Those of you reading this who know me know that I a couple months ago I finally got a bike, so my interest in the weather is no longer just for seeking delicious pow in the winter. You also know that there are times when something major comes up (Irene/Sandy) I’ll blog about it too. I’d be making this post regardless, buuuuuut the looming storm washes out most of my ability to ride this week and it is a very interesting meteorological event that could unfold in part because of El Nino.
While I haven’t blogged about the major El Nino, if you’ve spent anytime with me you’ve undoubtedly discuss while muttering curse words under my breath for the crappy ski season it’s going to produce on the east coast (luckily I have an epic pass so it may not matter). The reason we have had almost no rain this summer is due to the fact the El Niño has created a huge and very northerly ridge that allows Atlantic based high pressure (warmer air) to build up and “block” out the cooler arctic high pressure (cold air) and keep moisture to the south west–similar to a great left tackle and an NFL RB picking up a blitz. These same meteorological features (the ridge and Atlantic high pressure) are why, despite it being nearly October, it still feels like late summer during the day. However, that about to change, even if it is just temporary.
Starting this evening a “blitz” of cold air will bull rush the left tackle and the RB won’t pick up the blitz (kinda like LeSean McCoy!). This will bring cool air based high pressure (ie Arctic air) and moisture along the boundary to the east coast. At the same time a tropical system will be developing off the coast of Georgia (warm tropical based system) which I will call Tyrod Taylor. So what happens? Shady misses the blitzer (cold air and moisture) and we get rain and cold air later tonight and tomorrow. Unluckily for weekend plans, a tropical system will act similar to a nimble QB and step through his blockers and into the gap and then the chaos ensues!
Because the “blitzing” cold air will push the Atlantic high (warmer air) to the Northwest, the tropical system can step into the gap left behind–for our tropical system this means moving slightly up the coast to where it will run into the colder arctic high and the associated moisture along the boundary. When a warm tropical system, meets a cold arctic system, monster nor’easters usually develop overnight, thus the seemingly overnight and ridiculous success of Tyrod Taylor is a perfect analogy to what is likely to happen over the coming days.
On Thursday are warm tropical low pressure systems will meet cold air, and the associated low pressure at the boundary of the arctic air. The two low pressure systems will morph into a beast of a Nor’easter overnight. However, this won’t be a typical nor’easter.
Normally when a Nor’easter develops they will go through rapid intensification and move up the coast in an orderly fashion producing moisture (either snow or rain) and wind for 18-30 hours depending on the size and the speed it travels, but because of the strong El Nino, this Nor’easter won’t be orderly.
The big Atlantic high pressure block (warmer air) that’s given us the warmer than average weather thanks to El Nino will be pushed off to the northwest, but will remain very strong. The northwest push, and the strength of the Atlantic high means the Nor’easter can’t travel up the coast. Instead we get a Nor’easter that will park along the coast and spin. When Nor’easters stall there is a dramatic increase in the moisture that falls.
The first event (tonight through tomorrow) I have all confidence in and it should deliver between 1.25″ – 1.75″ of rain starting tonight into early Thursday. Thursday during the day there may be periods of on again/off again light rain/drizzle. Starting early Friday through sometime Monday is where the NYC will receive a profuse amount of rain via the Nor’easter. Given what the setup entails for Friday-Monday (where both high pressure systems end up sitting, and where the tropical low develops) there is still some variability in the forecast, but my confidence is growing that we could see anywhere between 3-5 inches of rain from the Nor’easter. That could mean NYC sees upwards 6.5″ of rain making in a very very wet storm and one that inevitably screws up the NYC MTA system!