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A few massive snowstorms have gained the respectability that every storm wants to gain.  The last few blizzards to strike the SNE region have not lived up to their predecessors.  The Blizzard of 2005 and 2015 are two storms that come to mind that blow everyone away when it comes to wind gusts and snowfall amounts in Harwich, MA.  When it comes to intensity of snowfall the Blizzard of 2005 is second to none, while the duration of the storm the blizzard of 2015 wins out.  Also wind gusts 2005 wins out over 2015 as Nantucket lost power as an 86mph wind gust hit the island, while Nantucket didn't lose power to the island in the 2015 storm where a 78mph gust ended up hitting the island.  As for snowfall amounts as I said earlier, the Blizzard of 2005 beat out the Blizzard of 2015 by two inches, 35" to 33" respectively. 

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This map is the combined storm threats the next four days, I included the Thursday storm because I believe that the models will come northwest with the coastal storm on Thursday enough to add a few inches to the forecast for Cape Cod.  I believe 12"+ will occur on the Cape, south and north shores of Boston, MA as this is combining all three events which it looks like all three will contribute 3-6" of snow to this part of the region.  Most of the rest of the region will be 6-9 or 9-12" from the Wednesday event alone.  Coastline gets their snow Wednesday into Thursday from two likely different events

January 15th through 19th Snowfall map second guess.gif


My next post is about the potential snows from Saturday evening through Thursday morning.  Models are in general agreement that the potentials for Ocean Effect Snow from Sunday through Tuesday and then storm produced snows from Wednesday through Thursday due to a coastal storm is on the table.  However, this post will solely focus on the Ocean Effect Snow potentials.  First is the event Sunday through Monday.  Mesoscale WRF-NMM and WRF-ARW both support a single band of ocean effect snowfall impacting the region of Cape Cod from Hyannis to Chatham and Provincetown on Northerly winds from 900mb to the surface, which means a single convergence band is more likely than multiple bands of snow which are less intense.  These two models keep the band over this region from about 12z Sunday to 00z Monday or later, that is at least 12 hours or more of heavy snowfall over this area of the outer cape, this could produce more than 6" of snow, we will have to see the next few runs until the event starts and then diagnose the real short range models and what they produce.  For now the potential exists of a few inches to as much as 6" or more over the Outer Cape Cod area.  Stay tuned!

00z NAM temp profile chatham jan 13 00z.png

00z NAM wind profile chatham jan 13 00z.png

00z Jan 13th Ocean Surface temps.gif


Latest NAM run 00z shows a strong potential for ocean effect snow event from the Cape Cod Canal eastward to Provincetown on northerly winds, also unidirectional wind flow from 900mb to the surface indicates a single band event is probable along with a strong instability burst from 850mb to surface ocean temperature differential (Delta Ts) of 18-20C which is sufficient enough to produce heavy snows over the Cape and Islands.  Also the flow is stronger than 10mph which should be sufficient enough for consistent band developing as we transition into a clipper low for the next few days.  Big storm potential if the clipper low slows down its movement like the latest 12z guidance suggests at H5 with the low developing and closing off the H5 flow over the Northeast US.  This will prolong the snow chances from Sunday morning to Wednesday afternoon for overall snow chances.  Stay tuned!

00z NAM wind profile chatham.png

00z NAM temp profile chatham.png


12z models trending towards a major coastal redeveloping nor'easter come next Tuesday into Wednesday.  NWS Taunton WFO has a 50% of snow in the forecast for Tuesday and 40% chance of snow for Wednesday, depending upon whether or not the trough closes off at H5 into a low will determine the duration of this winter storm, could be anywhere between 18-36 hours of snow


Good evening folks, 

This is my latest blog entry and the first official entry on the potential Blizzard of 2018, or Storm of the Century potential on January 3-5th 2018.  The first image is water vapor imagery taken as of this hour, it represents the different ebs and flows in our country.  Also it currently has three disturbances that will impact our storm potential this week.  The arctic disturbance is circled over NW Canada in a pink dot, the second disturbance is in red, the Pacific shortwave and then the third is in green the sub-tropical jet which is already providing moisture and rains in TX and LA this evening and will enter the Gulf of Mexico in the overnight into the early morning hours.  This green dot disturbance will be the southern stream disturbance that gets carried northward as our storm develops by the next disturbance in the polar jet and the arctic jet.  These will be our catalysts towards a destructive nor'easter, perhaps with the intensity we have never witnessed south of the benchmark in history.  I believe the only way this system hits the benchmark head on as it tracks up the coastline is if the trough is more centered over or west of James Bay, Canada and recent runs have adjusted this direction.  So I am now saying the track officially of the storm should be between 25-75 miles east of the 40/70 benchmark location as a sub 960mb low, stronger than the Superstorm of 93, stronger than the Blizzard of 2017, stronger than the Blizzard of 2016. 2015 and more.  My second image is my snow map of impacts to the East Coast and potential snow accumulations of light. moderate and heavy.  And I highlighted in red where on the coast can expect blizzard conditions.

Blizzard of 2018 water vapor imagery analysis.jpg

Blizzard of 2018 likely map.gif


What I am thinking preliminarily right now for this weekend as ocean effect snow gives way to a northern stream (arctic jet stream) disturbance running through the flow amps a bit as it reaches the East Coast of the US and perhaps tries to tilt negatively for a time this Friday and Saturday.  There are many different disturbances in the flow this weekend that could turn something meager into a beast of a storm.  The runs this weekend of showing a monster hit are no longer showing this due to the presence of a strong upper level low over the NE pacific Ocean influencing the departure of the positive values in the PNA region.  If this disturbance were to weaken or split into two groups, one moving westward into the northern Pacific and the other piece of the low moving into the US, then the ridge would be able to build itself upwards once again and positively influence our troughing in a more positive way this weekend.  However, there is poor sampling in this part of the Pacific Ocean, and there is no way in knowing how the PNA ridge will react to a split in the disturbance energy field.  Some models collapse the ridge temporarily while others recharge it later on into Monday through the rest of the New Year first week.  therefore, models are now signaling there will not be a full phase between the Arctic jet and the Pacific jet so there will be no bombogenesis present this weekend, however, models are keying in on a potential one jet bombing low pressure center as it takes off, off the NJ coastline sometime Sunday and produce its own snow shield, this could put down a 1-2" swath of snow from western VT to eastern and southern ME and north of the MA Pike, while areas south of the MA Pike see 2-4" generally, while the South Coast of MA, Ri and SW CT see about 4-8" due to the high snow ratios and then the cape cod area east of Barnstable and Hyannis could see upwards of 8-12" or more of snow as ocean effect adds to the fluff factor and a very little of moisture can lead to high amounts of snow.  I am expecting models to back more precip onto the SNE coastline than currently projected first because of the OES processes and also because I expect the storm to be further northwest in the end and strengthen a little faster in earlier developmental phase.  I will have another map after the 00z runs tonight if I need to change anything.

December 29-31st Preliminary Snow Map.gif


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.

December 25th Snow map last call.gif


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.


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.


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/

December 13-14th Clipper snow map.gif