May 15, 2011: Heavy Rain Tuesday, Wednesday

As a large, slow moving storm began moving into the region today, widespread rain fell in the Northeast, with moderate to locally heavy showers and thunderstorms affecting the area, especially from NYC and further west. Storms are still ongoing in the western parts of the area, especially in Warren, Sussex and Orange counties, adn while places further east are expected to see some storms tonight, by the time that the storms reach NYC, if they do so at all, they will be much weaker. Radar estimates show that rain totals as of now are up to 1/4", locally 1/2" in Long Island/southern Connecticut, and between 1/2 and 1 inch, locally up to 2-3", from NYC and further west.

Today's storms are just a preview of what this week will bring. The cut off low will drift south and stay nearly stationary through most of this week, drawing in Atlantic moisture and producing widespread moderate to heavy rain and thunderstorms, especially on Tuesday and Wednesday. Even though the storm will weaken by Thursday and Friday, scattered showers and thunderstorms will persist through the end of the week and into next weekend as well.


Tomorrow's Outlook:

Tomorrow will be the warmest day of the week for most of the area, as the low pressure is still to the west of the area, slowly drifting south, placing the area in the northern edge of the warm sector of the storm. With an east wind expected, high temperatures will rise into the upper 60s to lower 70s from NYC and further west, and the lower to mid 60s for the eastern parts of the area, potentially in the upper 50s in the immediate coast. The NAM is the cold outlier at this time, only showing highs in the lower to mid 50s across the area, and I sided with the warmer GFS/GGEM for tomorrow's temperatures.

Mainly cloudy skies are expected, though some breaks in the cloud cover are possible in the afternoon. In the afternoon and evening, scattered showers and thunderstorms are expected again, capable of producing locally heavy rainfall, but the storms are unlikely to be as strong/heavy as today's storms were.


Tuesday-Wednesday: Heavy Rain, Thunderstorms

As previously mentioned in yesterday's update, as the low pressure drifts south into North Carolina, it will pull in moisture from the Atlantic Ocean, resulting in a heavy rain potential for parts of the region. This will not be a solid area of widespread, consistent moderate to heavy rain, but rather widespread areas of moderate to heavy rain and thunderstorms capable of producing downpours. Steadier rain will move into the area early on Tuesday morning, and will continue through Tuesday, Wednesday and parts of Wednesday night.

During these two days, at least 1.5 to 3 inches of rain are expected, though amounts may be locally as high as 4-5 inches of rain. By the time that the main part of the storm ends on Thursday, rain totals including today will end up between 2-4 inches, with isolated locations potentially seeing as much as 6 or more inches of rain.

Behind this storm, scattered showers and thunderstorms will continue, but temperatures will get warmer. Tomorrow's update will discuss this in more details.