The models are showing an area of low pressure developing along the Mid-Atlantic or SE Coast tomorrow and take it well offshore. Depending how this area low pressure evolves, tracks, with a strong upper-level shortwave trough approaching from the Ohio Valley tilting negative, will decide how much snow we around here. At this time, it appears that main storm will stay out in the Atlantic. However, a inverted surface trough, is likely to form somewhere along the Northern Mid-Atlantic coast and Southern New England, with another weaker low developing a little closer to the coast on Sunday night. There will also be a strong 500mb vort max, coming around the base of this upper-level trof. Where this surface trough sets up and the vort max goes, 1″ to 3″ and perhaps little more of snow appears likely on Sunday night and early Monday morning. 6z runs of the NAM and GFS appear set this trof south of LI and across Central NJ and but the GFS moves the 500mb vort max further south than the NAM, causing more upward vertical motion on the south side of the trof. This results in heavier precip across Central and Southern NJ rather than on LI, as shown on the NAM.

Another storm is possible late next week coming up from the southern states, but the models will be all over the place with their solutions and I will focus on that storm after the storm on Sunday night.

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An arctic frontal boundary will be moving slowly south through the Northeast and Mid-Atlantic States this weekend. A couple waves of low pressure will be moving along this front and will bringing periodic precipitation to tri-state area this weekend. It should be remain mild enough, for mostly rain to fall. But as it gradually turns colder, snow, sleet, and perhaps some freezing rain may mix in times, across higher elevations of NW NJ and the Lower Hudson Valley and Conn. Particulary on Sat night and especially pm Sun. night. Some minor accumulations of snow and ice are possible in these areas.

On Monday, a stronger low pressure system will moving along the front and will bring more significant precip. to our area. The track of storm is bit uncertain at this time, as the 0z GFS and GGEM show the storm passing to our south and the 0z ECMWF and UKMET pass to our north. At this time, I will assume a track in between that goes right over the area. Therefore, mainly rain – perhaps heavy at times, is likely throughout the tri-state area, during the day Monday Then on Monday night as the low moves offshore, colder air will begin to rush in behind it and rain may mix or to change to snow or flurries before ending, across the entire area. No significant accumulations of snow and ice are expected at this time, but I will continue to monitor.

After this storm, it will be colder and drier next week. There will probably be a storm developing along or off the east coast between the 19th and 21th. At this time, most of models and ensembles take it out to sea, but I will continue to watch it for a track closer to the coast.

Overall, the pattern change to more winter-like weather will start occurring this weekend. It should stay colder with a slight moderation at times. This should increase our chances for some snowfall across the area in the next couple of weeks.

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Yes, the pattern change is coming, but not this week. The cold air that will come tomorrow and Wed, will be transient. There is chance of some snow showers tomorrow night as a weak disturbance moves through the area. But that should be it. It will turn much milder again later this week.

It looks like the longwave trof will that will come trough this area on the 15th will persist into the following weekend across the Central and Eastern US, according to the latest NCEP Ensemble Mean (http://www.cdc.noaa.gov/map/images/ens/ens.html) We will also have a +PNA. So this does appear to be a true pattern change. It may get very cold around from 1/17 – 1/20, with high temps 5 to 10 degrees below normal. By 1/21 temps may begin to moderate, but temps will only be closer to normal. Another reinforcing shot of cold air is likely come the following week.

The latest GFS and ECWMF show a couple of waves of low pressure moving up along the artic frontal boundary that will move slowly offshore during the middle of next week. We will see what future runs show.

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