[gradsusr] How to make wind/temp forecast chart with grads

[I Kadek Nova Arta Kusuma]

Dear all, I want to make wind/temp forecast by grads, 
when I displaying temperature point value, but I got a problem with put the "+" sign for positive number.I need to displaying positive sign on the left of number temperature if they're positive, and if they're negative they'll have no sign. 
anyone know how to put + sign on the left of  positive temperature number??
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