NY NJ PA Weather Forecasts

Evening Thoughts

I’ve been working on all the 12Z model guidance this evening, while watching the Mets game of course.  Hey, I got to make sure they get to the play offs, right?

The main theme I’m going with for the end of the week is that the further south you are in the forecast area, the heavier and more likely you’ll see rain on Thursday through Saturday.  The main question on Thursday is just how much influence will the upper low off the New England coast will have on the Northeast and Mid Atlantic.  The models have been wavering on the influence of this upper low and the strong subsidence found on the back side of this upper low.  The stronger the subsidence, the stronger the dry air at the mid levels, and thus the limit on how far north the precipitation and warm front gets over the Mid Atlantic.  

I don’t like the timing of the GFS from Thursday through Saturday because the slow nature of the trough seen over the Great Lakes on the 12Z GFS is opposite of the actual progressive nature of the overall Pacific pattern that will begin to impact North America.  I think the ECMWF has a better handle on this pattern and the faster nature, which drives the warm front into the Mid Atlantic on Thursday and Friday followed by the cold front on Saturday.  

So therefore, my forecast from this morning still stands.  I am going with showers and thunderstorms on Friday with a more sustained, wide spread impact south of New York City.  A continuation of these conditions will be expected on Friday as the warm front slows the progression to the north over the southern Hudson Valley.  The threat for severe thunderstorms will increase south of New York City in the more unstable and warm atmosphere.  This is of course dependent on how far north the steady rain gets and how much break in the clouds can develop.  The cold front will move through the forecast area on Saturday and move through a very warm, humid, and unstable atmosphere.  Again, the threat for severe thunderstorms will return to the forecast area on Saturday afternoon.

The good news is that high pressure can be expected on Sunday and Monday with clear skies, low humidity, and comfortable temperatures.

By the way, the ECMWF also agrees with my thinking that Gustav will be an issue for the eastern Gulf of Mexico by the end of this Labor Day Weekend.