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PREFACE Getting past the January 20th time frame and storm, there are indications that a cold air invasion is becoming more and more apparent for the eastern CONUS as we fast approach the last 10 days of January. With that in mind and considering that the southern stream over the CONUS should continue to be actively keeping the GOMEX rich moisture content available to be lifted and gathered for storm formation, I see a rather good opportunity for a storm to impact the region, which would include the Mid-Atlantic and even New England depending on how amplified the storm becomes. For a more amplified storm to come to be, we need a solid set of teleconnections (AO, EPO, NAO, and PNA) and the development of Greenland into North Pole blocking, or at least a Greenland block. Given the actual data available from the EPS 46 days and EPS products, the January 24-26 time frame, would benefit from a mostly solid teleconnection package and perhaps the advent of a Greenland into North Pole blocking. The blocking though, may not be totally established yet during this time frame, but by the end of January, it could be the big boss in town. Long range operational model signals do exist for a storm in this time frame, but as I usually do, I try to avoid using the operational model storm signals for possibilities that are in the 12 to 16 days in the future time frame for the thread openers, instead relying on the ensemble guidance signals or other longer range weekly or monthly models. Given that some operational models present "forecasts" or outputs for 15 to 16 days out, I use that range as my limit to consider opening a storm thread, to avoid turning the thread into a long-range pattern discussion thread. Overall Set up Continued southern stream activity with ample GOMEX moisture to be tapped and lifted along with deeper cold air presence perhaps with a high-pressure presence and CAD development. Teleconnection robust package, possible initial developing stages of Greenland blocking, aiding in a more teemed northwestern Atlantic Ocean. Track-wise, we could have one of the 3 most traditional tracks, the western/central PA cutter track, the northern Mid-Atlantic tucked to the coast track and the beloved benchmark track. Which track would be the verified one come the time frame, would be determined in good part by the depth of the cold air in place, blocking high-pressure placement, possible phasing time, if one ever comes to be, and interestingly enough, whatever influence the initial development stages of the Greenland block would have on this time frame, if any at all. Most of these mentioned can certainly be a result of how strong the teleconnection package for this time frame is. Below, an image showing the 3 possible storm tracks can be seen. Storm Track Visual Aid Before we move on the next page, on which you will be able to see the forecasted EPS North American and Northern Hemisphere setup, the EPS 46-days teleconnections and EPS precipitation output for this time frame, I would like to finish this page, with a couple of EPS control runs images and an very interesting, perhaps surprising to some, seasonal CFS MSLP output for this time frame. CFS Surface Pressure It´s very intriguing or interesting to me at least, that very robust storm would be shown on the CFS at such a time range, near the time frame that this thread discusses. It´s a neat piece of information or perhaps, let´s say evidence. Jan 9th, 2019 12Z EPS CONTROL (tucked and benchmark track hybrid) Jan 10th, 2019 00Z EPS CONTROL (western PA track hybrid) On the next page, you will see additional data related to this time frame. To start off this page, please see the Northern Hemisphere and North America set up for the time frame in discussion. January 7th, 2019, 00Z EPS 46 day Northern Hemisphere North America There´s no way to look at this setup and be indifferent to it. That argues for a real winter over the eastern CONUS. We can see the lower heights over northern Canada connect to the lower heights over the SE CONUS, setting up a deep negatively oriented trough over eastern North America, and the developing Greenland block. All that if were to verify, would translate to a much colder eastern United States and a much more promising storm track from the southeast to northeast CONUS with the less progressive component courtesy of the Greenland blocking. As we continue, you can see below the EPS 24-hour precipitation for the time frame in discussion. Jan 9th, 2019 12Z Jan 10th, 2019 00Z And now the EPS 46-days teleconnections (AO, EPO, NAO, and PNA) AO EPO There is not much to argue concerning this EPS AO/EPO combo as it relates to the time frame. Both teleconnections are in their negative state, which is primordial for the availability of a strong and more sustained cold air presence over the eastern CONUS. The -AO is around -1.5 to -1.7 while the -EPO is around -1.3 to -1.5, which is the most negative it has been in recent weeks. We like this. NAO PNA This combo, the way I interpret it, looks very promising and supportive of a storm track that could deliver the wintry goods and be more amplified, and perhaps not so quick to exit the region. The -NAO can lay a hand in allowing blocking conditions over the eastern areas of North America while the +PNA would argue for a ridge over the western US and depending on how it interacts with the -EPO aforementioned, a deeper colder trough could pass through the eastern US. Notice that the -PNA is in positive to negative trajectory during the time frame in discussion, and flips to negative sometime around January 28th. That changing magnitude could play a positive role in the flow pattern. Given the data, this time frame looks like it has more robust aspects to it to allow the region to at least have a better shot at a wintry storm that may impact areas that are snowless since November, What do you guys think? Does this one have a standing chance? Or is it another dream only reality? Later! UPDATES: Jan 11th, 2018 January 10th, 2019, 00Z EPS 46 day Northern Hemisphere North America January 10th, 2019, 00Z EPS 46 day AO EPO This combo has suffered a blow and is weaker now as compared to the January 7th run. The -AO continues pretty solid. However, the EPO has changed to neutral to slightly negative. Before on the 7th of January, it was decently in a negative state. NAO PNA This combo also has suffered from changes. Although the NAO continues to be negative, it is not as negative as compared to the output from the January 7th run. As for the PNA, it went from a more solid positive state to a slightly positive state, basically neutral and flat. We will see how this evolves on the next update scheduled to occur on January 14th, 2019.