We continue to watch the upper low off the east coast as low pressure develops. The National Hurricane Center is still calling for a 60% chance for tropical cyclone development however regardless of development be it tropical, subtropical, or non tropical, low pressure is forecast to edge up the east coast and this will have an impact on Sunday’s weather. Saturday appears to be fine with sun and clouds and that risk for a downpour or a thunderstorm for somebody. Sunday’s issue will be an onshore flow that will bring clouds in from the east and the possibility of some rain as it backs in westward from off the ocean. A least that may be the case for Long Island, Connecticut, back to about or just west of New York City and possibly along the New Jersey coastline. Inland it should be far enough west for just some clouds and breaks of sunshine with just the risk of a donwpour.
Day runs of the models were a little further to the east with the Canadian model a little more aggressive with the low development and the arc of rain that is offshore. Lows like this in the summer and the fall are always a bit tricky because sometimes the rain manages to find its way westward and often times it is low clouds and showers that are not that easily spotted by the radars. Should this system become tropical or subtropical in nature it could pull the rain closer to the center and away from land. Subsidence on the western edge could dry out the sky inland to no worse than partly sunny while a low overcast hangs tighter along the coast.
As far as any development is concerned it could be a problem for boaters out on the open ocean so it would be wise to keep abreast of latest marine conditions on the marine forecast page. It could also be an issue regarding the beach and rip currents over the weekend.
Models do push this system away to the northeast late Sunday afternoon which means that the next cold front approaches on Monday.
You can see that the gfs has a broader weaker look to it and that pushes rain back to Southern New England and into Northern New Jersey while the Canadian has a well developed possible tropical or subtropical low further northeast. Monday a cold front approaches with not much with it and this will lead to lower humidity with seasonal temps for the middle of next week.
Now with regards to Hurricane Danny if you remember my Joestradamus post from yesterday we went into detail about what you need to see in the upper flow for a hurricane or tropical storm to hit the northeast directly.
The upper flow next week appears to be dominated by a vortex in Hudson Bay with a strong west to east flow from the Mid-Atlantic states northward. This is not the flow that brings tropical storms up the east coast.
Even out through next Sunday the GFS has this strong westerly flow aloft. The narrow ridge means that Danny, if it is still around, will either be trapped underneath it or, if it manages to break through it it would get caught in that westerly flow and then get transported east northeast. What is interesting on today’s GFS run is that the model seems to be going to the European’s look of 2 days ago with a ridge building in the west and a trough coming back into the eastern states. The European last night was still in warm ridge mode in the east. It will be interesting to see what the European does in the longer term because the GFS would imply cooler air late in the period, which is what the European showed 2 days ago.