Tuesday, October 30, 2012


Climate Etc.
Judith Curry

Hurricane Sandy is the largest Atlantic hurricane on record in terms of diameter of the storm. Sandy was associated with an estimated 13 foot storm surge in areas near New York City.

The Wikipedia has a good discussion of the meteorology, preparations, and impacts of Sandy.

CFAN’s forecasts

Sandy was a highly predictable storm. Allow me some bragging rights regarding the forecasts made by my company CFAN (see this post describing our forecast methods).

We began watching the potential for disturbance in the Caribbean on 10/12, and on 10/16 we forecast a 40% of forming a TC and on 10/19 we predicted a high probability of formation. On 10/23, the NHC named Sandy as a tropical storm. CFAN’s forecast on 10/23 predicted a high probability of Sandy becoming a hurricane, with a 30% probability of landfall on the U.S. northeast coast. On 10/24, we predicted 50% probability of a landfall on the northeast U.S. coast on 10/29 or 10/30, with the most likely location between Delaware and New Jersey. On 10/24 we also forecast a horizontal size of 1250 km and a large storm surge.

Last Friday, CFAN’s lead forecasters conducted a webinar briefing for over 400 people in the energy sector, to help understand and plan for impacts in the energy sector (power outages, energy demand, impacts on northeast refineries).

Global warming (?)

I’m sure you have all spotted articles that blame Hurricane Sandy on AGW. Bill McKibben, in a post on democracynow, sums it up as:

Bill McKibben on Hurricane Sandy and Climate Change: “If There Was Ever a Wake-up Call, This Is It”

In the midst of a lot of unwarranted alarmisn on this issue, I have spotted two articles that, IMO, treat this issue appropriately


Eric Berger

One of my first blog posts at Climate Etc. was entitled Hurricanes and global warming: 5 years post Katrina. If you missed it the first time, have a look. Heck, even if you’ve read it before, read it again. The science has not changed, my assessment still stands.

The only possible impact of global warming that I am seeing on the Atlantic hurricanes is the extension of the tropical Atlantic warm pool eastward (towards Africa), which means formation is occurring further east than previously and results in more TCs curving North into the Atlantic (so called fish storms). Note: the impact of warming on hurricane intensity seems theoretically robust, but impossible to sort out an AGW signal from the the natural variability.

Kevin Trenberth frequently says that global warming is affecting all of weather. He is probably right, but apart from the relative magnitude of the effect, this begs the question as to whether the effect is good or bad; arguably in terms of Atlantic hurricanes, the warming is resulting in fewer U.S. landfalls.

2012 hurricane season

So far, the 2012 Atlantic hurricane season has seen 19 named storms, 10 hurricanes, and 1 major hurricanes, currently tied with 1887, 1995, 2010, and 2011 as the 3rd most active season for which we have records. At the beginning of the hurricane season, I had a post entitled 2012 Atlantic Hurricane Season. Pretty much everyone was predicting below normal activity; revisions on Aug 1 raised the levels to closer to normal activity. Note: I do not make seasonal hurricane forecasts myself.

What happened? A big part of the failed seasonal hurricane forecasts is ENSO. From my post:

Bottom line ENSO forecast: many forecasters think we are headed for El Nino by late summer/autumn. I agree that the most likely scenario is to have the ENSO index positive, it is not clear whether it will stay in neutral territory or make it to El Nino. Note: there is no sign of a Modoki (central Pacific warming), which is more predictable than ENSO.

In an ENSO neutral year, the AMO and PDO have substantial control. At the beginning of the summer:

With regards to AMO and PDO, the AMO index is currently moderately positive, the PDO index is currently moderately negative.

In this regime (which characterized the 1950’s), there were a large number of U.S. landfalls, particularly on the Atlantic coast.

Sandy impacts

At the time I am writing this, 16 people have been killed and the early estimates of insured damage are $10-$20B. Given the magnitude of this storm, size of population impacted and concentration of property in the path of the storm, these numbers are really astonishing low. The forecast for this storm was spot on, and the NHC pretty much had it right about 5 days in advance. FEMA and other agencies were on this very early in the game. Mayors of cities were primed for effective action after Hurricane Irene. NCY Mayor Bloomberg has done an exceptional job in this regard.

Sandy is a terrific example of how the U.S. is adapting to the elevated hurricane activity. Hurricane Katrina was a huge wake up call. A key element of this adaptation is good weather forecasts. Another key element is good partnership between the forecasters and decision makers. It is reassuring to see this success, particularly in view of the issues surrounding the Italian seismologists.

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