Why did Hurricane Sandy take such an unusual track into New Jersey?
We're used to seeing hurricane-battered beaches and flooded cities in Florida, North Carolina, and the Gulf Coast. But to see these images from the Jersey Shore and New York City in the wake of Hurricane Sandy is a shocking experience. New Jersey only rarely gets hit by hurricanes because it lies in a portion of the coast that doesn't stick out much, and is too far north. How did this happen? How was a hurricane able to move from southeast to northwest at landfall, so far north, and so late in hurricane season? We expect hurricanes to move from east to west in the tropics, where the prevailing trade winds blow that direction. But the prevailing wind direction reverses at mid-latitudes, flowing predominately west-to-east, due to the spin of the Earth. Hurricanes that penetrate to about Florida's latitude usually get caught up in these westerly winds, and are whisked northeastwards, out to sea. However, the jet stream, that powerful band of upper-atmosphere west-to-east flowing air, has many dips and bulges. These troughs of low pressure and ridges of high pressure allow winds at mid-latitudes to flow more to the north or to the south. Every so often, a trough in the jet stream bends back on itself when encountering a ridge of high pressure stuck in place ahead of it. These "negatively tilted" troughs have winds that flow from southeast to northwest. It is this sort of negatively tilted trough that sucked in Sandy and allowed the hurricane to take such an unusual path into New Jersey.
Figure 1. Inlet section of Atlantic City, N.J., after Hurricane Sandy. Image credit: 6 ABC Action News.
The 1903 Vagabond Hurricane
The only other hurricane to hit New Jersey since 1851 besides Sandy was the 1903 Category 1 Vagabond Hurricane. According to Wikipedia, the Vagabond Hurricane caused heavy damage along the New Jersey coast ($180 million in 2006 dollars.) The hurricane killed 57 people, and endangered the life of President Theodore Roosevelt, who was sailing on a yacht near Long Island, NY, when the hurricane hit. However, the Vagabond Hurricane hit in September, when the jet stream is typically weaker and farther to the north. It is quite extraordinary that Sandy was able to hit New Jersey in late October, when the jet stream is typically stronger and farther south, making recurvature to the northeast much more likely than in September.
Figure 2. The path of the 1903 Vagabond Hurricane, the only other hurricane to hit New Jersey since 1851.
The blocking ridge that steered Sandy into New Jersey
A strong ridge of high pressure parked itself over Greenland beginning on October 20, creating a "blocking ridge" that prevented the normal west-to-east flow of winds over Eastern North America. Think of the blocking ridge like a big truck parked over Greenland. Storms approaching from the west (like the fall low pressure system that moved across the U.S. from California to Pennsylvania last week) or from the south (Hurricane Sandy) were blocked from heading to the northeast. Caught in the equivalent of an atmospheric traffic jam, the two storms collided over the Northeast U.S., combined into one, and are now waiting for the truck parked over Greenland to move. The strength of the blocking ridge, as measured by the strength of the North Atlantic Oscillation (NAO), was quite high--about two standard deviations from average, something that occurs approximately 5% of the time. When the NAO is in a strong negative phase, we tend to have blocking ridges over Greenland.
Figure 3. Jet stream winds at a pressure of 300 mb on October 29, 2012, as Hurricane Sandy approached the coast of New Jersey. Note that the wind direction over New Jersey (black arrows) was from the southeast, due to a negatively tilted trough of low pressure over the Eastern U.S. caused by a strong blocking ridge of high pressure over Greenland. Image credit: NOAA/ESRL.
Arctic sea ice loss can cause blocking ridges
Blocking ridges occur naturally, but are uncommon over Greenland this time of year. According to NOAA's Climate Prediction Center, blocking near the longitude of Greenland (50°W) only occurs about 2% of the time in the fall. These odds rise to about 6% in winter and spring. As I discussed in an April post, Arctic sea ice loss tied to unusual jet stream patterns, three studies published in the past year have found that the jet stream has been getting stuck in unusually strong blocking patterns in recent years. These studies found that the recent record decline in Arctic sea ice could be responsible, since this heats up the pole, altering the Equator-to-pole temperature difference, forcing the jet stream to slow down, meander, and get stuck in large loops. The 2012 Arctic sea ice melt season was extreme, with sea ice extent hitting a record lows. Could sea ice loss have contributed to the blocking ridge that steered Sandy into New Jersey? It is possible, but we will need to much more research on the subject before we make such a link, as the studies of sea ice loss on jet stream patterns are so new. The author of one of the new studies, Dr. Jennifer Francis of Rutgers, had this say in a recent post by Andy Revkin in his Dot Earth blog: "While it’s impossible to say how this scenario might have unfolded if sea-ice had been as extensive as it was in the 1980s, the situation at hand is completely consistent with what I’d expect to see happen more often as a result of unabated warming and especially the amplification of that warming in the Arctic."
Jeff Masters
Reader Comments
Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 — Blog Index
Homeowners spared costly hurricane deductible
Most homeowners along the East Coast won't have to pay potentially huge hurricane deductibles before insurance coverage kicks in for damage caused by Tropical Storm Sandy, say state officials.
...
Although Sandy was designated a hurricane for the majority of time it traveled up the coast, it failed to sustain hurricane-force winds at landfall, so it was officially a tropical storm. That means homeowners in Connecticut, New Jersey, New York and Maryland won't be on the hook for costly hurricane deductibles, and state officials are putting insurers on notice.
As I said, I'm part of the conspiracy. So, yes I could tell you, but no I will not.
But remember... it's definitely a conspiracy and it was definitely not based on any of the data or analyses posted numerous times by my co-conspirators here.
If you're implying that the climate change we're seeing now is part of a natural cycle please do educate us as to which cycle is causing it. Scientists who study this topic professionally have ruled out all natural cycles, so I'm guessing you've got some pretty awesome data they haven't seen yet. Please share. You can trust me - I promise I'm not part of the conspiracy.
we have the so called experts saying sandy could be due to climate change......keep crying wolf and see how many people will belive.....prove to me that climate change does not go in cycles.....prove it....
On another note: Where are people under evacuation order supposed to go? A well-off person can decide that it's a good week to take a spontaneous vacation to San Francisco. What if you're just working class, living paycheck to paycheck, and have no relatives you can stay with? Do you just get on the road up the Thruway and hope you find somewhere safe, even though Sandy is supposed to strike the whole area with great force? What if you don't even have a car, like many people in NYC and NJ? It does no good to assume options that simply don't exist.
I would give you a threat index for Houston TX but it foods when a mouse drinks too much water before bedtime.
I mean nutria.
Those fire ant balls are horrid! and the water only needs to be inches deep for them to start building them. Our citizen had a hard time with them during restoration efforts after the Suwannee river flooded.
to say that that there was uncertainty in where it would make landfall is ridiculous all the models forecasted it to make landfall on the jersey shore
There are shelters everywhere for just this sort of emergency. With every "mandatory evacuation order" there will also be lists of places to go, and of ways to get there.
It was mentioned numerous times that this was "historic", unprecedented, and going to be a very dangerous storm for areas that don't usually take a direct hit. I'm in central Illinois, and we had couple very windy days from this storm! (hubby is from galveston area, lots of family down there-Rita got me hooked on this site-back to lurking....
Which part of the NHC statement didn't you understand?!
Forecast discussion states: TO AVOID A HIGHLY DISRUPTIVE CHANGE FROM TROPICAL TO NON-TROPICAL WARNINGS WHEN SANDY BECOMES POST-TROPICAL...THE WIND HAZARD NORTH OF THE TROPICAL STORM WARNING AREA WILL CONTINUE TO BE CONVEYED THROUGH HIGH WIND WATCHES AND
WARNINGS ISSUED BY LOCAL NATIONAL WEATHER SERVICE OFFICES.
As this piece talks about the UK's Forestry Commission I can perhaps comment with a bit of personal experience... not something I'd have expected for the Sandy threads! I live in the Forest of Dean, which is (by UK standards) fairly densely wooded -- lots of commercial coniferous plantations but also lots of native broadleaf species. Anecdotally, I haven't seen any evidence of ozone causing trees to die or rot from the inside. Occam's Razor suggests to me that a lot of trees that have fallen have rotten hearts because they're weaker than healthy trees, and the reason so many trees have come down is that the US NE hasn't had many storms with high windspeeds over a large area -- certainly nothing like Sandy -- for decades. In the absence of high winds, broadleaf trees will survive for many, many years after the heartwood has started to decay. If, say (picking a number at random) 1% of all trees get to the state where 70mph winds will bring them down, and you don't get such high windspeeds for 20 years, the number that fall will be pretty close to 20%.
Finally, if (as the blog piece linked to claims) ozone damage to trees is well established -- I've no reason to disbelieve this -- and if ozone levels are regularly monitored over a wide area -- as they are -- it would be pretty obvious what was happening. It's hard to suppress information about the composition of the atmosphere! [redact tangent about AGW here ;) ] I note that the 'Grauniad' piece linked to from the blog doesn't make any mention of ozone *or any other pollutants*, at all. The current problem with ash fungus attacks really *did* first break out in continental Europe, and it *has* spread to the UK. Again this is all easily verified from open sources. Now, 25 years ago acid rain caused by unscrubbed sulphur dioxide from coal-burning power stations really WAS a problem, and it WAS clearly visible in the Dean. How that problem was tackled is too far OT to go into here (but it's interesting in the light of more contemporary, er, "issues of environmental pollution".
And again, 7 years does not a climate make, especially for a data set that is particularly noisy from year to year. Get back to us in another 13-23 years when we are actually covering a period of time that can be described as climate. Until then, any comparisons of tropical cyclone activity and tropical cyclone intensity between years are best described as weather or climate variability.
Viewing: 901 - 916
Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 — Blog Index