Friday, November 9, 2012

Sandy Repeat On The Horizon?

Preword: The title 'Sandy Repeat' refers to a similar way to how Sandy formed, NOT the strength or effects.

The ECMWF model is printing out a scenario all too familiar for those who went through Superstorm Sandy. Please take a look below.

The ECMWF model is showing a tropical system moving up the waters off the East Coast about 10 days away. Storm systems on this map are defined by oranges and red- the deeper the color, the stronger the storm. As you can see, this storm looks pretty strong. But look out to the west. See that blob of oranges and reds? Yes, that is another storm system. My fear is that these two could phase (combine) into one stronger storm, the same way Superstorm Sandy formed. The reason this is a concern rather than an out to sea forecast is because the strongest vorticity values of this storm are located on the western flank, which means this likely-tropical system is being pulled west.

This is still the ECMWF model, and still for the same time frame. This map now shows 500mb geopotential height, the best level to show high and low pressure systems. High pressure systems are shown by arcing lines, and low pressure systems are shown by depressions in these lines shown above. As you can see, there is a big depression in the East in this image, showing a strong storm system. See the small black circle to the east of North Carolina? That is the same system that I showed you above offshore. Considering that there are only a couple black lines separating these two systems in the image above, I believe that the ECMWF is indicating that these two systems are phasing, just like Sandy.

Now, if this even happens (which there is no for-sure indication it will), it will probably not be as bad as Sandy. Sandy was a Category 1 hurricane just before landfall. This system looks like it would be a Category 1 hurricane at maximum- it will be weaker than Sandy. Also, the ONshore system would likely be weaker than the Arctic one that merged with Sandy, meaning that the possible new, combined system would be weaker than Superstorm Sandy.

However, keep in mind that the ECMWF kept on the right track of Sandy while other models incorrectly took it out to sea. Considering the ECMWF has been showing this Sandy-repeat system for at least two model runs, this is definitely something to watch.

I am not making a call yet, I want to see how the other models react to the ECMWF. Right now, the GFS is not in favor of this solution, so just keep an eye out. This is the wait-and-see mode, not PANIC-RIGHT-NOW mode.


1 comment:

Logan said...

I'm glad you post stuff like this, even if it is a couple to few weeks in advance. I still like to know what is possible for the next little while.
I don't if it is other people are too scared to not get it 'right', but you are the only person I know that forecasts this far out in advance. In my city, the local meteorologist that I follow doesn't like to get things wrong, so he doesn't do these too far in advance. However, I would rather you throw it out there and be wrong than nothing at all.
Same goes for winter forecasts as well.
You are wonderful in those aspects, Andrew :-)