SR/SSD 97-52

12-1-97

Technical Attachment

Houston/Galveston Coastal Flooding Seminar

November 14, 1997

Robert C. Van Hoven

NWSO Houston

A Coastal Flooding Seminar was hosted by the Houston/Galveston National Weather Service Office. The seminar was patterned after NWSO Tampa Bay's Coastal Flooding Seminar. However, NWSO Houston's seminar is somewhat different since every coastal marine area differs in many respects. The purpose of these meetings are to address upcoming changes in coastal flood forecast/watch/warning responsibility by NWS coastal offices. Forecasters from Brownsville, Corpus Christi and Lake Charles participated in this seminar.

Dr. Steve Lyons, Chief of Analysis and Forecasting Branch at the Tropical Prediction Center, discussed a broad range of topics relating to coastal flooding. He reviewed the mathematical relationships linking the characteristics of wavelength, wave period and wave height to wave speed in deep water and to wave energy. Other topics included wind stress on the ocean surface along the coastal zones, Ekman transport of water mass, wind/swell waves, breaking waves/surf forecasting, wave refraction and seiches. Overall, Dr. Lyons provided a very informative session that hopefully, will remain ingrained in the minds of forecasters attending the seminar.

Jimmy Don Ward, Science and Operations Officer NWSFO EWX/SAT, explained the procedures used by his office for coastal flooding. He discussed in some detail Part C, Chapter 43 of the National Weather Service Operations Manual. He also pointed out synoptic situations that may lead to coastal flooding.

Captain Stephen F. Ford of Texas A&M University at Galveston discussed the Houston/Galveston Physical Oceanographic Real-Time System (PORTS). This is a public information system that provides essential real-time information for safe and cost effective navigation, hazardous material and oil spill prevention and response, search and rescue, and scientific research. Meteorological and oceanographic sensors are part of PORTS. Sensors located along the Houston/Galveston Ship Channel have provided invaluable information to NWSO Houston's forecasters especially during severe weather events involving strong winds, and fog situations involving very low visibilities hampering maritime navigation. For those interested, PORTS data can be accessed from NWSO HOU's home page.

Dr. Peter Mantz of Lamar University at Beaumont discussed the Texas Coastal Ocean Observation Network (TCOONS) and, more specifically, the hourly tidewatch information for Southeast Texas bays and coast. This was a combined effort involving the government of Texas and several agencies of the federal government including NOS. Several of the tidal sensing sites also have meteorological sensors. The Internet site is http://tidewatch.lamar.edu/.

Harry Brown (Galveston County Office of Emergency Management) reviewed how past coastal flood events have affected Galveston County. He showed vivid before and after photographs of houses on the coast affected by coastal flooding. He also discussed different barrier methods used to alleviate further beach erosion. The bottom line - none are fully successful.

Don Ocker, Warning and Coordination Meteorologist NWSO BRO, discussed coastal flooding problems on the lower Texas coast including dangerous sandbar conditions which sometimes result in loss of lives. He also discussed how tides affect coastal recreational areas like South Padre Island. In many instances, campers on the island wake up in the morning knee deep in water due to high tides. He pointed out how the offshore weather buoys can be an invaluable aid especially when anticipating swells propagating toward the lower Texas coast. Don also dwelled on the lighter side making his presentation an enjoyable one for all participants.

The Coastal Flooding Seminar was quite successful and helped prepare participating forecasters for coastal flood watch and warning responsibilities.