Aug 132 min read

Historic Long Island flash flooding 10 years ago this morning!

- Many of you on Long Island will remember this!

- Incredibly, over 11 inches (11.19″) of rain fell in three hours, between 5 and 8 AM. About 10 inches (9.81″) of rain fell in 2 hours, a phenomenal quantity of water in such a short time. No hurricane or tropical storm to affect New York State has produced such an output.

- An official, New York State 24 hour precipitation record was set at Islip, NY on August 12-13, 2014 with 13.57" of rain.

- 1.08" fell in just 9 minutes from 5:39 AM to 5:47 AM.

- A total of 1.76" was recorded in just 16 minutes from 5:39 AM to 5:54 AM!

- An anomalously deep upper level trough was moving into the northeast the morning of August 13th, transporting deep moisture over Long Island. At the surface, a parent low pressure system was moving across southeast Canada, with secondary low development just south of New York City. Heavy precipitation focused along and just north of the warm front associated with the secondary low pressure system. The mean storm motion was parallel to the orientation of the warm front and was significant in helping maintain heavy rain over Islip, NY for several hours.

SUFFOLK COUNTY:

ISLIP AIRPORT 13.27 1030 AM 8/13

HOLBROOK 12.57 119 PM 8/13

WEST ISLIP 11.50 958 AM 8/13

DEER PARK 8.40 1240 PM 8/13

ISLIP 10.20 850 AM 8/13

DEER PARK 8.40 1240 PM 8/13

RONKONKOMA 8.20 640 AM 8/13

FARMINGVILLE 7.73 800 AM 8/13

CENTEREACH 6.71 918 AM 8/13

NASSAU COUNTY:

MASSAPEQUA 8.20 930 AM 8/13