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Musings about might be important for DCA


usedtobe

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Below is my discussion. in it I show the composites for the 500 h anomaly patterns for big snow seasons versus our crappy snow years and present a plot of the AO versus ENSO for the seventeen 20 inch or greater seasons at DCA.

http://www.washingtonpost.com/blogs/capital-weather-gang/post/winter-musings-for-washington-dc/2012/11/15/cf870c00-2f61-11e2-9f50-0308e1e75445_blog.html#pagebreak

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nobody really cared about the outlook this year either...I think it will take a genuine storm (3-5") to get people back in the saddle

No doubt.

I really think that last winter sucked the life out of most peoples' verve for winter, and that expectations are pretty low among your average person for this year. Back in late summer when there was plenty of talk about a reasonable Nino, people were excited. But the recent developments in the Pacific have knocked back that excitement quite a bit. It'll take a decent snowfall to get people interested again.

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Good read Wes. I really like this graphic. I saved it last year but forgot to use it with any posts. Someone may have posted before. This is the DJF h5 anoms for the 3 phases of the AO. It really helped me better understand what's going on at high latitudes when I first started trying to wrap my head around it.

I posted back and for with skierinvermont and njwinter in another thread about the Nov state of the stratosphere may be a better indication than just relying on snowcover to help hedge bets. Unfortunately, early Nov looked a lot like 06-07 and that was a big snowcover year and we know how that turned out.

Here's what the 70hpa temp anoms look like in Nov when the following Dec had an AO of +1.5 or more:

Here's the same for Nov's when the Dec AO was -:

And here's what it looks like month to date:

I don't like which composite that this Nov looks closer too. Good thing there are exceptions (not many that I could find) and 2010 is a good one. Here's Nov 10:

During Nov the area over asia apparently carries the most weight irt influencing the AO in Dec and beyond. Short version is cold strat over asia = bad and warm strat over asia and pole = good

I totally understand that relying on any one piece of data is precarious at best. So which is it this year? Snowcover or strat temp anoms? My best wag would be a tossup in Dec. Who knows in Jan-Feb.

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"I totally understand that relying on any one piece of data is precarious at best. So which is it this year? Snowcover or strat temp anoms? My best wag would be a tossup in Dec. Who knows in Jan-Feb."

Bob,

I don't know which is the answer but the stratosphere was one of the things that I didn't spell out that were correlated more towards a positive AO than a negative one. The correlation that Cohen found for snow cover increase is higher than the one for the stratospheric temps or winds but I'm not sure any of the correlations are high enough to have much confidence in an AO forecast. If the Ao goes massively negative in Dec, I'll be touting the season ending up negative. If it goes really strongly positive (3 sd or more), I'll be pretty discouraged. Of course one big storm and serendipity could always save us. Unfortunately the signals about eh AO are indeed mixed.

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This is probably one of the more uncertain winters when it comes to expectations that we've seen in a while. I personally enjoy it. Regardless of any pattern or teleconnecton or theory there are always exceptions. That's the allure of lr forecasting. So much data to ingest. So many analogs to looks over and even when you think you may have a handle on it some new factor comes in and reshuffles the possible. And weenies like me have it made because if I'm totally out to lunch...who cares? Lol

One thing all MA weenies should always have in the back of their mind is that odds will always favor things going wrong vs going right in these parts. I always try and look at what's right vs wrong in any pattern and try to set expectations accordingl. But I'll always get sucked into threading the needle or perfect timing. Lol

You do a really excellent job pointing out the right and wrong pieces of any setup and I really appreciate it. Looking forward to your take on Dec once we get close to the end of the month.

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This is what I like about you Wes... you have gift for simplifying things and explaining them in way that anyone can understand. I have read countless articles and posts on here about El Nino and how it correlates to snow in our region and quite frankly... this is the best explanation I have seen thus far-

"An active subtropical jet injects heat and moisture into the southern U.S. which increases the chances of low pressure systems having a storm track across the Gulf States to a position just off the coast of North Carolina. That track is our most favorable for producing a major snowstorm."

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I am not very technical when it comes to these things... but it would seems as though a Negative AO would favor a tighter pressure gradient for winter storms that traverse the storm track you describe in your article (gulf states to NC coast). When you have higher pressure to the north and low pressure to the south that has been enhanced by abnormally high levels of heat and moisture caused by El Nino... I would think that you would get strong pressure gradient and temp gradient on the north end of storm track. That is one thing I always noticed about good snow storms... PDII being a good example.

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LOL, in the article I wrote that the latest Euro monthlies were not favorable based on stuff from Adam from that I heard earlier in the week but I just read in the New England forum that they do look like they are trying to get a trough in the east with some blocking but with a more miller b look than miller a.

This sorry model likes cold

http://www.jamstec.go.jp/frcgc/research/d1/iod/sintex_f1_forecast.html.en

The cfs2 has been bouncing around like pingpong ball.

http://www.cpc.ncep.noaa.gov/products/people/wwang/cfsv2fcst/htmls/usT2me3Mon.html but right now keeps temps near nomral through the winter with the coldest temps in Jan.

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