Weather Models Showing Different Solutions...

Two commonly used weather prediction models, the NAM and the GFS are still producing different solutions to this Saturday's weather here in the NYC metro area. The NAM (1st map above) is wetter providing more precipitation to the west of the storm while the GFS is much drier (2nd map) taking the storm and rain/snow farther out to sea. Colder air will be moving in from the west, the 540 thickness (a commonly used line indicated the rain/snow boundary) is close to the NYC area so some snow is a good bet along with some rain. The NAM's 500 mb (indicated the wind field at approximately 500 mb or 18,000 feet) indicates that there is not a lot of cold air been driven into the trough (i.e., there is not a large "split flow" where the polar jet from the north converges with the moist southern jet from the south). However, the 850 mb map indicates that the 0 C (32 degrees F) line is over or just to the east of NYC which indicates that there should be a mix of snow, sleet and rain Saturday evening. Earlier this week, the NAM was a rather dry solution with the western edge of the precipitation shield just grazing the NYC area and Long Island. More recent runs have been trending towards more precipitation for the tri-state region. The precipitation should begin as snow and rain and then change to sleet and snow during Saturday evening with the precipitation ending by daybreak on Sunday morning. An inch or less can be expected along the coast with 1 to 3 inches inland across northern NJ and interio southern CT. This is the first storm of the season that could produce snow in NYC. In December 2002, 2003 and 2005 there were storms that produced snow during the first two weeks of December in the NYC area.

George Wright is a Certified Consulting Meteorologist and President of Wright Weather Consulting in NYC. Our website is WrightWeather.com.