It's safe, at this point, to say that we've seen the last of the sun for the next few days. An unseasonably deep and anomalous weather pattern will begin to set up later this week across the Eastern United States, impacting our area from Thursday through the end of the weekend, and quite possibly into Monday. All of the ingredients typically needed for a pattern mentioned above are there. The featured image to the left shows the pattern as depicted on the 36 hour 12z Operational GFS forecast at H5. A few select features are noted, beginning with the presence of a large west coast +PNA ridge (A).  This ridge is often responsible for resultant toughing across the Central and Eastern United States. Though the ridge is progressive/transient, heights are forecast to rise well into Western/Central Canada, aiding in the amplification of the trough downstream. A very progressive/weak blocking feature is in place across Eastern Canada/Greenland (B). A feature more typical to an anomalous east coast trough would be a more sustained block, but the presence of the +PNA ridge will tend to "substitute" for this missing block. The result (C) is a mean trough over the Eastern US. The pattern is still "dirty", meaning there are multiple shortwaves embedded within the trough and the forecast guidance is still struggling with the energy, specifically with determining which storm will be the main player and when the impact will occur. This creates havoc on the guidance including difficulties with strength and timing of each system.

The lead system is forecast to emerge out of the base of the trough as seen on the 36 hour forecast, with a surface low pressure traversing through the Middle Atlantic states and eventually off the Mid Atlantic coast. Unseasonably cold temperatures are in place and will be generally held in place as a surface high pressure builds southeastward into Quebec. This really is a mid-winter pattern, and a snow lover's dream. By 00z Friday (Thursday Night) it's reasonable to assume a ~1000mb low pressure system will be organizing off the Mid Atlantic coast and heading northeastward. Forecast soundings are interesting in a couple of ways with this system. First, the dynamics actually get interesting during the height of the system early Friday with modestly favorable omega values/uvv's. Additionally, the soundings indicate a good amount of cold air at the surface to start, indicating northwest interior/mountainous areas/higher elevations may actually begin the system with a short period of sleet or possibly snowflakes. These soundings are somewhat suspect, but the dynamics and cold air to begin with cannot be ignored. The image to the left shows the sounding for KSWF from the 12z NAM valid at 33 hours. It's easy to see how borderline the sounding is, with low level air barely -0.2 C. Still, if taken verbatim (not always the smartest idea) the 12z NAM would indicate a good 4-5 hour period of snowfall at the aforementioned station.

Digesting all of this may be somewhat difficult. The fact is that there is an extended period of precipitation forecast to impact the area (including the metro) over the next few days. It's not likely that snow will fall within the NYC Metro area, but rain amounts could total over 2-3 inches by the time the prolonged period of precipitation ends. Further north and west, especially in mountainous areas and higher elevations, a period of snow and or sleet to begin the storm can not be ruled out. The rain that falls elsewhere will be a raw, cold rain. Not very conducive to baseball, I may add. Some of the forecast models indicate a respite in precipitation Friday evening between systems, so they may possible be able to get in a cold, damp ALCS Game 1.

After this, the trough over the eastern coast becomes even more anomalous and cuts off from the upper level flow. Another coastal low is forecast to form along a boundary just a few hundred miles off of the Mid Atlantic coast. With a second area of vorticity moving northeast up the trough axis (aligned southwest to northeast along the eastern seaboard) this system, again, may be dynamic with areas of enhanced precipitation possible from Eastern Pennsylvania to NW New Jersey and possibly the Metro region eventually moving northeast towards New England. By this time, additional cold air will be filtering southeast from the broad upper level trough, and as such it appears possible that flakes may fall in the mountains of NE PA at this time frame. Really a wild pattern for this time of year: but for us, it adds up to a wet forecast over the weekend with possibly a brief period of white or grey well north and west. We'll have a post on storm number two later tonight with more details and buzzings about the upcoming cold and wet weekend. Take it easy.

Oh, and as an aside: Yes, the blog is fully up and running. Functional, comments and criticisms allowed. We hope you continue reading and leaving us your thoughts and comments on each post. We will continue bringing you our thoughts and information as often as possible, more than likely once a day or once every few days.  

John