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Bryce Anderson DTN Ag Meteorologist and DTN Analyst

Monday 03/03/14

Blocking High Is Key To Spring

The March issue of "The Progressive Farmer" magazine is out and subscribers should be receiving it in your mailbox in the next few days. I had the "honor" of writing the cover story for this issue on the spring weather forecast. I use the term "honor" advisedly, because many things can happen between submission date for the article in late January and the time planters actually get going to basically bust the forecast. But, this is a good exercise in identifying the big features that appear most likely to determine the planting weather scenario this season.

I'm not going to re-post the entire article here, but there are a couple things that hit me pretty hard when I was writing the article and I thought I'd share those in this space. First of all, the last few planting seasons have really been one way or the other--either wet and cool, or dry and warm. Going back to 2009, this is what we had to deal with:

2009--delays due to wet and cool conditions

2010--mild and dry with excellent progress

2011--stormy, wet, delayed (some season-long flooding along with many tornadoes)

2012--mild and dry ahead of drought

2013--mostly wet and cool except for one favorable week in May

2014--well, at this point it looks like we're going to see a resemblance to 2013's slow start to planting due to the extensive cold and snow that we have in much of the Corn Belt. And, that brings us to the second primary item I wanted to touch on for this spring in terms of what will drive the weather pattern--whether or not we have another season of far-northern blocking high pressure to re-route the northern jet stream south over the Corn Belt.

Blocking high pressure, as we have mentioned a number of times in this blog, describes a large upper-atmosphere ridge of high pressure, which has been a big feature since about mid-February 2013--more than a full year ago. This feature can play a big part in determining the path of storm system and, in turn, U.S. weather. Blocking high pressure near Greenland helped to bring the cold and wet spring, mild midsummer and the outrageous heavy rain and snow in the northern Rockies and northern Plains during the fall season, all in 2013. This past winter, the blocking high located along the west coast of North America. It brought the bone-dry conditions to the Far West, while allowing the polar vortex in northeastern Canada to send the record cold over the entire eastern half of the contiguous U.S.

At this point in early March, forecast models from the U.S., European and Canadian weather services are suggesting that the blocking high is going to show some moderation during the next ten days to two weeks. That will be very important in terms of allowing for some milder temperatures to develop and offering--possibly--some thawing-out of mighty cold ground in many sections of the Midwest, Plains and Prairies. We shall see what happens. As has been noted here before--forecast model proficiency in both identifying the development of these blocking features, and predicting their longevity, is not very good. And that is straight from NOAA descriptive content regarding far-northern blocking highs.


Twitter @BAndersonDTN


Posted at 3:18PM CST 03/03/14 by Bryce Anderson
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