Today is the last day to enjoy the current dry spell. The high pressure system that's given the city clear skies is beginning to move away. Before it leaves we should have a sunny and seasonable day with a high in the lower 70s..
Rain looks like it will arrive tomorrow afternoon, ending twelve straight days without precipitation. The rain is courtesy of an extratropical low pressure system that's off the coast of the Carolinas this morning. As that storms moves northward it should bring lots of rain, especially tomorrow night and into Friday. Tomorrow's high will only reach the mid 60s and it will be windy once the storm arrives. The rain may be intense enough to cause flooding in low-lying areas.
The behind-the-scenes details of the weekend forecast are complicated, but the end result is simple: rain. A tropical disturbance, currently just north of the Dominican Republic, is expected to follow very closely on the heels of the extratropical low. Now, you might think that when two storms get close together they would combine to form a giant storm. That's not true. If the storms are about the same size they tend to dance warily around each other in what is known as the Fujiwhara effect. Most likely this dance will lead to a rainy Saturday and there's a chance the rain will linger into Sunday. With the tropical air temperatures should return to the mid 70s.