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.
Over the Ohio Valley, rain is starting nudge northward again, prodded by one of a series of upper air disturbances embedded in the flow. It appears the rain will advance across Pennsylvania overnight, reach the area from New York City to Boston tomorrow... then head out to sea.
Farther north, the area from Chicago to Boston looks most likely to have sunshine and dry weather. Cloud cover will vary during the weekend, and I focus on that aspect of the weekend forecast in this video.
A band of heavy rain and locally violent thunderstorms moved from the New York City area at 4 a.m. to just past Boston (distance: 188 miles) by 9:30 this morning. Note the stunning contrast between where it is pouring (dark red) and where it has dried out.
On the map, showers and thunderstorms were located along and ahead of the gray line that cuts through Pennsylvania and along/ahead of the blue line. Both should be off the East coast by Thursday. Drier air from the Upper Midwest should filter into the Northeast later in the week.
The large storm that drenched the Northeast during the weekend has drifted out to sea and somewhat drier air is coming in to replace it. However, another upper air trough extending from Wisconsin to Louisiana is supporting several pockets of showers and thunderstorms.
From northern West Virginia across most of Pennsylvania and western and central New York, there could be several inches of rain with flooded streets and streams.