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

David Reed, Hydrologist In Charge Vol. 2 No. 1, Autumn 1998 Ethan A. Jolly, Editor


Features HADS Web Site
Updates
LDAD / AWIPS Station
Identifiers
MAPX


 

From the HIC

LMRFC has had a busy hurricane season. Heavy rains from Hurricanes Francis, Georges, and Hermene produced major flooding over parts of the LMRFC area. Couple this with the possibility of Georges making landfall in the Slidell area has made for an exciting and trying season. The office continued to provide high quality services during these difficult times.

 

LMRFC continues to implement AWIPS. We expect to use AWIPS as our primary forecast tool and support

our webpage this winter. The Local Data Acquisition and Dissemination (LDAD) functionality of AWIPS should be working this spring and provide an interface to obtain locally collected data for use in AWIPS. All sites should have AWIPS by the end of June 1999.

 

Through this work, LMRFC has continued to provide timely and accurate forecasts to support both the WFOs and cooperating water agencies. We look forward to continuing to serve our customers.

- Dave Reed


 

Hydrometeorological Automated Data System (HADS)

The Hydrometeorological Automated Data System (HADS) is a real-time data acquisition and data distribution system designed and operated by the Office of Hydrology of the National Weather Service. HADS was designed to provide random and self-timed data to assist the forecaster in various programs, including hydrologic forecasting. HADS decodes a wide variety of hydrometeorological data types, such as precipitation and stage, from more than 7,100 reporting sites. This important data is used as input it into our hydrologic models.

HADS receives observation messages (data) from Geostationary Operational Environmental Satellites (GOES) Data Collection Platforms (DCPs) and the Centralized Automatic Data Acquisition System (CADAS) data sites. As HADS decodes the data and produces reports, it interfaces with many computer systems. The data path and distribution process goes like this:

1. The National Environmental Satellite Data Information Service (NESDIS) operates and maintains the GOES Data Collection System (DCS). DCPs transmit data to either East or West GOES Satellites and these data are relayed to the NESDIS Command and Data Acquisition (CDA) located at Wallops Island Virginia. The data are then relayed to the NWS Telecommunications Gateway (NWSTG) in Sliver Spring, Maryland. From there the data are routed to the HADS computer systems where they are written to the HADS raw data files. To accommodate outages either by NESDIS or the NWSTG, 36 hours of raw data is maintained in the HADS raw data files.

 

2. CADAS data is made available to HADS through its collection of data via telephones from Limited Automatic Remote Collectors (LARC). CADAS data are collected every 6 hours by S230 computers and the data are transferred to the NWSTG four times a day. The CADAS data are then written to the HADS raw data files.

 

Finally, to receive the data, LMRFC defines Send On Receipt Reports (SORR) and Time Periodic Reports (TPR), tailored to our needs, to get DCP and CADAS data. SORRs are created based on data receipt and at specified time intervals while TPRs are generated based on a scheduled time. Reports are generated in Standard Hydrometeorological Exchange Format (SHEF) and delivered to the RFCs via FTP as soon as it is received in the HADS system. WFOs receive their data over AFOS. The SHEF coded data products are decoded and posted to RFC and WFO databases for use in forecast model runs.


 

Web Site Updates

We have just completed a major overhaul to the Lower Mississippi River Forecast Center's web site. Not only do we have a new look and feel, but we also have some brand new additions.

 

Due to the expansion of data that we have added to the site over the past two years, the first thing that we have done is to split our "Products" page into "River Forecasts" and "Precipitation Data". These pages can be viewed at:

 

http://www.nwslmrfc.noaa.gov/forecasts.html

and

http://www.nwslmrfc.noaa.gov/precip.html

 

If you have our old "Products" page bookmarked, then please update accordingly.

 

The new additions to the site include a "Flooding Safety"

page and a "Flooding Events" page. The flooding safety page has information on the different types of flooding, what to do before, during, and after a flood, as well as

links to other flood safety sites. This page is a must see for EVERYONE! It can be viewed at:

 

http://www.nwslmrfc.noaa.gov/flood/safety.html

 

Our flood events page has pictures and descriptions of flood events in the LMRFC area. It is broken up by state, so that you can easily find events in your area. This part of the site is in its infancy and needs more pictures. If you have any pictures, please send them to Ethan Jolly for review. This page can be viewed at:

 

http://www.nwslmrfc.noaa.gov/flood/events.html

 

I hope that you enjoy the new look to the site as much as I enjoyed creating it. If you have any questions, comments, or suggestions, please e-mail me at ethan.jolly@noaa.gov


 

LDAD / AWIPS

LDAD within AWIPS

 

Local Data Acquisition and Dissemination (LDAD) is the AWIPS interface to obtain data from external users and provide users access to information and products prepared by the NWS. LDAD provides a computer, router, firewall, and network connections to interface with local data sources such as mesonets and LARCs. With LDAD, an office will be able to retrieve local hydrologic and meteorological data and directly ingest it into the AWIPS system. Within AWIPS, the LDAD function will:

 

1.Disseminate critical hydrologic/weather information to the emergency management community;

2.Facilitate two-way communications between WFOs/RFC's and state and local government agencies;

3.Automate the acquisition and quality control of local hydrologic/weather observations obtained from local mesonets such as ALERT, IFLOWS, and LARCs; and

4.Provide a link to the world wide web to support disseminating data in graphical form on NWS web pages.

 

LDAD hardware has been installed in many NWS offices but will not be activated until the NWS installs AWIPS load 4.1 scheduled for field implementation this winter.

 

AWIPS Installation Update

 

The NWS has approval to install AWIPS at all field sites by the end of June 1999. Within the LMRFC area, Weather Forecast Offices New Orleans, Ft. Worth, Tulsa, Atlanta, and Paducah have AWIPS installed. These sites have AWIPS build 4.05 and will be upgraded to build 4.1 this winter.

 

Future installations should have AWIPS Build 4.1 installed. Following is the schedule of AWIPS installation for the remainder of the WFOs in the LMRFC area:

Nov 30- Dec 3 WFO Springfield MO
Dec 7-10 WFO St Louis MO
Feb 1-4 WFO Lake Charles LA
Feb 8-11 WFO Shreveport LA
Mar 1-4 WFO Blacksburg VA
Mar 22-25 WFO Morristown TN
Mar 22-25 WFO Little Rock AR
Mar 29-Apr 1 WFO Memphis TN
Mar 29-Apr 1 WFO Nashville TN
Apr 5-8 WFO Greer SC
Apr 26-29 WFO Jackson MS
Apr 26-29 WFO Mobile AL
Apr 26-29 WFO Birmingham AL

AWIPS systems will be commissioned during the summer of 1999.


 

Station Identifiers

In the Southern Region, each RFC maintains the station identifiers (SIDs) in its own RFC area. Each SID focal point is responsible for obtaining the SIDs and notifying each WFO when the SIDs are approved. SIDs are needed for all weather service observation stations. They consist of 5 characters (a 3 character ID plus a state designator). The SID Request Form is usually used to add, delete, or change an SID.

 

The RFC focal point e-mails the SID request form with two or three suggestions for a new SID to the Office of Systems Operation, where the SID list is managed on the VAX computer. These data bases are managed by

the Systems Integration Division, Office of Systems Operations. After an SID is approved, it is entered into a list called the Handbook-5 list. It is then sent back to the RFC focal points who then inform the WFOs of the approved SIDs. The office of Hydrology must also be informed of approved SIDs for RFCs to receive the DCP and CADAS data.

 

A current SID Handbook-5 list is updated and posted daily on the Internet at http://cmweb.nws.noaa.gov/. Call the RFC focal point for accessing this site. For more information on SIDs see ROML S-16-97 filed in B-91.



MAPX

Stage III computes a 4km x 4km grid of hourly precipitation estimates over the LMRFC area using the precipitation estimates from each individual WSR-88D as input. The MAPX function uses Stage III output to compute basin average rainfall for each LMRFC sub-basin for each hour. MAPX computes the basin averages by averaging each 4km X 4km grid point that falls inside the latitude/longitude boundaries of a basin. The MAPX averages are computed each hour and can be summed to obtain 6 and 24 hour totals.

LMRFC hydrologic models run on a six hour time step and have historically used mean aerial precipitation (MAP) computed from raingages as its primary input. MAPX values are now being tested in LMRFC hydrologic models runs replacing MAP computed from the raingages. Both MAP and MAPX are

combined with quantitative precipitation forecasts (QPF) from Weather Forecast Offices as input into soil moisture accounting model for the estimation of runoff.

 

MAPX is available in a finer temporal and spatial resolution than MAP based on raingage data. It is also available as often as every hour to allow the NWS to begin to run forecast models on an hourly time step. Running hydrologic models on a 1-hour time step instead of the 6-hour time step we now use may introduce biases into model results. For a given storm, MAP from ground truth may differ from MAPX based on radar estimates. These potential differences may introduce long-term biases into hydrologic models. These potential biases will be explored to determine how to adjust LMRFC hydrologic models to provide the best simulations.

 


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