August 17: Wednesday Night Storm Update

Today was yet another hot day, with high temperatures ranging from the mid 80s inland to the lower 90s in the immediate NYC area. Yesterday’s storms ended up being very heavy rain makers in the Jersey City, NJ area, with radar estimates showing as much as 3 inches of rain in a few areas. Another severe thunderstorm moved through northeastern New Jersey and Rockland County, leading to very heavy rainfall, gusty winds and some small hail. Despite this, however, the severe weather coverage area was not as widespread as expected, and the storms also weren’t as intense despite the favorable parameters, with low 700 mb relative humidity a possible cause.

Despite the locally heavy rainfall, most of the area only ended up with light rain at best, with monthly rainfall still well below average. With Thursday’s heaviest rains staying to the south of the area, and a consistently wet pattern unlikely to set up in the near future, the drought is expected to persist.

Wednesday – Thursday Storm Forecast Update:

Tomorrow will have mostly cloudy skies with showers becoming more likely for the late afternoon hours across the area. The storm, however, has trended much further south than it was yesterday, and while a north trend is expected, it is unlikely to reach the scenario that the models showed yesterday, with a widespread 1 to 3 inches of rain for the area.

Looking at the latest models as well as my thoughts of potential trends, the northwestern areas are likely to stay north and west of the cutoff line of the heavy rain, with near or a little over 1/4 inch possible. Up to 1/2 inch is possible in the wetter scenario. For the immediate NYC area, 1/4 to 1/2 inch of rain is likely, with up to 3/4 or 1 inch in the wetter scenario. Some models are showing a very sharp cutoff line for the immediate NYC area, with only less than 0.1 inch NW of NYC, and up to 1 inch SE of NYC, and at this time I am expecting a cutoff line not as sharp as these models are showing, and slightly further north than they are showing. For Long Island and S CT, 3/4 to 1.5 inch of rain are likely, with as much as 2 or locally more inches in the wetter scenario. This is also a very uncertain area, as some models have the sharp cut off line just north or just south of Long Island.

This storm is still very uncertain, and the next few model runs may help give a better idea of the expected scenario. A rain map will be posted tomorrow for this storm, as well as an update focusing on the longer range.

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