This morning's low in Central Park was 56 degrees, average for late May but highly unusual for late February. So unusual that it broke the previous record high minimum temperature record of 54 set in 1985.
The proximal cause of today's warmth is a perfect anti-storm of the jet stream ridging over the East Coast and a surface high pressure system over the Western Atlantic. That combination will warm the area up to the upper 50s right along the shore to the lower 70s in Manhattan and northern New Jersey.
In addition to this air mass being unusually warm, it also contains a lot more moisture than your typical winter air mass. The dew point temperature has climbed into the lower 50s and that level of humidity will affect our weather in a couple of ways. First, that humid air is going to be flowing over a very cold ocean. Surface water temperatures are presently in the low 40s and that means we are likely to see some fog overnight as the humid air cools down.
The humid air will also play into tomorrow's forecast. A cold front will approach on Saturday afternoon, giving us a chance of rain and possibly a line of thunderstorms. Cloudy skies early in the day will keep the high to the low 60s. Look for the rain to start in the late afternoon. If thunderstorms do develop they will hit around midnight.
A high pressure system will bring much cooler and drier air on Sunday. We can expect a high in the mid 40s but a brisk northwesterly wind will make it feel much colder than that. Cooler weather on Sunday is no indication that winter is returning as unseasonably mild temperatures will return for much of next week.