Why has there been son much rain in NYC lately?

Question

Apart from speculations, is there an official/researched reason as to why there has been so much rain/thunderstorms this summer in the NY area? I've noticed it's been a little cooler than usual as well this July. (Hasn't gone into the upper 90's/100's yet).

Answer 1

Hi Qanda!



We've been a LOT cooler than normal, and rainier.



The average temperature for the month of July in New York, according to the National Weather Service, should be 76.5 degrees. If July had ended yesterday, July 26, we'd be on track for a 71.8.



Since the National Weather Service started keeping records in 1869, we've had just one month of July that's been cooler. That was 1888, when the average for July came in at 70.9. Right now, we're in the second coolest of all-time, since records started being kept.



There's more. Since the 1990s, average summers here have been cooler. The decade of the 1990s saw an average July temp 1.0 degrees warmer than normal on average, including the hottest July ever recorded since 1869, coming in 1999 with an average temp of 81.4 degrees.



But in the current decade we've seen several chilly years, including a 72.3, the fourth-coolest of all-time. The average for the decade, not including 2009, came in at 0.6 degrees below normal. Now, with our 71.8, this year may break even that mark, if the cool days were to continue for the rest of this week.



Anyone think there's a pattern here?

Answer 2

The most likely cause is El Nino. In the central Pacific ocean, there is a band of warm water that oscillates back and forth across the Pacific every several years or so. When it's in the eastern Pacific (between Hawaii and Southern California), this is called an El Nino. When it's in the western Pacific (by Asia), this is called a La Nina.



The El Nino event causes the jet stream to take a more southern path. Usually, the jet stream would go across the southern part of Canada or the northern part of the US. But, when it dips because of the El Nino, it brings colder air down through the upper midwest and east coast. And, when this collides with the warm, moist air coming up from the Gulf of Mexico and the Caribbean, this results in the formation of precipitation-producing storms.



The dip in the jet stream has actually reached as far south as the Gulf of Mexico this summer. The resulting winds aloft have formed a wind shear effect, which is preventing the formation of tropical storm systems in the Gulf and the Caribbean. And, it's why we haven't had any named tropical storms in the Atlantic basin yet this year.



Note that the high pressure ridge over the Great Basin (upper deserts of Nevada and Utah) prevents the jet stream from dipping down over the Pacific Northwest and California. This results in hot, dry conditions all along the west coast throughout the summer.



In the winter, the jet stream will push warm, moist air from Hawaii into Southern California, instead of the Pacific Northwest. So, we should see torrential rains in the southwest and drought in the northwest this winter. With the lower jet stream, there should also be more frigid air with less moisture in it coming down from Canada and the Arctic, into the upper midwest and the east coast. So, look for especially cold temperatures, and relatively light amounts of rain and snow in NYC this winter.

Answer 3

It is most likely due to the el nino. Thats a warming trend in sea temperatures in a specific portion of the pacific which affects our weather patterns in the USA which means more rain for the west and east coasts, but the west coast will probably be spared until their rainy season sometime this fall.



Also a decrease in sun spots might be the cause too, but i dont think it has been proven as a fact.



Average temperature is 76.5 in central park Ny, which is the average of both the day and the night temperatures. Night temperatures average at approximately 67-70 degrees and day temperatures average at about 84-88 degrees according to exactly where you are in the NYC metro area.



Also usually an el nino also means a snowier (and slightly colder) winter than typical for the east coast which includes all the major cities from boston down to dc and even virginia down to western protions of north carolina.