In a matter of a few days, those of us in the southern New England/Tri State area are going to see a slow trickle of migrants quickly turn into a full onslaught. We'll go from seeing mainly Yellow-rumps and Palms to certainly 10+ warbler species (still with plenty of 'rumps and Palms though!).
The spring passerine migration typically accelerates into full swing as the calendar changes from April to May, and this year the weather will exaggerate this rapid change. A slow-moving low has dropped rain on us for the past couple days, backing up birds to our south. The storm is clearing out now, but gusty NW winds will likely keep migration slow until late in the week when winds shift to the SW and we get a shot of summer warmth.
Right now it's looking like tonight will be too cool and windy to promote much migration. Tomorrow night will be a bit warmer and less windy, but still conditions won't be ideal. One would expect Thursday night to be the first night of large movement, and conditions will be even better Friday and Saturday nights.
If you enjoy the spring passerines (and who doesn't), take care of your chores early this week so you can get out and play Friday through Sunday.
As an aside, this weather change will coincide with the best time of the migration period for many southern overshoots. This group includes Prothonotary Warbler, Yellow-throated Warbler, Swainson's Warbler (mega rare), Summer Tanager, and Blue Grosbeak.