June 16, 2006
Thank you for participating in todays discussion on hurricane preparedness. Last year we saw how devastating hurricanes can be, and there are many concerns about the severity of this season. Im eager to answer your questions about what is expected and how best to prepare.
Charles, from Bergenfield, NJ
Hi Mr. Mayfield,
I am a freshman in high school and I have always been fond of tracking
hurricanes. I wanted to become a meteorologist, however music education
seems to get to me now. I have 2 questions if you don't mind. There has
been some reports saying that the New York City and New England area has
a greater risk of tropical activity this area. Is this true ? Also, I
know from last year your forecast accuracy with Katrina was excellent.
You need to give credit to the computer models. How much have they
improved in these past few years? Thanks for your time Mr. Mayfield
Charles, I hope you area able to find a way to pursue both music and meteorology. The NOAA hurricane outlook does not focus on regions. Overall, we are calling for a busier than average hurricane season with 8 to 10 hurricanes to occur in the North Atlantic, Caribbean Sea and Gulf of Mexico. However, we have no way of specifying which coastal communities may be impacted. The entire U.S. Gulf of Mexico and Atlantic coasts are at risk and need to prepare, including New York and the New England area.
We are proud of our work during Katrina and the high level of accuracy for all the storms last year. I have to give credit to the forecasters at the National Hurricane Center and at the local Weather Forecast Offices. These men and women use tools such as the computer models to develop the forecast. There have been a number of advancements in hurricane modeling that make the forecasters' job much easier and help ensure more accurate forecasts. Dedicated employees at NOAA's Environmental Modeling Center and in NOAA Research have developed more realistic models for hurricane track and winds that are run on increasingly faster computers with more observations about the hurricane and its environment. Overall, hurricane track predictions have seen a 50% decrease in errors in just 15 years, though forecasts of the winds are improving at a slower rate. The bottom line is that improved hurricane predictions are really a team effort between many agencies and people both within and outside of NOAA.
barbara, from pa writes:
How quickly can you predict a serious hurrican with accuracy and how
quickly is this information filtered down to the preparedness units to
prevent danger to life, land, property?also what is the percentage of
Good question, Barbara. The National Hurricane Center issues forecasts out to five days in the future of both the track and winds of any existing tropical storms and hurricanes. These predictions can have very large errors in the 5 day forecasts with average errors of 350 miles for position and 25 mph for winds. For shorter lead forecasts, we have much smaller errors: 3 day track errors average 200 miles and 3 day wind errors average 20 mph, 1 day track errors average 75 miles and 1 day wind errors average 15 mph. In general, our ability to predict the track is very skillful (and improving substantially every year), but we still are not very good at predicting the winds of storms. All of our forecasts are made available to FEMA and the state and county emergency managers within seconds after they are produced. Additionally, we have conference calls with the FEMA and state emergency management officials if a tropical storm or hurricane is threatening the United States. National Weather Service local Weather Forecast Offices routinely provide briefings to local officials within their area of responsibility during tropical storm and hurricane threats.
Austin, from Wisconsin writes:
How do you dedice on hurricanes names?
Since 1953, Atlantic tropical storms have been named from lists originated by the National Hurricane Center. They are now maintained and updated by an international committee of the World Meteorological Organization. The original name lists featured only women's names. In 1979, men's names were introduced and they alternate with the women's names. Six lists are used in rotation. Thus, the 2005 list will be used again in 2011. The only time that there is a change in the list is if a storm is so deadly or costly that the future use of its name on a different storm would be inappropriate for reasons of sensitivity. If that occurs, then at an annual meeting by the WMO committee (called primarily to discuss many other issues) the offending name is stricken from the list and another name is selected to replace it. For more information, visit http://origin.www.nhc.noaa.gov/aboutnames.shtml.
Sharon, from Anderson, SC
When does the hurricane season actually start? I heard on the news the
other day it has already started and there will be about 10 this year.
What can people do to be more prepared?
The official hurricane season is June 1 to November 30, but it is possible to have tropical storms well outside that period. For instance, Tropical Storm Zeta formed last year on December 30. NOAA is predicting 13 to 16 named storms this season, with 8 to 10 becoming hurricanes, of which 4 to 6 could become 'major' hurricanes of Category 3 strength or higher. But I dont want you to focus on the number. It only takes one hurricane in your community to make for a bad year. The key to preparedness is for your family to have a plan that includes the hurricane hazards of storm surge, high winds, tornadoes and flooding.
For more information, visit www.nhc.noaa.gov/HAW2/english/intro.shtml.
Ben, from Davenport, Iowa
Why do hurricanes have the same amount of energy in one storm that
America uses in one year and is it possible to obtain some of that
energy?If it is possible why hasn't anyone done it before?
Excellent question, Ben. Hurricanes release an incredible amount of energy as you mention due to the conversion in clouds of water vapor to liquid water (This process is known as latent heat release from condensation.) Unfortunately, there does not appear to be a way to harness this energy being released by the hurricanes for beneficial use. This is because there is no way currently to capture or store this energy that the hurricane is releasing. This is not to say that it is impossible, but such use of hurricanes as energy sources is not likely in our lifetime.
Matthew, from Detroit writes:
Mr. Mayfield, your topic was partially described as preparedness for
hurricane season. With early predictions of the east coast to be the
'target' of a few powerfull hurricanes, how can New York, Virginia, New
Jersey and Maryland prepare for any serious flooding storm surge? Is
it possible for half of NYC to be under standing water like New Orleans
due to storm surge?
As I mentioned in an earlier reply, NOAA's seasonal hurricane forecast does not specify exact regions for hurricane strikes. However, the mid-Atlantic coast of the United States including New York, New Jersey, Maryland, Delaware and Virginia are at risk from a hurricane this and all hurricane seasons. State and local emergency managers already have storm surge maps available that simulate a wide variety of possible hurricane strikes in those states. These help to determine who along the coast is in danger of being flooded by storm surge and who should evacuate to prevent drowning as the water comes ashore. The massive flooding that occurred in New Orleans was a unique situation because of their location between the Mississippi River and Lake Pontchartrain and because most of the city is below sea level. However, it is possible that significant portions of New York City could be under water, if a Saffir-Simpson Hurricane Scale Category 2 or 3 hurricane makes landfall right over or just to the southwest of the city. Thus it is very important that if a hurricane threatens New York City (or any other city along the coast) that people listen to their local emergency managers and evacuate if requested.
josen, from Hawaii writes:
I wonder the Hurricane if affect Hawaii?
NOAA operates the Central Pacific Hurricane Center in Honolulu. Two to three tropical cyclones are expected to occur in the central Pacific basin this season, which would be a below average season. Often the Northeast and North Central Pacific hurricane seasons are quieter than usual when the Atlantic is active, and that is the expectation for 2006. However, even if it is a below average season in the North Central Pacific, Hawaii could still be significantly impacted by a tropical storm or hurricane. The Central Pacific Hurricane Center Web site is www.prh.noaa.gov/cphc.
Christopher, from Hartsdale, NY
Is it true that global warming increases the severity of the hurricane?
Christopher, there is an ongoing scientific debate about the relationship between man-made global warming and hurricane frequency and intensity. Hurricane theory does predict that global warming will cause hurricanes to become stronger, but only by about 2% more intense per degree Fahrenheit warming. There have been some studies published that suggest a large increase in hurricane winds over the last few decades, which is not consistent with the theory. However, Atlantic hurricanes also have been observed to have decades that are very busy (such as the late 1920s to the late 1960s as well as since 1995) and other periods that are quiet (such as the period of the early 1900s to the mid 1920s as well as the 1970s to the mid-1990s). Knowing how much of the increase we have seen in the Atlantic hurricane activity in recent years is due to natural cycles and how much is due to global warming is a very important issue and one that many researchers both in NOAA and elsewhere are trying to better understand.
Austin, from Wisconsin writes:
Are we doing research to see if there is a way to stop hurricanes
Austin, at one time, the U.S. government did research into what we refer to as 'hurricane modification.' Information on the project is online at www.aoml.noaa.gov/hrd/tcfaq/C4.html. I encourage you to read more about it.
It is important to remember that hurricanes have immense energy. The American Meteorological Society issued a policy statement in 1998 stating there is no sound evidence to support weather modification. No federal agencies are presently doing, or planning to do, any research or experimentation on the modification of hurricanes.
Better building codes, wiser land use, more accurate forecasts and family preparedness plans are probably wiser investments in dealing with the destructive nature of hurricanes.
Scott, from South Carolina
What actually causes low pressure in the atmosphere?
For a tropical storm to form, there are several conducive precursor environmental conditions that must be in place:
- Warm ocean waters of at least 80°F throughout at least 100 ft of depth. Warm waters are necessary to fuel the heat engine of the tropical storm/hurricane.
- An atmosphere which cools fast enough with height such that thunderstorm activity can occur.
- A relatively moist atmosphere. Dry mid and low levels are not conducive for allowing the continuing development of widespread thunderstorm activity.
- A minimum distance of at least 300 miles from the equator. For tropical cyclogenesis to occur, the impact of the earths rotation on the winds (known as the Coriolis force) is needed, but this is not felt near the equator. Without at least a modest amount of Coriolis force, the low pressure of the disturbance cannot be maintained.
- A pre-existing near-surface disturbance with sufficient spin and low level inflow. Tropical storms/hurricanes cannot be generated spontaneously. To develop, they require a sizable disturbance to continue providing warm, moist air to fuel the system.
- Low values (less than about 25 mph) of vertical wind shear between the surface and the upper level of the atmosphere. Vertical wind shear is the amount of wind change with height. Large values of vertical wind shear disrupt the incipient tropical storm and can prevent genesis.
Having these conditions met is necessary, but not sufficient, as many disturbances that appear to have a conducive environment do not develop. Predicting the formation of a tropical storm is a difficult forecasting challenge for us at the National Hurricane Center.
Cliff, from Brimfield, Ohio
Director Mayfield: When it comes to the prediction of hurricanes, what
do you use or look for? Is it weather conditions or a combination of
conditions that need to be present in order to predict a hurricane? Is
the hurricane center a 365 day 24 hr. operation or does the center
become active or more active DURING HURRICANE SEASON ONLY? Thank You
Cliff, in forecasting the track of hurricanes, we try to diagnose the large-scale "steering patterns" that move hurricanes. Key features include the strength and location of the Bermuda High (as hurricanes move clockwise around this high) as well as any dips in the jet stream (or troughs of low pressure) that can cause a hurricane to turn to the north. Computer models do an excellent job in providing guidance as to how these steering patterns will change over the next several days. However, predicting hurricane intensity is more difficult. Hurricane wind changes depend upon the ocean and atmospheric temperatures, the amount of moisture in the atmosphere, and how much wind shear (how the winds change with height) is occurring. Thus the intensity of the hurricane also depends on where it tracks. Providing useful, skillful forecasts of hurricane intensity is a very challenging problem that many folks in NOAA are addressing.
To address the second part of your question, the National Hurricane Center is an operational unit staffed 24 hours a day, year round. Our busy season is June to November. During the "off season," we continue to monitor weather patterns, but are also heavily focused on outreach to help coastal communities prepare for the next season.
Thank you for your thoughtful questions. If you live anywhere along the coast, please take time this weekend to prepare. Coastal residents and visitors need to act on the instructions provided by local emergency management officials. Prepare now so you are ready to act at the appropriate time.