Son of the Perfect Storm on the Way???

Mar 19, 2005
Independence, MO
The weather situation could get very, very interesting the next few days. The NHC guidance now shows Wilma and Alpha almost colliding between North Carolina and Bermuda on Tuesday. In the meanwhile, the westerlies steering Wilma are being caused by a deep trough which extends almost all the way to the Gulf Coast, moving eastward and picking up Wilma on it's way. Some models are now showing these three systems merging between the Delmarva and Nova Scotia on Wednesday and rapidly deepening into an extremely powerful extratropical low. This caught my attention instantly because this is where the Perfect Storm of October 1991 formed, and it's only a few days to the 14th anniversary of the Perfect Storm. I looked up the setup for this extraordinary weather event and found this excerpt from the NWS report about the event especially interesting:
On October 28, 1991, a extratropical cyclone developed along a cold front which had moved off the Northeast coast of the U.S. By 1800 UTC, this low was located a few hundred miles east of the coast of Nova Scotia. With strong upper air support, the low rapidly deepened and became the dominant weather feature in the Western Atlantic. Hurricane Grace, which had formed on October 27 from a pre-existing subtropical storm and was initially moving northwestward, made a hairpin turn to the east in response to the strong, westerly deep-layer mean flow on the southern flank of the developing extratropical low.
No, this isn't an identical setup, but the similarities are there and it is the right time of year for the formation of such a system. Now in my mind if this setup comes to pass(which it well could) the trough plays the part of the cold front, the low riding the trough acts as the extratropical low and the Wilma/Alpha hybrid serves as Hurricane Grace. As the trough emerges off the coast, the low riding it strengthens. The Wilma/Alpha Hybrid accelerates along the trough and smashes into the low. Wilma/Alpha's circulation will likely get undercut by the trough (similar in fashion to what happened to Grace) and it's warm, tropical moisture feeds into the low, causing rapid deepening and possibly the formation of either a tropical system (which would be called Beta) or a powerful extratropical low similar in fashion and strength to the Perfect Storm. The current Day 3 forecast map shows this deep system east of the Tidewater of Virginia, along with three other areas of low pressure aligned along a warm/occluded front over the Canadian Maritimes ,with a cold front connecting one of the Maritime lows, running southwards with the dominant low riding on the middle of it and draped clear down to the northern Carribean:
It also depicts three strong areas of high pressure across eastern North America: one in central Quebec (the one I am most immediatley concerned with as far as causing a strong pressure gradient), one in the northern Great Lakes and one in the Red River Valley. The highs in Quebec and the Great Lakes could turn out to be quite the players in this setup, as the day 4 shows:
With the high pressure building in southern Canada, a shot of cold, dry air will be following on the heels of the trough and New England/Appalachian low. This combined with the previously mentioned factors could create a very intense storm similar to the Perfect Storm of 1991. The pressure gradient won't as tight, I think, because the high will be in northwest Quebec, rather than southern Quebec, as the high was during the Perfect Storm, but if it shifts closer to the St. Lawerence River Valley the pressure gradient will be much stronger and result in considerably higher winds/surf along the coast.
All in all, has the potential to be a very, very nasty storm which could bring catastrophic wind driven rains to the coast and a fierce, blizzard of heavy wet snow farther inland which could cause massive power outages and tree damage. In between the rain and snow could see a narrow band of ice and sleet which could cause a nasty ice storm.
The evolvment of this potentially catastrophic culminations of three storm systems into one beastly storm needs to be monitored closely the next few days.
This is the last thing New England needs at this point in time; unfortunately they are looking to get at least a moderately strong lashing at least, a severe, profound, crippling beating at worst.
Thoughts, comments, forecasts or questions welcome.
Hmmm, interesting speculation, Mark. As I was looking over the maps tonight, my mind was kind of swimming with the question - what happens when low meets low meets low? Nominally, I was more concerned with how the path of the hurricane evolves, but it was hard to picture in my mind's eye and I knew some part of my thinking was missing. So, I had completely forgotten the "perfect storm" scenario, but, come to think of it, I should know better. Tropical, sub-tropical, whatever, I know what they call nor'easters can do this time of year when things come about just right. Thanks for bringing this scenario to the fore, and it will be that much more interesting to watch with your scenario in mind!
This is a very interesting setup...and does indeed remind me of the 1991 Grace storm. Can two tropical systems merge/integratee and become just one bigger storm? I have only seen one other storm (comes to mind) that prooduced snow/ice's a prety rare thing, as far as I am concerned.
Yes it does look like a classic extratropical transformation that will yield an intense Atlantic storm. The models have not even yet come to good consensus on how the transformation will come about and the subtleties will determine whether this will be a big event with severe storm surge or not. I'm tending to favor the idea that it will be mainly a wind event with not the surge and wave damage found in the 1991 storm. Here's why I think so:

1. We're off the peak lunar tide cycle and that will somewhat limit surge
2. The event is fast moving which will not allow maximum wave buildup. The surge could be strong in a fast mover except that...
3. The storm will most likely move parallel to or away from the coast.

Another interesting difference about the 1991 storm was that in its weakening phase, once the baroclinicity was exhausted, a warm core system developed in the center of the closed upper low and eventually developed into an unnamed hurricane, much like Vince. It should've been an "H" storm.


I'm now wondering how this could happen. How can they merge/collide, since Wilma, is pretty far ahead of Alpha, then the only way they could meet is if Wilma slowed down, or Alpha speeds up dramatically....and the chances aren't great for it to speed up. Are you saying that Wilma/Alpha itself will become very intense, or what?