Pattern Shifting Back to Stormy Next Week

We can all agree that the weather around here over the last month has been quite varied and even extreme. Two powerful storms have left their toll over the Northeast, with the effects of Sandy likely to be felt for many more months.

A nice reprieve was in order this past weekend, with a true "Indian Summer" occurring on both Sunday and Monday. Despite a raw day today, tranquil weather awaits us for the rest of the week. Strong high pressure will dominate our weather from Wednesday-Saturday, with very seasonable conditions but plenty of sunshine.

As we look at next week, which of course is the busiest travel week of the year, we are starting to see indications that the East coast will return to a more stormy pattern. Our main source of concern is what we call a negative NAO (North Atlantic Oscillation)

Many of you heard this referenced when Sandy was making her way up the coast. Indeed, a negative NAO correlates to more atmospheric blocking which generally results in a tilted jet stream that allows storms to travel along or close to the coast. 

The image above shows that indeed the NAO appears to be heading to a big negative phase after November 16th. And some of our long term models are picking this up and hinting at 2 possible coastal storms on the week of Thanksgiving.

There is no details to give as this is WAY to far out to try and forecast specifics. But these large scale indices like the NAO are becoming more vital and more accurate at predicting large swings in the atmosphere's flow.

Just something to keep in the back of your mind if you have travel plans next week! 

Desvestating Hurricane Sandy Was Not As Rare As You Might Think

It's been days since Hurricane Sandy began to effect the East Coast of North America. Yet some of the images and stories we continue to hear come out of the most hard hit regions, like New York City and New Jersey, still shock us to the core. Most of us, including myself, have yet to fully comprehend just how such devastation could have occurred in areas that typically don't have this type of catastrophe.

Some of the statistics and effects attributed to Sandy are hard to believe as well. 180 killed across 8 countries, including 98 in the United States. Upwards of some 50 billion dollars in estimated damage done along the East Coast. A two day shutdown of the NYSE, the first time a weather related issue has forced the closer of the Exchange since an 1888 blizzard. NYC transit service coming to a halt, half of Manhattan without power. The list goes on and on.

From a meteorlogical standpoint, Sandy set some records as well. Sandy had a record low pressure for a hurricane north of Cape Hatteras, NC. At her peak size, she had tropical force winds extending out for a total of 580 miles from her center! And several high water mark records, the most notable being the 13.88 ft record height reached at Battery Park in Manhattan. With such a record breaking storm, its easy to assume that Sandy was the first of her kind. But if we look a little closer at hurricane track history, we find that Sandy wasn't that unique at all.

Umass Lowell graduate meteorology student Lance Frank compiled a record of tropical systems, dating all the way back to 1851, that all had a storm track that traveled to the west well north of Cape Hatteras, NC and occured late in the hurricane season between the months of September and October. These are very specific guidelines, especially considering how obscure this type of behavior is for a tropical system.

What he found was quite interesting. A total of 16 storms fit the criteria, with 7 of those storms making landfall somewhere along the Eastern coast of North America. Three of those storms actually made landfall in Massachusetts in 1869, 1896 and 1923.

Whats more, Sandy was not even the strongest of the this group of storms. You will notice that both the hurricane of 1938 as well as the previously mentioned 1869 storm were both stronger in terms of maximum wind speed. Lance actually went further into the historical weather data and was able to connect large scale weather patterns for each storm. I am sure most of you have heard the term "blocking" as one of the main causes for Sandy's odd track. It turns out that with just about all of these storms, a similar sort of "blocking" pattern was present, helping to push all of these systems back to the West, when they should go out to sea.

So what does this information tell us? Well, for one, it tells us the a Sandy type of storm has clearly happened before. Not all of these storms hit land and Sandy was certainly unique in both her sheer size as well as her landfall in the most heavily populated part of the country.  It should also put the breaks on any premature talk of climate change influencing Sandy. It is incorrect and scientifically immoral to suggest that Sandy's destruction was driven by climate change. The fact is, we just don't know. There is not enough reliable information to connect the two.

With large scale events such as Sandy, we must deal with what we know to be true and not try to infer otherwise. Having analogous historical data like this helps immensely in understanding why Sandy did what she did and more importantly, it helps us to be able to recognize similar situations in the future which will lead to more accurate forecasting.

Regardless of any similarities to the past, Sandy's swath of destruction and devastation will be felt for many years to come, meaning we certainly won't be forgetting this Hurricane anytime soon.

Sandy is Coming!

There is no doubt about it now. Sandy is going to make landfall somewhere in New Jersey late tomorrow night. And she will be a monster of a storm, packing a central pressure somewhere in the 940-950 mb range. Where we had no model consensus earlier this week, we now have an almost unanimous landfall location.

So lets get right to it, what can we expect?

Rainfall- This won't be a huge rainmaker for those of us in Southern New England. I expect some showers to break out as early as this evening, but the bulk of the moisture should hold off until about 5-8AM tomorrow morning. Expect heavy rain through Monday night and Tuesday morning with totals ranging from 1-3 inches. Nothing drastic, but when the rain does fall, it will be heavy. Nothing compared to the totals the mid Atlantic will see. Check out some of those totals below.

Wind- This will be the biggest impact of Sandy for us. I know that it must be hard to understand, since Sandy is clearly making landfall well to our south. For most tropical systems, this landfall location would spare us any real wind damage. But as I have said again and again, this storm set up is like nothing we have seen before. Sandy's strongest winds are actually going to be break away from her center and pivot up into Eastern and Southern Massachusetts. Her wind field is going to become MASSIVE as well, with sustained tropical storm force winds extending some 300+ miles from her center in both directions!   So here are some numbers. Winds are already picking up this afternoon. By Monday morning, sustained winds in Boston will be on the 25-45mph range, with stronger winds along the coast and south to the Cape. By about 1 or 2 pm, we are expecting the strongest gusts to begin to effect our area. From Monday afternoon into Monday evening, sustained winds in Boston will be 30-50mph, with frequent gusts of 65mph+. This will be an extremely dangerous time, where I suspect most of the power outages and wind damage will occur. Along the south shore and on Cape Cod, Monday afternoon will feature sustained winds of 50-65mph with frequent gusts of 75mph+! It goes without saying, that this figures to be the most destructive time frame of the storm. I have to mention the very real possibility of some gusts over 100mph in extreme southern Mass and Cape Cod. Take a look at the projection of wind speeds at 1000 feet above surface for tomorrow afternoon. That maroon area over Cape Cod indicates wind speeds of 90-100knots (103-115mph!) which could very easily mix down to the surface in an isolated gust. Just one gust of that strength would be devastating.

Coastal Flooding- This will be a concern for coastal areas over about 3 high tide periods, Monday in the afternoon, Monday at midnight and Tuesday afternoon. The full moon is tomorrow night, which means tides are running a bit higher right now. Sandy is also in no rush to go anywhere once she makes landfall, which means water is going to continue to pour in for a 36 hour period, making each successive high tide more dangerous than the last. Storm surge(the amount in height that the ocean will rise) is going to be about 2-5 feet for Eastern MA. Bad but not catastrophic. The biggest issue will be the duration of the storm surge. The storm surge in Long Island and further south to NYC will be in the 4-8 foot range with even some higher amounts. That DOES have the potential to be catastrophic, especially for parts of NYC. I would imagine that parts of lower Manhattan will see some of their worst flooding ever.

 Phew! That was a lot to cover. If I could convey one message to you, it would be to take Sandy seriously. Power outages are going to be the biggest issue for us and I expect them to be quite extensive. We have not seen wind speeds of this velocity in quite some time around here. I suspect that many work places and schools will be making decisions about canceling tomorrow. Most probably will. The timing will be a bit tricky, as the worst effects will be felt Monday afternoon. At the very least, it would make sense for most organizations to offer an early release tomorrow, before the heavy wind moves in.

That is all for now! I will be updating this blog later once the storm gets underway.

Why the Stakes Are High with Hurricane Sandy

By now, most of you have heard the chatter surrounding Hurricane Sandy and her potential impacts in New England early next week. The wise and clever meteorologist will always preach caution when projecting confidence in a forecast period over 100 hours away, so I must preface this entry by saying that there is still a lot of changing variables and factors that can alter the outcome. That being said, special attention needs to be paid to this storm as the stakes will be higher than normal. It is quite likely that should the storm make landfall near our region, some communities will experience devastating conditions, the likes of which haven't been felt here in some 60 plus years.

I fear that some of the public might not take this storm as seriously since we just had a tropical system (Irene) last summer. Irene certainly took her toll in terms of devastation, but as far as tropical storms go, most of us got off lightly. However, this storm will be different than Irene, and different from most mid-latitude tropical storms that we sometimes see. And here is why.

1.) Strength/Duration- Typically, a tropical storm or hurricane that travels up the East Coast will quickly lose a lot of its tropical features the further North it goes. What that amounts to is a decrease in wind strength, lose of any eye wall features and a sharp cut off in the position of strong winds and heavy rainfall placement within the storm. Sandy won't be so quick to lose her tropical features. She will be aided by an abnormal feature currently setting up over the lower 48, as seen in the image below. The jet stream, upper level steering current, is about to become very tilted. Strong cold air diving south from Canada will result in a jet stream that will run from south to north by the weekend. Whats worse, this jet stream will set up just to the West of Sandy, who will be emerging from the Caribbean with a tremendous amount of energy.  Tropical systems exist outside of the jet stream and any steering currents, so this jet stream position will be two fold. It will capture Sandy and push her North but also infuse her with even more energy, allowing her to maintain and even gain strength.

2.)Abnormal blocking- In meteorology, blocking refers to a large pool of cold air way up in the atmosphere that acts as a blocking agent to normal atmospheric flow. We hear a lot about blocking in the winter, since it is a favorable pattern for nor'easter development. It just so happens that a strong block developed early this week, eliminating any escape route for Atlantic storms. It will also slow Sandy down tremendously, in a spot where tropical storms usually speed up. Remember how quickly Irene was over with? Take a look at the image above again and you might notice what looks like a "path" that is carved out right up the East Coast.  With a south to north upper level flow, an abundance of tropical moisture and strong blocking to the East, the triple threat has been set in place.

The terms like "perfect storm" and "storm of the century" have been used quite liberally in the past. But this atmospheric set up is the closest thing that meteorologists have seen to an actual perfect storm set up. As such, the negative impacts we can expect to feel will be greatly amplified, something I will address in a later post.

For now, a heightened vigilance is all that is needed. Specifics won't be reliable until we get closer to the weekend.

Wind and Soaking Rain On the Way

If you have been outside at all today, you certainly noticed how windy it has been all day. In the past few hours, those wind gusts have increases in intensity, with several locations in Eastern MA reporting gusts in the range of 45-55 mph. Powerful enough to knock down some trees and power lines. Reports of power outages in eastern NY and western CT have been on the rise all afternoon.

All of this wind is in advance of a strong cold front that has extended from a parent Low pressure system over the Great Lakes. This Low will continue to grow stronger overnight, aided by a convergence of the Northern and Southern jet streams, feeding tropical moisture into our region. This same "phasing" of jet steams is what gives us big snowstorms in the winter!

But alas, no snow with this one. Here are the highlights.

- Strong winds and wind gusts continue into the morning. Scattered power outages and moderate wind damage is expected with gusts upwards of 50-60 mph.

- Severe thunderstorms are also a possibility. Main treats with these include damaging straight line winds. Just above the surface, there is some REALLY strong wind gusts. Some of these gusts could get mixed down to the surface as heavy rainfall develops over the next few hours.

- Rain. And lots of it. This front is loaded with moisture and will drop a good 1.5-2.5 inches of rainfall over Eastern MA in the next 8 hours. This will lead to some urban flooding. Heavy rain hits Boston between 11-midnight. This is also the best time frame for any severe weather.

- Luckily, this front is a fast mover. Earlier indications showed the front becoming stalled out near Cape Cod on Wednesday, wedged between the Low in the Great Lakes and the High over the Atlantic. But that does not appear to be the case anymore. Tomorrow morning will feature some left over showers and will still be breezy. Although nowhere close to the wind gusts we will see tonight. From there, gradual clearing is expected and maybe even some peaks of sunshine before the day is all done!

Keep an eye on the news for any severe thunderstorm warnings over the next few hours and bring all lawn furniture and other light objects in before the rain hits!

More Trouble for the Gulf?

Issac may not be done with the Gulf Coast just yet. Over the last week, the remnants of Issac were stationary over the Midwest before a strong cold front pushed the former Hurricane off to the east, resulting in the rainy and humid conditions we saw over the past 2 days.

Interestingly enough, a piece of what was Issac also broke off from the main portion of the storm circulation and moved southeast towards Alabama and has since moved offshore and over the Gulf waters.

Looking at the satellite image above, you can see that this cluster of thunderstorms is not very organized. And in fact, there is significant wind sheer (poison to hurricanes) as well as loads of dry air all around the disturbance. In addition, the passage of Issac last week sucked up a tremendous amount of cold water from lower depths of the Gulf, which has resulted in much cooler surface water temperatures. All of these factors suggests that this former piece of Issac won't develop into much over the next 24 hours or so, but after that, conditions become much more favorable for intensification.

A strong low pressure over the East coast (which will make Saturday a wet one for us) will push this system off to the southwest by the weekend and the NHC anticipates that this is when a tropical depression or even tropical storm will develop. They put that possibility at 40% right now but that percentage is likely to increase.

This storm won't be a big one and certainly not a big wind producer but it does promise to bring another dose of heavy rain to an area that does not need any more precipitation. As of this moment, it looks like the Florida panhandle is under the gun come Sunday into Monday but as with anything in the tropics, the situation bears watching!

Elsewhere in the tropics, Leslie continues to sit and spin southwest of Bermuda. Little intensification or movement is expected over the next 48 hours but once that East Coast disturbance moves off shore by Sunday, Leslie will get a kick in the ass and start accelerating to the north and then to the northeast, making a very close pass to Bermuda as a Cat 1/2 and ultimately making landfall somewhere near Nova Scotia next week.

Hurricane Michael, wayyyyyyy out in the middle of the Atlantic is the first major hurricane of the season. Currently a cat 3 with winds of 115mph, Michale sure looks pretty on satellite imagery but he won't make any threat to land.

Welcome Back!

It's welcome back time here at NE Weather Rants! I had big plans to write 3-4 blog posts a week over the summer. You can see how well that went. No matter, its a new month, a new school year and shit is about to pop off! Alright, that was a little too much excitement.

What better day to start blogging again than a rainy and muggy day? Honestly, we have nothing to complain about in the weather department here in the Northeast. We have enjoyed a BEAUTIFUL stretch of weather.  From August 19th - September 3rd, we had sunshine and temperatures in the 70-80 degree range for 15 of 16 days. With some real gorgeous days mixed in there as well. You couldn't have asked for a better and more comfortable stretch of weather to end the summer. So today and tomorrows rain shouldn't dampen your spirits too much.

As for that rain, most of the shower activity for today will begin to tamper off as the afternoon rolls along. You may have noticed that the air is much stickier today, you can thank our dearly departed friend Issac for that. After drenching the Gulf Coast last week, Issac moved into the Ohio River Valley and essentially spun himself out for the last 4 days. A strong cold front pushing south through the mid-west finally got whats left of Issac moving again, which is what we are dealing with over the next 18-24 hours. Tropical air, and tropical downpours. All without the ambiance of a tropical setting with fruity drinks. You can see from the QPF image below that most of the heavy rainfall will stay over Northern New England. Much of that heavy rainfall will occur very early tomorrow morning, which should make for a nice 1st back to school commute of the year. Expect heavy rainfall in the Boston area from 5-10AM with slow clearing and isolated downpours after that.

But enough of that talk of rainfall for now. Lets talk tropics! Take a look at the spaghetti plot for potential tracks of TS Leslie.



Leslie is a funny little storm. She is going to get caught in between strong High pressure over the central Atlantic and a somewhat inverted Northern Hemisphere jet stream to here west.
 

This will cause her to sit and spin in place just to the south of Bermuda for a few days, while intensifying to a category 2 storm. You can see that once she does get moving, she makes a close pass to New England, but not close enough for any real effects. Except of course for some pretty high surf. Take a look at this predicted wave height model for the East Coast as Leslie makes her pass on Sunday/Monday. Expect seas as high as 12 feet off shore with some coastal beach erosion likely all weekend.