|David Reed, Hydrologist In Charge||Vol. 4 No. 3, Spring 2001||Ethan A. Jolly, Editor|
|Spring Flood Events||NWS Acronyms|
|From the HIC|
2000 has been an eventful year so far. We had major and record flooding during February and March over most of the LMRFC area. During this period, LMRFC was open continuously for over 4 weeks keeping a constant hydromet watch for our area. The LMRFC staff performed well during this period. We are highlighting the flooding in this issue of the Crawfish Tales.
Our procedure development efforts are in full swing. We continue to implement ArcView in our operations and to improve our website. We are working to implement databasing technology to make our website more efficient and provide forecasts on hand-held devices such as personal data assistants and wireless phones. We are also working to improve our modeling with our Sacrament Soil Moisture Accounting Model calibration effort.
We will continue with the implementation of the river flood watch program. The target date for implementation is July 1. Each of you should have received a survey to provide feedback on the format of the graphic product and content of the text product. National Weather Service Headquarters is also looking into a flood potential product to address possible flooding out to 5 days.
As you can see, we expect a busy summer. We will continue with our development efforts while maintaining a hydromet watch. This is especially important as we move into hurricane season. Our number 1 priority will remain providing timely and accurate forecasts and quality service to our customers and partners. We look forward to continuing to serve you in 2001. Please do not hesitate to call with any questions or needs for additional services.
|Spring Flood Events|
Winter and spring months tend to be wet, as many locations across the LMRFC climatologically receive maximum rainfall during these months. However, the past two winter and spring seasons have been relatively dry, leading to continued drought conditions over much of the area. The Winter and Spring of 2001 saw several rainfall events, which helped alleviate some of the dry conditions. These rainfall events brought minor to significant flooding to many of LMRFC's basins, and in a few cases the floodingreached record levels.
The first rainfall event, which occurred from January 15th through the 20th, 2001, produced rainfall over most of the LMRFC area, with the axis of heaviest rainfall (greater than 4.00" total) from north Alabama, southwest through north Mississippi, and extending across south Arkansas and north Louisiana. A secondary axis of maximum rainfall extended from southwest Mississippi through southwest Louisiana. Hardest hit were the Bayou Bodcau and Bayou Dorcheat basins of southwest Arkansas and northwest Louisiana, and the Yazoo, Yalobusha, and Skuna Rivers in Mississippi, with the largest rainfall amount of 6.80 inches at Yazoo City.
For the second rainfall event, which occurred from February 11th through the 17th, the axis of heaviest rainfall was located farther to the north, extending across much of Tennessee, northwest Mississippi, and south Arkansas. Rainfall amounts, in general, were much higher than the previous event, with several areas reporting in excess of 6.00 inches for the event. In Mississippi, the heaviest rainfall was near the Coldwater, Little Tallahatchie, Tallahatchie, and the upper portion of the Sunflower basins, and in western Tennessee, near the Hatchie basin. Bayou Bodcau and Bayou Dorcheat, along with the lower Red in southwest Arkansas, were also hardest hit.
The third rainfall event, from February 26th through March 5th, had most of the rain falling across south Arkansas, Louisiana, and central and south Mississippi while the remainder of LMRFC's area received at least some rainfall. The axis of heaviest rainfall was much farther to the south with this event, affecting the lower Red and Ouachita River systems in Louisiana, and the lower Pearl and Pascougoula River systems in Mississippi. On the lower Pearl, the heaviest rainfall of 9.45 inches occurred near Mize, Mississippi.
The final overrunning event, occurring from March 8th through 15th, was similar to the previous three events in that most of the LMRFC area received some rainfall, however the rainfall amounts were not as great as the earlier events. For this time period, the heaviest rainfall was focused across extreme south Mississippi, with Pascagoula 2ENE receiving 6.88 inches. Areas of maximum rainfall also occurred across central Mississippi, south Arkansas, and portions of north Louisiana.
Figure 2 shows the contoured gauge analysis, in inches, for the convective event of April 4th through 5th. While the areal extent of the rainfall wasn't as great as the overrunning events, the rainfall amounts were just as impressive. The heaviest rainfall occurred over the upper Big Black, upper Pearl, and Yockanookany Rivers, with Kosciusko receiving 9.97 inches of rainfall for the 24-hour event.
The flooding proved to be record-breaking along some tributaries of the lower Red River system, in both Texas and Louisiana. Bayou Bodcau at Bayou Bodcau Dam, Louisiana, which has a flood stage of 172.0 feet, crested at 197.39 feet on March 18th, which represented the highest level since 1958 when the Bayou reached 196.67 feet on May 11th. The South Sulphur River at Cooper Dam, TX reached a record pool level of 446.04 feet on March 4th, a few tenths of a foot below the top of the flood control pool. Finally, the Sulphur River at Talco, TX, where the flood stage is 20 feet, crested at 29.10 feet on February 18th, which is the second highest crest, second only to the crest of 29.40 feet on December 11th, 1971.
|National Weather Service (NWS) Acronyms|
AFOS - Automation of Field Operations and Services
ASOS - Automated Surface Observing
AWIPS - Advanced Weather Interactive
CONUS - Continental United States
DCP - Data Collection Platform
GOES - Geostationary Operational
NCEP - National Center of Environmental Prediction
NEXRAD - Next Generation Weather
NOAA - National Oceanic and Atmospheric Administration
NWS - National Weather Service
NWSRFS - NWS River Forecast System
RFC - River Forecast Center
RPG - Radar Product Generator
SBN - Satellite Broadcast System
SHEF - Standard Hydrometeorological
WFO - Weather Forecast Office
WHFS - WFO Hydrometeorological
WSR - 88D - Weather Surveillance Radar 1988 Doppler