The storm that originally looked like it could bring heavy snow from Ohio and Pennsylvania to southern New England moved south of the track that would have produced that result. Instead, the heaviest snow today is in Virginia, parts of Maryland and Delaware and extreme southern New Jersey.
So why did this happen to make the forecast so wrong? When the main energy from the storm was over the Pacific last week, the data that was fed into the models had less detail than that available over a continent where data sources are more densely packed. This problem has been somewhat reduced in recent years, but not eliminated, by an increase in satellite and aircraft-based observations.
All along, it was perceived that the heaviest precipitation would fall in a narrow stripe. As it turned out, we were off on the exact position of this band. As the storm storm came ashore and we knew more about its nature, the forecasts improved. However, if you heard a foot of snow was in the forecast Friday and didn't check for updates, then woke up to see no snow this morning, you'd think no storm ever formed. One thing I can assure you is that this will happen again sometime. That's why it is important to look at updates as often as possible whenever you have a weather sensitive decision to make. Here is today's video.
This map shows accumulations as of 8 a.m. They have continued to increase since then in Delaware, Maryland and Virginia.
This map shows where Hurricane Joaquin was just before 8 a.m. ET. You can also see the stripe of clouds centered just of the Middle and North Atlantic coasts.
There are competing forces acting on it, and each move it makes will place it under different influences. This has made it very difficult for computer models and meteorologists to judge where it will actually go. This is reflected in the track model collection on this map:
In assessing the final impact of the storm system coming into the East, there are three main components. First is the cold front coming across the Appalachians tonight in a very rich moisture field with ...
On this map, the cold front that will eventually move through the Northeast is in the far northwest corner of the picture. There are areas of showers moving northeastward well ahead of the front, but the steadiest rain is not likely until the cool air moves in and the front stalls.
The Midwest and Northeast are in the latitude zone where winds are primarily from the west. The direct opposite is the case today, as seen on this pressure analysis. The easterly flow brings in moisture from the Atlantic.
The infrared satellite picture below shows the cloudiness as of midmorning on Thursday. If it stays the way it is now, there is no problem in the Northeast. However, on another screen I have been watching the whole area expanding north and west, as indicated on the map.