[GFS 500 mb forecast map for Wed AM; courtesy NOAA]
Our stretch of pleasant weather will be coming to an end shortly in the Mid-Atlantic region as moisture beings to increase ahead of an intensifying upper-level trough. This upper level trough will take on a “negative” tilt by Wednesday morning (see forecast map) as it pushes southeastward towards the I-95 corridor enhancing upper motion in this area. The combination of the intensifying upper level trough, an impressive low-level jet and high moisture content will help generate significant rainfall for much of the Mid-Atlantic and Northeast US between tomorrow morning and late Wednesday with 2-4 inches in most locations and up to 5 inches or so possible in isolated locations. The heaviest rainfall for the I-95 corridor from DC-to-Philly-to-NYC will occur from late tomorrow into early Wednesday. During the day Wednesday, the heavy rain threat will shift northeastward into New England where a wild day of weather can be expected. Along with the potential for flash flooding, there is a threat for isolated severe weather in the Mid-Atlantic and Northeast US during this upcoming weather event. One final note, there is now a new tropical disturbance just off the west coast of Africa that bears watching as we are now approaching the heart of the Atlantic Basin tropical season (i.e., mid-August through September).
[Visible satellite image of the eastern Atlantic; courtesy Penn State eWall]