Please use the register command inside the grunt/pig shell to add the jar and then you can perform transformation such as :
register udf_corrupt.jar;
A = load '/weatherPIG' using TextLoader as (data:chararray);
AF = foreach A generate TRIM(SUBSTRING(data, 6, 14)), IfCorrupted(TRIM(SUBSTRING(data, 46, 53))), IfCorrupted(TRIM(SUBSTRING(data, 38, 45)));
store AF into '/data2' using PigStorage(',');
S = load '/data2/part-m-00000' using PigStorage(',') as (date:chararray, min:double, max:double);
dump S;