This post covers the planned update for yesterday, 12/22. Two posts will be added tonight, a pattern outlook and an additional discussion on the upcoming storms.
Monday Night – Tuesday: Christmas is shaping up to be wet rather than white for most of the area, although parts of the area still have a chance to make it to Christmas morning with snow on the ground. Light precipitation will develop early on Monday night, ending by Tuesday morning; this will be mostly, if not entirely rain from NYC and further south and east, with light snow quickly changing over to rain for the north/west suburbs with a longer period of light snow for the interior northwest parts of the area. Accumulations will be limited to north/west of NYC, with up to 1 inch possible for the suburbs and 1 to 2 inches towards NW NJ and interior SE NY.
Wednesday – Thursday: The model guidance is still not consistent with the storm mid-late next week, with the GFS having gone all the way from a coastal low with a major snowstorm in NYC to a low pressure over Ohio with heavy rain and 50 degrees for the area. The 18z GFS run last night showing this outcome is likely a western outlier, just as the 18z GFS run 2 nights ago with the major snowstorm is also an outlier. For now, I’m making little revisions to my original thinking, going with a slightly more west track and a warmer outcome with the low pressure tracking over or not far west of New York City. Most of the area is likely to see plain rain, with some snow to start changing over to rain north and west of NYC as well. The exact timing is uncertain at this time, but appears to be mostly a Wednesday night event into Thursday. The main risk at this time appears to be heavy rain over 1 inch and strong winds, although some accumulations are still possible further inland towards NW NJ and interior SE NY.
These storms will be discussed in more detail tonight, along with another storm potential towards the end of the month. A pattern outlook focusing into early January will be posted as well.