Crawfish Tales
A Quarterly Publication of the National Weather Service Lower Mississippi River Forecast Center
Slidell, Louisiana

David Reed, Hydrologist In Charge Vol. 5 No. 1, Autumn 2001 Ethan A. Jolly, Editor

Features Special Issue: Southern Region River Forecast Center’s Technology Transfer Workshop 2001

From the HIC

We are nearing the end of an eventful 2001. We had widespread flooding in the Spring followed by the remnants of Tropical Storm Allison causing major flooding over much of southern Louisiana in early June. The NWS conducted a Services Assessment on TS Allison and LMRFC received many kudos. To quote from the Assessment “The LMRFC provided outstanding service to its customers and partners”. Congratulations on a job well done to the staff at the LMRFC.

During this period, we have been busy on many fronts to implement technology to provide you better products and services. Some of our forecasts are available on a personal digital assistant (PDA) and all should be available soon. Our web presence continues to improve and we have more products that will meet your needs. We continue to implement new forecast techniques to improve our forecasts.


This issue will be devoted to some of those technological advances. LMRFC recently hosted a workshop to transfer technology between the four Southern Region RFCs. At this workshop, our technological advances along with those of the other RFCs were highlighted. Work teams were formed and we will be working together as a region to implement some of the emerging technology to improve services at LMRFC and the other RFCs in SR.

We will do all this and continue to prepare for the coming 2002 flood season. Please let us know if we need to provide additional products and services. We always enjoy hearing from our cooperators and partners.

- Dave Reed

Southern Region River Forecast Center’s Technology Transfer Workshop 2001

During the week of November 5, 2001, representatives from all the Southern Region River Forecast Centers met at the LMRFC to share technological advances and service improvements. The goals of the meeting were:
1. Share Existing Technology - Provide a forum for RFC developers to share information and resources
2. Establish Regional Project Teams - Establish regional project teams to implement new technologies and improve products and services. Both goals were met and the conference was considered a success. Attendees included representatives from each SR RFC, Southern Region Headquarters, and the Office of Hydrologic Development. The LMRFC gave presentations on several topics which are summarized below. The full presentations can be downloaded from our web site.

PDA Forecasts
As the needs of mobile community continue to expand, the LMRFC has stepped forward to accommodate our users by posting all of our forecasts online in an PDA format. A PDA, acronym for Personal Digital Assistant, can store a calendar, address book, send email, pull up web pages, and handle many other functions. Since the PDA is small enough to fit into your hand, specially formatted web pages have been created to best suit this environment.

Figure 1: Screen Shot of New Orleans’ forecast on PDA
PDA Forecast for New Orleans
Click for larger image

The LMRFC has been posting PDA formatted pages for the lower Ohio and Mississippi River for several months and is currently working on adding all forecasts in the LMRFC area. The forecasts for the Ohio and Mississippi can be found at

The forecasts for the other rivers in the LMRFC will include the latest river stages along with the three to five day forecast. These should be online by the end of the year and will be found by visiting the above URL.

- Ethan Jolly

Arcview GIS
Activities at the LMRFC Technology and its rapid advancement over the past few decades have led us into a world of high resolution/better quality data and information. Geographic Information Systems such as ArcView and GRASS, have made it possible to process, display, and manipulate high-resolution geographic data to solve many real-world problems. LMRFC has combined the functionality of ArcView with gridded data products and digital elevation data to support its webpage and provide high-quality graphical products for its customers.

The Lower Mississippi River Forecast Center (LMRFC) collects, processes, and analyses a large amount of data. To keep its users informed, the LMRFC prepares a significant number of products using ArcView/GIS. These products are used internally at LMRFC and within the NWS and may be posted to the LMRFC webpage. Some products prepared using ArcView include:
a) precipitation estimates from the NWS WSR-88D Radar for time periods ranging from hourly to yearly;
b) contoured observed precipitation for time periods ranging from daily to yearly;
c) monthly normal precipitation maps and departure from normal;
d) forecasted precipitation in 6-hour increments for 24 hours in the future including gridded model output;
e) and maps displaying the status of river forecast locations. Images are made available via the website, however these data (in GIS format) will be made available for download.

Some future emphasis will be place on 3D analyst tools and what it may offer as well as the Arc-IMS internet map server. The map server will allow any internet user to create and zoom in on any arcview compatible dataset.

- Keith Stellman

Work Station ETA
The workstation Eta is a numerical modeling package used by the Hydrometeorological Analysis and Support (HAS) group to get high resolution model data into the LMRFC. The model runs twice daily at 00z and 12z on a dual 800 MHZ Linux PC. The workstation Eta has a domain roughly the size of the LMRFC with a model resolution of 20 km. The model uses input from the Eta model run at the National Centers for Environmental Prediction (NCEP) in Washington DC.

The meteorological output from the workstation Eta model has a time step of 6 hours with model output to 60 hours. Output from the workstation Eta includes the following: pressure, temperature, wind, and precipitation. Other meteorological output is available from the workstation Eta model to determine the possibility for heavy rainfall and severe weather.

The workstation Eta has been running at the LMRFC since March 2001. The HAS group uses the information from the model to determine the possibility for heavy rainfall. To determine how well the workstation Eta predicts rainfall, graphical and statistical based verification has recently been established. The graphical verification is run twice a day on a 4 panel display and allows the forecaster to compare observed rainfall to the precipitation from the workstation Eta model, Eta model, and forecasted rainfall from the HAS forecaster. The statistical verification is run once a month and compares the workstation Eta to the observed rainfall estimates from ground instruments and radar derived precipitation. Mean absolute, mean, and root mean square errors have been computed for southeast Louisiana with general trends showing a high rainfall bias for the workstation Eta. Since the statistical sample size is quite small, more months are needed before more definitive results can be completed.

The workstation Eta will continue to run at the LMRFC to help HAS forecasters with heavy rainfall. Future work will include lowering the resolution to 10 km for a smaller domain of the LMRFC area to possibly study sea breeze effects along the Louisiana and Mississippi coast. Verification will continue to be perform to validate benefits from the workstation Eta.

- Jeff Graschel

SLOSH and the Interface with DWOPER
The LMRFC has developed joint river surge operational procedures with the Weather Forecast Office New Orleans/Baton Rouge(LIX) and the Tropical Prediction Center(TPC). When a hurricane approaches the Louisiana coastline, one area of concern is the storm surge and its affect on the lower Mississippi River. To hydraulically route river waves, the LMRFC implemented the NWS Dynamic Wave OPERational Model (DWOPER) to forecast the effect of storm surges. The TPC Sea-Lake Overland Surge from Hurricanes (SLOSH) model is run at TPC to determine storm surge MSL heights at specific locations along the Gulf Coast.

DWOPER is the LMRFC river surge model and was developed for a 254 river mile reach along the lower Mississippi River running from Red River Landing to West Pointe ala Hache (WPHL1). River forecasts are prepared for both boundary stations plus the following river locations: Bayou Sara, Baton Rouge, Donaldsonville, Reserve, New Orleans, and Chalmette. The SLOSH surge hydrograph output is used as input to DWOPER at the WPHL1 downstream boundary to allow forecasting of surge heights at the above 8 locations.

Operational action taken by LMRFC is dependent on hurricane status. For a Hurricane Watch (landfall > 24 hours) situation, LIX provides LMRFC forecasters with five possible surge scenarios based on a TPC catalogued set of surge hydrographs for WPHL1. The five possible surge hydrographs are then input at WPHL1 and dynamically routed upstream providing a range of crests at each of the 8 forecast locations along the Mississippi River. These possible crests are issued to LIX for inclusion in the public Hurricane Local Statement product. When a Hurricane Warning is in effect (landfall < 24hours), a single surge hydrograph based on TPC’s best forecasted track is input at Pointe a la Hache, LA and a single crest for each river location is issued by LMRFC using the NEWRVASIL mainstem product.

- Bob Stucky

Storm Surge/SLOSH Interfaces
The National Weather Service, Lower Mississippi River Forecast Center (LMRFC) is responsible for forecasting river storm surges within the Mississippi/Louisiana Gulf Coast Region. In a joint effort with the Tropical Prediction Center (TPC), realtime automated procedures have been developed to download and process storm surge hydrographs generated by the Sea, Lake and Overland Surges from Hurricanes (SLOSH) Model. The SLOSH surge hydrographs are processed through a series of local programs and scripts on the AWIPS platform with selectable output in text format for forecaster analysis and review. These hydrographs show predicted water levels at the mouth of several rivers draining into the Gulf of Mexico.

These surge hydrographs are input directly as downstream boundary conditions to the NWS River Forecast System (NWSRFS), Dynamic Wave Operational (DWOPER) Model for forecasting river crests as the surge wave progresses upstream. The forecast output from the DWOPER model is used as important hydrologic guidance for several points along the lower Mississippi River beginning at West Pointe ala Hache, Louisiana, and upstream 254 river miles to Red River Landing, Louisiana; which includes the New Orleans metropolitan area.

- Eric Jones

The LMRFC has begun to utilize PHP and MySQL in order to create a more dynamic web environment. PHP is a server side programming language that is easily embedded into standard HTML code which makes it quite easy to create web sites using PHP. Also, all of the calculations are done on the server before sending the page to the users, thus eliminating slow downloads and browser compatibility issues. MySQL is a database that works seamlessly with PHP for data extraction and manipulation. Both of these technologies are open source which makes them highly refined by many the users that have developed them and, best of all, it’s free.

The LMRFC is currently working with PHP and MySQL on several interactive Intranet projects and plans to implement this technology onto the LMRFC web site in the near future. Some uses of this technology for the LMRFC include forecast standardization, custom searches, and inclusion of latest river stages.

- Ethan Jolly is the U.S. government's official web portal to all federal, state and local government web resources and services.