Tropical Two-Step

Two types of tropical weather will be the weather story to watch out for over the next several days. You may have noticed that this morning is much more humid than in the past few days. The humidity and warmer air are courtesy of the large high pressure system that has finally moved offshore. The southerly flow of air around the backside of that high pressure system will bring us a day or two of mid-summer weather. Expect today to be sunny and warm, with a high in the mid-80s. A few clouds may move in tomorrow, but it should remain warm and humid. Warm weather, humidity and a nearby front add up to a chance of showers, or a thunderstorm, beginning Saturday night and into Sunday.

Earlier in the week we mentioned that a disturbance near Bermuda had the potential to develop into a tropical storm. Upper level wind shear, which if too strong blows off the top of the system faster than the storm can develop, has, until a few hours ago, prevented the storm from developing. The wind shear calmed down last night and the old frontal boundary is beginning to take shape as a tropical disturbance. The same high pressure system that is giving us a summery day today is likely to push the disturbance eastward over the warm waters of the Gulf Stream. Forecasts for the development of the storm are showing great uncertainty. The most likely scenario seems to be that it will become a tropical storm or minimal hurricane and make landfall in the Carolinas.

After striking the Carolinas there's a lot of uncertainty as to what the storm will do. Most models have the storm turning out to sea before it makes much northward progress. The local Weather Service forecast reflects these scenarios. Much more unlikely, but still slightly possible, is that the storm hugs the coast as it moves northward. This would be bad news as it would bring high winds, lots of rain and a storm surge to the city. WCBS-TV and AccuWeather are hinting that such a scenario might occur. We have no idea what NY Press is talking about in their summary of the WCBS story.

Gothamist will keep our eye on the tropics this weekend. For now though, the chance of having a summer-like day like today is rapidly disappearing as we move through September, so we're telling The Man that we'll be enjoying an extra-long lunch outside today.

Model forecasts of the movement of the tropical disturbance near Bermuda, all of which show the storm staying far from NYC, from the Weather Underground.