Technical Attachment



Rick Dittmann

Regional Transition Hydrologist

On August 1, 1996, the NEXRAD Weather Service Office (NWSO) in San Angelo, Texas, will assume responsibility for its Hydrologic Service Area (HSA). This will mark the culmination of the HSA transition for the Southern Region of the National Weather Service (NWS). The result is 30 NWSOs/NWSFOs across the Southern Region with 19 Service Hydrologists. These Service Hydrologists have hydrologic program leadership responsibility for their own office and, in some cases, support roles for one or more adjacent NWSO. For example, the Service Hydrologist at San Antonio provides hydrologic support for his NWSFO, as well as NWSO Brownsville and NWSO Corpus Christi. As a result of modernization throughout the NWS during the 1990s, great improvements have been made and continue to be made in the technologies used to help mitigate loss of life and property from weather-related hazards. The Service Hydrologist during and after this modernization will have not only the benefits of these new technologies, but also faces the increased challenge of learning these new technologies and how to use them to better meet the needs of our hydrologic product customers.

According to their position descriptions, Service Hydrologists have dynamic, challenging jobs requiring physical labor, a high level of knowledge, the ability to learn, exceptional communications skills, interagency liaison work and training of staff members. As more and more people move into flood plains, coastal areas, etc., the work of the Service Hydrologist becomes more critical. Education, preparedness, and awareness efforts are key for not only fellow WFO staff members, but media, emergency management officials, and the public. As we move into the 21st century, the Service Hydrologist must take the responsibility to act in concert with the SOO and WCM to bring about the highest level of service from the hydrologic programs of the NWS.

Community Outreach

The Service Hydrologist position description reads in part, "In coordination with the WCM, lead the NWS effort to encourage flood preparedness activities in local communities. Give presentations on the dangers of flooding to local civic groups and schools." The reason for this cannot be said enough--floods and flash floods kill more people in the United States annually than any other weather-related phenomena. Not only should the Service Hydrologist be making presentations to groups with a focus on specific flood and flash flood hazards within their HSA, but he/she should also be encouraging the WCM and other staff members to focus at least part of their presentations on flood and flash flood hazards. There are a number of nationally produced brochures, handouts, slides, and videos which can enhance these presentations. The Awesome Power and The Hidden Danger, Low-Water Crossings are two videos that should be shown as often as possible.

Annual awareness efforts specifically directed at the flash flood problem in a WFO's HSA should also be implemented. One example of a successful program exists at NWSFO Albuquerque, where an annual flash flood and lightning awareness week has been incorporated since 1989. This awareness week is an opportunity to focus attention on safety rules, NWS technologies, the forecast, watch and warning program, NOAA Weather Radio (NWR), and specific areas of concern within an HSA subject to flooding or flash flooding. This awareness week is also a prime time to coordinate with emergency management officials, spotter groups and the various news media for greater dissemination of the flood and flash flood message. Several other offices in the Southern Region have similar educational and awareness programs dedicated solely to flooding and flash flooding.


Training forecasters to be much more familiar with hydrologic databases, collection platforms and stream response theory is critical. A working knowledge of basic hydrology is paramount for shift forecasters. Since more hydrology will be worked into the modernized forecast system, shift forecasters will need a greater knowledge of hydrologic processes to make hydrologically-based forecast, watch and warning decisions. A recommendation from the natural disaster survey for the northern California floods of January, 1995 (DOC 1995), was:

The Service Hydrologist must work with both the CNRFC and NWSO Sacramento to ensure an effective hydrologic program for both mainstem river flooding and flooding on the smaller tributaries. This includes making sure the staffs of all offices with hydrologic responsibility in the HSA are fully trained and have sufficient resources (E-19s, hydrologic tables, etc.) to fulfill their operational responsibilities.... ...Office managers should ensure that hydrology is a "station" function and that all staff members are aware of their responsibilities and have been adequately trained.

The SOO, WCM, and Service Hydrologist are responsible for training on-station and for offices with potentially catastrophic flood and flash flood areas should place great emphasis on the hydrologic training of staff members.

This training should focus on making forecasters cognizant of individual stream responses within their HSA. Stream response histories of past events and potential events should be highlighted. This will help give forecasters an idea of the severity of future events helping them to issue more timely, more specific, and more accurate warnings and statements. Another recommendation from the January, 1995, California floods disaster survey suggests:

Offices with HSA responsibility should ensure that additional meaningful "added value" information is included in public products in a timely manner. Information such as damage expected from a forecast stage, how a river level compares to past flooding, and call to action statements can be essential to private citizens and local agencies in making emergency decisions.

Case studies of past events showing rainfall amounts, radar echoes, and related river response behavior within a WFO's HSA should be prepared and shown to forecast staff members. These are most critical for rapid response streams, the time scales for which RFCs are not yet able to provide appropriate modeling and forecast support.

Other training should take the form of field trips by operational personnel. By seeing first hand the terrain in question, forecasters can gain tremendous insight as to potential flood and flash flood hazards within specific basins. These field trips are still irreplaceable as learning tools for forecasters charged with issuing warnings to mitigate the loss of life and property. Service Hydrologists could actually prepare a map highlighting critical flood and flash flood sites to visit. A forecaster could then visit these sites when time allows, as when on an extranumerary shift.

Interagency Interaction

The makeup of Southern Region WFOs ranges from the Desert Southwest and southern Rockies, through the southern Plains and associated "tornado alley," the Lower Mississippi Valley, the southern Appalachians, the Gulf Coast and associated "hurricane belt," and Puerto Rico and the U.S. Virgin Islands. We (NWS meteorologists in general) may tend to place more energy in tornado alley on tornado and severe thunderstorm awareness than we do on the flood and flash flood threat. However, more lives are lost annually as a result of flooding and flash flooding than they are from severe thunderstorms and tornadoes, even in tornado alley. Similarly, along the coast, we may tend to place more emphasis on the wind damage associated with hurricanes rather than the damage caused by tidal surges and flooding rains. However, aerial surveys from Hurricane Opal revealed water (storm surge) was the primary culprit in producing damage as it undermined buildings and roads and eroded miles of beach.

Tropical Storm Alberto created quite a media spectacle as it approached Florida during July 1994, but the spotlight seemed to disappear when the storm was quickly downgraded to a tropical depression just hours after landfall. In reality, though, the real threat from Alberto was just being realized. The next several days were marked by excessive rains (over 27 inches of rain at Americus, Georgia) resulting in flash floods and mainstem river floods which claimed 33 lives. From the Alberto disaster survey report (DOC 1995) came these recommendations:

More emphasis should be placed on public awareness and preparedness training for flood and flash flood events. The continued high number of vehicle-related deaths during floods and flash floods indicates the need to educate the public of the risks involved with vehicles in flood situations.

The NWS should work with the media to educate the public on the fact that heavy rains and widespread flooding from tropical storms and hurricanes may have as much, and in some cases even more, detrimental impact as winds at landfall.

...the WCMs in all areas which might be affected by the aftermath of decaying tropical cyclones should reenforce the potential for severe flooding from such storms with the user community.

This user community as stated in the Alberto disaster survey includes county emergency managers, Corps of Engineer districts, Federal Emergency Management Administration officials, U.S. Geological Survey, and other local and federal agencies interested in the reduction of property damage and loss of life from weather-related phenomena. Typically, leadership for this coordination and communication has been the responsibility of the WCM and the MIC/HIC. More and more, though, Service Hydrologists must pursue this avenue as a means of improving education, awareness, preparedness, and response with respect to flood and flash flood events.

Jack of All Trades

Making people aware of the hazards of a tropical weather system, not just when it makes landfall, but for the next several days due to its flood potential; making people aware of particularly dangerous streams in popular recreation sites; educating people on how to take quick action when flash flooding occurs; enhancing the ability of the forecast staff to make quick, accurate and informed decisions to warn on flood or flash flood events; improving cooperation and coordination of local and federal agencies before, during and after flood and flash flood events; maintaining knowledge of new technologies and incorporating these new technologies into mainstream hydrologic forecast, watch and warning programs--these are a few of the challenges Southern Region Service Hydrologists are being asked to accept in their role of mitigating the loss of life and property from floods and flash floods--currently the leading cause of annual, weather-related deaths in the United States.


U.S. Department of Commerce, 1995: Natural Disaster Survey Report, Tropical Storm Alberto Heavy Rains and Flooding Georgia, Alabama, Florida, July, 1994; NOAA, National Weather Service, Silver Spring, Maryland.

U.S. Department of Commerce, 1995: Natural Disaster Survey Report, Northern California Floods, January 7-15, 1995; NOAA, National Weather Service, Western Region, Salt Lake City, Utah.