It's not particularly strong (especially not compared to GAC-2012), but it stays in the same spot for quite a while and so is bound to have some effect on the ice below. Now, according to the Naval Research Laboratory's ACNFS forecast model , this effect is quite pronounced. And to show you just how pronounced, here's their sea ice concentration animation from May 22nd, with a forecast up to June 6th:

In the first Arctic Sea Ice update of the 2013 melting season that was posted a couple of days ago, I announced that a cyclone was forecasted to move over the Arctic Basin and stay there for a while. It's been there for a couple of days now as can be seen on this animation of Danish Meteorological Institute SLP images:

As usual, it's all about the if. Allow me to explain what this is about:

And it's only logical for their sea ice thickness animation to follow suit:



Basically, ACNFS is forecasting a 'hole' in the middle of the ice pack, with much lower concentration and thus overall thickness compared to the surrounding ice. I don't place a lot of trust in this particular model, but if this would come about at the start of June... Well, let's say it would be something we haven't seen before and the melting season would already be memorable before it started for real. On the other hand, more surprises shouldn't be a surprise, of course, given recent trends.

There's nothing showing up on the concentration maps (at the top of the ASIG front page) as of yet, but I've just had a peek at the LANCE-MODIS satellite images and I think I'm seeing a bit of divergence, with some open water showing up between floes. On the right you see the quadrant from which I've zoomed in on the left (click for a larger version):

Update May 31st: A-Team posted this animation in the comments below that shows the ongoing divergence more clearly:



It should get much worse though to come anywhere near the ACNFS projection. And so it makes sense to have a look at what the ECMWF weather forecast model has in store for the next 6 days (again, click for a larger version):

Oh my, the cyclone peters out, but is then followed by a pretty intense high pressure system, meaning the Barentsz, Kara and Laptev Seas are going to receive a lot of sunshine for a couple of days (with the high pulling in warm air from Northern Eurasia as well), after which the cyclone re-strengthens and moves back into place to do some more churning and diverging! This forecast can still change, but it's been like this for 2 days now, with events coming closer, and usually ECMWF does a reasonably good job of forecasting stuff 4-5 days out.

I initially wasn't taking the current ACNFS forecast so seriously, thinking it was some sort of model artifact, but after seeing what ECMWF has to say I'm not so sure any longer. This could be big, meaning it could have a big impact on the ice, and also be a very meaningful event at this stage of the melting season.

Because what's causing that cyclone to remain so stable? Cyclones usually move around, and gain and then lose strength quickly, but just like the Great Arctic Cyclone of August last year, this baby is staying put for 4-5 days. Ever since I've added a map showing the Northern Hemisphere jet stream to the ASIG with a link to these jet stream analyses, I'm trying to make sense of it.

Here's an animation of the last 10 days:



I've highlighted the area of concern with a green circle, just above the area roughly between Novaya Zemlya and Greenland, at 300 mb (top of the troposphere, 9000 metres or 30,000 feet). Grey areas of heightened wind speeds continuously emerge there, at the edge of the cyclone, but they then either stay put or disappear again.

Now, as I've understood, the jet stream causes weather systems to move eastwards, but in this case the jet stream doesn't seem to have nudged the cyclone away from the central Arctic. I'm still a total n00b when it comes to meteorology and the Jet Stream (I will have to read John Mason's excellent rough guide to the jet stream again), but it looks like atmospheric blocking to me, probably related to the relative cold that has been holding large parts of Europe in its grip since a week or so.

But enough about the old continent. Let's see if that hole emerges in the ice pack or not.