The National Weather Service says a wet and mild series of storms will move into the Northwest early next week, bringing heavy rains and heightening flood potential.  A hydrologic outlook today by the Weather Service office in Portland indicates snow levels will begin to rise on Monday night, reaching near 7,000 feet Tuesday morning and 8,000 feet Tuesday evening, and combined with the expected heavy precipitation that could bring in around five inches of rain will lead to rapid snowmelt.  The outlook says with above normal snow depths and the lack of a thawing cycle this season, the snowpack in the Cascades will likely will be able to absorb a lot of the rainfall, especially above 3,500 feet.  But it does add the amount of heavy rain will remain the most significant factor in flood potential for area waterways.  The Weather Service says details of the rainfall totals and expected flooding will be refined as the storms approach the Pacific Northwest.