Intense Low Pressure System to hit East Coast

[tenkiforecast]

To explain what this is, this is the five-day forecast model by the ECMWF--the European forecast model, the 12Z run from showing the 500 mb heights (height of the atmosphere at 500 mb) in color, and the mean sea-level pressure as the black contours. What exactly does this mean? Well... basically, a huge storm is going to hit the northern east coast. Why is this such a huge event?

This is a visible satellite image of Tropical Cyclone Sandy, valid on Oct 25 at 17:45 UTC, or 1:45 Eastern Time. What is currently forecast to happen is that Sandy is going to move along the East coast and merge with the mid-latitude trough shown in the 500 mb map. Usually, the storm would undergo a transition from a tropical system to a mid-latitude system and stay out at sea. This is not what is forecast to happen. The trough is moving east at a faster pace than usual, and Sandy is moving north very quickly. The Tropical Cyclone is going to be drawn into the trough's circulation, intensify, and then start transitioning. When the trough moves close, there is a phenomena in fluid dynamics called the Fujiw(h)ara Effect. where two lows or eddies will rotate around each other and then merge. The models are showing this.

Ordinarily, I would not be so alarmist about a weather event, especially not this far out in time--five days is huge for forecasting, it is very close to the limit of accurate forecasts. The problem is that the atmospheric flow right now fits with the model output, as well as Sandy's movements--they match ordinary Tropical Cyclone movement patterns. Furthermore, of the models that I look at, five of the six are in agreement that this storm is going to occur. The one that is not in agreement is usually the most unreliable--the NAM. Other models, the CMC, UK-MET, GFS, ECMWF, and the Navy NOGAPS all show the merger of TC Sandy and this mid-latitude trough. The problem is that they do not agree on where this thing is going to make landfall and where the maximum precipitation will fall. This... is going to be a mess, and I am flat-out terrified by this event.

My advice for anyone along the northern East Coast, as well as Virginia, East Pennsylvania, New York, Delaware, Maryland... stock up on supplies now before the rush hits. Where exactly this thing is going to make landfall, I do not know. Where the max precipitation is going to occur, I do not know. All I know is taht this is going to be a severe storm event--not severe in terms of supercellular convection, but a major pseudo-winter storm. If anyone wants, I will update this over the next few days as the numerical models reach a better consensus...and as I can make a better prediction myself.

[Rehab]

Thanks for the heads-up, dude :{

[Momentai~]

Interesting...

Thanks for the heads-up, dude :{

[Anacybele]

I'm in North Carolina, and most of my family is in Pittsburgh, PA. Would this storm have a big effect on us too?

[cyron]

i would defenititly appreciate you looking into this further as i live in p.a.

i secretly pray for snowdays

[Emeraldfox]

I'm down here in Jacksonville, all we have are clouds.

[Original Alear]

All I know is taht this is going to be a severe storm event--not severe in terms of supercellular convection, but a major pseudo-winter storm.

Skimmed until I read this - then reread carefully (obviously most continued to go over my head).

Insofar as something that seasons not only have a role in the weather we will have, but how well our environment is suited for receiving it (duh), I pay more attention when someone tells me they expect weather that's not quite in season.

Thanks.

Edited October 25, 2012 by L1049

[Ϲharlie]

lol

I'm currently on a ship, and hurricane Sandy is nipping at our heals. The boat was going to make three stops at different islands, but the captain was forced to cancel them because of the storm.

[tenkiforecast]

NC won't be hit hard. Higher winds, probably, the northeastern parts of the state have a higher chance of precipitation. NC is too far south to be significantly impacted by the storm.

Right now, all the models I look at are in agreement that this thing will happen. The problem is when and how. The European model has the storm making landfall in 4 days (on the 30th) along the coast of Maryland and Delaware. The NAM has the storm center making landfall in about 4-5 days along the NJ/NY coast. The GFS keeps Sandy out at sea much longer, and has it retrograde to the west and land on the NY/NJ coast in 5 days. The CMC keeps the storm out further in the ocean, and it then retrogrades and lands in Maine in 5 days. The Navy's model shows the storm landing in 4 days along the maryland/Delaware/NJ coast.

Obviously...this is a bit of a mess right now. The system is gigantic, so anyone in Maryland, Pennsylvania, New York, New Jersey, Virginia, and Delaware will probably be affected by this storm. Personally, I am more inclined to lean towards the European model and the Navy's model because those two handle tropical cyclones better than the NAM, GFS, and CMC. My prediction right now is that as time passes, the GFS, CMC, and NAM will start to trend towards the European model, but the Euro and Navy models will probably trend somewhat towards the NAM and GFS solutions. Yes, it is a mess. Anyone along the coast near Sandy, be prepared for moderate-to-heavy rainfall due to rainbands moving onshore--Sandy is not a small storm, and the fact that it will begin to transition into a mid-latitude storm will only make things worse for the storm impact...the most intense precipitation is focused on the northwest side of the low pressure center for mid-latitude cyclones. Add to that there is a cold front approaching the East coast may also cause a heavy rain event before Sandy's landfall/merger with the upper-level trough...ugh, the nightmare keeps getting worse. Even better is the SPC prediction that the front will go stationary as Sandy approaches, meaning more lift and heavier precipitation along the front.

Dear lord, it just keeps getting worse.

The reason I used the term "pseudo-winter storm" is to try and help explain what a mid-latitude cyclone is. Usually, these types of storms impact the United States during the late fall, winter, and early-to-late spring. In winter, the temperatures are cold enough for snow. The same type of storm will occur, but I do not know if it will be universally cold enough for snow--especially because a hurricane is involved.

[Freohr Datia]

lol

I'm currently on a ship, and hurricane Sandy is nipping at our heals. The boat was going to make three stops at different islands, but the captain was forced to cancel them because of the storm.

Noooooooooooooooooooooo Mumuuuuuuuuuuuuuuuuuuuuuu

I'm in Indiana so I never have to worry about hurricanes because the most we get from hurricanes that reach us are drizzles~ Well... drizzles that last a long time x3

It's kinda cool having a meteorologist in these forums~ (or are you a meteorologist or a student? =o)

[tenkiforecast]

Noooooooooooooooooooooo Mumuuuuuuuuuuuuuuuuuuuuuu

I'm in Indiana so I never have to worry about hurricanes because the most we get from hurricanes that reach us are drizzles~ Well... drizzles that last a long time x3

It's kinda cool having a meteorologist in these forums~ (or are you a meteorologist or a student? =o)

Grad student. I am a qualified meteorologist, if I wanted I could find a job as a forecaster right now. Problem is that it is unlikely I would get said job, if you are not working in broadcast Meteorology, a master's degree is almost required.

I remember Hurricane Gustav's remnants moving across MI in 2008. I wouldn't refer to that as a drizzle myself, the rain was heavier than most precip we get in Michigan.

And yes, you want to stay the hell away from Tropical Cyclones on the ocean. If anything, they are more dangerous for sea vessels than on land...

This is why.

[Wist]

I like you.

Any idea when it'll be apparent where it will and won't be cold enough for snowfall during the event, or will that remain unclear until it lands?

[Sunwoo]

We discussed this in class today. This storm looks like it's gonna be bad.

[tenkiforecast]

The areas for snowfall... unfortunately, I can't say. I don't have access to the model data to customize views myself, unfortunately...

What I *can* see so far is that there is a ton of uncertainty with snowfall. One of the guiding lines for forecasting snowfall only shows up in a few of the models, which are also the ones that delay the storm's landfall--more cold air moves south before the storm occludes or fills in (basically, at its peak intensity). The areas that would likely get snowfall...anywhere that is elevated in the Appalachians, it might be cold enough in the mountains for snow. Even then it depends on which model is right, it's too far out for me to guess right now. I can offer a better guess tomorrow... right now there is a lot of variation with the temperature. Check your local NWS station, and their forecast discussion is my advice.

Just type in your zip code under local forecast and then scroll down to the "Forecast Discussion" to hear what the NWS forecasters are predicting. Snow is very likely... and it seems that only the European model keeps temperatures above the 32 degree threshold. Then the question becomes how wet is the snow... and I'm not touching that topic.

I'm in Charlotte, NC... I'm going to be expecting high winds... probably up to 40 mph if the European model verifies.

[Anacybele]

Blarg, I'm in Fayetteville, NC, which is closer to the coastline than Charlotte. Yeah, it can get windy here, and on occasion, we get tornadoes nearby too. But they're pretty rare.

[tenkiforecast]

Blarg, I'm in Fayetteville, NC, which is closer to the coastline than Charlotte. Yeah, it can get windy here, and on occasion, we get tornadoes nearby too. But they're pretty rare.

Tornadoes in the sense of march, april timing? I'm thinking hurricane-generated right now, as that's part of what I'm researching.

I'll update on this later, once the 12Z model runs are available.

[Melonhead]

Great. I'm in the D.C. Area, and this does not look good.

[tenkiforecast]

Models are out!

Well, I was half right. Sandy is forecast to follow the ECMWF/CMC/NOGAPS track, and the forecast time for landfall is starting to reach consensus at 60 to 66 hours out from the 12Z model runs (translation... 8 PM yesterday. Yes, that is how long it takes for these models to run). The location of landfall the models are predicting is...one of the worst possible outcomes.

This map is the Sea Level Pressure and 6 hour Precipitation

The models are forecasting this system to make landfall in New Jersey or New York City. I really don't need to explain why this is a *really* bad thing. Add to that, the forecast pressure levels are around 960 mb, which is the same as a Category 3 Hurricane--granted, this is an extratropical system by this point, but the point is--THIS THING IS GOING TO BE REALLY, REALLY INTENSE. I can't give an estimate on winds, I really can't, and for anyone hit by this thing, I am sorry.

I will say this, as a result of the models taking the more ECMWF/CMC/NOGAPS track, less cold air is advected south. This means that chances for snow are less, so there may not be that hazard. Instead it will be high winds and flooding... this is going to be really, really bad.

[eclipse]

First, thanks for the weather site! I could've used this a few weeks back, as Hawaii's weather has been really, really bad (in a weird way).

Second, do you think Sandy's gonna be upgraded to a hurricane before it hits land?

[tenkiforecast]

I'll list some of the MET sites I use. If you're not familiar with meteorology though, a lot of it is gibberish.

CIMSS Tropical Cyclones

E-Wall

College of DuPage models

Weather Underground

As for Sandy's intensity... it is a hurricane. It's a Category 1, and forecast to stay that way, even as it makes extratropical transition. Given how much of a nightmare intensity forecasts are, if it *stays* a Category 1, I would be slightly surprised. Then again, it is a favorable environment for hurricane maintenance, so it should not be a huge difference.

[tenkiforecast]

If anyone is curious, I am linking a site that I found through my advisor that has documented all the radar scans that capture Sandy's movement from when it was first detected by US ground radar. There is not much else I can say about this system...only I feel sorry for anyone in its path.

Tropical Cyclone Ground Radar