HKY_WX Posted November 30, 2010 Share Posted November 30, 2010 I was just looking at comparisons to the possible Dec we have coming up. Not to jump the gun, but this thread is assuming the massive block developing over Greenland is a feature that will be hard pressed to be removed any time soon. Or at least moved in totality, meaning there could still be ridging and higher pressures in place even if the block itself breaks down. Just a quick look at the 18z GFS surface map below at 48 hours. It's hard not to notice the huge high pressure over the north Atlantic. It sticks out like sore thumb, as I haven't seen such a huge warm core HP system in that location since following the models at the NCEP site. Below is a loop of the day 1-10 12z euro ensemble from today. If it's not working correctly, you can click the link below it to go to Allan's website. The obvious feature showing up is of course the huge block over the southern tip of Greenland and the North Atlantic. Also you can see the semi-present trough that continues to redevelop over the Pacific Northwest and just offshore the Western Canada. http://raleighwx.ame...alyNA_loop.html This continues to line up with the theme from November which you can see on the 500mb pattern from Nov 1st - 27th below. Using these features to extrapolate into December 2010, I am presuming we see the NAO average at least -1.00. Combining that with the mod-strong la-nina, I looked back at the other DJF months with -1.00 or lower NAO averages, which also had the MEI below -1.00 to simulate similar la-nina/pacific conditions. Those were Dec 1950, Feb 1956, Dec 1970, and Jan1971. Dec 1950 Feb 1956 Dec 1970 Jan 1971 When you look at the patterns above, only Dec 1950 and Jan 1971 line up well with this year. February 1956 and December 1970 have an Atlantic pattern with an east based -NAO which is not looking likely at least through the first half of December. I would consider the first two perhaps the best analogs for December 2010. Anyone have stats on those two months as far as storm data, temps, or snow totals along the east coast? Maybe even for the winters of 1950-1951 and 1970-1971 may be interesting. Link to comment Share on other sites More sharing options...
FoothillsNC Posted November 30, 2010 Share Posted November 30, 2010 Anyone have stats on those two months as far as storm data, temps, or snow totals along the east coast? Maybe even for the winters of 1950-1951 and 1970-1971 may be interesting. 50-51 wasn't good for NC. CLT had less than an inch total However 70/71 was above average with 2 accumulating snows, a small one in Dec, and a bigger one in March. Both of those storms were big in Asheville (the Dec and Mar storm). Almost 11" at GSP that season. Link to comment Share on other sites More sharing options...
Lee Posted November 30, 2010 Share Posted November 30, 2010 Both were decent on this side of the Apps. Dec. 1950 featured average snowfall 1970 featured a white Christmas for the 2nd in a row. I remember snow beginning late in the day quickly covering the ground and mounting up fast. Here's a plot from then. : http://vortex.plymouth.edu/cgi-bin/gen_reanal-u.cgi?re=us≤=500&va=hght&in=60&pl=cf&yy=1970&mm=12&dd=25&hh=12&overlay=no≤=&va=&in=&pl=ln&yy=&mm=&dd=&hh= Link to comment Share on other sites More sharing options...
JBG Posted November 30, 2010 Share Posted November 30, 2010 I was just looking at comparisons to the possible Dec we have coming up. Not to jump the gun, but this thread is assuming the massive block developing over Greenland is a feature that will be hard pressed to be removed any time soon. Or at least moved in totality, meaning there could still be ridging and higher pressures in place even if the block itself breaks down.How does that occur? Doesn't the high being in place equal a block being in place? Link to comment Share on other sites More sharing options...
HKY_WX Posted November 30, 2010 Author Share Posted November 30, 2010 How does that occur? Doesn't the high being in place equal a block being in place? I probably should have worded that better. I meant that even if the block weakens, but there is still ridging in place, the overall pattern is not really going to change that much. There's no way the block can hold as strong as it will be in the next week, all month long. Link to comment Share on other sites More sharing options...
nzucker Posted November 30, 2010 Share Posted November 30, 2010 How does that occur? Doesn't the high being in place equal a block being in place? Yeah, I don't understand. Higher pressures means that a blocking ridge is in place, like what we have over Greenland right now. Link to comment Share on other sites More sharing options...
Chinook Posted December 1, 2010 Share Posted December 1, 2010 This continues to line up with the theme from November which you can see on the 500mb pattern from Nov 1st - 27th below. The pattern of anomalies for November 1st to 27th that you posted was the chart for only the 27th. This is the correct pattern for November 1st to 27th. It doesn't show much of a positive or negative in the USA, because upper level patterns were changing so often. Blocking in Greenland is big! Link to comment Share on other sites More sharing options...
tacoman25 Posted December 2, 2010 Share Posted December 2, 2010 1950-51 and 1955-56 were two of the top analogs in my winter forecast. 1970-71 and 1971-72 were secondary analogs. Link to comment Share on other sites More sharing options...
HKY_WX Posted December 2, 2010 Author Share Posted December 2, 2010 The pattern of anomalies for November 1st to 27th that you posted was the chart for only the 27th. This is the correct pattern for November 1st to 27th. It doesn't show much of a positive or negative in the USA, because upper level patterns were changing so often. Blocking in Greenland is big! hmm could have sworn it was that. here's the NH view. Link to comment Share on other sites More sharing options...
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