Thursday, December 22, 2011

December Drenching Brings Ice Cobbles to River

Yesterday was a rainy day, as forecast, and as anticipated (dreaded?) in my last post.  It went about as forecast - some icing and freezing rain in the morning, followed by surprisingly heavy rain, for this time of year at least, that lasted several hours.  The headwaters of the Middlebury River picked up more than half an inch of rain - which would be insubstantial for a summer thunderstorm, but is rather unusual for late December.  Much of the ground was frozen, and the water ran off fast.  The river is running high right now.

As i expected, most of the ice in the river was ripped out.  What I did not expect was to find piles of ice, rounded like river cobbles, laying where the high water left it.

Ice is lighter than liquid water, of course, but quite hard.  I suspect that a combination of melting and smashing against rocks and other ice created these ice chunks... melting alone often accentuates corners rather than smoothing them.

These rounded 'ice cobbles' are scattered along the riverbank right now.

In some places the ice remained mostly in place:

The excessively warm weather this fall has been brought to us by an unusual jet stream pattern.  Last year at this time the jet stream was in a somewhat similar pattern, but with very different results, which I wrote about in this blog entry.  This year, so far, the jet stream has been almost as convoluted, but it has dived straight south through the Interior west, bringing dry conditions to the Pacific Northwest, unusually cold conditions from southern California through the Southwest, and far more snow to Texas, Oklahoma, New Mexico, and Kansas than to Vermont.  The jet stream then is picking up Gulf of Mexico moisture and warmth and rushing it up the East Coast into Vermont.  The forecast is for this to change to a more normal pattern, bringing small storms and average temperatures from west to east into Vermont.  This has been in the forecast several times, though, and hasn't happened, so we will see if tomorrow's forecast of 2 inches of snow holds true, and if so, if the pattern persists or if we go back to more rain, or perhaps a pattern more similar to that of last year.

We'll see!

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