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Post by kiwistonewall on Feb 25, 2009 2:20:42 GMT
Great Lakes still well ahead of mean. Looking at historical cover, I think I can eyeball a trend to less ice with minimum in 1998, and rising since. We need to exclude "weather effects" which can produce unusual lows or highs in any season, but it seems clear to me (given my slant on things) ;D
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Post by magellan on Feb 25, 2009 4:15:05 GMT
Great Lakes still well ahead of mean. Looking at historical cover, I think I can eyeball a trend to less ice with minimum in 1998, and rising since. We need to exclude "weather effects" which can produce unusual lows or highs in any season, but it seems clear to me (given my slant on things) ;D That is quite observant and to be frank I didn't study the GL ice data that close until you brought up the subject. This will be an interesting year to watch, but I'll be happy when Spring officially arrives, meaning WARM. This morning was at least below zero (-2 at 7:30 am). Wed and Thu is warming up (yahoo!), but back to cold again. My (and other Michiganders) thoughts are there will one big snow storm left in the cards this winter. Oh, btw, those few days of warm weather and rain did decimate the snow and river ice. Our town flooded, but not as bad as it could have been. One more day of rain would have been bad. We even made it on Fox News LOL. Fortunately the ground quickly froze to slow the runoff into the river. I haven't been to the bay (Lake Huron) since so can't say what its doing, but may this weekend. BTW, we live out in the country away from any flood danger.
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Post by hilbert on Mar 1, 2009 17:35:12 GMT
I'm not sure what the central blue portion of Lake Superior is--is that partially iced over? Very thin ice? Water with some ice in it? The termperature forecast for Marquette, Michigan looks favorable for more freezing, at least until Thursday. Also, is there a way to shrink posted images? Thanks.
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Post by Pooh on Mar 2, 2009 16:42:50 GMT
For super large images- just post a link - or copy the image & reduce .... See Help Section, Reply #8 solarcycle24com.proboards106.com/index.cgi?board=help&action=display&thread=3ProBoards does support in-line image scaling: Modify the "img" tag with one space before "width=" and "height=". Units are pixels. [img width=700 height=1000 src="http://ice-glaces.ec.gc.ca/prods/NAIS25WCT/20090226180000_NAIS25WCT_0004241316.gif"]
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Post by kiwistonewall on Mar 2, 2009 22:26:38 GMT
Neat trick BillAlexander - thanks for the tip.
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Post by hilbert on Mar 3, 2009 0:01:33 GMT
Thanks for the tips on reducing the picture size!
Here's the latest--Lake Superior is almost frozen over, with two more days of sub-freezing, before some warming on Thursday.
[img width=700 height=1000 src="http://ice-glaces.ec.gc.ca/prods/NAIS25WCT/20090302180000_NAIS25WCT_0004248153.pdf "]
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Post by hilbert on Mar 3, 2009 0:02:54 GMT
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Post by hilbert on Mar 3, 2009 0:07:13 GMT
Ack--I forgot that pdf's don't transfer well, and I can't get back to the Canadian Ice Service page. I'll post the picture soon.
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Post by hilbert on Mar 3, 2009 0:13:48 GMT
Okay, here's the picture (I hope):
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Post by jimg on Mar 3, 2009 0:28:42 GMT
You beat me to it. I was going to post that Lake Superior is almost solid. or at least a 9/10 out of 10 concentration.
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Post by kiwistonewall on Mar 3, 2009 2:22:37 GMT
And the other lakes also well frozen- not bad when 2009 is going to be the warmest on record! ;D
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Post by hilbert on Mar 3, 2009 2:27:40 GMT
Kiwi's post might be more interesting. My sense is that Lake Superior freezes over occasionally, but Lake Huron only very rarely. Perhaps magellan knows?
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Post by magellan on Mar 3, 2009 3:42:43 GMT
Kiwi's post might be more interesting. My sense is that Lake Superior freezes over occasionally, but Lake Huron only very rarely. Perhaps magellan knows? Huron doesn't freeze over very often AFAIK. It's very close this year though. Saginaw Bay is froze completely and thick. Now you've got my interest up, so will ask a few of the more serious folks this week. As stated earlier, I never paid much attention to how much the GL freeze over despite living in the area for 30 years. Talking to others, they say it is a rare occasion for Superior to freeze over completely; maybe every 20 years or so. The last time I was there in winter was about 4 years ago; 5 ft. of fresh snow (normal the locals said), perfect snowmobiling in Paradise, MI. We rode on Superior, but didn't venture out more than a mile or so. Believe this, the winter of 2009 is a very cold one. I'd like to compare reality at season's end, with what NOAA predicted. ;D Another GL ice analysis. coastwatch.glerl.noaa.gov/cwdata/lct/glsea.png
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Post by kiwistonewall on Mar 3, 2009 4:36:40 GMT
The water surface of Huron shows all water is less than 3C. This means that the denser 4C water has gone to the bottom, and the surface can now freeze that much easier.
When a lake freezes, the entire water column has to cool below 4C. That is the densest water. Only then can the surface layers cool quickly down to zero and freeze. Fish can survive in the unfrozen 4C depths.
Lake Michigan still has some surface water at 5C which means that the water column hasn't cooled all the way yet.
Huron last froze over (95%) in 1978 and 1994, 1977 & 1979 were over 90%. 2003 nearly made 90%.
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Post by Pooh on Mar 3, 2009 8:01:01 GMT
Incidental information: The depth of Lake Ontario reaches 600 feet over a wide area, and will tend to turn over when the surface becomes cold. Therefore the lake is slow to freeze over.
The greater depths extend relatively "close" to the southern shore. This is useful when sailing south at night, in fog. When the depth sounder starts to read less than 200', it is time to start looking for the hard places around the water. ;D
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