Saturday 1 PM EDT
Sandy is still wobbling northward well off the South Atlantic coast. As a strong trough aloft approaches Sandy, the storm's circulation will be drawn into and become part of a greatly expanded upper air storm.
Since the storm will be a hybrid that includes some of the characteristics of the non tropical storms that cause most the cold season precipitation we see in the Great Lakes and Northeast, its circulation will be more spread out (rather than more compact). A lot of rain will be generated as tropically moist air is forced westward over air that is much cooler. This is something we typically do not see with pure tropical storms/hurricanes.
What all this means is that the heavy rain and increasing wind will reach places long before the center arrives. Delaware, New Jersey, as well as parts of eastern Pennsylvania and Maryland, are likely to start getting damaging winds and torrential rain tomorrow night, perhaps escalating into the worst conditions Monday morning. The center will come ashore after this, and by that time the rain and even the wind will be weakening.
Unless the storm tracks farther north than expected, the New York City area may be near the northern edge of the very worst conditions. Where the wind and rain are the worst, there will be streets flooded with water and massive tree damage and power outages. And, the wires have to be restrung one at a time... that's what takes so long (as well as other challenges of accessibility and maintaining safety.
It is important to complete your planning and preparation before the worst conditions approach later tomorrow. This video shows the situation and forecast as of early Saturday afternoon. Please check more recent information that will be continuously updated on AccuWeather.com. Also, your local emergency management people are trained on helping people avoid and deal with the most critical things that can kill and destroy.
Enhanced infrared satellite picture from early Saturday afternoon.
It appears likely that many normal activities can go on through the day Monday, as long as the typical cautions for light to moderate snowfalls are observed. Tuesday will be an <strong>entirely different story</strong>. This map shows the GFS- predicted snowfall through 7 P.M. ET Monday:
The second storm we have been talking about will affect the Middle Atlantic region late Sunday and Sunday night. This GFS forecast map is for 7PM ET Sunday and shows precipitation amounts for the 6 hours up to that time.
This was our snow accumulation projection as of mid-morning. A storm that will develop in the Midwest on Sunday is likely to track to the Virginia-Maryland coastal area by Monday morning, then turn east. It will probably bring some to snow places that get mostly rain out out of the first storm.
Just a 1- or 2-degree temperature difference in the lowest 5,000 feet of the atmosphere can make the difference between heavy wet snow and heavy wet rain. Here is a draft of our snowfall map from mid-morning.
Much can still change with regard to the Saturday storm. This draft map from this morning shows how the accumulations may turn out. The AccuWeather.com staff will be watching this closely. I am happy to see many of our newer forecasters making major contributions.
n the Northeast corridor, this winter has not created much happiness among people who like snow. In New York City, this is the first year out of the last nine to have no 2-inch or greater snow event to this point in winter. Ralph Fato (WxNut27) sent out one of his wonderful charts to illustrate the widespread lateness of the first significant snowfall: