Potential NYC Area Snowstorm for Friday?

Models forecast potential snowstorm for NYC metro area (one day earlier now) for Friday, January 1, 2010. The last two maps above are the 84 hr. forecast for Wednesday at 7 PM from the NAM model. The model is forecasting developing rain and thunderstorms along the Gulf coast in response to a moist southerly jetstream flow and upper trough that is moving across the Midwest at 500 mb. The trough axis at 500 mb extends approximately from Nebraska through Texas. This energy generates a weak coastal low that spreads rain and some snow to the north across the Southeast and Mid-Atlantic states. However, most importantly, there is strong jetstream energy injecting through the Southwest US and this develops a coastal storm off the Mid-Atlantic coast that tracks northeast just to the south and east of NYC and Long Island. Another vigorous shortwave trough over western Canada also moves to the southeast and phases in with the southern trough producing a large cyclonic vortex over the Northeast and Ohio Valley by Saturday. This will result in snow showers in the Tri-State area after the storm has moved into eastern New England. This storm is similar to the one that occurred on December 19-20, 2009 in that it follows a similar track. The GFS model runs are provided in the first three maps above for the surface, 500 mb and 850 mb levels. The upper air support differs and this creates the main difference between these two storms: the 850 mb low passes closer to NYC and the 32 F 850 mb temperature isotherm is forecast to be farther west setting up over NYC, northern NJ and southeast CT. This would result in a mix of snow, sleet and freezing rain with a potential changeover to rain along the Jersey Shore and Long Island later in the morning and into the afternoon on Friday. Before any mixing, there will be some accumulation of snow. Of course the pattern could change on future model runs.

Right now, the models are indicating that this storm will move quickly, will be weaker, may not produce all snow and it will not produce anything close to the 2 ft. + snowfalls that occurred in eastern Long Island, southern NJ, MD and southeast PA on December 19-20, 2009. Future model runs could change drastically in the next couple of days. The UKMET keeps the coastal storm well off the coast and out to sea by Friday, January 1, 2010 but the European model forecasts a coastal storm. All models agree that behind this storm, very cold Arctic air will plunge down producing very cold weather for the first weekend of 2010 for the upper Midwest, the Great Lakes, the Ohio Valley, the Northeast and Mid-Atlantic States.

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