NY NJ PA Weather Forecasts

Thoughts On A Potentially Very Snowy Week For The Forecast Area

8:06 PM

I issued an upgrade to the alert levels (Alert Stage Two) because there is increasing support via the model guidance AND (more importantly) the actual evolution of the current pattern to support a likely winter storm for the forecast area.  

The focus here is from Tuesday night through Friday night.  The forecast area will be impacted by two distinct low pressure system in this time period.  The low pressure systems are expected to be weak in general with the deepest low pressure system I expect to be no deeper than 1002 MB.  

The first low pressure system will track from southeastern Oklahoma on early Tuesday morning to the  Tennesse Valley by late Tuesday night and south of Long Island by Wednesday afternoon.  The low pressure system will be weak, limiting the advance of the low level and mid level warm air, but strong enough to produce a period of moderate to possibly heavy snow to all of the immediate Philadelphia metro through what now looks to be all of the New York City metro as well.  The storm track has not shifted north from my previous thoughts, but I am expanding the northern extent of the moisture due to the position of the high pressure system being further north.  This means that the strong suppression from the Arctic high will be further north and allow moisture to expand into the New York City metro.  There is a snowfall potential for 4+ inches of snow throughout the entire forecast area and 6+ inches for New York City on south through the Philadelphia metro with the first storm.  There is also a potential for mixing of snow, sleet, and rain for extreme southern New Jersey.

The second storm will feature the strong upper level system as the remnants of the upper low to the west of California race towards the East coast.  Right now, I think the northern and southern branch does NOT merge due to the speed of the southern branch versus the slower, yet stronger northern branch.  However, I do want to say that should the southern branch disturbance and the northern branch interact to produce a phased solution, then the developing low pressure over the Mississippi Valley would track along or over the coastal plain, thus changing the precipitation to rain along the coast before a heavy “front end” snowfall.  At this time though, I am staying with my original idea for the past several days as I think the upper low will shear out and produce only a weak yet moisture loaded low pressure system that will track from southern Mississippi on Wednesday morning to the Virginia coast on Wednesday night and towards the bench mark (40/70) by Thursday night.  I think this low pressure system will have more moisture than guidance is currently showing.  There is a potential for a snowfall over 4″ as well throughout much of the forecast area, but I have concerns about mixing issues as boundary layer problems are likely with a lack of surface high pressure to the north.  

As for Sunday night into Monday, I will issue a snow map and discussion on this minor event in the next post.

Tags: Albany, Allentown, area, Atlantic City, Belmar, Bridgeport, california race, city metro, coast, Connecticut, Disturbance, early tuesday, east, East Coast, evolution, extent, extremes, forecast, forecast area, forecaster, forecasters, Freehold, front, guidance, Hartford, heavy snow, high, interaction, Islip, Long Island, low, lows, map, maps, metros, mid, Mississippi, Model Guidance, models, moderation, moisture, New Jersey, New York, New York City, Newark, north, northern extent, Oklahoma, Pennsylvania, periods, Philadelphia, philadelphia metro, plains, Poughkeepsie, precipitation, precipitations, Rain, Reading, remnants, Scranton, Shear, sleet, snow, snow sleet, snowfall, south, southeastern oklahoma, Storm, storm track, storms, surfaces, Sussex, systems, Tennesse, time period, tuesday morning, tuesday night, valleys, Virginia, warm, wednesday afternoon, weeke, west, White Plains, Wild Wood, wills, Winter, winter storm