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Spring 1999

U.S. and World Weather Research Programs move to new stages

Hurricane Georges, one of the powerhouses of the busy 1998 Atlantic season, caused billions of dollars in damage in Puerto Rico and hundreds of deaths in the Dominican Republic, remaining strong even as it passed over the mountainous islands. The WWRP is planning a tropical-cyclone research activity between 2001 and 2004 centered on the Caribbean as part of the USWRP's hurricane-landfall studies.

Their sights are fixed on a few of the world's knottiest, but most rewarding, weather-prediction problems, and both the six-year-old U.S. Weather Research Program and the one-year-old World Weather Research Programme are ready to carry out their research plans. This new stage in the closely related programs' lives is marked by a change in personnel. Richard Carbone (NCAR Mesoscale and Microscale Meteorology Division), who has been the USWRP's lead scientist for five years, stepped down from that position on 28 February. Robert Gall, director of MMM, is the new lead scientist. Carbone will continue as chair of the WWRP's Science Steering Committee.

The WWRP, which Carbone describes as "a consolidation of all the research programs related to weather prediction in the World Meteorological Organization," is catching up with the U.S. program because it could build on the USWRP's groundwork. Through years of research and planning, Carbone explains, the U.S. program identified "a handful of prediction problems" whose solution--with the resulting improved forecasts--would provide a substantial benefit to society. Both programs have put these problems among their highest priorities, with differing emphases that arise naturally from the difference between a national and a global program.

Richard Carbone. (Photo by Carlye Calvin.)

Several of the forecast problems fall into two areas: prediction of heavy precipitation and flooding, and prediction of the landfall of tropical cyclones (hurricanes). Carbone explains that prediction of the onset of heavy precipitation is the area of lowest skill in all of weather forecasting. Yet heavy rainfall and flooding wreak more damage than more widely feared events, such as tornadoes. "You have to be able to predict exactly when and where the precipitation is going to start. Research models can't do it well; operational models do it less well. A critical research problem is prediction of the start of organized convection--not so much the isolated thunderstorm, but when clusters get together and modify atmospheric circulation for 5 to 100 hours."

Predicting the landfall of tropical cyclones "is a problem for a sizeable fraction of the countries around the world," Carbone says. Although predictions of where a cyclone will reach land have improved, there has been very little progress on predicting the intensity of the storm at landfall beyond 12 to 24 hours in advance.

WWRP plans

The WWRP will sponsor two categories of projects; so far, it has approved one of each kind. The Mesoscale Alpine Programme, reported in the last issue of the UCAR Quarterly is the WWRP's first research-and-development project. Sydney 2000 will be its first forecast-demonstration project. This program will focus on urban nowcasting and very short-term forecasting.

"The WWRP puts higher priority on urban nowcasting than does the USWRP," Carbone says. Urbanization is skyrocketing in the world's poorer countries, with more and more people concentrated in a small land area. For all its ill effects, this trend does mean that "just a few instruments and forecasters can benefit a large part of the world population."

For Sydney 2000, groups from four nations--Australia, Canada, the United Kingdom, and the United States--will take their most advanced experimental forecast systems to Sydney from mid-August to mid-November 2000, which encompasses the summer Olympic games. In a sense, this team will be competing too. During the Olympics, Australian meteorologists will make two forecasts: the official one, which will use results from both operational and demonstration systems, and a second one without benefit of the demonstration information. Evaluating the impact of the demonstration results will be a group of social scientists, who will assess the value added by the experimental systems. In addition, an independent team, led by Radmila Bubnova of the Czech Hydrometeorology Service, will do forecast verification according to physical science metrics.

Floods account for more losses than any other natural disaster in the United States, yet forecasting of heavy precipitation is the area of lowest skill in weather prediction--a problem that both the USWRP and WWRP will seek to remedy. (Photo by Curt Zukosky.)

The U.S. team's member systems include NCAR's Auto-Nowcaster (which projects short-term thunderstorm development) as well as university and NOAA candidate subsystems for a future National Weather Service nowcast/forecast system. Other experimental systems originate at Canada's Atmospheric Environment Service, Salford University in the United Kingdom, and the U.K. Meteorology Office. "All of these systems have been tested in research mode, and we know that they work in their native countries," Carbone says. "The question is, how portable are they and how much value do they have individually and in combination."

Sydney 2000, like all WWRP projects, will include a strong component of education and training. After the Olympics, 10 or 15 highly experienced forecasters from other parts of the world will visit to observe and operate the experimental systems. "They'll learn about techniques used by the experimental systems and implement some of these, or borrow ideas, for use in their own countries."

Beyond MAP and Sydney 2000, WWRP is working with various groups to develop other projects. These include

Back in the USWRP

The U.S. program, which has been sponsoring initial research for several years, will report some of its findings at the First USWRP Science Symposium at NCAR on 29-31 March. The audience will include interested people in many fields--physical and social scientists, forecasters, policy makers, and other users of forecasts. "I hope [the symposium is] as multidisciplinary as the USWRP should be," says Roger Pielke, Jr. (NCAR Environmental and Societal Impacts Group), who helped organize the panels for the meeting.

Both of the USWRP's focus areas, forecasts of hurricanes and precipitation (at this meeting, specifically quantitative precipitation forecasting) will be addressed. For each area, there will be panel discussions of the state of the science and its human impacts as well as scientific talks and poster sessions. The presenters will not only explain their work but discuss how it could be used to improve or to show the value of forecasts.

As the symposium shows, the USWRP is making an impact. Its funding levels, however, have been less than needed to fulfill all the program's plans. The federal budget for fiscal year 2000 for the program's four funding agencies (NSF, NOAA, NASA, and the U.S. Department of Defense, primarily the Navy) will not allow the program to proceed with all its research. The full program would require incremental funds of about $130 million from now through 2005. UCAR, a strong supporter of the weather program, is engaged in an advocacy effort under the direction of UCAR vice-president Jack Fellows, with assistance from Burke Associates in Washington, D.C. "I personally have high expectations," says Carbone, "because this is not a partisan issue." Currently, hurricane and flood damage costs exceed $10 billion a year on average, so even if the USWRP could eliminate only a small part of that total, the program would pay for itself.

USWRP's new leadership

Robert Gall. (Photo by Carlye Calvin.)

The USWRP "has been near and dear to my heart for a long time," says Gall. "I think it's important to the nation. As an NCAR division director I've been involved in the program for many years." Gall will spend full time on the program for the next six months or so while on sabbatical from his divisional responsibilities. Russell Elsberry (Naval Postgraduate School) will be deputy lead scientist in charge of hurricane landfall studies, and deputy Thomas Schlatter (NOAA) will head efforts in quantitative precipitation forecasting.

At MMM, senior scientist Richard Rotunno will step in as interim director. While Rotunno is out of the country next fall at the Mesoscale Alpine Programme, there will be another acting MMM director. After Rotunno comes back, Gall will split his time between the USWRP and the MMM directorship, with Rotunno as deputy director filling in the other half of the latter responsibility.

USWRP science results

Some 50 scientific presentations are booked for the First USWRP Science Symposium. With the program's research phase just getting under way, many of these talks and posters will cover works in progress. Below are a few of the highlights. The full set of abstracts can be accessed at the USWRP's Web page.

Hurricane evacuations. Current estimates hold that each hurricane evacuation costs an average of $1 million per mile of coastline. However, Christopher Adams (Colorado State University) will show that the costs may exceed $50 million per mile in key areas along the Atlantic and Gulf coasts.

Despite these costs and despite NOAA's increased skill at hurricane track forecasts, the average length of coastline warned for a given hurricane has nearly doubled since the 1960s. Hugh Willoughby (NOAA Hurricane Research Division) is studying the factors behind this increase, which include tradeoffs between lead time and overwarning.

Model development. NCAR is teaming with NOAA and the University of Oklahoma to create a next-generation mesoscale forecast model that will build on current mesoscale models at each institution. Joseph Klemp (MMM) and colleagues have begun testing alternatives for the architecture and coding of the weather research and forecast (WRF) model. A community version for research may be ready in two to three years, with an operational version possible by 2004. The WRF will feature multiple nesting of model grids at 1 to 10 km to better depict thunderstorms and other mesoscale precipitation features.

Meanwhile, a series of field projects is testing the use of ensemble blends that outperform any single model. Dingchen Hou and colleagues at OU's Center for Analysis and Prediction of Storms tested four mesoscale models last May across the Southeast. Each model was run with slight variations at the starting points to produce a suite of possible outcomes. The resulting set of up to 25 forecasts per period showed that each model excelled in one or more measures, but the model consensus was superior to any single run.

Heavy summertime rainfall. Christopher Davis (MMM) will present findings on long-lived mesoscale cyclonic vortices that help trigger multiday rainfall episodes. These vortices appear with mesoscale convective systems (MCSs) that typically develop overnight and dump heavy rain for 6 to 12 hours. Davis and colleagues have found that when the vertical wind shear is fairly weak, the vortices can persist for hours after an MCS dissipates, sometimes forming the seed for a new MCS the next night. If mesoscale models can track these seed vortices, then there is hope for better forecasts of multiday heavy-rain events and possibly better forecasts of tropical cyclone formation.

Carbone and other scientists from USWRP, MMM, and NOAA have embarked on a major climatological study of MCSs using satellite, radar, and profiler data. Condensed water vapor will be calculated in three dimensions, providing an estimate of the latent heat added through condensation and the radiative effects of dense clouds devoid of rainfall. The study will help test and improve data assimilation techniques for mesoscale models.

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Edited by Carol Rasmussen, carolr@ucar.edu
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Last revised: Tue Apr 4 15:10:30 MDT 2000