If you're going for a HoH, you'll need keys for each value in the inner hash (like you're using $date as a key in the outer hash). Instead of:

$GSPmsgHash{$date} = {
    $alertLv,
    $src,
    $srcD,
    $probD,
    $days_between,
}
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You probably want:

$GSPmsgHash{$date} = {
    alert_level    => $alertLv,
    source         => $src,
    source_detail  => $srcD,
    problem_detail => $probD,
    days_between   => $days_between,
}
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This way, to get the alert level for $date, you would do the following:

my $alert_level = $GSPmsgHash{$date}->{alert_level};
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