Usage:
  weighted_average_raws.php?area=name&ids=id_list&cats=cat_list&weights=weight_list&day=DD&month=MM&year=YYYY
    where:   
                area = name asigned to group of RAWS stations
             id_list = a comma-separated list of RAWS stations by WIMS id (see: http://nfdrs.smkmgt.com/nfdrs_indices.txt) 
            cat_list = a comma-separated list of WIMS climate/fuel identifiers corresponding to the id_list stations
         weight_list = a comma-separated list of weights to apply to the stations in the id_list 

    the following are optional parameters can be omited if you only want the latest data:
                  DD = day to retreive
                  MM = month to retreive
                yyyy = year to retreive

        example URLs (from complext to simple):

        http://nfdrs.smkmgt.com/scripts/weighted_average_raws.php?area=test&ids=350113,350215,350216,350308,350505,350604&cats=7G2P3,7K3P4,7K2P3,7G3P3,7G1P4,7G3P3&weights=10,20,20,15,15,20&day=05&month=05&year=2020
        http://nfdrs.smkmgt.com/scripts/weighted_average_raws.php?ids=350113,350215,350216,350308&cats=7G2P3,7K3P4,7K2P3,7G3P3&weights=25,25,25,25&day=24&month=05&year=2020
        http://nfdrs.smkmgt.com/scripts/weighted_average_raws.php?ids=350113,350215&cats=7G2P3,7K3P4&weights=60,40