Winnipesaukee Forum - View Single Post - Boating Accident/Death off Diamond Island

CanisLupusArctos · 06-15-2008, 10:03 PM

It always saddens me to offer weather info in these situations. It has helped in the past, so I do.

The following is taken from automated observations; I was asleep for the night.

Black Cat Island weather at 2 a.m. was most likely a light fog, based on the fact that the temperature and dewpoint were only 2 degrees apart. They were 57 and 55, respectively. Wind was absolute calm: Average zero, gust zero. The temperature was in the process of cooling. The air was laden with moisture (rel. humidity above 90%) and was not experiencing any drying.

Water temperature was 65 at the surface, 66 at 10 feet. Water temperature warmer than the air temperature can produce lake fog, or thicken an existing fog over the lake.

Per info in a weather-section thread on water temp, several warm pools of water (around 70 F) developed in the lake during the most recent heat wave. In the two days of northwest winds following the heat wave, the warm pools relocated to the southeast end of the lake. The water temperature has been greatly variable from place to place. This would have made patchy dense fog (visibility under 1/4 mile) a possibility. Patchy dense fog is often deadlier than widespread dense fog because of its ability to create sudden, dramatic loss of visibility for anyone riding into it. For anyone traveling outside the fog patch on open water at night, a localized fog patch can hide an object in such a way that it looks like open water. The local fog patch would not be obvious in the dark, and therefore the traveler would have no reason to question what is really there.

Conditions at Laconia were similar, also conducive to light fog (temp/dewpoint about 2 degrees apart, and calm wind).

It would be good to have data from the Varney Point and Weirs Beach weather stations also.

I offer all of the above only as a possible answer to anyone who asks how this event could happen to an experienced boater. While the accident investigators will determine the official cause and will probably consider weather, this is something we can think about in the meantime: It is entirely possible that it was a factor. Whether or not patchy dense fog was part of the cause this time, it is a phenomenon on this lake that can catch the most experienced boaters amongst us completely off-guard. Conditions at the time could have supported it.

My condolences to all those involved.

06-15-2008, 10:03 PM	#19
CanisLupusArctos Senior Member Join Date: Jan 2007 Location: Center Harbor Posts: 1,049 Thanks: 15 Thanked 472 Times in 107 Posts	A word from science It always saddens me to offer weather info in these situations. It has helped in the past, so I do. The following is taken from automated observations; I was asleep for the night. Black Cat Island weather at 2 a.m. was most likely a light fog, based on the fact that the temperature and dewpoint were only 2 degrees apart. They were 57 and 55, respectively. Wind was absolute calm: Average zero, gust zero. The temperature was in the process of cooling. The air was laden with moisture (rel. humidity above 90%) and was not experiencing any drying. Water temperature was 65 at the surface, 66 at 10 feet. Water temperature warmer than the air temperature can produce lake fog, or thicken an existing fog over the lake. Per info in a weather-section thread on water temp, several warm pools of water (around 70 F) developed in the lake during the most recent heat wave. In the two days of northwest winds following the heat wave, the warm pools relocated to the southeast end of the lake. The water temperature has been greatly variable from place to place. This would have made patchy dense fog (visibility under 1/4 mile) a possibility. Patchy dense fog is often deadlier than widespread dense fog because of its ability to create sudden, dramatic loss of visibility for anyone riding into it. For anyone traveling outside the fog patch on open water at night, a localized fog patch can hide an object in such a way that it looks like open water. The local fog patch would not be obvious in the dark, and therefore the traveler would have no reason to question what is really there. Conditions at Laconia were similar, also conducive to light fog (temp/dewpoint about 2 degrees apart, and calm wind). It would be good to have data from the Varney Point and Weirs Beach weather stations also. I offer all of the above only as a possible answer to anyone who asks how this event could happen to an experienced boater. While the accident investigators will determine the official cause and will probably consider weather, this is something we can think about in the meantime: It is entirely possible that it was a factor. Whether or not patchy dense fog was part of the cause this time, it is a phenomenon on this lake that can catch the most experienced boaters amongst us completely off-guard. Conditions at the time could have supported it. My condolences to all those involved.