(*Chip Merlin’s Note–Rocco Calaci has been a noted meteorology expert witness in the Katrina Legal Wars. After meeting him at a recent FAPIA Convention, I invited him to write a series of guest blogs. His previous guest blog was, Is The Saffir-Simpson Scale Still Relevant.)
Is a hurricane only wind and water?
I have been collecting and analyzing meteorological data from Hurricane Ike for the past several months. The actual date of my research and analysis began on September 14, 2008, the day after Hurricane Ike hit southeast Texas.
Everyone talks about the maximum wind speed, the highest wind gust, the storm surge and how all of it fits together as part of Hurricane Ike. What puzzles me is why aren’t more people focusing on many of the other weather elements found within Hurricane Ike (and other hurricanes) that routinely cause ground damage, most of the time hours before a storm surge hits the coastline.
Hurricanes are more than just high winds and water. Hurricanes also spawn tornadoes, microbursts, straight line winds, extreme ground turbulence and phenomena that have the definite capacity to destroy houses, rip off roofs, uproot trees and do lots of damage. There are also induced dangers such as funneling winds and wind maxima areas (an area where two wind bands converge together to form a small area of increased wind speeds). These meteorological elements occur during hurricanes, yet everyone focuses on the highest wind speeds and storm surge heights.
Some of these mentioned elements can be detected and measured by the latest weather technology, but most of what I mentioned can not be measured. That doesn’t mean that the phenomena do not occur or can not be proven. I’ll start with mesocyclones.
As defined by the National Oceanic and Atmospheric Administration’s National Weather Service (NOAA/NWS), a mesocyclone is a storm-scale region of rotation, typically around 2-6 miles in diameter and often found in the right rear flank of a supercell. The circulation of a mesocyclone covers an area much larger than the tornado that may develop within it. In other words, mesocyclones have the capacity to spawn tornadoes.
Another specific point about mesocyclones as defined by NOAA/NWS – Properly used, mesocyclone is a radar term; it is defined as a rotation signature appearing on Doppler radar that meets specific criteria for magnitude, vertical depth, and duration.
This means that if all the physical characteristics of a mesocyclone are present, but it doesn’t meet ALL the specific criteria based on magnitude, vertical depth and duration, this phenomena will not be detected by NEXRAD. This is why some people state that NEXRAD may miss as many mesocyclones as it detects. The same goes for NEXRAD detected tornadoes. If NEXRAD doesn’t detect it, the meteorological event can still happen.
For example, the NEXRAD Doppler weather radar located in Houston and operated by the National Weather Service (NWS) detected numerous mesocyclones moving across Bolivar peninsula, the Sabine Pass area, northwest Houston, and along Galveston Bay. If you apply simple statistical data, 30% to 50% of all mesocyclones develop tornadoes. If there were 60 mesocyclones, they would spawn 18 to 30 tornadoes.
Just because there were no “confirmed” tornadoes doesn’t mean there were not any tornadoes. You have to understand the limitations of the NEXRAD radar, the rules, guidance and responsibilities pertaining to the National Weather Service and what you should do in the event you spot a tornado during a hurricane (or any other time). This is another subject for a later blog.
Please accept that no technology is perfect. The NEXRAD radar is a great upgrade from what meteorologists had before as the dedicated meteorological radar. NEXRAD provides all types of data and information used at all times by the NWS and National Hurricane Center (NHC), but it is not perfect. NEXRAD products are the visual results of algorithms. There is no algorithm for any meteorological event that can cover all possible scenarios. Even algorithms have limitations. Due to these limitations, NEXRAD can not detect each and every meteorological element that occurs.
Some people think the workers at NWS/NHC should be responsible for providing weather data for all people at all times. The NWS/NHC workers are already overworked, undermanned and unfunded and to have the inferred responsibility of having to provide weather information that applies to each person at any chosen time is unrealistic. This is impossible!
As for the rules and responsibilities of the NWS and NHC; these are dictated by people at high levels of government that really don’t have a clue as how a real weather situation creates more work than anyone could possibly expect. We expect miracles from the NWS/NHC and complain when miracles don’t occur.
From what I see as an impartial observer, The NWS and NHC are doing exactly what is mandated by higher headquarters and the government. Their job is to protect and warn the public, not determine the winds specifically at 123 ABC Street in Anywhere Texas.
(For further explanation of the damage caused by Ike, apart from the hurricane winds and water, please read Part Two of Rocco Calaci’s guest blog tomorrow.)