HENRI IS GOING TO BE SOME KIND OF THREAT TO SE NEW ENGLAND ….
At Midday HENRI continues to strengthen. It could become a hurricane by Friday. HENRI formed near Bermuda two days ago and has been drifting slowly westward. Meanwhile the remains of what once was tropical storm FRED is still bringing rain to upstate New York and portions of New England on Thursday morning and midday. The remains of FRED have interacted with a cold front which is pushing this way through the East Coast.
This cold front is going to turn HENRI to the north so it parallels the Middle Atlantic Coast during the next few days. As a result HENRI does not pose a t significant threat to the Middle Atlantic Coast. Along the immediate coast there will be some high surf and strong tides along with some gusty winds this weekend.
That portion of the forecast is fairly easy and straightforward. The complicated part has to do with New England. There are several issues / factors to take into consideration in the forecast. To begin with it must be kept in mind that the New England coast sticks out into the Atlantic Ocean. Most of the Middle Atlantic coastal region runs fairly close to 75 degrees west longitude. But the New England coast sticks out as far east as 70 degrees west longitude, with the eastern edge of Cape Cod actually reaching the 70 degrees longitude line. This is one of the reasons why New England’s climatology shows a far more active hurricane history than the coastal areas of Virginia, Maryland, Delaware, New Jersey, and New York City.
In this instance, if tropical storm HERI were to travel straight north as the hurricane models are depicting, It would likely clip southeast Massachusetts and the Cape Cod region with some kind of impact. Perhaps the system will be a weak hurricane or strong tropical storm. This kind of track would undoubtedly be a lot of wind and a lot of rain and coastal flooding that would be enhanced because of the full moon.
In trying to figure out where any tropical cyclone (TC) will move beyond 48 hours, the emphasis needs to be placed on the upper air or jet stream patterns to the west, north, and east of the TC more than the actual Hurricane models. Indeed getting access to the hurricane models on the Internet is fairly easy as there are several excellent sources where the hurricane model tracks and projections. But once a TC moves north of 25 degrees north latitude (north of the Tropics) the upper air patterns are more important. The overemphasis on the hurricane models once a TC leaves the tropical regions is a mistake that many weather hobbyists and meteorologists make. It needs to be kept in mind that most of the hurricane models are based on the GFS model grid which is generally inferior to the European and British models.
There are two very important features in the jet stream or the upper levels of the atmosphere which will determine the ultimate track and intensity of HENRI
First is the development of a very large deep closed Upper Low in the jet stream between Labrador and the southern tip of Greenland. This big pool of cold energy in the atmosphere will result in a Ridge developing in the jet stream in eastern Canada and it is this Ridge that builds into Maine and Nova Scotia which is going to impact the forward motion of HENRI as it approaches Southeastern Massachusetts this weekend and early next week..
The second important piece of energy in the jet stream that has to be watched is the development of a closed upper Low this weekend in Ohio and West Virginia. The development and placement of Upper Low pressure systems in the jet stream are very important in figuring out the tracks of Tropical Cyclones when these features move out of the tropics and start interacting with the mid-latitudes. This is true in the Atlantic, the Pacific and in the Indian oceans.
If this closed upper Low were to stay centered in northern Virginia or Pennsylvania, it would probably grab HENRI and pull it northwest into the coast — probably into southeastern New England or Long Island. But the problem is that most of the model data shows the upper Low progressing slowly but steadily eastward as the tropical Cyclone is coming up the coast.
The result is a possibility of the Upper Low capturing the HENRI and holding it either along southeastern Massachusetts/ Cape Cod or just to the south and east. This is the solution that WxRisk currently favors but a further west track is a possibility.
The latest hurricane models continue to shift slightly to the east except for the latest two runs of the European model. The operational European model and the European ensembles show a “HOOK” into Cape Cod or very close to Cape Cod then a stall for about 24 hours before it begins to slide eastward.
The midday Canadian end GFS models and their respective in the samples are also shifting somewhat more to the east.
Another factor to take into consideration is that at some point HENRI is going to cross the Gulf Stream and it could undergo a period of Rapid intensification into either a category 1 or Category 2 hurricane. That being said, the trend with the intensification models is weaker. Many of the hurricane models on the afternoon data are now showing a minimal hurricane at maximum intensity before HENRI reaches Cape Cod and this is a step down from the intensity they were depicting earlier Thursday morning and on Wednesday.
There will be a full moon this weekend and a stalled TC, either over Cape Cod or just to the east will mean a prolonged east wind which will pile the water up into Cape Cod Boston Bay Narragansett Bay, eastern Long Island. The prolonged easterly winds and higher than normal storm tides will produce coastal flooding which could be moderate to significant in some places depending on the shape of the coast.
Recent rainfalls have also made the ground condition saturated and saturated ground conditions often means that trees come out of the ground much easier and this of course has implications for power lines across all of Eastern New England.
This does not look like a major event with respect to the size or intensity or the power of HENRI but this TC does have some issues which have to be faced and dealt with including the risk of prolonged coastal flooding and higher-than-normal tree damage because of recent rainfall.