Crawfish Tales
A Quarterly Publication of the National Weather Service Lower Mississippi River Forecast Center
Slidell, Louisiana
David Reed, Hydrologist In Charge Vol. 1 No. 1, Autumn 1997 Suzanne Van Cooten, Editor
Our Office

Features Operations
Site Service

From the HIC
During my 2-year tenure as Hydrologist in Charge (HIC), the Lower Mississippi River Forecast Center (LMRFC) and the National Weather Service have undergone major changes. Three new hydrologists will join the LMRFC staff in November, bringing the office to a fully modernized staffing level of 16. Our technology has changed from making "batch" forecast runs remotely on a mainframe computer to interactive river forecasting locally on scientific workstations.

To make optimum use of the additional staffing and new technology, LMRFC operations and services have changed and will continue to change at a rapid pace. This winter, LMRFC will implement a second shift and open 16 hours per day, 7 days a week. With these extended hours, full Hydrometeorological Analysis and Support (HAS) operations will be

implemented, forecasts will be updated more frequently, and LMRFC will be staffed for 24 hour operations more often.

These changes have occurred at such a rapid pace, we could not easily keep everyone informed of our activities and plans. This newsletter, LMRFC Crawfish Tales, will be one way we will keep our customers such as the U.S. Geological Survey (USGS), Army Corps of Engineers (COE), Tennessee Valley Authority (TVA), and others abreast of changes and events at LMRFC.

The LMRFC Crawfish Tales will be provided to you quarterly and will contain information on accomplishments and activities planned for the future at the RFC. We welcome any comments or ideas you may have to assist the LMRFC in serving you, our public.

- Dave Reed

Operations Overview
Hydrologic operations HAS Operations
The LMRFC is staffed weekdays from 6:00 AM to 4:00 PM and from 6:00 AM to 3:00 PM on weekends and holidays. At 7:00 AM, hydrologists begin preparing daily river forecasts by simulating runoff using the Sacramento Soil Moisture Accounting (SAC-SMA) model. The Dynamic Wave Operational (DWOPER) model and Lag/K routing are used to route water downstream on most rivers. Across the LMRFC area, a total of 2890 river/ rainfall stations are used in our modelling efforts. All operations and modelling efforts of the LMRFC are performed on a computer network consisting of five Hewlett-Packard (HP) servers.

A total of 18 river forecast products and 18 flash flood guidance products are issued daily. All river/ flood forecasts contain QPF covering the next 24 hour period, 12 UTC-to 12 UTC. The LMRFC prepares forecasts for 3 days at 120 locations and 5 days at 25 locations. Weekly 28-day forecasts for eight locations along the Ohio/ Mississippi are issued each Wednesday.

Upstream RFCs and TVA provide daily flow forecasts to LMRFC at seven locations: 1) from the North Central RFC for the Mississippi at Chester, IL, and Big Muddy at Murphysboro, IL; 2) from the Ohio RFC for the Ohio at Smithland Dam, IL; 3) from the Arkansas Basin RFC for the Arkansas at Pine Bluff, AR, and Red at Fulton, AR; and 4) from TVA for Barkley Dam and Kentucky Dam releases. These flow forecasts are used as input to LMRFC hydrologic models.

Hydrometeorological Analysis and Support (HAS) operations started routine shifts in September of 1996. The HAS function is made up of 3 HAS forecasters working one shift per day, 7 days per week. RFC hydrologists augment the HAS unit staffing. Ths HAS operation was created to assist the LMRFC/WFO with hydrometeorological activities which are critical to flood operations. A major task of HAS personnel is to analyze and quality control rain gage reports and hourly precipitation estimates from WSR-88D radars which cover the RFC area . This quality control function includes Stage III software which allows HAS forecasters to remove erroneous rainfall estimates due to radar reports of anomalous propagation and/or hail contamination. The Stage III software combines the estimates from 26 WSR-88D into a mosaic of radar rainfall estimates for the entire LMRFC. The rainfall mosaic is used in our local hydrologic models.

The HAS forecaster assesses the hydrometeorological situation over the LMRFC area and briefs the staff during the day on the latest developments vital to hydrologic operations. The HAS forecaster assists in coordination of Quantatative Precipitation Forecast (QPF) from each of the WFO's and prepares the data for input into the hydrologic models. The forecaster produces two products, the Hydrometeorological Discussion (HMD) and the Hydrometeorological Coordination Message (HCM). The HMD consists of information used for coordination between the LMRFC and the WFO. It includes the flood potential for the LMRFC area for the next 24 hours. The HCM outlines those basins which may go into flood based on WFO QPF, allowing offices to determine if a Flood watch or warning is required. Throughout the day, the HAS forecaster quality controls hourly observed precipitation reports and maintains proficiency in hydrologic operations by working hydrologic forecast shifts.

Staff Structure
A part of the modernization of the NWS is expanding the staff at RFCs. With this staffing, an RFC will improve the hydrology of its area and staff the office routinely 16 hours per day, 7 days a week. The LMRFC staffed with 8 people in the early 1990's currently has 13 people. When three additional people arrive next month, LMRFC will reach its fully modernized staff level of 16 people.

The mangement staff includes the HIC, Dave Reed, the Development and Operations Hydrologist (DOH), Bob Stucky, and Administrative Support Assisstant, Nana Miestchovich.

Senior hydrologists Marty Pope, Randy Rieman, Mike Shields and Eric Jones, are technical and operational leaders in the office.

Hydrologists Angelo Dalessandro, Laurie Hall, Ethan Jolly, Julie Jones, E.J. Leche, and Janet Spurgeon complete the hydrologic forecast staff. Jeff Graschel, Senior Hydrometeorological and Analysis Support (HAS) forecaster, is the technical leader in implementing the HAS functions at the RFC. John Kuhn and Suzanne Van Cooten serve as HAS forecasters and provide a vital link between the WFO forecasters and the RFC hydrologists.

Site Service Area

The LMRFC is one of thirteen River Forecast Centers (RFC) spanning the conterminous States including the Alaska RFC. The LMRFC hydrologic service are covers approximately 220,000 square miles of drainage and includes most or parts of twelve different states.

Daily river and flood forecasting responsibility covers the Mississippi River Basin and all itsHydrologic Services Area tributaries draining below Chester, IL, including 1) the Big Muddy River in Illinois below Murphysboro, 2) the lower Ohio River and tributaries at and below Smithland Dam, IL,including the Cumberland River Basin below Barkley Dam , KY, and the Tennessee River Basin and tributaries (excluding the mainstem at and above Kentucky Dam, KY), 3) the lower Red River Basin below Fulton, AR, and 4) all gulf of Mexico drainage between and including the Pascagoula and Escatawpa basins in Alabama and Mississippi to the Calcasieu River Basin of southwest Louisiana.

River and flood forecast responsibility for all tributaries of the Tennessee River rests with LMRFC. All forecasts for the mainstem of the Tennessee River, at and above Kentucky Dam, KY, are prepared by the Tennessee River Valley Authority.

Web Whimsy
We here at the LMRFC are going through some exciting times when it comes to our presence on the World Wide Web. The LMRFC now provides three forecasts for the lower Mississippi River along with daily flash flood guidance for our area of responsibility. This comes under a new and exciting format which uses many of the latest web tools.

The three Mississippi River forecasts include a daily five day river height and flood forecast, a weekly seven day forecast, and a weekly extended forecast which goes out 28 days in

the future. The five day forecast is updated every day by 10:30 AM Central Time with the seven and 28 day forecasts going out every Wednesday by 2:00 PM and 4:00 PM, respectively.

We are now featuring hourly Stage III precipitation mosiacs which are quality controlled and updated several times per day.

Future plans for the home page include daily river forecasts using interactive river basin maps and technical papers from our staff.

QPF Facts
Quantatative Precipitation Forecasts (QPF)s are prepared by 17 Weather Forecast Offices (WFO)s in NWS Southern, Central and Eastern regions. With each morning forecast package, WFO staffs prepare 24-hour QPF values from 12 UTC to 12 UTC for each of their hydrologic basins using WIN QPF software and national QPF guidance. By mapping rainfall isohytes over these defined basins for four 6-hour intervals, the WFO staff is able to produce a formatted 24 hour QPF product with the click of a mouse button. These QPF products are also generated routinely with the evening forecast packages in the Southern and Central region WFOs for 00 UTC to 00 UTC . Eastern region WFOs issue evening QPF products when hazardous weather is anticipated or at the request of an RFC.

All LMRFC forecasts include this basin specific QPF for 24 hours into the future. The HAS forecaster coordinates QPFs among individual

offices to assure values which are consistent between neighboring basins and prepares the QPF data for input into the hydrologic models in the NWSRFS system.

Hydrologic forecasters issue 3 to 5 day stage forecasts based on observed precipitation and QPFs from the WFOs. Occasionally, a forecast will exceed flood stage based on WFO QPF but remain below flood stage with zero QPF. For these situations, the hydrologic forecaster will issue a forecast on the expected stage and the time the point will go into flood. The HAS forecaster then issues an HCM outlining the affected Hydrologic Service Area (HSA), the river system, and the hydrologic forecast point. For these locations, the WFO with hydrologic forecasting responsibility may issue a Flood Watch (FFA) or a Flood Warning (FLW) based on this forecast guidance from the LMRFC.

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