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Welcome to the New York City Metro Weather Blog. I am Danny and I am 22 years old. Here, you will find daily forecasts for the NYC/LI, NJ, PA, and CT areas. I will post model images when it's pertinent. I will sometimes delve into the long-range, so if you something coming up, you can get an idea of what the weather will be like. I will post historical weather events from time to time that have affected my home of Long Island. Sometimes, I will go on a rant. But you can always count on the New York City Metro Weather Blog!

Sunday, May 16, 2010

Forecast Discussion for May 16, 2010

Hi guys. Gonna do a forecast discussion for the next several days, let's get started.

A weak shortwave trough pushed through the area today, but that did not deter the beautiful weather we've had since yesterday. Scattered clouds can be found across the area, but that will lead to clearing skies this evening, before mid and level high clouds move in overnight. I am expecting party cloudy conditions across the metro tonight. The southwest-west winds should begin to diminish and a NW wind should become established aloft and a pretty decent radiational cooling night can be expected, especially away from the coast. I expect upper 30's to low 40's in the interior, and upper 40's along the coastline. Looking at the MOS guidance, I cut a few degrees off. But it has a pretty good handle on this.

The upper level ridge axis (576dm) will pass south of the area on Monday morning. This means the beautiful weather we've experienced will begin to go downhill. A cut off upper level low (cut off from the northern stream) will develop over the Tennessee Valley and slowly trek northeastward towards the NYC metro area. At the same time, a surface low will develop in the OH Valley. Then that low will secondary to another surface low pressure system off the Mid-Atlantic coast. Strong PVA is forecast to develop, that will help to allow the secondary low to intensify a little bit as the ULL closes off.

I'll increase clouds tomorrow afternoon, but not go to high chance pops until tomorrow night. Why? precip may initally be slow to develop before the coastal storm forms, plus there is not a lot of model support with regards to a stronger LLJ and insentropic ascent. Hoever, with the presence of a developing h85 theta ridge moving towards the area, the forcing for ascent will begin to increase. I will increase pops to likely on Tuesday

The NAM was an initial outlier, before the other models trended more northwest with the surface low. Better agreement regarding the NAM with the ECMWF/GGEM/GFS models. Because of this, we might not see such a tight gradient (northwest to southeast) in regards to the precip shield located with the surface low. The 12Z GGEM gets the low down into the upper 990's, while the ECMWF/GFS/NAM is weaker. With the strong PVA, I'll take the middle of the approach between the stronger GGEM and the weaker GFS/ECMWF/NAM. Undercut temperatures by a lot as the GFS/NAM were too warm. Mid to upper 50's will be the norm under a east-northeast wind in the low levels and moderate to heavy rain under a thick cloud deck. The H5 trough will be slow to move out, as it meanders eastward. Showers will linger into Wednesday evening before the H5 trough is kicked out by approaching high pressure at the surface and a mid level ridge. Temps a little warmer on Wednesday. Temperatures moderate rapidly under a building southwest flow aloft. Very well could see 80 degree temperatures next Friday. Latest ECMWF/GFS guidance show another upper level cut-off for next weekend, with another development of a coastal storm. Stay tuned!
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