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Hello everyone! As we continue our journey through the 2018-19 winter season and endure disappointment when it comes to the snow aspect of winter, our next storm chance comes around the President´s Day holiday time frame, which I then took the opportunity to dub this one the Commander-in-Chief winter storm. Let´s just hope it does come with all the splendor that the title brings with it. This storm could be an overrunning type of storm that comes from the central Rockies region and tracks eastward across the country. As with any storms 10 days out, a few outcomes are on the table. Let´s talk about them. A flatter storm crossing the Southern Plains which may amplify enough after crossing the Appalachian mountains as it emerges over the Atlantic Ocean somewhere near or south of Long Island; A more amplified storm that could track ENE/NE and pass by south of the Great lakes and when possibly cut tracking over Michigan or western NY, Option 1 but with a coastal redevelopment over the offshore waters near VA, which would then track to the ENE or NE. A primary low track the could take it over Minnesota and then cyclogenesis occurs far south over South or North Carolina or just offshore near either one of those two states. Given the conflicting teleconnections signals, it´s perfectly fine to expect the possibility of different outcomes at the 10 days out range. Please take a look at the teleconnections outputs from the ESRL/PSD map room and the EPS ones: Ensemble guidance support has been so far not too clear, which is not alarming. Some EPS control runs have hinted at this storm affecting the region. However, what is interesting is that the GFS, FV3, and ECMWF have been showing a storm during this time impacting the region. The GFS and its successor FV3 are more on then overrunning bandwagon while the ECMWF is playing with the idea of a coastal redevelopment near the VA offshore waters. The images will not be posted because they are readily available on well-known sites sources. Track Scenario Maps Perhaps a more simplistic thread opener, but still respecting the need to content addition and textual descriptions, may work to make this storm potential a candidate to take over the Commander-in-Chief title.
PREFACE Well, the discussion and discovery must continue. It cannot stop. So, even though we have been getting burned by big ghost storms, or if you prefer big snowstorms fairy tales on the models, we must keep the conversation about storms going and this way hopefully we are graced with a good winter storm for most of the region. Having gotten that out of the way, the time frame in question is at least almost entering the medium range, as this time we will use this thread, to tackle the February 7th-8th time frame which is about 8 to 9 days out. Hopefully this time, with a shorter lead time, we avoid the drastic and volatile model swings we have been dealing with this winter with model depictions beyond 10 days out. SET UP DESCRIPTION The time frame in question appears to present a possible overrunning type storm originating from Texas and tracking towards the Mid-Atlantic on an ENE motion. Along its way towards the Mid-Atlantic coast and then off the coast over the Atlantic, moisture from the GOMEX should be introduced and lifted and thrown over a colder air mass to the north of the storm´s low-pressure track; overrunning. Additionally, it´s possible that some northern stream vort energy gets introduced into the dominant southern stream flow, which may cause an increase in strength and consequently a bigger storm. That though, as we all know, can bring to the table farther north track outcomes resulting in mixing and rain issues for the areas close to the storm´s low-pressure center. Furthermore, as the storm approaches the Mid-Atlantic region, there is a decent possibility that an off the coast redevelopment farther to the SE may occur and thus, some areas may experience snow or a wintry mix to rain to snow scenario as the redeveloping low-pressure takes over, if that kind of coastal cyclogenesis occurs at all. Things to watch for: How far south the storm originates in Texas Possible northern stream vort getting enthused into the dominant southern stream low-pressure system Southcentral and southeast Canada High pressures Cold air strength and location Cold air damming (CAD) Baroclinic zone Coastal redevelopment Southeast ridge Suppression SIMPLE OVERALL ILLUSTRATION Please find data relevant to this time frame on the next page. RELEVANT SUPPORTIVE DATA Teleconnections ESRL/PSD The ESRL/PSD teleconnection package looks pretty beneficial for a storm over the eastern US that may be a somewhat amplified and allow for possible redevelopment off the coast. EPS 46-days AO EPO AO and EPO combo looks supportive for cold air availability. NAO PNA Negative NAO and negative PNA send a conflicting signal. Suggests a possible overruning type outcome. ENSEMBLE GUIDANCE Jan 29th, 2019 00Z Jan 29th, 2019 12Z Jan 29th, 2019 EPS All in all, this time frame looks active and is another shot for the region to get a storm that depending on how the players present themselves, could deliver wintry precipitation for areas to the north of the low-pressure system. The track may be far enough south that areas from Philadelphia to Boston may be affected by wintry precipitation. Let it evolve! Let it do what it gotta do!