Nor'easter coming Wednesday and Thursday

An early-season Nor'easter will form off the coast of South Carolina on Tuesday evening. Once over the warm waters off the coast, the low will intensify, spreading heavy rains of 1 - 2" over coastal North Carolina on Tuesday night and Wednesday morning. The storm will accelerate to the north-northeast on Wednesday and pull in cold air from Canada, and intensify into a medium-strength Nor'easter with a central pressure near 984 mb by Wednesday evening. While the exact track of the storm still has considerable uncertainty, the models are pretty unified on the timing and strength of this storm. A 12-hour period of strong winds of 40 - 45 mph will likely affect portions of the coast from Maryland to Massachusetts. A more westerly track, as currently predicted by our top model, the European ECMWF model, would likely result in the storm's strongest winds affecting the New Jersey coast. A storm surge of 2 - 4 feet would likely hit the New Jersey coast, and a storm surge of 3 - 5 feet would likely impact the western end of Long Island Sound. These surges would be accompanied by high, battering waves, capable of causing moderate to locally severe erosion along the coastal areas pounded by Hurricane Sandy last week. Fortunately, the high tides this week will be some of the lowest of the month, since we are midway between when the new moon and full moon occur. A more easterly track for the storm, as predicted by the GFS model, would put the Nor'easter's strongest winds along eastern Long Island and coastal Massachusetts, resulting in lower storm surges for New Jersey and New York City. Accompanying the storm will be a swath of 2 - 3" of rain, with the heaviest rains falling over Eastern Massachusetts and Rhode Island. The storm isn't going to tap into a large reservoir of cold, Arctic air, which will limit its intensity and snowfall amounts. Snow is not expected in coastal area, but the Nor'easter has the potential to bring more than a foot of snow to mountain areas of New England.


Figure 1. Predicted wind speed for Wednesday evening, November 7, 2012, from the ECMWF model (left) and GFS model (right). The ECMWF model was run using data from 00Z (7 pm EST) Sunday night, and the GFS model was run using data beginning at 06Z (1 am EST) on Monday. Winds tropical storm-force (39+ mph) are predicted to extend from coastal Virginia to Massachusetts.


Figure 2. Predicted storm surge at Atlantic City, NJ for Wednesday's Nor'easter, from the experimental Extratropical Storm Surge model, run by NOAA"s Meteorological Development Laboratory. This model used winds from this morning's 6Z (1 am EDT) run of the GFS model. The peak storm surge (yellowish-brown line) is predicted to be 3.3', occurring just after midnight local time on Wednesday night. High tide (green line) occurs near 1 am Thursday morning, resulting in a peak storm tide of approximately 7.4' around 1 am Thursday (black line). For comparison, Sandy delivered a 5.81' storm surge to Atlantic City, with the highest storm tide reaching 8.9' above MLLW.

Jeff Masters