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Friday, January 29, 2016

Winter 2016, there is hope for you yet !

Good news on most fronts today as we head toward the last few days of January. Not sure if we can escape all of the adversity in this upcoming week but perhaps it can be minimized. There was a tweet  out there referencing the Mt Mansfield snow stake which graphically showed that the snow depth this year was about the worst ever recorded (in just over 60 years of data). It's actually a close race with a few years in the mid 50's and 1979-80. A mild February with minimal snow could certainly cement the winter as one of the worst ever for snow depth but it doesn't look like that will be the case. Over the past two days ensembles have been painting an ever more promising picture starting around February 4th and likely continuing for at least two weeks.

We enjoyed a bit of snow on Friday and advection induced precipitation late Saturday into Saturday night could bring upwards of an inch. Trouble starts after that with a somewhat innocuous above-freezing Sunday. Monday is even warmer as readings could surge to 40 along with some rain showers. I had offered a glimmer of hope regarding the potential rainy disaster this upcoming Wednesday and that hope remains. Monday's system will indeed usher in a layer of cold, dry air for Tuesday which we will so desperately need as a giant system  winds itself up and heads for the Great Lakes. Current indications suggest that this will ultimately travel through the land gully in between Lake's Huron and Erie. It will then proceed northeastward either right over the St Lawrence Valley.

This is hardly ideal but I've seen worse. The layer of cold, dry air should allow for a period of icing at the very least and the period of plain old liquid rain appears reduced to a handful of hours. If the storm can just move 50-100 miles further south, not a lot of ask, we would turn this ice/rain event to more of a snow/ice base building event. Not a likely scenario as of yet but not eliminated from the possibility spectrum either.

Then February 4th comes and suddenly mother nature waves her magic wand and everything is just swell. A beautiful looking west coast ridge starts to take shape and extends vertically up the west coast and eventually adjoins with a weak area of blocking in the Arctic. Even the EPO forecasts have trended more negatively in the past two days and are now indicating a slightly loose Pacific Jet in about a week's time. What does it all mean ? Cold weather and lots of it. In addition, with the axis of the ridge setting up from the American west coast northward to the Yukon/Alaskan border, the east coast becomes a tinder box of activity for storms. El Nino should provide the fuel for it as well. There have been hints of storms embedded within this pattern all over the place and one way or another the mountain should benefit. The cold will settle into the region February 4th and the first snow is likely to come from a clipper system February 6th (A Saturday). I won't speculate on when the snow comes after that but I would be shocked if significant amounts of the good stuff doesn't fall between the 6th and 20th of the month. More on this in the coming days.

Wednesday, January 27, 2016

Tough times next week perhaps but snow in the short term and a more favorable pattern starting February 4th.

I was holding out yesterday and early today, hoping for some better news regarding next week.  I don't really have any in that time frame, unfortunately, at least not today. The pattern should align itself more favorably starting around February 4th and a few dinky systems may provide a few powder hours over the next 3 days or so. An occasional bout of mild weather is a fairly routine part of a New England winter and it looks as though we will contend with it starting late on January 31 and persisting through February 3. It's not etched in stone just yet but we need some late inning heroics perhaps from Big Papi if you're a Sox fan or from Yoenis Cespedes if you're a Mets fan. Sorry Yankee fans, I am no mood to give A-Rod any love today but maybe Beltran who was an under appreciated Met in his days in Queens.

The weather map later tomorrow will have another juicy southern streamer near the Carolina coast but this one will advance well off shore Friday. The models teased us with this storm a few days ago but there was never a consensus for a big New England hit and it certainly won't happen. At the same time, a weaker clipper system will deliver some moisture to Vermont albeit in limited amounts on Friday. We should see snow develop during the morning and continue throughout the day. This is the good low density stuff and we could see several inches of it (3-7 inches) by late Friday evening.

As one system exits later Friday another weaker disturbance arrives with its small amount of moisture later Saturday. This looks like a weak area of advection/overrunning type snow but another few inches could fall late in the day Saturday into Saturday. Moisture looks best the farther north you go with the Saturday system.

The first above-freezing day follows for Sunday. This is in response to many of the upstream changes with the jet stream we've discussed but most directly a massive snow-producing Rocky Mountain system which plans to pummel much of Colorado with snow Sunday and Monday. Temperatures will creep above freezing Sunday but will struggle to fall Sunday night thanks to a mild flow of air and clouds from an advancing but relatively weak storm. Rain showers are possible later Monday from this but temperatures should remain in the 30's and melting will be fairly minimal.

The threat of tumultuous times rises thereafter. I was hoping this initial, relatively innocently looking Monday system could dig a little downstream of us and help push both colder and drier air back into the region Tuesday. Models continue to hint at that a bit but are struggling to advance the cold into New England in any real material way. A mostly unfrozen and relatively warm Great Lakes aggregate isn't helping us with this I might mention. The very strong Rocky Mountain system then advances into the plains on Tuesday and takes aim at the Great Lakes. The track of this system is not a good one and it doesn't appear to want to break apart at all. One big consolidated system in the northern Great Lakes will push mild air and potentially a lot of ice and rain into the region Wednesday. We can hope that the system simply occludes in the Great Lakes to a point that a coastal low takes over in the Gulf of Maine and thwarts the push of milder air. It's not a total lost cause yet but isn't looking good as of Wednesday afternoon.

The outlook does improve thereafter with a period of colder weather scheduled to begin around February 4th. There is a minimal amount of blocking in the Arctic which will keep the AO in check and although the jet stream in the Pacific moves from adverse to marginal, a ridge in the jet stream which will set up shop in western North America will help provide the pipeline for cold. The middle part of February looks like a competing forces situation as well but no glaring signs of another thaw at all.

Sunday, January 24, 2016

Potential thaw next week looks weaker and forecast might yet include some new snow

Weather and snow was front and center across the entire east coast media landscape this weekend. Watching Washington D.C. and Philadelphia get buried in a massive east coast storm reminded me of a few other big El Nino seasons. Both the 1982-83 and 1986-87 featured mild starts to the winter. 1986 also featured a massive storm in the arctic which was responsible for a big spike in temperatures near the north pole just like one that occurred this past December. 1983 featured the famous "Megalopitan" storm in February and 1987 featured an epic 10 days of winter in late January. The biggest of the storms in 1987 also occurred on January 22-23. Interestingly, much of the weather discussed in this paragraph also missed Vermont. The storm which was quickly labeled "historic" and "record breaking" actually fits somewhat into the pattern of big El Nino winters along the east coast. Generally mild weather over the course of 3 months but also a short and very epic stretch of winter weather which typically includes one memorable winter storm. Hopefully we can get ours as well.

"Ours" probably won't come this week. A brief spike in temperatures arrives Tuesday with readings eclipsing the freezing mark for the first time since the rain a few weeks ago. A benign shot of colder weather brings some light snow Wednesday but accumulations will be in the 1-3 inch range.  There is yet another system in the invariably active southern branch of the jet which is going to try and organize itself off the Carolina coast late Thursday. As this is happening a weaker clipper system will approach and there have been hints that the two will try and get together and dance a little but even this scenario wouldn't promise great results for the mountain or the state as a whole.

Another surge of mild air makes a run at the mountain early next week. This is in response to the tightening jet in the Pacific we have been discussing. Storminess will consolidate somewhat in the west but a few pieces of energy will cross the country and prevent a full scale onslaught of warmth but it doesn't entirely reduce the risk of rain either. It honestly looks on multiple days that Snow/Rain/Ice line will be very close to central and northern Vermont and it will take a few days to sort out some of the details. That said, frozen precip and specifically snow is still a possibility for part of next week in spite of the generally milder outlook.

The outlook improves after about February 4th and 5th thanks to the Arctic Oscillation which will keep its negative state and a weak ridge which will develop across western North America. This should set the stage for another period of sub freezing temperatures and open up the opportunity to accumulate some snow.

Thursday, January 21, 2016

Big Mid Atlantic blizzard does Vermont no favors so time to look beyond

What a storm for the Mid-Atlantic ! They missed out on a lot of the action since the famous "Snowmageddon" of 2010 and they never seem to mind. When the DMV area does get clobbered, such as what will happen on Friday night and Saturday, all hell breaks loose and their is a massive run on food, gas and other basic necessities. That's not how we roll in Vermont however which is why we deserve a storm such as this and they don't.

With the exception of the south shore of New England, most of the entire region will in fact miss this storm. New York city is right on the edge. The storm  closes off well underneath the relaxing polar jet and allows the powerful southern branch of the jet stream to simply push it out to sea before it make a real northward turn. Some might disagree with this assertion but if the El Nino was perhaps a little weaker, and the southern branch of the jet was a little weaker, we might have had a more fruitful outcome.  Still, we have done quite alright with the smaller systems and terrain enhancement and there is more of that to come.

Temperatures will have a chance to moderate Saturday thanks to a full day of sunshine. By Sunday, readings could reach the 30 degree mark. 30 degrees is about the warmest we will reach for the duration of the month fortunately. Unfortunately, the prospects for big snow are reduce but smaller amounts of powder remain in the cards. A decaying system from the southern Rockies will fail in its  attempts to grab any serious Gulf of Mexico moisture. What moisture it does have though will fall in the form of light snow Tuesday and Tuesday night. This storm is worth a few inches but not much more than that. A nice little jet buckling is beginning to show up on the some of the medium range models as of Friday. There will be a clipper associated with this undoubtedly and some snow should fall in advance of the last full weekend in January.

My thoughts on early February have improved somewhat. Yes, I still expect the EPO to make a sign switch allowing the evil empire to show its ugly face. That said, the arctic oscillation will remain negative and some ensembles suggest solidly so. The door will open for a rain event and a few above freezing days, but the chances of a December 2015 mild air onslaught are reduced in my view. In addition I think one could argue that a few big Rocky Mountain systems will track in our direction bringing lots of moisture with them. It should be a great pattern for the west and perhaps not such a bad one for New England.

Tuesday, January 19, 2016

Big weekend noreaster still appears to far south for us Vermont powderhounds

The valley is enjoying a nice taste of winter and everyone seems very thankful for that. We've enjoyed a nice stretch where fluff seems to be arriving daily. Mad River has gotten more than 20 inches of snow in the last 8 days with more falling as of Tuesday morning. Most of the discussion relating to weather has shifted to the late week and weekend potential noreaster.

The storm is the work the work of the powerful southern branch of the jet stream which has, as expected, been extremely active thanks to the work of the strong El Nino. The storm will not receive any help from the relaxing polar branch of the jet stream which will recede into Canada as this storm begins its interaction with the Atlantic Coast on Friday. The proper ingredients are in place and there is no risk for mixed precipitation or rain. The storm will strengthen to about 990 mb and proceed northeast from there. 990 mb is quite strong but not historic as far as noreaster's go. It's the moisture which makes this event particularly distinctive. The Gulf of Mexico will provide a large share of it on Thursday and the Atlantic Ocean will provide additional fuel for the fire Friday into Saturday.

Speaking for us Vermont powderhounds, the track of this system appears problematic. The storm reaches the Virginia Tidewater late Friday which is terrific and then heads northeast. We just need the storm to head more north and less east. With the pattern more or less relaxing around the storm, there is nothing to prevent the storm from moving in any particular direction. Simple continuity of momentum will take the system too far south but sometimes the natural baraclinicity provided by the coastline can guide these systems farther north verses expectations. Recall, the Valentines Day storm of 2007 was forecasted to be a coastal hit only and the track shifted north at around the 10th hour. I wish I could say this was more likely again but it isn't. Models have converged and remained relatively consistent with the trajectory of this storm. The areas most impacted by snow would be interior Maryland, eastern Pennsylvania, northern New Jersey and southern New England. Vermont would get mostly missed with the exception of perhaps the southern third of the state.

A brief window of milder weather arrives in the wake of the big noreaster. Not extremely mild but Sunday's temps will reach the high 20's with the help of some sunshine and Monday's readings could reach 30. Winter will make a return next week however with snow coming from a clipper system late Monday or Tuesday. The pattern will then re-amplify and allow for another potential winter storm. There has been no agreement on this hypothetical midweek system but it remains a possibility for now.

Still not liking the look of early February right now. A jet tightening in the Pacific will try very hard and cause a jet trough consolidation in the western United States. This is not what we want at all. We can hang our hat on the Arctic Oscillation however which is not expected to switch signs but rather remain slightly negative or neutral. This might thwart the  massive onslaught of mild weather which was featured during most of December.

Sunday, January 17, 2016

6 or more inches of fluff Monday/Tuesday while we watch a potentialy massive storm for the upcoming weekend

We are in the midst of a decent little stretch of weather as the snow continues to slowly pile up . Snow, from a healthy looking polar jet disturbance will provide the fluff for Monday. The wind is likely to blow it around a bit on the summits as temperatures drop through the teens but 5-10 inches is still the range. Though the snow will become more occasional as we advance through MLK day, it should continue. A much weaker disturbance will help intensify the terrain enhanced snow Tuesday providing another 2-5 inches. Tuesday will be a cold one though with readings hovering between 5-15 most of the day along with wind chills well below zero. Flurries should continue into Tuesday night before tapering off entirely by Wednesday.

The end of the week including the aforementioned Wednesday appears dry and a touch on the chilly side of normal. All three days should feature relatively calm winds and terrific visibility. Most of the weather eyes will be watching what appears to one of the big winter weather events of the year which should strike the east coast on the 22nd and 23rd of the month or this upcoming Friday and Saturday. Now, lets give the American GFS some credit here. The model has endured quite a bit of bashing on the SCWB and much of it deserved, but it has shown hints of this system the last several days and other models are now climbing on board the train. A weak polar high pressure center will provide just enough cold air as a large and moist system in the southern branch of the jet makes a brisk march across the southern plains. The pattern will soften around this system which more or less provides a bit of "free play time" for east coast storms. Models are indicating a rapid intensification Friday night and a mammoth snowfall event for mostly coastal areas of the northeast or perhaps areas just off the coast. The lack of a stronger polar high pressure center opens the door for a few areas to see more of a rain event. Though the Canadian model is the only of the three major medium range simulations to indicate a big hit for Vermont, it is very possible that this northward trend in the expected track continues from the other two models. Again, there is no polar jet energy to suppress this system so it can do what it wants, so lets just see where we are in 2 days or so.

The last week of January will feature a clipper system and the possibility for a bigger more organized storm late in the week. It will not be especially cold but generally below freezing. There are some ominous signs as we head into February as the EPO is expected to flip to positive. This basically means that the jet stream will tighten in the Pacific forcing more unsettled weather out in the west while milder weather dominates eastern North America. There is a long way to go still and 2 weeks of generally favorable weather in front of it so lets not get too far ahead of ourselves. 

Friday, January 15, 2016

No epic storm for the holiday weekend but 2 out the 3 days will feature accumulating snow

Our Saturday system is about one-step out of phase and most of the "juice" with the storm will remain along the coast or too far off shore for any big snow to occur across Vermont. Still, the conglomeration of low pressure centers, one too far off shore and the other which will travel into Quebec Saturday, will manage to bring another light snowfall to the mountain.  A refreshing 3-5 inches of snow will fall during the day, but temperatures will be within a few degrees of the freezing mark resulting in a wetter consistency to the snow at the base while snowfall should be powdery closer to the summits. There are some hints that precipitation Saturday could begin as a little mixed bag but I am confident that of a snow event after the first half hour or so.

Temperatures Sunday will return to the lower and middle 20's. The high country should continue to see flurries and an occasional snow shower but Sunday is the day where Vermont is in between pieces of jet energy and thus accumulating snow will be minimal if any. On Sunday night, a very potent piece of polar jet energy will approach, bringing with it a blast of modest chill, but more importantly a healthy layer of boundary level instability. I really like the way this setup looks Sunday night into Monday and most of the higher terrain in Vermont stands to do quite well in spite of limited moisture on MLK day. We should see a few inches of snow by first tracks time Monday morning a few more during the morning before the snow tapers to flurries/snow showers and temperatures drop to 10 during the evening. The holiday Monday is setting up to be the best ski day of the year for the northeast and particularly at MRG with 5-10 powdery inches. Just dress for the chill.

Flurries and occasional snow showers will continue all the way into Tuesday and some additional fluff is possible though this will be on the lighter side.  Temperatures will only reach the low teens Tuesday and will only gradually moderate for the rest of the week making it the coldest of the season so far. The Wednesday to Friday stretch is expected to be mainly dry.

Our next shot at a significant storm comes during the next weekend. The pattern seems to be locked into one that produces storms on about a weekly basis and I expect to be talking about one next weekend as well. Models have been on again and off again regarding any potential system and ensembles means are hinting more at a coastal impact. That being said, it is way too early to marry oneself to any solution. We have another chance next weekend (the 23rd and 24th) and need a few days to determine how good that chance is.

The MJO phase index describes the cyclic activity of low latitude Indian Ocean and Pacific Ocean convective activity. It has a lot of say over the looseness and tightness of the middle latitude Pacific Ocean jet stream. It moved from warm North American phases in December to cold North American phases in January and is currently in a relatively cold phase right now by supporting a looser Pacific Jet. Over the next two weeks, the MJO is expected to either be neutral or just slighty supportive of a colder North American phase. Meanwhile, teleconnection indices will move from supportive to only marginally supportive. This will allow the El Nino, which is off its high's for the season to become a bit more pronounced and allow for the possibility of a period of milder weather around the end of the month. Still no big thaw is expected and there still is a chance for another storm around the 27th to 29th of the month I think.

Tuesday, January 12, 2016

Snow is falling but we would like and need some more

Our little "downeast digger" helped us get a few inches closer but we could still use one big storm to get the mountain completely skiable. The weekend will provide such an opportunity and Vermont sits in a relatively ideal location for some potentially big snowfall amounts. In short, there is some good news with this evolving weekend storm but ways we could still get screwed out of the snowfall we so desperately need.

Following a chilly day Wednesday, temperatures will moderate Thursday and Friday and reach to within a few degrees of 30 during the afternoons. Still appears to be some very light snowfall on the menu for Thursday with a very fluffy 1-2 inches possible.

El Nino is providing us with a highly energized pattern and much of the east coast will see the effects of this over the weekend. The cold air that is enveloping the region as of the middle of the current week will turn rather stale as two significant pieces of shortwave energy rotate around an amplifying jet stream. We had some questions as of the last update regarding which of these two storms would dominate the news. The later 2nd storm had the biggest potential due to its proximity to the overall jet amplification but we had discussed the possibility of this system getting yanked out too far over the ocean. As it turns out, it will be the first storm that will be the big precipitation producer.

This is good news as most of New England will be in the line of proverbial fire. Cold air will be in limited supply but the track of this first storm on Saturday will be favorable enough so that precipitation, when it falls, will fall as snow. Models have established some consensus regarding this "favorable" track suggesting that it passes just to the east of Cape Cod. It is a relatively strong system endowed with plenty of Gulf and Atlantic Ocean moisture but will be moving quickly and is expected to remain well out of phase with the larger scale amplifying jet stream. As a result, it might prove to be a bit of a challenge for that deeper moisture to work its way back to Vermont. We should at least get some of this moisture however which will lead to a modest accumulation of snow in the range of 3-7 inches. If the storm can deepen as it moves north a bit more than currently forecast, totals on Saturday and Saturday night would go up.

The 2nd storm will indeed move well off the coast but the pool of instability associated deepening jet trough is notable and conditions will not entirely dry out in the wake of any Saturday snowfall. Both Sunday and Monday appear to be good ones for some terrain and local lake enhanced snowfall capable of bringing additional inches of fluff to the mountain. Between Saturday and Monday I would be shocked if we didn't get at least 6 inches of new snow and think it's probably we end up receiving upwards of a foot. Temperatures in the teens and single numbers Monday and Tuesday will also help to keep that wintry feeling in the air.

The cold weather should gradually retreat and temperatures again should resume their slightly above average tendencies though there is no real indication of a thaw. The end of the month just appears to be dominated by a very typical super El Nino-like pattern. Not a lot of arctic air to play with, some above normal temperatures but no outright thaw, and several storms. We should see another chance at one around the time of January 22-23, and then again 5-7 days after that. Both storms will probably have limited amounts of cold to work with but lots of moisture and thus lots of potential for what I think will be snow. Lets hope.

Sunday, January 10, 2016

Good opportunity to accumulate some snow over the next 3 weeks.

Long stretch of sub-freezing temperatures begins Monday and although the pattern will never become extremely cold, we will get a sustained window of time to accumulate some snowfall. Certainly the largest of this pathetic winter season so far. A powerful clipper system kicks off the party on Tuesday spreading snow across all of New England. The storm won't gather any serious moisture until it interacts with the relative warmth of the Gulf of Maine and thus the heaviest snows will fall well east of Vermont. Nonetheless, the weather system will still be a dynamical and mechanical force even without serious moisture. Light snow should continue into Tuesday night and become snow showers Wednesday. 4 to as much as 8 inches of snow across the high country by late Wednesday should provide a nice wintry setting to build on. The storm will also ensure the continued dominance of colder weather which will continue through the end of the week

More light snow can be expected Thursday from a much more benign disturbance. Accumulations from this will be on the lighter side but after a dry day Friday the stage is set for an interesting weekend. The jet stream is poised for another serious amplification and there are two areas of shortwave energy within this larger scale pattern that will be focus for storm development. It is no surprise that models have been rather inconsistent regarding the results. Beyond a week, medium range models have difficulty especially when there are multiple playmakers on the field. Which player actually makes the play ? One potential storm Saturday appears to be a bit out in front of the main thrust of jet energy which appears more likely to rev up of the second potential storm Sunday/Monday. Another concern involves the position of the mean large scale trough in the jet stream early next week. Ensembles are generally suggesting it sets up a bit too far east for our total liking. It takes rain out of the equation but we don't want a potential big storm going innocently out over the ocean.

More "soft" chilly weather can be expected in the wake of any storm Sunday/Monday. This means that temperatures stay sub-freezing but will not categorically fall in the "below normal" range. A very typical outcome during such a strong El Nino. Another in the series of strong impulses in the southern branch of the stream has the potential to do something interesting during the middle of the week (January 20th) but 10 days out is way to early to get excited. It's just nice to know it's there. Beyond that, I expect the continuation of a generally favorable pattern. Not incredibly cold but productive due to a loosened Pacific Jet and an Arctic Oscillation on the negative side of zero. Ensembles restrengthen the ridge in western North America between the 23rd and 25th of the month giving me some confidence that sub-freezing temperatures could prevail through the rest of January.

Thursday, January 7, 2016

Swing and a big miss this weekend but we get another good pitch to hit the following weekend

We still can expect 1-3 inches of snow very early Saturday but the much stronger storm that will ultimately develop out of this whole situation arrives Sunday. No change in the thinking here, this storm is not going to do us any favors and will eventually wipe away a large percentage of the limited snowpack on the mountain.  No point in spending too much time on this. The rain should arrive in one large chunk around noon on Sunday it will turn heavy for a time shortly after it commences. Temperatures will start out in the middle 30's Sunday but move into the low 40's by the evening. It's all very disheartening to say the least.

We should be able to move onward and upward from there however I am happy to say. Snow showers and snow flurries will arrive Monday along with sub-freezing temperatures. It then gets a bit more intriguing Tuesday as a potent impulse rotates around the large Hudson Bay polar vortex, grabbing a bit of moisture as it heads past the unfrozen Great Lakes. There are scenarios that involve an explosion of this storm off the coast resulting in some snow for coastal areas. I think we would actually prefer something less dramatic and a healthy 3-6 inches from the passing clipper system either late Tuesday or early Wednesday. Chilly arctic air, though not extreme, arrives behind the clipper along with more terrain enhanced snow showers. Another clipper could then spread additional snows Thursday.  So in spite of the weekend setback, Vermont should return to it's typical January wintry self right away.

Several operational models and more importantly a few ensemble runs have suggested a storm of great significance around the time of January 17th and 18th. This would be the following Sunday and Monday. The necessary ingredients should be on the table. More in the way of cold air to work with, energy in the southern branch of the jet stream and a jet stream poised for another amplification and potential phasing. This pattern, though not incredibly cold, will certainly deliver its share of chances for a big one. We strike out this weekend but it looks very much like another, even better chance follows next weekend.

Tuesday, January 5, 2016

Lots of weekend storm details and much much more in this expanded update

The mountain is basking in some sunshine and enjoying a much more wintry setting. A tip of the cap to those who have managed to earn their turns the hard way. For those awaiting lift operation, we are probably one big storm away from such discussion and the opportunity for such a storm comes in the weather situation that presents itself to us this weekend. Though the possibility remains for a big dump, I have lost some enthusiasm for this this event since there are some problematic missing ingredients, some timing issues and possibly some storm track issues.

We have an initial storm in the plains late this week which will more or less tap itself out. A wave of low pressure along the east coast tries to get organized Friday night but ultimately fails. In spite of all that, clouds will be on the increase on Friday, the 2nd of two days where temperatures should get close to the freezing mark. Limited moisture should be able to work its way into Vermont Friday night allow for a period of light snow either during the overnight hours or early on Saturday amounting to an inch or two. Temperatures will be sub-freezing by a degree or two but the snow will be more wet than powdery. There is a very weak supply of cold and dry air which will help keep temperatures under the freezing mark for a while Saturday. This thanks to a weak jet max over the maritimes of Canada. The 2nd more potent storm organizing near the Gulf Coast needs a more ample supply of cold and since it doesn't really have it, will need to track in a very optimal way for Vermont to get a big storm.

I have been waiting got the models to more or less establish some consensus regarding this system but as of Tuesday afternoon we have yet to see it. The U.S. modeling from the GFS has been atrocious, only occasionally acknowledging the potential strength of this Sunday system and in many cases taking a flattened wave out over the ocean with little resulting precipitation for any east coast locations. This is proving to be and will continue to be an embarrassing problem for the American GFS model this winter which will, in too many instances, fail to adequately quantify the potency of the jet stream in the lower part and more critical part of the mid-latitude northern hemisphere. Given the strength of the El Nino, this part of the jet stream becomes exponentially  more critical and rarely is entirely overwhelmed in a split flow set up. Yet that is what the GFS consistently shows and will be consistently wrong in such debates with other models.

Three of the other medium range simulations show a major system gathering strength along the Gulf Coast with the entire jet stream amplifying behind it. There is a lot of fuel for this storm, both from the jet stream and from both Gulf and Atlantic Ocean moisture. With the cold air all focused behind the system however, the track of this storm needs to be utra-favorable. Canadian modeling showed a big snow event, the british UKMET hints at such at least to a lesser degree. The European model and it's associated ensemble members not so much. Specifically, the European Ensemble mean has shifted the track of this system westward with low pressure center moving through central New York state and into eastern Quebec. We aren't far from the good stuff, but precipitation would go to ice and subsequently rain later Sunday given such an outcome. Even a blend of the various solutions, excluding the garbage modeling from the GFS, suggests a miss on Sunday. There still is a decent chance but I would put the odds 70/30 against at this point.

What we will see is some snow in the wake of the passage of this system Sunday night and Monday. Arctic air will be establishing itself over the eastern part of the U.S. with the vortex of cold at jet stream level moving south to the lower Hudson Bay and later retreating during the middle part of the month. Weaker systems rotating around the aforementioned vortex will bring periodic snow to the mountains. Terrain enhancement and an unfrozen and relatively warm Lake Champlain will help produce what should be some respectable snow totals across the high country. Might only be a few inches at a time but this should happen on multiple days.

There has been a lot of debate surrounding the evolution of pattern during the middle part of January and beyond. There is no doubt, some of the teleconnections that typically drive eastern U.S. and specifically New England cold will weaken between the 15th and 17th. We will certainly lose the support of the PNA or any large ridge in western North America. We will have the benefit of a loosened Pacific Jet next week allowing for the outbreak of cold weather but this jet stream is expected to re-tighten somewhat (it's hard to keep that completely down in a El Nino) mid month. I don't argue any of this but the MJO does not support a complete EPO flip. In addition, we should continue to see some limited blocking near the poles preventing the pattern from going entirely warm. In my opinion, we should see lots of storminess so even if the event this weekend doesn't materialize as we would like, we should see additional chances during the middle part of January and beyond with temperatures closer to normal if not slightly above normal.

Sunday, January 3, 2016

Big storm potential this weekend with variety of outcomes still in play

Lots to talk about in the early days of 2016 as the wait for better days is over. Winter is here and is poised to stay for a while. Snow squalls and a burst of some extreme chill will be followed by a succession of drier days in the Wednesday to Friday time frame. Afternoon temps might sneak above the freezing mark on one or two of the sunnier afternoons but this is merely an afterthought with the focus shifting to what should be an interesting weather weekend. Powerful pacific jet energy in a split jet stream will break down the ridge over eastern North America this weekend ultimately turning the eastern seaboard into a tinderbox for storms. Keeping track of the evolving details has been trying for model huggers but one way or another, MRG will be a snowy beneficiary.

The storm system in question is a large one, winding itself up in the plains and occluding somewhat late in the week. A new area of low pressure will form in the southeast U.S. on Friday  and begin to focus a broadening area of Atlantic moisture and precipitation on the east coast. Even the interior locations will have minimal cold air to work with and a period of mixed snow/sleet ice is possible early Saturday. As the weekend continues however, the system will prove potent enough to gradually eliminate any above freezing layers within the lower troposphere keeping the precipitation snow. The El Nino fueled jet stream though will not rest. As the threat for at least light snow continues on the mountain Saturday, another potential doozy of an east coast system will gather strength near the gulf coast. This second storm has a ton of potential though models are a bit unsure regarding the details of its impact. By early Sunday however it will likely be churning through the Carolina and looking to take a more northward turn while rapidly gaining strength. It could ultimately miss much of interior New England or it could bury parts of the northeast with snow. Models have been all over the map on this potential storm the last two days, displaying great difficulty exhibiting any consistency but this potential late Sunday/Monday event is worth watching and within a few days we should have a good idea regarding the expected result.

Snow showers and an eventual surge of arctic air follows the passage if this big storm. Though there will be a period of days when drier weather prevails, the pattern will not go dormant. Initially the large ridge in western North America will suppress the storm track but ensembles weaken the strength of this ridge while keeping the all important AO in place. Meanwhile, the Pacific should continue to produce potent storms and the threat for another big system increases for the northeast for the middle of the month. Overall, I think this could amount to a multi-week love-fest that I hope begins in earnest this weekend. Will keep the blog and tweets updated with all the changes.