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


All future issues of the LMRFC' s Crawfish Tales will only be posted to our web site.
Please send Dave Reed an email at dave.reed@noaa.gov with the subject “Newsletter
Reminder” to receive a reminder email when our latest issue becomes available online.
David Reed, Hydrologist In Charge Vol. 9 No. 1, Summer 2009 Glenn Carrin, Editor

 


Features

 


From the HIC

It' s been four years since Hurricane Katrina and, coincidentally, the last newsletter. With the changes that Katrina brought, we suspended the newsletter to focus on more pressing issues. In our personal lives, some have rebuilt homes while at the LMRFC we made many improvements and changes. We now have a more hardened building, more robust communications, and an enhanced backup system. We are much better prepared, both physically and mentally, for the next big disaster, whenever it may occur.

The NWS and LMRFC have experienced tremendous change over the past few years and the pace of that change will accelerate. New technologies will require that we continue to adapt our forecast process and methods of disseminating information. We are entering an era of enhanced support to assist our partners and customers in making decisions. We will use this newsletter as a method to convey these changes so that our partners and customers can make the most use of the services we have to offer.

In this issue, we focus on the changes that have occurred since Katrina with a few of the exciting enhancements we are making to our forecast with hydraulic modeling. We will focus on more of these changes in future newsletters.

We hope this newsletter will stimulate thought on new and innovative ways our forecasts and products can be used. Feedback on our products and services are greatly appreciated. Please do not hesitate to contact me or any of the staff members with any feedback on how we can improve these vital services to the citizens of the lower Mississippi River Valley.

- Dave Reed


Operational Changes Following Hurricane Katrina

Many changes have taken place at the Lower Mississippi River Forecast Center since Hurricane Katrina. Along with the many new faces, our hardware and software upgrades allow us to work better and more efficiently when providing hydrometeorological forecasts to save life and property.

When a hurricane threatens southeastern Louisiana, the LMRFC deploys some staff to an offsite location to provide back-up operational support using laptop computers. If the RFC in Slidell loses communications, the back-up team assumes forecasting operations. During Hurricane Katrina, the laptops provided essential backup operations but were inherently slow when supporting forecast operations. One major improvement since Katrina was upgrading the laptops used for backup operations, which vastly improved the processing capabilities to support forecast operations. New laptops also improved LMRFC's capabilities to update its website during backup operations. During Hurricane Katrina, LMRFC was able to maintain only a small portion of their website because of hardware and software limitations. Upgraded hardware and software capabilities now allow the LMRFC to fully support our website while running backup operations.

During Katrina, LMRFC lost communications for several days. LMRFC now has a dedicated satellite phone and limited satellite internet capabilities to allow employees to keep in touch with the outside world. Through NOAANet, LMRFC is expecting to be able to provide a limited set of operational products to NWS comms circuits through satellite communications.

Linking hydrologic forecasts to storm surge models has improved. Procedures were in place since the 1980's to combine Sea, Lake, and Overland Surge from Hurricanes (SLOSH) output to our hydraulic model on the Mississippi River. In 2006-2007, services were extended to include the Vermillion River in southwest Louisiana. In 2008, procedures and scripts were created to generate surge heights from SLOSH for small coastal streams where hydraulic models were unavailable. After its implementation, forecasters were able to see forecasted river heights based on the extra-tropical surge models.

The LMRFC and the Southeast Regional Climate Center jointly developed a tropical cyclone precipitation climatology for the southeast United States. An intranet website was setup to graphically display precipitation data from 77 tropical systems from 1971-2000. The precipitation data could then be downloaded and used as input into hydrologic models for what if scenarios based on historical tropical systems.


Tropical Cyclone Precipitation Climatology Display

Other improvements include setting up the communications to facilitate the coordination of Mississippi River forecasts with the US Army Corps of Engineers, placing a situational awareness display in our operations area to make it easy for forecasters to evaluate the weather and flood conditions, converting our website to the content management system, and creating a new Service Coordination Hydrologist position.

As you can tell, many changes have taken place since Hurricane Katrina. We are also excited about the upcoming improvements as we transition into the Community Hydrologic Prediction System environment.

 

- Jeff Graschel

The Mississippi River Model Transition from DWOPER and FLDWAV to HEC-RAS

The LMRFC is preparing to transition from our current river forecast system, the National Weather Service River Forecast System (NWSRFS), to the Community Hydrologic Prediction System (CHPS) based on the Delft-Flood Early Warning System (FEWS). FEWS was developed by the Dutch and is used extensively across Europe. CHPS is based on service oriented architecture allowing the NWS to easily and rapidly implement models developed by other scientists and agencies. As a result of this capability, the NWS will implement the U.S. Army Corps of Engineers Hydrologic Engineering Center – River Analysis System (HEC-RAS) for hydraulic modeling.

                      HEC-RAS Graphics

The hydraulic models from our current NWSRFS system, such as the NWS Flood Wave Dynamic Model (FLDWAV) and Dynamic Wave OPERational (DWOPER), will not be transitioned to CHPS. The LMRFC has four operational DWOPER models: 1) the Upper Mississippi/Lower Ohio/Tennessee Junction, 2) the Middle Mississippi, 3) the Lower Mississippi,and 4) the Lower Mississippi River Storm Surge, as well as  one FLDWAV model on the Vermilion River in South Louisiana; all of these must be converted to HEC-RAS. The transition involves using conversion software developed at the NWS Office of Hydrologic Development (OHD) to convert the existing symmetric geometry used in DWOPER and FLDWAV to HEC-RAS format. HEC-RAS uses the same hydraulic fundamentals in the calculations as DWOPER and FLDWAV. It is user friendly with convenient graphical user interfaces, has more modeling options, and is capable of representing more physical details. Furthermore, the HEC-Geo-RAS ArcGIS extension will enable NWS River Forecast Centers to develop new geo-referenced hydraulic models derived from high resolution digital elevation data, and has the capability to generate maps of the water surface elevations from the simulated stages produced in HEC-RAS. Using HEC-RAS instead of DWOPER/FLDWAV will also allow the NWS to utilize the HEC-RAS models already developed by the COE and other agencies.

The output from the current DWOPER models and newly developed HEC-RAS models should be the same. Because of key differences in the geometry processing, this is not the case, and the newly converted HEC-RAS models will require some calibration to improve their performance. During the transition, both the DWOPER and HEC-RAS models will be run and compared.

The LMRFC has nearly completed the Upper and Middle Mississippi River transitions from DWOPER to HEC-RAS, and is currently working towards completing the Lower Mississippi River Model. The Lower Mississippi River Surge and Vermilion River models will be converted this fall. Completing these models ahead of the initial delivery of the CHPS hardware and software, which is scheduled for October 2009, will greatly assist in a smooth transition. In the future, the LMRFC will develop more physically based models in HEC-RAS that will incorporate existing hydraulic structures, bridges and storage areas to be used as guidance during daily operations. By using the same software as the COE, we can make use of their HEC-RAS models already developed.

 

- Katelyn Costanza

 
The Development of Hurricane Storm Surge Forecasting Model for the Pascagoula River


River forecast models incorporate rainfall, flow, and soil moisture data to generate river forecasts. In coastal locations, river stages may be affected by astronomical tides, high water levels in the Gulf of Mexico, and storm surge from tropical systems as well as upstream river stages. The LMRFC is working to dynamically model these combined effects on the Pascagoula River watershed to prepare river stage forecasts. In addition to these forecasts, inundation maps showing the depths and extents of flooding as a result of this complex situation will be developed in real-time.


Gustav Storm Surge at Gulfport

A very important aspect of this work is accurately representing the topography of the river basin, flood plain, river channel, and estuary. Much effort has been put into creating an accurate digital elevation model of these areas. First, the initial river channel geometry data was determined by surveys performed by the USGS and the U.S. Army Corps of Engineers (USACE). Using this survey data, the University of Central Florida' s Coastal Hydroscience Analysis, Modeling & Predictive Simulations (CHAMPS) Laboratory developed a digital surface of the lower Pascagoula River channel and its estuary area (a gridded bathymetric representation). Next, a digital elevation model of the flood plain was merged with the CHAMPS bathymetric grid to produce a continuous surface representation of the lower river channel, flood plain, and estuary. Finally, this topographic surface of the lower river was merged with a similar digital elevation model of the upstream tributary reaches in order to complete the geographic picture.


The Lower Pascagoula Basin

The new hydraulic model for the lower Pascagoula River will use the USACE HEC-RAS model. Upstream river flow input into the new model will come from the National Weather Service River Forecast System (NWSRFS) model, which produces stream flow and stage hydrographs using the continuous Sacramento Soil Moisture Accounting model, unit hydrograph, and Lag and K hydrologic routing. Downstream data input will come from observed tide data blended with National Ocean Service astronomical tide forecasts, routine extratropical storm surge forecasts from the NWS Meteorological Development Laboratory, and storm surge forecasts generated from either the CHAMPS Lab or NOAA' s SLOSH Model.

In summary, this new hydraulic model procedure will model the combined effects of upstream river flows from excessive rainfall with downstream water levels at the Gulf of Mexico to prepare more accurate river and flood forecasts. These procedures will also allow for real-time flood inundation mapping. As resources allow, these procedures will be transferred to other coastal river systems in the LMRFC forecast area.

 

-Dave Ramirez

 
LMRFC Public Outreach Activities

The Lower Mississippi River Forecast Center has invigorated its outreach efforts. Under the direction of our new Service Coordination Hydrologist, Jeff Graschel, we have upgraded our outreach equipment and capabilities, including marketing posters for the local office, expanded graphics displays, hands-on activities for children, and a diverse arsenal of outreach material. The end goal is to provide expanded outreach services to support our emergency managers, service hydrologist, and co-operators as well as increase our public visibility.

 

LMRFC Poster

Gina Tillis-Nash and Jessica Smith actively planned and implemented the New Orleans Federal Executive Board's (FEB) Public Service Recognition Week (PSRW) activities with other local federal employees, including the annual Mall Outreach Event, blood drive, and federal agency banquet. Their leadership will spill over in to next year' s PSRW activities and expand public outreach to include involvement from school districts covering 11 parishes. They also provided support for the FEB Equal Opportunity Advisory Council' s (EOAC) Annual Federal Employees' Leadership Training Conference held in New Orleans on August 20th.

The LMRFC also hosted a booth during the Asian-Pacific Islander Heritage Festival at Audubon Zoo. Many festival attendees were unaware that the New Orleans metro area had a local National Weather Service presence. Numerous attendees, who derive their livelihood from the Mississippi River and coastal rivers, expressed their delight with LMRFC's presence at the festival. The LMRFC booth marketed our website as well as products that better support informed decisions concerning riverine conditions, increased the public's awareness of the LMRFC and its services, and opened channels to improve communication with part of our customer base that experiences both cultural and language barriers.

 

Open House

Recently, the LMRFC and co-located New Orleans WFO hosted an Open House event. This event showcased our recent facility upgrades as well as services that the NWS provides. Ten external partners, including the Corps of Engineers and local emergency management agencies, participated with information booths and hands-on exhibits, such as the “Tornado Trailer”. The turnout was tremendous, from the public as well as Emergency Managers, Federal Agencies, and local leaders. Over 600 visitors toured the combined facility and were briefed on operations and services and participated in hands-on demonstrations and activities.

For further information on how the LMRFC can provide support for your upcoming outreach event, please contact Jeff Graschel at (985) 641-4343 or jeffrey.graschel@noaa.gov.

-Gina Tillis-Nash

 
 

 


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