STATE COLLEGE -- Warmer temperatures and impending rain are making the conditions for flooding more likely in Columbia, Montour, Northumberland and Luzerne counties, along with most of central Pennsylvania, the National Weather Service says. It has issued a flood watch spanning from Saturday afternoon through Sunday evening. Warmer temperatures this weekend will lead to melting and ice breakup on streams and creeks. Forecasters say that melting, along with up to an inch of rain, could cause flooding, especially with the potential for ice jams that could block waterways. Ice jams can form quickly, the NWS says, and they pose the greatest risk on small streams and where streams flow into rivers. The Susquehanna River isn't yet forecast to spill its bank, according to the service. Its flood gauge forecast projects that the river will get to 12 feet by noon Monday. Flood level is 19 feet in Bloomsburg. A flood watch is less serious than a flood warning, and means there is a potential for flooding on small streams and creeks, along with poor-drainage and low-lying areas, the NWS said. For the full watch statement, click here. For Susquehanna River flood-gauge readings, click here.