The Cone on the Map: Hurricane Risk Management

Hurricane Ian (photo: NOAA, via Wikipedia)

In the wake of Hurricane Ian, risk communication is in the news again.

The Washington Post had an article about the limitations of the hurricane forecast cone (Scott Dance and Amudalat Ajasa, "The confusion and controversy over the forecast cone," October 5, 2022).  Rebecca Morss, from the National Center for Atmospheric Research, said "Some people think the cone represents the size of the storm, which it doesn't.  Some people think it represents the area of impact, which it doesn't."

5-day Forecast Track, 8:00 P.M., September 25, 2022 (Source: NOAA).

The deficiencies of this single graphic were significant because the forecast hurricane track changed rapidly in the days before landfall, as the National Hurricane Center's archive shows.  At 8:00 P.M. on Sunday, September 25, 2022, the line in the middle of the five-day cone crossed the Big Bend area of Florida, approximately 300 miles north of Fort Myers.  At 8:00 P.M. on Monday, as the hurricane approached Cuba, the line in the middle of the three-day cone crossed the west coast of Florida just north of Tampa Bay, and Fort Myers was just outside the edge of the cone.  By the next morning, that line crossed the coast just south of Tampa Bay.  By Tuesday evening, the line had moved to Port Charlotte, and Fort Myers was inside the cone.

The miscommunication was preventable.  As mentioned in The Washington Post article, the forecast cone graphic includes the disclaimer: "Note: The cone contains the probable path of the storm center but does not show the size of the storm.  Hazardous conditions can occur outside of the cone."

Also, the National Hurricane Center publishes numerous other graphics that do indicate the expected size of the storm: the Hurricane-Force Wind Speed Probabilities is a particularly useful one.  On Sunday evening, this graphic showed the probability of hurricane-force winds in Fort Myers was at least 10%.  By Monday evening, this probability had increased to at least 20%.  By Tuesday morning, it was at least 40%.

To me, because I am familiar with it, the hurricane forecast cone is useful, but it clearly has limitations, and I don't rely on it, especially when my family is in harm's way.  The media can better inform the public by showing the wind-speed probability and storm surge graphics and emphasizing the reach of the storm instead of focusing on where the center of the storm makes landfall.  

The Hurricane Ian archive includes a Graphics Archive that will present a slideshow of the graphics, which is useful for seeing how the forecasts changed.

Too Many Warnings?

At 5:35 P.M. on September 17, 2018, the University of Maryland Police Department (UMPD) sent a tornado warning by email and text message to university students, faculty, and staff: "A Tornado Warning has been issued for the UMD campus. The sirens will be activated. Seek shelter immediately, avoid windows."  This message did not mention that the warning was issued by Accuweather.  The National Weather Service (NWS) did not issue a tornado warning.  At 6:04 P.M., the UMPD sent the following message: "The Tornado Warning that was issued by AccuWeather is now cancelled as of 6:00 PM."

Part of Accuweather's business is generating severe weather alerts for its clients. Its website touts the benefits of Accuweather's warnings and its "null tornado notifications" that a NWS tornado warning will not affect a client's facility.  The website discusses the benefits of knowing that a tornado warning is not a direct threat, so a shutdown is not necessary, and claims that Accuweather's false alarm rate is lower than the NWS false alarm rate (10% to 80%).

When one organization issues a warning while the other does not, the inconsistency could decrease trust in warnings, increasing the likelihood of ignoring warnings.
An article in The Washington Post about the false alarm (Angela Fritz and Sarah Larimer, "Red flags at U-Md. over false alarm for tornado," September 19, 2018) quoted Gary Szatkowki, a former NWS meteorologist, who asked "What do we want to do about a weather organization issuing a tornado warning when the Weather Service does not?"

Although the University of Maryland is a large institution (approximately 40,000 students), its cost of a false alarm is smaller than the same cost for a factory (where a shutdown directly impacts throughput and revenue).  Moreover, many students and others are outdoors, and the university has a strong desire to be viewed as a safe place, so the potential impact is large.

In that case, the university should be willing to tolerate more warnings.  Too many warnings?  No, in this case.

Turn around don't drown video

Managing risk requires understanding the risk; the National Weather Service is doing its part with this video about the risk of driving across a flooded road: 

How to React to an Earthquake

One cannot prevent an earthquake, but one can protect people and property from its impact.  Traditionally, this means designing and building structures that will survive the earthquake without damage (preventive actions).  Now, because of earthquake warning systems, contingency planning is becoming feasible.

Earlier this month, The Washington Post's Eric Niiler wrote about technology that can tell that an earthquake is about to happen.  The November 3 article ("Last-minute warnings may make quakes less destructive") states that a combination of ground sensors and satellite-based instruments can give a warning a minute or two before the earthquake occurs.

The technology works by detecting the P-waves that precede the earthquake's shock (the sound waves are an earthquake precursor).  The ShakeAlert earthquake early warning system for the west coast of the United States was developed by the United States Geological Survey (USGS) and university partners.  According to Niiler, Chile, Mexico, China, Taiwan, Turkey, and Israel are developing similar systems.

Although a minute is not enough time to evacuate large buildings or a city, it is enough to shut down (or put into a safe mode) critical systems such as trains, gas lines, elevators, tunnels, and bridges.  Unfortunately, it is not enough time to send text messages to millions of people simultaneously, so earthquake alerts go only to emergency agencies, utilities, and similar high-priority organizations.

For more about ShakeAlert, see the fact sheet at http://pubs.usgs.gov/fs/2014/3083/pdf/fs2014-3083.pdf

Traveling in Pennsylvania

Last weekend we used the Pennsylvania Turnpike for our drive to the Pittsburgh area.  Because we were headed away from Philadelphia, we were surprised to see roadside emergency signs "warning" us about the visit by Pope Francis.  At the Somerset service plaza, we found cards on every table reinforcing the message (see photo).  The back of the card had advice about safe driving that would normally be relevant to a severe winter storm.

The Turnpike's website also had this "highway advisory" (the original was in ALL CAPS):

To all travelers on the Pennsylvania turnpike Interstate 76, Interstate 276, and Interstate 476. Motorists are advised of the upcoming Pope visit in Philadelphia on September 26 and September 27, 2015. This event is expected to cause significant congestion around the Philadelphia region from the Reading interchange to the Delaware River bridge, and from the Pocono interchange to the mid-county interchange. For travelers not destined for Philadelphia during this time, find an alternate route.

Although the Pope poses no threat, the traffic surrounding his visit will be disruptive, so the Pennsylvania Turnpike staff prepared a standard risk communication message that describes the potential problem, its extent (time and place), and what one can do to mitigate it.