas or providing ULV truck-spraying of adulticides.

 

Weather:

A rare week with little precipitation anywhere in the state, with parts of Plymouth and Bristol Counties the only locations to receive more than 1 inch:

 

 

As this report goes to press, we are ending Epi Week 30 with abnormally cool temperatures that left almost a fall-like feel to in the air. Expect a return to summer for the start of August, with average to above-average temperatures, similar to what we had in mid-July.

 

Epi week #28, July 9 – July 15, 2017

 

General Statement: We have now had 7 WNV-positive mosquito pools in in the state, including several in and around the Boston area, a region of the state known to be a hotspot for this virus. Given current trends in mosquito populations and the existing weather pattern, it is likely WNV levels will continue to build.

 

Weather:

Another precipitation map split down the middle this past week, with the western half of the state receiving up to 1.5 inches of rain or more, while the eastern half remained relatively dry. We are at the time of year when rain accumulation is dependent more on scattered storm events than big systems, which means that even within a county the precipitation amounts can vary greatly. Looking back at the summer so far, the Boston area has accumulated about 7.5 inches of rain, which is slightly above average, but far above the 2 inches received during last year’s drought.

 

 

As this report goes to press (July 20), we are rounding out a week filled with 90’F+ days and extremely warm and humid nights. Looking into Epi Week 30, expect average precipitation and cooler than average temperatures, though temperatures should return to normal by the end of the week.

 

Epi week #27, July 2 – July 8, 2017

 

General Statement: We have now had 3 WNV-positive mosquito pools in wide-ranging parts of Massachusetts (Suffolk, Berkshire, and Bristol Counties, indicating that this arbovirus is likely around at low levels throughout the state. It is still too early in the season to make predictions as to how this will impact potential human cases. However, EEEv predictions have panned out so far this season, with Culiseta melanura levels staying low despite repeated rain events.

 

Weather:

Precipitation was fairly limited for Epi Week 27, though most of the Cape and Islands received 2 inches or more and the southern edge of the state got as much as 1.5 inches in some areas. We are at the time of year when rain accumulation is dependent more on scattered storm events than big systems, which means that even within a county the precipitation amounts can vary greatly.

 

 

As this report goes to press (July 13), Ep Week 28 has already brought us two days of storm events, with flash flood warnings panning out in several parts of the state along with lightning, thunder, and hail. Looking into Epi Week 29, expect slightly below normal precipitation and temperatures that finally warm back up to the low to mid-80s, with a few days near or above 90F. Climatologically, the next two weeks are the hottest of the year, and we should not see cool, dreary weather like we had at the end of Epi Week 28 for a long time.

 

Epi week #26, June 25 – July 1, 2017

 

General Statement: Collections were back up again this past week after a drop for Epi Week 25. We also had our first WNV-positive mosquito pools, in opposite ends of the state (Berkshire and Suffolk Counties). This is a little earlier than is typical but no cause for alarm. Some MCDs are reporting seeing a larger than usual mix of species this season; it will be interesting to see if this holds up as we hit mid-summer.

 

Weather:

Most of the state had moderate precipitation this past week, with pockets of rain exceeding 1.75” in several areas including Franklin/Hampshire County, central Worcester and central Middlesex Counties, and northern Essex County:

 

 

As this report goes to press (July 7), the state is in the middle of yet another storm event, with a Canadian airmass the big variable that will determine whether things carry into Saturday or just clear up. Expect downpours to hit some areas at the end of Epi Week 27. Looking into Epi Week 28, expect slightly below normal precipitation and above-average temperatures.

 

Epi week #25, June 18 - 24, 2017

 

General Statement: Though the rain continues to keep drought conditions far at bay, collections are down for 2017 when compared to the past 3 years of data. As predicted, populations of the EEEv-carrying Culiseta melanura remain low despite the precipitation; thoughts are that this will be a year of “rebuilding” for this species following 2 years of dry conditions.

 

Weather:

Our weather expert notes that we have already had 7 days this year above 90’F in Boston. That is several weeks ahead of schedule when compared to the past 3 years. Rain continues to be a frequent part of our weather schedule, though the map shows things switched over to focus on the western part of the state (vs. the accumulation in the eastern part of the state in Epi Week 24):

 

With the heat returning at the end of Epi Week 26, we should expect to see even more hot days as we round out June. For the start of July, expect above-average temperatures (average is typically 80’F) followed by a slight cool-down, and average precipitation. Outlook maps for Epi Week 27 and beyond are below:

 

Precipitation:                                                                                    Temperature:

 

 

 

 

Epi week #24, June 11 - 17, 2017

 

General Statement: After two years of starting off the mosquito season under drought conditions, we find ourselves in quite a different place in 2017. Not only have drought conditions been alleviated, but May precipitation totals were above average across the state (see map below). Despite the precipitation, several mosquito control projects noted that levels of Culiseta melanura larvae remain low, likely a factor of the lack of water (i.e. lack of habitat) the past two years.

 

 

Weather:

 

Our weather expert (with, as always, a caveat that long-term weather predictions are difficult) notes that the current long-term outlook from NOAA is strongly predicting a hot and humid summer in the Northeast:

 

 

Rain continues to be a frequent part of our weather schedule. As you can see from the Epi Week 24 map below, a band of storms brought significant precipitation to the eastern part of the state, with some parts of Essex County measuring rain in excess of 2.5 inches:

 

 

The weather outlook shows average temperatures to continue through the end of Epi Week 25 (June 24th), followed by slightly cooler than normal temperatures into the start of July. There are also currently two tropical storms in the Atlantic region that, while extremely unlikely to threaten Massachusetts, still have the potential to bring rain.

 

Outlook maps for Epi Week 26 (6/25/2017 – 6/29/2017) are below:

 

Precipitation                                                                                           

 

 

Temperature

 

 

 

 


 

t  2016 messages from the SRMCB

 

t  2015 messages from the SRMCB

 

t  2014 messages from the SRMCB

 


 

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