NYC Weekend Weather – Eye on Jose – Sep 15, 2017

The main weather headline going into the weekend is the eventual track of Tropical Storm Jose. Depending on its proximity to land, we could see some nasty effects from the storm next Tuesday or Wednesday. The weekend itself should be rather uneventful, the veritable calm before the storm.

Rest of today – warm and mostly sunny. Small chance for an isolated PM pop-up thunderstorm especially inland and west.

Saturday – more clouds but still a nice day with highs around 80°F.

Sunday – probably the best day of the weekend with mostly sunny skies and a high around 80°F again.

Monday – pleasant enough to start the week. Increasing clouds, which will end the streak of above normal weather. With Jose approaching from the south we may also see increasing onshore winds cooling things off.

 

Jose an Increasing Threat to the East Coast

While Texas, Florida, and parts of the Caribbean are still reeling from the impacts of major hurricanes Harvey and Irma, Jose could pose a problem for us along the East Coast. Jose has been meandering aimlessly in the western Atlantic over the last few days and has done an anti-cyclonic loop. It’s now beginning to move west-northwest and there are a few forecast models that show it making landfall along the East Coast or coming very close to it.

It shouldn’t be too surprising that the cone of uncertainty in the official National Hurricane Center’s forecast is so large at day 5 given the substantial spread that exists amongst individual members of different modeling systems. Note that there is still plenty of time for this storm to curve out to sea with primary impacts being limited to beach erosion and coastal flooding. However, if the storm comes closer to shore or makes landfall, then we’re talking about a much more substantial problem.

Critical factors for steering this storm will include the strength of a blocking ridge (area of high pressure) which you can see in the upper right of the following image, and whether Jose gets picked up by a frontal boundary and pushed east. A stronger high pressure would block Jose’s eastward progress, and the timing of the frontal boundary passing over the East Coast will be crucial.

Jose is expected to intensify somewhat back to a minimal Category 1 storm over this time. On its approach to this area, it’s possible that it might begin the process of extratropical transition, where its center becomes less defined and loses a warm core. However, this process could also infuse some energy via baroclinic forcing that actually strengthens the storm, much as was the case with Superstorm Sandy. The concern for this storm is the long period it spends over open water where it has the potential to churn up storm surge. Even if there’s no landfall, it doesn’t mean it can’t affect coastal areas with surge or flooding.

This model run of the GFS shows Jose stalling out very close to Long Island, then brushing Cape Cod, much like a Nor’easter.

 

And don’t look now but we could be seeing the formation of tropical storms Lee and Maria in the Atlantic as well. The storm further to the west could pose a threat to the southern Lower Antilles next week.

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