(SeaTac, WA)  --  Officials say more than a dozen flights were diverted last night to Sea-Tac International Airport because of a ground stoppage at Portland International Airport due to snow.  PDX officials say the airport remained open, but the runways were closed to allow crews to plow the snow.  Sea-Tac airport tells KOMO-TV there was a small traffic jam there caused by the diversions.  Officials at both Sea-Tac and PDX say passengers slated to fly today are being urged to check with their airlines for any delays or cancellations prior to their arrivals.