The National Weather Service forecasts heavy rainfall and possible thunderstorms this afternoon and into this evening for Northwest Oregon and Southwest Washington, according to a special weather statement and a hazardous weather outlook.The weather system moving inland is estimated to bring a half an inch or more of rain to the Vancouver area between this morning and midnight, according to the weather service. The downpours are capable of localized flooding of small streams and could cause standing water on roadways, according to the weather service.The bulk of the showers are expected this afternoon and evening, mainly impacting the Vancouver and Portland metro areas, but the advisory is in effect until 4 a.m. Friday, the weather service reports.Temperatures today are expected to stay between a high of 68 degrees and a low of 59 degrees, with similar temperatures expected for Friday.