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Hydrology Laboratory

Special Announcement

The Office of Hydrologic Development maintains historical hydrologic data up to September 30, 2005.

Description of Point Data

These data are the point data that existed in the River Forecast Center's operational database. They represent the set of data that was available to the River Forecast Center for use in operational processes such as NWSRFS and Stage II/III Precipitation Analysis.

We unload these data from the tables in the RFCs' Informix database to ASCII flat files. The files for a month of data are concatenated and then compressed with the UNIX compress utility into monthly files with the name "vlmmyyRFCID.Z" where mm is the two digit month, yy is the two digit year, and RFCID is the two character identifier for the River Forecast Center. For example, vl0297AB.Z would be the point data for February, 1997 from ABRFC.

Point data are saved into a file by records. There is one record for each data value and 17 fields in every record. Each field is separated by a pipe "|" delimiter. These fields are laid out as follows:

    	 Field 1;  char(8);  Station identifier
    	 Field 2;  char(2);  SHEF physical element
    	 Field 3;  char(2);  SHEF type/source code
    	 Field 4;  smallint; SHEF duration code
    	 Field 5;  char(1);  SHEF extremum code
    	 Field 6;  integer;  Observation date(yymmdd) (UTC time)
    	 Field 7;  integer;  Observation time(hhmmss) (UTC time)
    	 Field 8;  float;    Data value
    	 Field 9;  integer;  SHEF revision code
    	 Field 10; integer;  Posting date(yymmdd) (local time)
    	 Field 11; integer;  Posting time(hhmmss) (local time)
    	 Field 12; integer;  Message date(yymmdd) (local time)
    	 Field 13; integer;  Message time(hhmmss) (local time)
    	 Field 14; char(9);  AFOS product identifier
    	 Field 15; char(1);  SHEF data value quality flag
    	 Field 16; smallint; Quality control flag
    	                          1=failed siipp qc test
    	                          2=failed ofs_de qc test
    	                          3=failed both qc test
    	 Field 17; smallint; Transfer flag
    	                          0=not transferred to either dhqc
                	          1=transferred to ofs_de only
			          2=transferred to siipp only
                        	  3=transferred to ofs_de and   
To use the information, you must first uncompress the file using the UNIX uncompress utility or an equivalent.

Remember, these monthly files are large when they are uncompressed. They are in the magnitude of 100 to 200 Megabytes. Make sure you have enough disk space before you start uncompressing.

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National Weather Service
Hydrologic Data Systems Branch
Page last modified: March 23, 2006

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