Hurricane Sandy: Challenges Posed by a Transitioning Storm

17th Severe Weather Symposium

March 22, 2013

Jay Hobgood

Effects of Hurricane Sandy

• 147 direct fatalities (72 in the U.S.)

• 87 indirect fatalities

• at least 50 billion dollars in damages

• 650,000 houses damaged or destroyed in the U.S.

• 8.5 million customers lost power

Challenges with Sandy

• Meteorological Challenges

• Warning Challenges

Meteorological Challenges

• Track forecast - excellent

• Intensity forecast – very good (near the long term average)

• Extratropical Transition - problematic

Extratropical Transition

Extratropical transition – is the process by which a warm-cored tropical cyclone transforms into a cold-cored extratropical cyclone.

Types of Cyclones

Tropical cyclone – is a warm-core, non-frontal low pressure system of synoptic scale that develops over the tropical or subtropical oceans.

Hurricane Sandy north of Cuba on Thursday morning.

Types of Cyclones (continued)

Extratropical (midlatitude) cyclone – is a cold-core synoptic scale low pressure system whose primary source of energy is baroclinic. It is often associated with frontal systems.

Strong extratropical cyclone over the North Pacific Ocean.

Types of Cyclones (continued)

Subtropical cyclone – is a low pressure system that develops over subtropical oceans and initially has a non-tropical circulation but exhibits some elements of the cloud patterns associated with tropical cyclones. It is often considered a hybrid system with some characteristics of tropical and extratropical cyclones.

Subtropical Storm Nicole in 2004.

Hurricane Sandy on Saturday afternoon.

What kind of cyclone is this?

What kind of cyclone is this?

Extratropical cyclone

What kind of cyclone is this?

What kind of cyclone is this?

Extratropical cyclone

A broader view of the same cyclone.

Post-Tropical Cyclone

A post-tropical cyclone is an umbrella term that covers any low pressure system that was a tropical cyclone at one time.

It includes extratropical cyclones, remnant lows and other systems.

Why did the classification of Sandy matter?

Why did the classification of Sandy matter?

Uncertainty about the potential future classification of the cyclone that was Hurricane Sandy created challenges about the most appropriate warnings to issue for the storm.

Warning Challenges

• What types of warnings to issue for Sandy?

Overarching Consideration

“the NWS understanding of the preference of the emergency management (EM) community that the warning type not change once watches and warnings were initiated, …”

One Option

“follow existing protocol and transfer forecast responsibility to other NWS offices, cancel the hurricane warning, and switch to local WFO warnings.”

not chosen because of overarching consideration for continuity in warnings

Another Option

“continue to call Sandy a hurricane when it really was not one (potentially for a full day or two) in order to maintain NHC advisories and the hurricane warning.”

not chosen because of potential loss of future credibility

A Third Option

“to properly call Sandy post-tropical but continue to issue NHC advisories and leave up the hurricane warning.”

not chosen because of concerns that automated vendor software might malfunction and disrupt the flow of information

Procedure Followed

“the NWS decided to issue non-tropical warnings, communicating this warning strategy clearly to NWS partners, while placing special emphasis on Sandy’s hazards …”

Possible Change for the Future

“it would give the NHC the option to continue issuing formal advisories on post-tropical cyclones as long as those systems pose a significant threat to life and property, and it would give the NWS the option to keep hurricane and tropical storm watches and warnings in place for those systems.”

Did Hurricane Irene (2011) Contribute to Complacency

Sandy

Irene

Sources

Blake, E.S., T.B. Kimberlain, R.J. Berg, J.P. Cangialosi, and J.L. Beven III, “Tropical Cyclone Report Hurricane Sandy”.

Avila, L.A. and J. Cangialosi, “Tropical Cyclone Report Hurricane Irene’.

NRL Monterey Tropical Cyclone Page.

NOAA GOES Server.