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December 25th Christmas Snowstorm Snow Map Final Call

Here is the more detailed snow map for the final call, I added an 8-12" amount region and a special 12" amounts region for the mountains of NW ME and N NH.  I think some of the mountains in northern ME could see 12-18" of snow considering nearby arctic air mass and ratios.  Also I added a blizzard conditions possible area and a high wind 60mph+ gusts area, mostly the ocean northeast of CHH, but includes CHH and the Outer Cape Cod area.  This storm will bomb out as it develops over the Cape Cod Canal, Boston is a tricky spot for the forecast, could be as little as an inch and as much as 6" possible, NE MA is most certain location for 6" in SNE.

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2 or 3 Storms possible next week 25th through 31st

As of the 12z and 18z runs this morning and this afternoon suggest that we have three storm potentials this holiday week coming up.  With the NAO in flux, the PNA positive and the AO in flux, this is the best time to get snowstorms across the Northeastern US.  With the AO going negative long term and the PNA staying above neutral, we have a chance at transient ridges and shortwave amplification potential.  The first system is for Christmas Day, where an inverted trough/norlun trough bring accumulating snows for interior SE MA and RI into NE MA and S NH Christmas morning into the afternoon.  The second storm is a weak coastal storm on the GFS and the EURO is out to sea with the low, but as long as the potential threat exists I will mention it, seems like this storm is for Wednesday the 27th.  The third and final storm is potentially a long duration miller B coastal storm, with such a large high in Ontario, and Quebec, Canada banana high as in its shape and orientation favors an East Coast snowstorm impacting all of the Northeastern US.  Stay tuned, this one could be our first 2' potential since the Blizzard of 2015.

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Snowstorm in the future???????????????

Somewhere in the pattern fluctuations, there is the potential for a snowstorm for Mid Atlantic and the Northeast come next week, after Monday or maybe on Monday the 25th, Christmas day onward as an arctic air mass invades from the central us towards the East Coast.  Teleconnections support a three day period for a snowstorm on the coast from about the 24th to 27th that week.  The pattern evolves to support a +PNA/-NAO and -AO all line up for a coastal storm, it could be a big QPF producer and maybe not much of a wind producer, but we will deal with that when the time comes.  Just know the period exists for a potential storm.

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December 13-14th Clipper Snowfall Map and Discussion

Thursday morning could bring our first snow fall accumulation of the season for Cape Cod and the Islands, a shortwave rounding the base of the H5 trough this evening will bring a shot of arctic air to the region where highs tomorrow and the rest of the work week will remain below freezing.  We now have a very potent vorticity max disturbance in the northern jet stream flow that will amplify some as it rounds the base of the somewhat negatively tilted trough over the Northeastern US.  Snow will be falling across central MI tomorrow morning and then will quickly move towards western PA and Pittsburgh area by the evening and then redevelop off the NJ coastline by Thursday early morning hours, and then be around the benchmark 40/70 location by midday Thursday.  Depending upon the jet dynamics and the oceanic influence of the surface cyclogenesis process we could see a rapidly developing system bring snow to the south coast of New England by 6z Thursday morning and lasting for nine to twelve hours.  If enough lift can develop we could see a good to decent snow amount and especially if we can get NE to NNE winds going than moisture will be a little problem.  Therefore I am predicting a could 2" on the Cape while the Islands can receive 3" of snow the most snow will occur across central WI to central MI and then islands of MA.  Still a lot of nowcasting to go and things could change drastically if that vorticity maximum is stronger on the models/

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Mid Week Potential Nor'easter Scenarios

There are two camps for the scenarios on the midweek storm potential for December 12-14th 2017.  I will illustrate them below.  Scenario One is a full blown Blizzard from NYC to BOS to Bangor, ME.  Scenario Two favors the Great Lakes and NNE with the heaviest snows.  Which one happens will be determined by jet dynamics, phase potential, and baroclinic zone potential placement as well as track of clipper and arctic shortwave troughs in the flow.  Scenarios are not forecasts, they are there to show potential either way.  I will be updating the blog with my newest snow fall map for this weekend's storm shortly.

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**00z Model update**

00z models show some moving southeastward with the snow threat this weekend and the GFS and CMC bring a coastal nor'easter threat and clipper threat to the Northeast next week, I will have an update after I wake up in the morning and then again after the 12z runs.

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**12z Model Update for storm this weekend**

Most of the afternoon and late morning model guidance has trended towards a much larger and more severe event with the exception being the GFS, while the GFS produces over 8" of snow for the Cape, it also is weaker with the storm for Saturday.  We are less than 72 hours away from the first impacts of this winter storm, mix with rain is possible on the MA coastline, including the islands of Nantucket and Martha's Vineyard.  Winter storm watches could be issued as soon as Thursday afternoon from Taunton and as early as tonight for the Deep Southern states of LA, TX, GA, FL, and NC and SC.  This storm reminds me of the 2004 Boxing Day Snowstorm, December 26-27th 2004

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**12z Model Update for storm this weekend**

Most of the afternoon and late morning model guidance has trended towards a much larger and more severe event with the exception being the GFS, while the GFS produces over 8" of snow for the Cape, it also is weaker with the storm for Saturday.  We are less than 72 hours away from the first impacts of this winter storm, mix with rain is possible on the MA coastline, including the islands of Nantucket and Martha's Vineyard.  Winter storm watches could be issued as soon as Thursday afternoon from Taunton and as early as tonight for the Deep Southern states of LA, TX, GA, FL, and NC and SC.  This storm reminds me of the 2004 Boxing Day Snowstorm, December 26-27th 2004

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Nor'easter Alert **

While I am sounding the alarm currently for preparations, I am not sold on the current solution in the model consensus.  WE have explosive dynamics coming into play that the models are overlooking currently.  First we have arctic air spilling over the Gulf Stream gradient, that is so useful for nor'easters.  Second we have an arctic jet disturbance that is so amplified and caught in a very amplified flow the trough will move into a negative tilted state.  This will allow extreme cyclogenesis to occur south of Southern New England and east of NJ.  Models including the 12z GFS and 12z EURO have caught their eyes on the second shortwave in the bunch and want to amplify the flow to favor this nor'easter.  The current amounts in the model fields are 3-6" and 8"+ for the coastline of Massachusetts.  However, I think this may be a case of overachiever central, a massive amount of snow is possible.  I will have more after the 18z GFS

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Comparing the Last Two GFS runs for Fantasy storm 2

These images on top are from the 18z GFS run tonight, from hours 300-348, they show the evolution of our southern stream disturbance phasing with the large northern stream long wave trough, acting as at least a double phased jet structured storm if not three jets with the arctic jet also getting involved.  Only triple phased streams allow a 940mb surface low to develop over DE ME.  Could a storm of this magnitude evolve in this pattern for mid month?  Absolutely, but how accurate is the model?  Horribly inconsistent, but when it smells out a storm potential this is the time range it does it in.  For the last two consecutive model runs for the GFS it has shown two monster storms back to back mid month of December, this first one is a triple point low, the second is a consolidated low, but we have potential for snow next week, so I won't get carried away with this shortwave, as the first shortwave with this new pattern can slam New England hard with heavy snow.  So I will focus next few blogs on the short term.

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