It seems like the new Yankees Stadium was built with a very good drainage system. Although it sounds like there is a 50-50 chance of rain, a thundershower isn't forecast until 7pm, and only during one hour-period - http://www.accuweather.com/en/us/new-york-ny/10007/hourly-weather-forecast/349727?hour=6 (hourly forecast)
If Estrada pitches quickly, as usual, then I think they can get two games in. I hope pitchers won't waste any time out there today.
(source: http://newyorkyankeesfanclub.com/Yankee_Stadium_2.html )
The field is made up of Kentucky bluegrass, the same surface as the previous stadium, which is grown on a 1,300 acres (530 ha) farm in Bridgeton, New Jersey. The grass is equipped with a drainage system (featuring over 14,000 feet (4,300 m) of pipe) that makes the field playable an hour after taking 2 inches (51 mm) of rain.
HOT DIGGITY! A doubleheader today!