From Glossary of Meteorology
(Also called colla tempestada.) In the Philippines, a fresh or strong (less than Beaufort force 8) south to southwest wind, accompanied by heavy rain and severe squalls.
It is experienced most frequently in June and July and may persist for several days. It occurs when an extensive trough of low pressure runs from east to west or east-northeast to west-southwest, north of Manila, and is either stationary or moving slowly northward.