A powerful coastal storm with very strong winds and heavy rainfall is undergoing bombogenesis near the East Coast, resulting in tree damage, power outages and flooding.
Rapid intensification of the low pressure system is ongoing near New York City, and it is expected to continue to rapidly intensify as it moves into the Hudson Valley overnight.
Bombogenesis is a rapid deepening of pressures in a storm, which rapidly increases winds near the center of the storm. Scientifically, bombogenesis is defined as a drop of 24 millibars in 24 hours.
So far, winds are gusting in the 30-50 mph range so far near the coasts of New Jersey, Maryland, Long Island and Massachusetts. Winds as high as 70 mph have been reported in the higher elevations of New England. These winds may increase through the late evening into the morning hours.
One of the ingredients for this coastal storm is a powerful jet stream disturbance sweeping through the eastern states that will help induce the formation of a strong low-pressure system near or off the mid-Atlantic and Northeast coastline. This storm system is receiving an injection of moisture and energy from ex-Tropical Storm Philippe, currently tracking quickly northward to the east of this parent low pressure system, as well as the cold front sliding through the East.
The National Weather Service office in Boston noted in its Saturday morning discussion that this is an unusual and truly strong, potentially dangerous storm system for late October.
Rain is currently increasing across the Northeast due to the approaching cold front and tropical moisture streaming northward.
More than four inches of rain has been reported already in a few spots in New Jersey and New York.
Here's an overview of the timing and possible impacts of this storm.
Overall, this East Coast storm will be a quick-mover as it races northward on Monday.
High winds are likely in the Northeast overnight into early Monday, with damaging winds most likely along the coast from New Jersey to Maine.
Numerous trees have been downed across southern New England so far.
We expect to see wind gusts up to 70 mph in some areas, and they could be higher depending on the intensity and track of the storm. The potential for higher-end wind gusts will be greatest along the immediate coast and in higher-terrain locations, particularly in New England, where a few gusts may reach 75 mph.
Funneling of winds in between high-rise buildings and mountain and hilltops may also create locally higher winds.
High wind warnings have been issued for New York City and Long Island and much of New England including Boston for Monday morning. High wind warnings have also been posted for parts of eastern New York and near Lake Ontario.
In addition, hurricane-force wind warnings have been issued for the coastal waters from eastern Massachusetts to southern Maine.
There will be three main impacts from the winds in portions of the Northeast:
In addition to the overlying wind threat, a few waterspouts and/or tornadoes are possible in coastal Massachusetts this evening into early Monday as Philippe's energy moves through a relatively warm, moist pocket with abundant wind shear.
Given the tropical moisture tap, a large portion of the Northeast could see more than 3 inches of rainfall. Heavier totals topping 6 inches are likely. At this time, the heaviest rainfall is expected in portions of Upstate New York and in the higher elevations of New England.
The heavy rain could contribute to flooding not only in urban and poor-drainage areas, but also on streams and rivers. This concern has prompted flash flood watches to be issued by the National Weather Service for much of New England, New York, New Jersey and eastern Pennsylvania.
After a very dry start to October, the Northeast saw heavy rain this week from another storm system. Now that the ground has become more saturated, particularly in parts of New England, that will make those areas more prone to flooding through Monday.
The rain will also likely erase some of the abnormally dry and moderate drought areas on the latest U.S. Drought Monitor.
In addition to the rainfall, heavy snowfall is possible in parts of western Maryland, West Virginia and the mountains of North Carolina and Kentucky where the air is coldest. Up to 4 inches of snow is possible in central West Virginia in the highest terrain.
As this coastal storm rapidly intensifies, waves are expected to quickly ramp up from the mid-Atlantic northward to New England. These waves will make boating extremely dangerous, and boats should stay out of the water.
People should also stay out of the water along the coast due to these high waves and likely rip currents that will be life-threatening.
A storm surge of 1-3 feet is expected along the coast, especially on east- or southeast facing coastlines. Minor inundation is expected.