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


David Reed, Hydrologist In Charge Vol. 7 No. 1, Autumn 2003 Ethan A. Jolly, Editor


Features Enhancements to River Forecast Web Pages New River Forecast Point Arlington, TN Know Your River Systems:
Ouachita-Black River Basin
Turn Around, Don’t Drown

From the HIC

Hurricane season has been relatively quiet here at LMRFC. This has given us a chance to complete activities to provide additional information to our partners and customers and continue to work to improve our forecast models.

In this issue, we highlight the additional information available on our website. In the last issue, we talked about our work to provide data and graphics of rainfall for the southern US. In this issue, we discuss changes made on the LMRFC webpage to make information at each forecast point easily available. We also highlight the agencies that support the data networks we use to provide them credit for supporting the NWS Hydrology program.

In addition to our activities to provide better information, we are also working on our forecast models to enhance them. We are working to calibrate several basins in the LMRFC area and hope to get funds in 2004 to have a contractor assist us in improving the hydrology defined in our forecast models.

Feedback is always welcome. Please let us know if there are additional products or services you need from the LMRFC. We always enjoy hearing from our cooperators and partners.

- Dave Reed


Enhancements to River Forecast Web Pages

To help serve our customers’ needs, three new enhancements have been added to individual forecast point web pages on the LMRFC web site. The three enhancements include links to the owners and operators of the gage, links to real-time and historical data, and the current stage for the forecast point. These additions assist our users in easily finding all of the hydrologic information they need for a particular forecast point.

The links to the owners and operators provide access to the web site of the agency that supports the gage, giving the owner/operators recognition for maintaining and funding these gages. Without their support of these gages, the National Weather Service would not be able to provide a high level of service that is essential to the public in order to minimize the effects of flooding.

Users have sent countless emails inquiring where they can find historical information. The US Geologic Survey (USGS) and the US Army Corps of Engineers web sites provide this information so direct links were created to this data where available. Along with the historical information, links to USGS real-time information provides our users quick access to the USGS data.

The last enhancements to the forecast pages is the inclusion of the latest stage available for the forecast point. Every ten minutes, the latest stage in the LMRFC database is sent to our web site to ensure timely information is always posted. At most sites, river stages are transmitted via satellite to our office every four hours so the stage posted on the web should not be more than four hours old.

The integration of hydrologic data across cooperating agencies is exactly the type of effort that our users have been requesting. This effort will empower our users with all of the information they need in one concise location in order to make informed decisions.

Figure 1: Example of a New LMRFC River Forecast Page with Enhancements Circled in Red
PDA Forecast for New Orleans
Click to go to example page

- Ethan Jolly


New Forecast Point

On Oct 21, 2003, LMRFC began issuing daily 5-day forecasts for the Loosahatchie River near Arlington, TN (ARLT1). This is a USGS automated gaging site and is located in Shelby County on the U.S. Highway 70 bridge; approximately 1.5 miles east of Arlington. Gage zero is 246.43 feet above the NGVD of 1929. Establishment of this official NWS forecast location was in response to the Shelby County EMA request for additional river forecast and warning services.

During the past few years, extensive construction and agriculture developments in the local area has added to increased flooding problems along the

Loosahatchie. A River flooding death which occurred during the past flood season, further supports the new forecasting service.

The Loosahatchie overflows its banks mainly during the wet, winter and spring months when area soil moisture levels usually approach saturation. Backwater effects from the Mississippi River can also cause additional flooding problems. A flood stage of 20 feet above gage zero was established by the Memphis WFO.

- Laurie Hall


Know Your River Systems: Ouachita-Black River System

The headwaters of the Ouachita River originate near Mena, Arkansas, in the Ouachita Mountain Range of southwest Arkansas. Flows continue southeastward for approximately 600 miles across south Arkansas, then southward across northeast Louisiana. Near the city of Jonesville, LA, the River changes its name to the Black River traversing the last 56 miles and emptying into the Red River. The total drainage area of the Ouachita-Black system is 24,237 square miles.

Figure 1
PDA Forecast for New Orleans
Click to enlarge image

The Ouachita-Black River complex is modeled as two forecast groups: 1) the

Upper Ouachita running from the headwaters to Felsenthal Lock and Dam (L&D) in AR, and 2) the Lower Ouachita which includes all drainage below Felsenthal L&D. Daily river forecasts are prepared and disseminated to Weather Forecast Offices located in Little Rock, AR, Jackson, MS, and Shreveport, LA.

The larger tributaries of the upper Ouachita include the Little Missouri, Caddo, Moro, Smackover, and the Saline River. Tributaries contributing to flows along the lower Ouachita include Bayou Bartholomew, Bayou Darbonne, Little River, Boeuf River, Bayou Lafourche, Bayou Macon, and the Tensas River.

The Basin-wide annual rainfall average is approximately 51 inches and ranges from 49 inches in the greater part of the west and north basin to more than 60 inches near the mouth of the Black River.

The headwaters are located within mountainous to hilly terrain and streamflows generally respond with quick runoff times. Further downstream, the Ouachita-Black system transitions to the flat Mississippi River Delta region which has a much slower runoff response time. Along the Ouachita River, the Mississippi Delta generally begins near the AR-LA state line and extends to the mouth of the Black River. Backwater from the Red River can be significant and is observed as far north as the Columbia L&D in LA.


- EJ Leche
UPPER OUACHITA RIVER BASIN
River Location Flood Stage Record
Ouachita Arkadelphia, AR 17 30.3 3/30/45
Little Missouri Boughton, AR 20 27.2 3/31/45
Ouachita Camden, AR 26 44.8 4/3/45
Ouachita Thatcher L/D, AR 79 96.3 4/6/45
Saline Benton, AR 18 29.7 1/30/69
Saline Rye, AR 26 31.4 5/18/68
Ouachita Felsenthal L/D, AR 70 88.4 4/11/45
LOWER OUACHITA RIVER BASIN
River Location Flood Stage Record
Ouachita Monroe, LA 40 50.8 4/15/45
Ouachita Columbia L/D, LA 65 70.7 5/13/73
Little Rochelle, LA 32 45.9 12/29/82
Boeuf Alto, LA 25 30.7 9/7/90
Boeuf Ft. Necessity, LA 50 62.6 5/19/91
Tensas Tendal, LA 25 34.0 5/15/27
Tensas Newlight, LA 55 60.6 5/19/73
Bayou Macon Como, LA 62 61.9 4/24/95
Tensas Clayton, LA 55 60.1 4/26/45
Black Jonesville L/D, LA 50 59.7 5/17/73
Black Acme, LA 48 62.7 5/17/27


Turn Around, Don't Drown

“Turn Around Don’t Drown”™ is a National Weather Service sponsored campaign designed to increase public awareness of the dangers of flooding. Each year in the U.S. an average of 100 deaths occur due to flooding. That is more than from any other thunderstorm or hurricane related hazard. During flooding events, people often underestimate the force and power of water. This can be a deadly mistake. Many casualties result when unsuspecting motorists attempt to navigate flooded roads. To help prevent such casualties, the National Weather Service is providing flood safety information and warning the public to “Turn around… don’t drown!”™

Here are some important flood safety rules to follow:
•If flooding occurs, get to higher ground. Get out of areas subject to flooding. This includes dips, low spots, canyons, washes etc.
• Avoid areas already flooded, especially if the water is flowing fast. Do not attempt to cross flowing streams. It takes only six inches of fast flowing water to sweep you off your feet.
• Don’t allow children to play near high water, storm drains, or ditches. Hidden dangers could lie beneath the water.
• Flooded roads could have significant damage hidden by floodwaters. NEVER drive through floodwaters or on flooded roads. If your vehicle stalls, leave it immediately and seek higher ground. Water only two feet deep can float away most automobiles.
• Do not camp or park your vehicle along streams and washes, particularly during threatening conditions.
• Be especially cautious at night when it is harder to recognize flood dangers.
• Monitor the NOAA Weather Radio, or your favorite news source for vital weather related information.

For more information on flood safety and to learn about floods and flash floods visit the National Weather Service at www.noaa.gov/floods.htm or visit the Federal Alliance For Safe Homes, www.flash.org.

- Connie Kilmczac

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