UP CLOSE: LOUIS UCCELLINI
DIRECTOR OF THE NOAA NATIONAL CENTERS FOR ENVIRONMENTAL PREDICTION DISCUSSES WINTER STORMS

February 8, 2007 — Louis Uccellini isn’t just the Director of the NOAA National Centers for Environmental Prediction, he has been passionate about weather – especially Northeastern snowstorms – ever since he can remember. As a child, he used to read every weather book he could get his hands on. Today, things remain much the same, only now he is also responsible for directing and planning the overall science, technology and operations related to NCEP's Central Operations and Environmental Modeling Center, as well as seven national centers that forecast specific weather phenomena. These centers include the National Hurricane Center, Storm Prediction Center, Space Environment Center, Ocean Prediction Center, Hydrometeorological Prediction Center, Climate Prediction Center and Aviation Weather Center.

NCEP, a central component of the NOAA National Weather Service, has been the focal point of the nation's environmental modeling efforts for 53 years. Its mission is to deliver national and global weather, water, climate and space weather guidance, forecasts, warnings and analyses to its partners and external user communities. These products and services ultimately help to protect life and property, enhance the nation's economy and support the nation's growing need for environmental information.

Since joining NOAA in 1989, Uccellini has held three high level positions at various NOAA National Weather Service offices — first as the Division Chief for the Meteorological Operations Division (now the Hydrometeorological Prediction Center), then Director of the Office of Meteorology at the National Weather Service headquarters, before becoming the Director of NCEP in 1999. Prior to coming to NOAA, Uccellini was Section Head for the Mesoscale Analysis and Modeling Section in the Goddard Space Flight Center's Laboratory for Atmospheric Science. He received his Ph.D. (1977), Masters (1972) and Bachelor of Science (1971), degrees from the University of Wisconsin-Madison (Click NOAA image for larger view of the location of the seven NOAA National Centers for Environmental Protection. Please credit “NOAA.”).

He has published more than 60 journal articles and chapters in books on subjects ranging from the analysis of severe weather outbreaks, cyclones and winter storms to the use of satellite data in analysis and modeling applications. He is the co-author of a widely acclaimed book entitled Snowstorms Along the Northeastern Coast of the United States: 1955 to 1985 and a two-volume book: Northeast Snowstorms — both of which were published by the American Meteorological Society.

Uccellini has received numerous awards in recognition of his research and operational achievements, including the American Meteorological Society's prestigious Clarence Leroy Meisinger Award (1985) and the National Weather Association's Research Achievement Awards for Significant Contributions to Operational Meteorology (1996). He was elected as a Fellow to the AMS in 1987, and received the U.S. Presidential Meritorious Executive Rank Award in 2001 and the U.S. Presidential Distinguished Rank Award in 2006. NOAA and the nation agree that Uccellini has and continues to play key role in advancing the agency’s weather and climate mission through improved forecasts, products and services.

Below Uccellini shares his thoughts on his work at NCEP and his expertise regarding winter storms — Northeast snowstorms in particular.

Q: Thus far, what has been your most memorable moment while working at NCEP?
A: One of my most memorable moments at NCEP was the central computer fire in 1999. I had just come onboard as the Director of NCEP and the fire caused a temporary loss of NOAA’s central operational computer. Not only was the fire damaging, but fireman sprayed the computer systems with a fire extinguisher that was not certified for use on computers — causing even more damage. Fortunately, the backup plan we had in place at the time successfully accessed other computer centers allowing us to provide products to our many users. I remember being very impressed with how NCEP staff, users and other government agencies worked together to provide a back up. Today, based in part on user demands, NCEP has full “primary” and “backup” super computer systems in place — one located in Maryland and the other in West Virginia. Each system is capable of processing 14 trillion calculations per second at maximum performance and currently ingests more than 240 million global observations daily.

Other memorable events involve the incredible advancements in forecasting extreme events days, and now even weeks, in advance. From the National Hurricane Center successfully forecasting the track of Hurricane Katrina in 2005 and the HPC accurately predicted the March 1993 snowstorm (“super storm”) five days in advance, to the incredible performance of the Storm Prediction Center and the local National Weather Service Weather Field Offices in forecasting the severe weather events of April 2006, days in advance. The ability of forecasters and the increasingly sophisticated numerical models implemented at NCEP over the past 10 years to make accurate forecasts of extreme events three to seven days in advance has been truly remarkable.

Q: How did you become interested in winter storms and other related weather phenomena?
A: My parents used to say that as soon as I learned how to talk, I was interested in and asking about weather. Growing up on Long Island in the 1950s and 1960s, I can remember several hurricanes affecting my home town (Bethpage) especially Hurricane Donna in 1960, and of course, snowstorms, which seemed to happen every year. I was always reading weather books and curious about why some winter storms generated rain, while others produced snow. Also, I wondered why it was so difficult to predict the type of precipitation associated with these storms. I remember liking the New York Times, not for its news, but for its great weather maps and staying up late to watch Tex Antoine’s weather forecast update on the 11 o’clock news. So, I always loved and have been interested in understanding the weather.

Forecasting Snowstorms
Q: What is the role of the NOAA National Weather Service in forecasting and warning for winter storms (including products and services)?
A: NOAA’s role in forecasting winter storms involves data observations, data assimilation and analysis, which are used by weather forecasters and serve as input into global and regional scale computer models. Computer models are able to predict weather developments days to weeks in advance. NCEP’s computer models generate a number of diverse products, including climate predictions, hurricane forecasts, air quality forecasts and even aviation weather products. Computer models are also used to predict flooding events. Forecasters use the guidance products from the numerical models to issue forecasts, watches and warnings for winter storms with 18 to 24 hours lead times, based largely on the use of the numerical models.

Another important point to remember is that NOAA’s job does not just end with forecasts; NOAA also promotes education and outreach so that people are able to understand and effectively use NOAA products and services for decision making. Our goal is not only to get the forecast right, but to provide climate, weather and water information that saves lives and property and safeguards our national and economic security.

Q: What is the biggest challenge NOAA faces in predicting winter storms?
A: There are many challenges confronting NOAA in predicting winter storms, including the need to predict all types of precipitation associated with these storms — rain, freezing rain, sleet, and snow — with the boundaries between these different types of precipitation being very small. Different regions will experience different types of precipitation and the NOAA National Weather Service does its best to differentiate between the type and how much precipitation will occur in each area, days in advance. This makes winter storm prediction especially challenging since you need to have the right combination of cold air secured near the Earth’s surface and warm moist air above the Earth’s surface to produce significant amounts of snow, sleet and freezing rain. Determining where these precipitation bands will set up and specifying the narrow boundaries which separate these areas is one of the important difficult forecast challenges facing the NOAA National Weather Service and the larger meteorological community.

Q: How has the science of winter storm prediction changed over the past few decades?
A: Winter weather forecasts have improved greatly since the 1980s. The most dramatic changes have been the development and use of global models and data input from the Global Earth Observing System. Today, the global models are run out to eight days with 35 km horizontal resolution. Regional models are run out to three and a half days with 12 km horizontal resolution, and special runs are made for very detailed forecasts with four to five km horizontal resolution. With increased resolution, the models now account for the dynamics and physical process that produce the “weather” with much grater fidelity. The progress in all of these areas has been simply outstanding.

Q: What do you perceive as being the most important winter storm forecasting issues in the future?
A: The most important winter storm/forecasting issues in the future will deal with meeting the ever growing expectations of the user community and regional forecasters, who rely on NCEP data and forecasts to make important decisions. My constant concern is that an expectation will exceed what we can actually produce in terms of accuracy, timing and geographic specificity.

NORTHEAST SNOWSTORMS
Q: What makes Northeast snowstorms so different from similar storms in other parts of the country?
A: All snowstorms are cyclonic events that form primarily when a low pressure develops to the south and east and combines with colder high pressure systems generally located to the north and west of the developing storm. What makes snowstorms in the Northeast unique in some respects is that the Appalachian Mountain chain helps to trap cold air along the coastal Plain. This combined with the moisture and warmth provided by the warm waters in the Gulf of Mexico and Atlantic Gulf Stream give these storms the moisture and energy they need to develop rapidly, making for a very interesting forecast challenge. Indeed, the “explosive” nature of these storms, which can develop in a matter of hours along the Carolina coast and then move Northeast toward the urban corridor from Washington, D.C., to Boston, has challenged meteorologists for years.

I was told that when Commerce Secretary Ron Brown was visiting the NOAA National Weather Service in 1993, he was briefed on the upcoming March 1993 “Super Storm” that had been in all the forecasts and news for the past several days. At the end of this briefing, he looked at the national satellite imagery and said, “Well, where is it?” The briefer noted that the storm had not developed yet, but our models agree that it will develop within the next 12 hours — and the models were right. Given how rapidly a storm can develop and the complex nature of the precipitation (snow, ice and rain) associated with them, it is hard to imagine how snowstorms were ever predicted in the days when there were no computer models or national radar and satellite images to depict exactly how the precipitation bands evolve during the storm’s lifetime.

Q: What is the Northeast Snowfall Impact Scale (NESIS), why is it important and how does it compare to the Fujita tornado scale and Saffir-Simpson hurricane scale?
A: Paul Kocin and I developed the Northeast Snowfall Impact Scale after describing and analyzing 70 historical Northeastern snowstorms for a monograph that was published by the American Meteorological Society, entitled “Northeast Snowstorms.” We determined that when all is said and done, what makes the event “memorable” in terms of its impact is the amount of snow which fell over populated areas. We then used this as a premise to quantify the impact of snowstorms on the Northeast United States by developing a scale based on an equation that essentially links the total snowfall over the lifetime of the storm and the population density affected by this snowfall. We call the resulting equation and related scale, the Northeast Snowfall Impact Scale or NESIS. Since NESIS takes into account the total integrated snowfall amounts and affected population densities, NESIS can be linked to the economic impacts (i.e., GNP, employment, etc.) of any snow event that affects the Northeast. NESIS can also be used to rank historical and current snowstorms and provide quantitative comparisons between storms that were previously based on people’s memories and qualitative accounts.

The Fujita tornado scale and Saffir-Simpson hurricane scale are also impact scales, based on the impact of the tornadic and hurricane force winds on building structures. However, these scales are based on instantaneous measurements and not cumulative measurements over the duration of the entire storm, as with NESIS.

Q: What Northeastern winter snowstorms rank highest on the NESIS?
A: The NESIS scale has been used to establish separate categories for Northeast Snowstorms that ranges from one to five. A value of one is given to “Notable Storms,” two to “Significant Storms,” three to “Major Storms” with ten to 20 inches of snow over a large area, four to “Crippling Snow” with 20 to 30 inches of snow, and five for “Extreme Events,” such as the March 1993 and January 1996 snowstorms (which are the two highest ranked storms). The third highest ranked storm occurred on February 2003, categorized as a level four. It is interesting to note, that from a 120-year sample, the three top snowstorms all occurred over the last 13 years.

Also, it is important to remember that the NESIS is based on the integrated impact of the entire snowstorm over a large area and shouldn’t be confused with local snow records. For example, New York City had a record snowfall in February 2006, but the storm only received a NESIS category of three since the very heaviest snowfall was very localized within a narrow band.

Q: Are there plans to implement NESIS in other parts of the county in the near future?
A: Yes, the NOAA National Climatic Data Center is planning to expand the NESIS to include the Midwest, Rocky Mountains and the South next year. They are currently working to calibrate the equation using historical events for those specific regions.

Q: Has the climatology of Northeast snowstorms changed in the last few decades?
A: Snowstorms are episodic in nature. You can go two to three years with very little snow and in one year, that can all change. For example, there was a snowy period in the late 1950s and early 1960s, followed by a snow drought in early-to-mid 1970s and 1980s, only to be followed by record setting snowfalls in the 1990s. Therefore, the pattern tends to change very rapidly from episodes of snow drought to periods of repeated storms.

Q: What can people expect to find if they read your two volume book entitled “Northeast Snowstorms?”
A: Reviewers have said that the books are the “most comprehensive treatment of snowstorms ever published.” The November 4, 2006, edition of the Wall Street Journal also called this book a “gold standard” for weather reference books.

Volume I contains an overview of Northeast snowstorms from both a meteorological and climatological points of view, describing how Northeast snowstorms develop, what factors help determine the type of precipitation that will fall, discusses forecast challenges, and also describes the NESIS application described earlier.

Volume II contains a case by case review of 70 snowstorms. It describes how they evolved and what makes them unique. It even includes a DVD containing all the data used in the book. The book and the DVD are now being used as part of the curriculum at several universities. The book took Kocin and me 10 years to write; we both spent many weekends to complete both volumes.

Q: What advice do you have for aspiring meteorologists?
A: I encourage all students to follow their dreams if they are interested in any of the geophysical sciences, including meteorology. They will need to focus on applied mathematics, physics, atmospheric chemistry, oceanography and computer science. Things are different now then when I was a student back in the 1960s and 1970s. In the past, you could get away with just being a “meteorologist,” but today you have to have a more diverse, interdisciplinary background because NOAA and other agencies are doing so much more from an “Earth Systems” perspective — rather than just an atmospheric perspective. You also need to understand that the ocean and atmosphere are “coupled” and that even physical processes associated with soil moisture can impact the energy balance in the atmosphere and thus influence the evolution of weather patterns on very short time scales. It is also important to understand the relationship between climate-weather, oceans–land, and the atmosphere chemistry linkage and other interdisciplinary attributes. Finally, I stress the important of communicating effectively to ensure one’s chances of success in this exciting field.

Relevant Web Sites
NOAA The Northeast Snowfall Impact Scale (NESIS)

NOAA National Centers for Environmental Prediction

NOAA National Climatic Data Center

NOAA Climate Prediction Center

Today's National Weather

NOAA National Winter Weather Forecasts

NOAA Weather Service

NOAA Operational Daily Snow Cover Analysis (Satellite Imagery)

NOAA Snow Water Equivalent

NOAA U.S. Snow Monitoring

NOAA Weather Service Suite of Official Weather Products

NOAA Winter Weather Safety/Wind Chill

NOAA Storm Watch

Media Contact:
Carmeyia Gillis, NOAA Climate Prediction Center, (301) 763-8000 ext. 7163