Monday 10:40 a.m.
Just before 11 a.m., The National Hurricane Center officially called a storm near Jamaica T.D. 18, the 18th tropical depression of this year's tropical storm/hurricane season. It is likely to strengthen, so naming it Sandy would be the next step.
There is a significant historical precedent for a storm to form around where this is located... and then turn into a real hurricane. In 1878, a storm formed near Jamaica (near where the new storm is) then became a Category 2 hurricane and moved right up the East coast. The center passed east of Florida, then came ashore in eastern North Carolina and stayed inland until it turned almost straight east over the southern parts of Vermont and New Hampshire. There was extensive damage from the Carolinas to New England, and more than 71 people were killed. This storm came to be known as the Gale of '78.
A history of the storm was prepared by David M. Roth and High D. Cobb III of the National Weather Service in 2000. They point out that aside from Hurricane Hazel in 1954, all hurricanes with somewhat similar tracks occurred in the 19th century. Here is the storm track, as shown in the article referenced:
Now, since the newest storm has not yet had much impact, it could be asked why the new development could be important. In this video, there is one map from last evening's ECMWF (European) Model. A storm like the one depicted would be disastrous in the Middle Atlantic states, threatening death and serious injury and causing billions of dollars in damage.
Here is one of the maps that looks so threatening:
If this were to actually happen and hurricane-force winds hit places like Philadelphia and New York City, there would be a major storm surge, massive power outages, flooding rain.... and then least a foot or two of heavy wet snow near and southwest of Somerset, Pa., in the Laurel Highlands and in Garrett County, Md.
But how likely is this event? At this point, it would be irresponsible to say it is likely at all. The model showing it has changed the track with successive runs, and other models, such as the GFS, have the storm tracking well east of the area targeted on the map. Here is the GFS model forecast for the same area at the exact same time. The difference is awesome.
In the meantime, the weather seems almost anything but threatening in the Middle Atlantic states. Temperatures will be above average all week, and no rain is forecast in the I-95 corridor from Philadelphia south past Washington, D.C., all week.
Wet weather is coming toward the Northeast, and episodes of rain may be spread out over a two- to three-day period. Supporting this idea is this satellite/radar image from mid-morning Monday showing pockets and bands of rain affecting several areas.
On this map from 10 a.m. ET Thanksgiving Day, you can see the high pressure area that is causing dry and mild weather in the East and the cold front farther west.
During the late afternoon and early evening hours, the cold front of a knife will slice through the turkey and cause it to accumulate 1-2 inches on plates...
This satellite picture shows clouds over parts New York and Pennsylvania, as well as areas of low clouds, fog and snow cover from Michigan to Illinois. Most of the Northeast should have at least some sunshine through Thanksgiving Day.
As we go through the week, the flow aloft over the East will become southwesterly. This will promote a major warmup. This map shows the projected upper-air flow for Thanksgiving afternoon:
A major snowstorm will affect the area from Iowa to Michigan tonight and tomorrow. At first, snow can melt on streets, but as it continues and the temperature drops, the area impacted by slippery conditions will increase dramatically. This map shows expected accumulations: