Coastal storm to snap dry spell in Philly, NYC and Boston

Soaking rain is coming for some in the Northeast, but many may stay dry well into next week, especially in the Midwest. Meanwhile, renewed onshore winds at the coast may lead to beach erosion problems.

A new storm will take shape just off the mid-Atlantic and southern New England coasts and will bring rain to part of the Northeast with the risk of localized flooding from Wednesday to Thursday, AccuWeather meteorologists say. However, where rain does not reach from the coastal storm, many more days of dry conditions are in store.

The new storm will tap into some moisture from the recent tropical rainstorm that rolled ashore in North Carolina, which dropped over a foot of rain and inundated some North Carolina communities.

At midweek, the northern fringe of the storm will reach into the central Appalachians and mid-Atlantic region before pivoting to the Atlantic coast. Then, as the coastal storm ramps up, rain near the coast will increase.

"Some areas that could be drenched by downpours intense enough to trigger urban and flash flooding include Long Island, New York, part of southern New England and perhaps the immediate New Jersey and Delaware coasts," AccuWeather Senior Meteorologist Dave Dombek said.

The coastal storm will attempt to throw enough moisture westward to reach portions of eastern Pennsylvania, southeastern New York and central New England. Once the pattern gets damp, the moisture may be tough to get rid of into the weekend in some coastal areas. Low clouds will tend to hold temperatures back compared to the many recent warm afternoons.

Still, it may not be totally successful and is unlikely to produce rain much farther to the west.

There has been a very persistent wedge of dry air in the Northeast, and that is likely to hold on for many more days over the eastern Great Lakes and into the Ohio Valley, Dombek said. That dry wedge is likely to persist into portions of the central and northern Appalachians as well.

Where has the rain gone?

Following what was a wet spring and early summer for many and even a generous amount of rain during August, the weather pattern has flipped. Instead of storm after storm affecting the Northeast and part of the Midwest, high pressure has been ruling the roost in recent weeks and will continue to do so—perhaps well into next week.

Locations that miss out on any rain into the end of this week from the southern and coastal storm could stay free of rain through much of next week or perhaps even longer. A storm from the Plains may finally bring some rain to Chicago this weekend and perhaps Detroit by early next week.

September has been quite dry in the region, and this month may rank high on the list of driest Septembers on record from portions of the Midwest to parts of the Northeast should rain continue to avoid the region.

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Detroit has only received 0.06 of an inch of rain, with the current driest September being way back in 1877, with 0.39 of an inch. Chicago has only picked up 0.04 of an inch so far, with the record being 0.01, set in 1979. Washington, D.C. (Reagan National Airport), has only picked up 0.02 of an inch through midday Tuesday, with the driest September being 2005, with 0.11 of an inch. There are many dozens of locations that could end up with a significantly very dry September in terms of records.

The dry conditions may accelerate the leaf change and leaf drop, as trees that have been stressed by the lack of rain may enter dormancy earlier than average to conserve moisture.

Extended rough surf, beach erosion possible

The combination of the new coastal storm from Wednesday to Thursday and the re-emergence of a large area of persistent high pressure in the Northeast that follows will increase the onshore wind pattern from New England to part of the southern Atlantic coast into next week.

This pattern will mean many days when tides run above the typical astrological established levels. The east-to-northeast winds will also create erosive wave action at the beaches. The same pattern will also create frequent and strong rip currents for late-season swimmers.

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