wpostServer: http://css.washingtonpost.com/wpost2

Most Read: Local

Posted at 04:23 PM ET, 11/05/2012

Storm, flood and high wind watches issued ahead of Nor’easter in Sandy-stricken areas


Model simulations show very strong storm forming off the Mid-Atlantic or Northeast coast late Tuesday into Wednesday. Wind speeds are indicated by the color shades in knots. The NAM model simulates the storm developing far enough to the northeast such that the brunt of the storm bypasses the Delmarva and New Jersey coast. (WeatherBell.com)
As two waves in the atmosphere merge off the Mid-Atlantic coast, one from the north and one from the south, a major Nor’easter will rapidly develop Wednesday. High winds, rough seas, and coastal flooding are a threat from the Delmarva Peninsula into New England - many of the same areas devastated by Superstorm Sandy.

Latest model data indicate the brunt of the storm may just graze the southern half of the Mid-Atlantic, from Washington, D.C. to the southeast. But storm impacts are likely to increase to the north and east, as low pressure “bombs” or develops explosively offshore the Delmarva.

The National Weather Service has issued high wind watches for the western half of the Delmarva Peninsula northward through southeast Pennsylvania and western New Jersey. Along the coast, storm watches and coastal flood watches are in effect from the beaches at Maryland/Delaware border to northern New Jersey. These watches will likely be extended northward over the next day into southern New England.

Here are some significant excerpts from these wind and storm watches (bold text indicates added emphasis):

In the high wind watch area

* Winds...Northeast to north at 20 to 35 mph with gusts of 50 to 60 mph. Some wind gusts could easily reach 65 mph, mainly along the coastal areas.

* This is a particularly dangerous situation, especially for the areas that were hardest hit by last weeks storm.

* Timing...the strongest winds should occur from about noon Wednesday through Wednesday evening, with the highest winds occurring closer to the coast.

* Impacts...Structures and trees weakened by last weeks storm may be further damaged by another round of high winds. This can also result in renewed power outages, particularly in areas where the electrical system remains in a weakened state. Debris from last weeks storm could become a hazard during this new storm, especially if it is light enough to become airborne.

In the storm watch area

* Winds...Northeast to north 30 to 40 kt [35 to 45 mph] with gusts up to 60 kt [70 mph].

* Seas...13 to 19 feet across the Atlantic coastal waters, and 3 to 7 feet in Delaware Bay.

In the coastal flood watch area

* Seas...Wave heights in the surf zone along the coast are expected to build into the 6 to 10 foot range.

* Coastal flooding...Moderate flooding is anticipated around the times of high tide on Wednesday and Wednesday night. Water levels may not recede much between the two high tides.


Forecast storm surge from the GFS model (NOAA)
Throughout much of the coastal flood watch area, forecast tides levels are expected to be near 7.5-8 feet above mean lower low water, including in Sandy Hook, Sandy Heights, Atlantic City, Cape May, Breakwater Harbor (DE), and Rehoboth Beach (DE).

It’s important to note this is a tricky forecast which is dependent on exactly where the storm forms and intensifies. Some models (NAM and European model) suggest the storm could develop far enough offshore and far enough north to spare the Delmarva and Jersey shores from the strongest winds and highest seas.

However, the GFS and the Canadian both simulate a rapidly developing storm that would produce powerful sustained winds over 40 mph at the coast (with gusts to 60+ mph).

Unfortunately, New York City is also likely to face another round of wind and high seas, but less severe than Sandy. Writes the National Weather Service in New York City:

Regarding the mid to late week coastal storm...A surge of 3 to 5 ft is possible. Highest tidal anomalies will likely occur across the western long island sound due to piling of water in northeast fetch. South shore bays will likely see high anomalies as well...With NY Harbor observing slightly lower anomalies.


GFS snow simulation shows potential for over 4” of snow over the western Delmarva peninsula (StormVistaWxModels.com)
Another wrinkle in the forecast is that the latest models have trended colder, which would increase the threat of snow over southeast Pennsylvania (potentially including Philadelphia), the west side of the Delmarva and western New Jersey. Even New York City could experience snow if the storm tracks far enough east, which would draw in cold winds from the north.

While this storm has the potential to generate more power outages and add to the misery of those recovering from Superstorm Sandy, this storm will not be as intense and we can hold out hope some of the weaker, less wound up storm scenarios materialize.

By  |  04:23 PM ET, 11/05/2012

Categories:  Latest, U.S. Weather, Winter Storms

 
Read what others are saying
     

    © 2011 The Washington Post Company