#!/usr/bin/env perl

use strict;
use warnings;

my ($in,@array,$array,$i,@foo);
$in=0;

while(<>){
        if (/^OBS ASH CLOUD/) {
                $in=1;
        }
        elsif (/^\n/) {
                $in=0;
        }
        chomp;
        if($in) {
                @array=split(/\s+/);
                push(@foo, @array);
                #print "@array\n";
        }
}
shift (@foo);
shift (@foo);
shift (@foo);
shift (@foo);
print "@foo\n";

OUTPUT:
N1705 W06244 - N1702 W06227 - N1643 W06210 - N1641 W06211 - N1633 W06220 - N1648 W06241 - N1705 W06244 MOVING NW 5-10 KNOTS.