You can get day name for tomorrow (and and other day after that) by inserting the inserting the following formula into the watch script and calling it when needed

     function dwplus(daystring,n) 
        local days = 'SunMonTueWedThuFriSat'      
        local found = string.find(days, daystring)
        local new = 1+((3*n + found-1)%21)
        return string.sub(days,new,new+2)
     end

So, if today is Sunday, dwplus('{ddw2}',1) will return "Mon"

Note that this only works in English--you need to change the string days if you are working in another language.