I now divert from the realm of politics for a moment to alert the readership here that I may soon be dead.
Kidding, of course. But – and this forecast is coming to you from the land of ridiculous model uncertainty and high stakes probabilistic forecasting – there exists an increasing potential for one of the worst east coast cyclones in recorded US history. I strongly emphasize the word POTENTIAL, here, because the various models we use to forecast weather conditions 3-6 days in advance are all over the place, and the source of the diverse model solutions is not easily pinned down to one key forecast element to watch.
I’ve been monitoring this situation since last Friday when the long range models began showing the potential for both a major tropical storm threat and a rapid trough amplification over the Eastern US. So let me lay it out for you.
In the Caribbean and just South of Cuba, we have a rapidly intensifying Hurricane Sandy- it’s tropical envelop of circulation is extremely large and it is sitting over some anomalously warm waters (the Caribbean has been largely untouched by tropical troubles this season due to a weak El Nino that helped cut down tropical waves in that region). It is expected to continue to deepen for a time over the Caribbean and eventually the Bahamas as it makes a strafing run along the Carolina coast. And that is where the troubles begin.
Because as this storm lifts N or NNE, an intense ridge of high pressure is forecast to blossom south of Greenland associated with a blocked flow regime over this region. Aficionados of winter weather will know that blocked flow over Greenland frequently forces storm systems dropping down from W Canada to amplify into deep troughs over the NE US. And that is just what the models now agree is likely to happen. As the flow becomes blocked, a shortwave trough is expected to approach from the west and then explode into a very deep trough over the Eastern US. If the timing is right, this rapid deepening combined with the blocking ridge over Greenland may act to steer Hurricane Sandy NW or NNW instead of NE and out to sea. And as Sandy begins undergoing a transition from tropical cyclone to nor’easter, if the timing is just right, it may explosively deepen (conditions in the upper atmosphere could come to favor natural cyclonic turning and upward motion).
I will begin monitoring this twice daily here, because this has the potential to be truly catastrophic. I would place the odds at a coastal impact at 30-35% and the catastrophic scenario at at least 10%. The NWS is now releasing extra upper air soundings until the event comes into better focus – that is an almost unprecedented event and it tells you how deeply concerned they are. You hear folks talk about how bad it would be for a category 3 hurricane to hit NYC? This actually has HIGHER upside for damage to NYC because the winds would last longer and mix better to the surface in a cyclone as opposed to a hurricane, whose winds tend not to mix to the ground well after landfall.
Just be on your guard…because this blog could end up a man down for a long time if this hits the way some of the models are now suggesting.