LI's severe drought may ease with possible autumn storms, experts say

Browning lawns may give way to much browner leaves this autumn, thanks to Long Island’s still severe drought. But September could prove a catchup month, with enough rain to ease conditions, experts said.

There even is a remote chance Hurricane Fiona, still deluging Puerto Rico with “catastrophic and life-threatening floods” late Monday, according to the National Weather Service, might dampen the East Coast and possibly New York later this week.

Two of the National Hurricane Center’s 23 models for the storm’s track show it might sweep up the Eastern Seaboard from the Carolinas, said Mark William Wysocki, a senior lecturer of Earth and atmospheric sciences at Cornell University and New York State’s climatologist.

In the world of betting, “That’s what we call outliers,” he said, explaining Fiona’s path partly hinges on the location of the Bermuda high and how it interacts with the jet stream, either continuing to push the storm out into the eastern and northern Atlantic or instead curling it west, toward the U.S. coast.

While the “vast majority” of Fiona’s models show it heading out to sea: “We’ve got to be careful here, if the thing delays, and stays over the ocean, it could slowly drift northward, it could possibly get to New Jersey.”

Even without Fiona, the Island’s arid patch already has begun easing — and should improve further — though only about half the typical amount of rain fell from June 1 to Sept. 18, just 6.25 inches instead of 13.61 inches, said Dominick Ramuni, an NWS meteorologist based in Upton.

Now, however, “We have a couple of shots at wet weather,” he said.

The showers that may arrive overnight, Wednesday evening and Thursday, and possibly next week, mainly may only add up to a bit less than an inch, he said.

Yet the Island already this month — one of the wettest all year — has gotten about half of the 3.6 inches of rain that falls in September, he said.

Still, this was the second warmest summer since the NWS begun keeping records for Islip in 1963. The average temperature was 74.6, just a tenth of a degree below the 2010 record. Islip’s average summer temperature is slightly cooler by two degrees.

New York’s escape — so far this hurricane season — from the devastating floods Atlantic storms can deliver — might not last much longer, as the Western heat dome, which steered Pacific storms north, into the Great Lakes, and then south, toward the Gulf Coast, now is traveling east, explained Wysocki.

“That pattern started to shift in late August and going into early September, where we managed to start getting storms to move through our area from the west, and now we’ve started to pick up some more precipitation."

 And the later part of the June 1 to November 30 Atlantic hurricane season can turn perilous, cautioned Samantha Borisoff, climatologist, Northeast Regional Climate Center, in an email: “The Northeast tends to see larger, slower-moving storm systems instead of hit-or-miss convective storms like during the summer.”

The number of named Atlantic Basin storms predicted was cut by two to 18 in August predictions made by Colorado State University, updating from its June forecast. The total number of hurricane days fell by ten to 30, in the newest projection.

The reasons for the surprisingly quiet hurricane season – so far – includes, said David A. Robinson, distinguished professor at Rutgers University and New Jersey State Climatologist:  “Rather strong winds at mid levels of the subtropical atmosphere.”

An abundance of dust blowing east from the Sahara is another driver.

“This tends to warm the upper atmosphere, thus stabilizing it and deterring storms from developing,” he said by email.

And La Niña might be having less of an effect on this side of the world.

That weather pattern arises when the east to west trade winds around the equator intensify, pushing the Pacific Ocean toward Asia, allowing the coldest layers of the ocean to rise to the surface off the west coast of South America.

Explaining the atmospheric pressure has been lower in the Atlantic basin, where hurricanes form, Robinson said: “This may be associated with cooler than average sea surface temperatures far away in the central equatorial Pacific.”

He added: “Original forecasts thought that cool water would be further east, which would coincide with lower pressures in the Atlantic Basin.”