Time for an iceout discussion!

[Chaos]

So, I've been wondering if anyone has ever cross-referenced the winter snow depth data with iceout dates before. With all of the talk about poor ice conditions due to the slush layer under the snow and now the cancellation of the Alton Winter Carnival, I just can't help but wonder if the snow depth on the ice will contribute to an early iceout, a late iceout or an average one. Does the insulating effect that inhibits ice growth also inhibit the ice melting?

I prefer the lake on the soft side, not hard, so I hope I don't bumb out those folks enjoying it's winter use, but I already have the itch and can't seem to shake it. I've been out of the water for 3 and 1/2 months and am ready to get back.

[trfour]

Originally Posted by Chaos

So, I've been wondering if anyone has ever cross-referenced the winter snow depth data with iceout dates before. With all of the talk about poor ice conditions due to the slush layer under the snow and now the cancellation of the Alton Winter Carnival, I just can't help but wonder if the snow depth on the ice will contribute to an early iceout, a late iceout or an average one. Does the insulating effect that inhibits ice growth also inhibit the ice melting?

I prefer the lake on the soft side, not hard, so I hope I don't bumb out those folks enjoying it's winter use, but I already have the itch and can't seem to shake it. I've been out of the water for 3 and 1/2 months and am ready to get back.

Hi Chaos, we have a app for this over in the weather threads already under way.
http://www.winnipesaukee.com/forums/...660#post150660

[Merrymeeting]

I subscribe mostly to the law of averages, and Mother Nature has an amazing ability to even things out over time.

Given that last year's Ice Out was the earliest on record, I'm doubtful that it will be that early again.

But... 2 years over a 100 year average isn't significant. It could happen

[Lakegeezer]

This year will likely be very different than last. In February 2010, the snow was gone from the lake and the sun was able shine through the ice till iceout, warming the water and melting the ice from below. This year, the sun is reflected, so solar warming is not a factor - however the weight of the snow pushed some water through the ice and it has been slushy. My guess won't be recorded until the last minute, but I'm thinking its going to be a fairly average ice-out date - ie, in the middle two weeks of April.

[Lakesrider]

Well I can't account for the ice conditions, but I noticed something else today. We had some snow removed from the grass area at work today with a Bobcat. The snow was about 3' deep. At the bottom of the snow it was very powdery. But the ground underneath was not frozen. At all. It was muddy and very soft.
I would imagine the ice is going to have the same issue. If the ice is bad now, in Feb. What will it be like in March? In Alton there are many Bob Houses sitting out there right now, and I saw numerous vehicles out there tonight.

[robmac]

The snow acts like insulation,I don't think we have the same ice as in past years. If I am correct in that we could see a big change with this weeks warm up. Can CLA give us more accurate data?

[Winnisquamguy]

Originally Posted by robmac

If I am correct in that we could see a big change with this weeks warm up. Can CLA give us more accurate data?

They are only talking a 2 day warm up, with possibly more snow coming in Monday. The 10 day forecast has the temps not getting above freezing, so there is not any February thaw going on yet.

[Pineedles]

April 18th 4:05 PM


Is my guess, but I am second guessing my guess. I think it will be earlier, much earlier! Late March?

[BoBo]

I would have to agree that this is only a small warm up period. There is plenty of ice out there, with water and snow on top and even water below.

[CanisLupusArctos]

Originally Posted by robmac

The snow acts like insulation,I don't think we have the same ice as in past years. If I am correct in that we could see a big change with this weeks warm up. Can CLA give us more accurate data?

At Black Cat, which is always one of the last to freeze over, ice fishermen in January measured 8 inches of solid clear ice (the strongest kind) underneath a huge snowpack that was melting into slush at its bottom layers.

The strength of the ice has been safe all winter. There were even full size pickup trucks driving from Three Mile down to Five Mile during the fishing derby last weekend. That's good ice.

Their tracks, however, left deep slush tracks that later re-froze.

Deep snow can create unsafe conditions for other reasons than weak ice. When there is deep snow on top of the ice, it's very challenging to conduct activities, even for people who are experienced with being on the ice. Just ask anyone who partook in the 2008 Rotary Fishing Derby. Surface conditions can become unsafe for certain crowds, especially the target audience of Alton's Winter Carnival.

Snow turns to slush on the lake ice because there is always a small amount of heat coming up from the lake, as long as the air is colder than the water. There is always 33-degree water under the ice, except in shallow areas where it freezes right to the bottom. When the air is colder than 33 degrees, the lake is trying to give off more heat to the air. That's how lake ice gets thicker. On colder mornings the heat loss becomes visible as fog above the lake ice.

But snow is a great insulator. In between each flake is a tiny air space. Tiny air spaces are what make insulation effective. A small amount of it on your rooftop will help to hold the heat in your house. It does the same on the lake, however. So, as heat tries to transfer from the 33-degree lake water to the much-colder air above, it goes right through the clear ice like a window, but the snow doesn't allow the heat to 'just pass through,' so the lower layer of snow starts to melt.

The snow works for and against the lake ice thickness. Early in the season, when the sun is low in the sky, the ice will get a lot thicker without snow -- just cold, dry weather. In early February the sun gets high enough in the sky to wage war on frozen things. The ice growth season ends when the ice loses as much to sunlight as it gains at night.

When that point is reached, snowcover on top of the ice will then insulate it from heat coming down, (sun to lake.) In the early part of the season, heat going up (lake to air) is what makes the ice form and thicken. Thick snowcover will slow down the heat transfer no matter when it falls, but will have different effects depending on what direction the heat is trying to go.

Clear ice will thicken much more easily in the early season, but will just as easily melt when the sun gets high enough to reverse the heat loss.

Snowcovered ice will not thicken as easily in the early season, but it'll also resist the late-season sun.

Addendum: Wind plays another major role in iceout, even when the ice is fully "in." Watch the time lapse on the WeatherCam on a windy day (tomorrow is expected to be windy.) You'll see the lake ice, in the time lapse, going up and down.

Strong winds passing over something lower the air pressure right above it. That's how the wind picks up a piece of plywood that is lying flat on the ground. It's also how the air picks up an airplane, but the aircraft's speed has to generate the wind that sucks the wings up into the air.

When the wind is strong, it's trying to pick up the entire lake ice pack. It doesn't blow evenly over the lake, but in localized gusts. So the ice gets drawn upward and let down again, according to the wind pattern. This action of repeatedly flexing the ice makes it weaker. Remember the April 16-17, 2007 storm? The ice wasn't ready to go, when that storm started. But after several hours of sustained 45 mph wind, with gusts to 64 (here on land -- hurricane force in the middle of the lake) the ice broke apart into thick chunks of solid ice that crashed into and took out many well-built docks.

Watch in the WeatherCam next time it's windy. Go to "Previous Images" and start the time lapse. If the wind is strong enough, you'll see the ice going up, down, up, down... That motion is weakening the ice, and thus wind plays a huge role in the annual iceout date.

[SIKSUKR]

I'll just add to CLA's post on snow helping to preserve ice from Feb on.The reflective properties also help as well as the insulative value as ice is generally darker and will absorb more heat.

[Chaos]

So, I understand the physics of the insulation effect as well as the absorbtion or rather transmissive properties of nice clear ice. I was hoping to hear some bizzare semi-scientific reason that a thick snow pack on top of the ice would produce an early iceout. Then I woke up!

Oh well, I guess I'll have to wait until mid-April.

[webmaster]

These snow-free conditions last year probably contributed to the early Ice-Out: