Think Snow, Tweet Snow !!!

Tuesday, December 31, 2013

Thursday's potential snow and lots of other ramblings to end 2013

I've been waiting and hoping that the information out there would converge into something very big for the mountain Thursday. Unfortunately, for our late week storm, the consensus of data suggests a loose more disorganized conglomeration of low pressure centers that will push through the Ohio Valley and off the east coast before intensifying into anything significant. I throw the word "phasing" the blog like I would throw a frisbee (which is a lot) but for most of our potential winter storms, the process is critical in determining whether we are "in" or "out" of the best powder. I like to think of phasing as the jet stream and the weather at the surface achieving a perfect harmony like a Jerry Garcia with his electric guitar and Phil Lesh on bass (I think Phil would be the Jet Stream and Jerry might be the winter storm). Phasing occurs quite often in New England because many of the necessary ingredients are always present such as jet stream energy, the accessibility of moisture and the ambient clashing between cold dry arctic air and a relative warm moist Atlantic Ocean. The best storms in Vermont phase early, but often not too early (as they did many times last year). These storms more frequently track very close to the coast or even inland and interior areas of New England are the best spots for the big snow.

The surface map is a tinderbox right now and one good injection of upper air support would mean big things for MRG and the surrounding region. Such support does come but it will come just a little later than we wanted. Snow will expand into New York State and much of New England but unless something changes, the storm will ultimately consolidate its energy off shore and pull the heaviest snowfall to the coast and eventually out to sea. Anyway, that was a lot of rambling for a paragraph and a half and in the end, WE SHOULD A POWDER DAY THURSDAY. Light snow should begin around day break and continue for a good part of the ski day. I think this is a 3-7 inch event, but when it comes to questions of phasing LOTS CAN CHANGE. The Valentine's Day Storm of 07 reached hall of fame status but was not expected to be until very late in the forecast period. Thursday and Friday will be two of the coldest days New England has seen in some time. Temperatures will be near zero all day Thursday as its snowing and below zero all day Friday. Saturday morning's temps could be near -15 F but readings should moderate to more tolerable levels by the afternoon then warm into the 20's Sunday.

Another storm is going to require our attention by late into the weekend into Monday. This is another interesting one and perhaps a storm that might phase too early. The Euro model is indicating a one of those classic "bowling ball" trough's and one for the ages as well. These types of events are dangerous for New England ski country as they send 50 degree readings north to Quebec while sub zero temperatures hit the Ozarks. This is not the consensus solution yet however as other medium range models suggest that potential "bowling ball" never achieves perfect symmetry. A partial phase and a more squashed system could mean some powder for Sunday into Monday. The Euro does bring at least a chance for rain however. The arctic cold that follows this storm could be very memorable as readings, particularly in parts of the Mississippi and Ohio Valley's get well below zero and even challenge records. We saw cold of this intensity in '09 but nothing like that since. The "evil empire" is showings its face as we move beyond January 10th although ensembles have performed horrendously so far this winter so I won't expand on any of those details until later.

Lets hope at least some of this storm pans out. Happy New Year to everyone and think powder !!

Monday, December 30, 2013

Another batch of the good stuff brewing for Thursday/Friday ?

By the time most of you will be reading this, the few inches of glop Sunday night will have turned to a somewhat windblown layer of powder. Temperatures will turn very cold so hopefully the snow consistency is good enough to be considered a powder day for those of you that venture on the mountain. The focus now has to shift very quickly to the New Years day period and another rapidly evolving weather situation in the days that follow New Years. It is amazing how fluid the weather forecasting has been this year and we should expect that to continue. It has been somewhat easier to predict temperatures relative to normal in a general sense but day-to-day weather specifics has been a challenge outside of the 5 day window. Forces the SCWB to earn its money with more frequent updates I suppose.

This will be a very cold 6-day period as has been discussed previously. Temperatures through the upcoming weekend will struggle to get above 20 at any point and we will have several mornings at or below -10 and at least 2 days with wind chills well below zero. We had hoped to get some new snow out of this very bone chilling ordeal and its looking more and more likely that this will indeed be the case. The first snow will come New Years eve from an upper air impulse that will produce some terrain enhanced snow. Snow accumulations from this will be on the order of a few inches and unlike the glob, will be a very fluffy variety. If we are lucky, we will get a somewhat powdery New Years Day.

The "BC Bomber" that has entered the equation in this very evolving weather picture arrives Thursday Jan 2. This system has been discussed but its potential before now has been somewhat underrated. Pretty much all of the major medium computer models are now on board that the system will gather some limited amounts of Gulf moisture, deepen and then strengthen rapidly off the Atlantic Coast. Models disagree with the intensity of strengthening and the track and it is this question which should now be the prevailing debating point as to how much powder actually falls Jan 2/3 at MRG. The European model is the dream scenario because it is suggesting an all out explosion south of Cape Cod and a 1-2 footer for much of Vermont. The Canadian and GFS suggest a more modest deepening with this system, a flatter system overall and confine much of the heaviest snowfall totals to coastal sections. The final answer might have to wait until New Years Day to be answered but we should at least look forward to some modest powder Thursday into Friday. Timing of course will have to be fine tuned in the next few days.

There is some additional fine tuning that is required on what appears to be shaping up to be a volatile week beginning Sunday January 5. There are some potential trouble spots, some more potentially bone chilling arctic air and maybe even some additional powder. A bit of the "all of the above" which was my favorite multiple choice answer on those old high school exams but perhaps not so much when it comes to winter weather.


Saturday, December 28, 2013

Wet snow late Sunday and Sunday night will turn more powdery Monday as temperatures nosedive

Most of the current weekend will be on the cloudier side but temperatures will be rather mild for late December, achieving and exceeding the freezing mark both Saturday and Sunday. The question we all want answered though is whether or not to use that last vacation day of 2013 on Monday (or fake sick). There has been some small modifications in the thinking regarding the storm that is expected to advance up the Atlantic Coast Sunday and spread precipitation into the region Sunday afternoon but we think we have enough information to provide some detailed expectations.

Given the prevailing mild temperatures encompassing the mountain, you would be right to say that temperatures will be in that marginal category Sunday afternoon as precipitation commences. Model cross sections are in fact indicating some above freezing layers in the lower troposphere, and as a result, precipitation may begin as some rain or sleet. Within an hour or so of the precipitation start time, we should begin seeing all snow. Temperatures will hover around the freezing mark through a good part of Sunday night and the snow consistency could be a bit gloppy in low lying areas while closer to powder near the summits. In areas below 1000 feet, precipitation could remain mostly rain or simply a rain/snow mix. The snow should taper to flurries or snow showers Monday morning as the arctic deluge reaches the mountain but a few hours of heavy snow overnight should push snow totals in the 6-12 inch category. As wet as the snow might seem Monday night, plummeting temperatures during the day Monday will alter the consistency of the snow to a dense powdery layer. It will also be quite blustery creating wind chills of near zero as actual temperatures to near 10 by late in the day. 

The arctic cold will prevail through the New Years holiday and into the first full weekend of 2014. Models are not at all conclusive regarding some of the fast moving systems that might be on the weather map during much of this time frame. The American model suggests that a clipper system will rotate into the Ohio Valley around New Years Day and later intensify off the northeast coast into something fairly interesting by Jan 2nd or 3rd. The European Model keeps much of the precipitation from this system well south of the region and by the weekend has a massive coastal system near Cape Hatteras with historic snows in the Virginia Tidewater area. The Canadian model is also on the dry and cold side for interior New England. There is undoubtedly a few things that need to be sorted out. For the mountain, our best  shot at some additional snow comes late New Years eve into New Years day. We do know it will be very cold with temperatures near -10 on a few mornings between Tuesday and Friday and struggling to get above zero during the days. 

In the longer range, we still have the negative AO competing with a retrograting ridge. In summary we will go from two favorable teleconnection indices late next week to just one by around January 8th or so. This leaves us somewhat vulnerable for trouble between the 8th and 10th of the month. 

Thursday, December 26, 2013

Weather in the pre - New Years Day period "evolving"

We have a bit of powder covering the frozen crust and can now look toward the end of the weekend for some more potentially good news. The weekend weather has been "evolving" and the medium range models have more or less failed to indicate with any consistency how it will all play out. We had an idea that temperatures would at some point make a run at the freezing mark and we knew that by Sunday, we had a chance for some snow from a clipper system marking the leading edge of very cold arctic air that is poised to send temperatures below zero on the mountain by New Years Eve. Things have gotten more interesting with the southern branch of the jet stream, which a few days ago appeared as if it would have a negligible impact on the weather through at least New Years. With each cycle of model data however, there is more and more evidence that a low center with Gulf of Mexico origins will indeed move up the Atlantic Coast and impact New England with its moisture.

We discussed the idea of the limited amount of available cold air this weekend over New England. The current air mass will modify and the bitterly cold air will advance to most of the east coast a day after this system exits. Across coastal sections of New England, precipitation will fall as plain rain through much of Sunday. Moisture from the Gulf/Atlantic southern branch system pushes into Vermont just as energy from the clipper system begins arriving from the west. If the two storms were to phase, a bit earlier it would open the door for some incredible upside. Models right now are indicating that this won't quite happen, but we do have barely enough cold to support some snow late Sunday into Sunday night. Remnants of the clipper system and some lingering instability will help support some additional terrain induced or Champlain induced snow showers Monday. I think there will be some better clarity on accumulation totals in the coming days but snow Sunday afternoon, Sunday night and snow showers Monday should total at least 4 inches over that 24 hour period and perhaps upwards of a foot. Because this situation has evolved so much in just 48 hours, we have to leave some room in the forecast for some additional changes so I would expect some modifications in the coming days or so.

Bitterly cold temperatures will make a grand entrance Monday with the aforementioned snow showers. The region, as mentioned in previous updates, will be in the firm grip of arctic air through much of the New Years week thanks to the emerging western North American upper ridge and the negative Arctic Oscillation (AO). Snow could fall from a weak clipper system around the time of January 2nd. By the first weekend of 2014 there have been hints of some southern branch activity combining with the Polar Jet to produce a storm of significance but those hints were mainly yesterday. Today's models/ensembles suggested some additional snows from a clipper along with what should be the continuation of very cold weather. There are also indications that the position of the western North American ridge will retrograde toward Alaska allowing arctic air to loosen its grip on the region around the 7th or 8th of the month. This would go against my idea of the cold weather persisting through January 10th. The AO though is expected to remain negative throughout much of the first half of January, an important ally to have in the prevention of any damaging thaws.

Tuesday, December 24, 2013

Arctic chill looking for a long tenure at the throne


We took a few good upper cuts from the recent thaw but we did make it through. Perhaps I should try anesthesia for the next thaw because mentally, its rather tough to watch good powder go to slush and then crust. The cold weather is back in a big way though as temperatures on the mountain will hover near 10 degrees during the afternoon of Christmas Eve and Christmas day and should fall below zero Christmas morning. Aside from some snow flurries, enough perhaps for a dusting, it should be a relatively dry two days on the mountain. The next chance for accumulating snow comes Thursday from this clipper we have been watching. We continue to hope that as this system swings through southern Canada, it can tap at least limited amounts of Atlantic moisture and deposit at least a few inches of snow on the mountain (because we need it). The European model continues to be the more vibrant solution regarding this storm and even this result would generally suggest less than a 1-4 inch event for the 26th into the 27th. The Canadian and American models show a meager dusting to an inch or two. 

The cold weather will remain in place for the first part of the weekend but temperatures could actually sneak above freezing Sunday given enough sunshine. After snow flurries and a few snow showers Friday, most of the weekend will be free of snow or any precipitation. The warm day Sunday will occur as the overall weather pattern re-aligns itself into one that will, for the first third of January produce a large amount of brutally cold arctic air into both the Great Lakes and New England. Given what we have seen from the intensity of these air masses so far this winter, it is a good bet that readings will nose dive into the -10 to -20 degree range on 3 or 4 of these first 10 days of January. The culprit is will be development of a weak to moderate positive-PNA pattern which will align itself with what we expect will be a weak to perhaps moderate negative AO. The PNA magnitude (although it isn't actually measured this way) can be loosely measured by the strength of the ridge in western North America. So far this winter, we have not seen much of a ridge in that part of the continent and Vermont has been cold in spite of it. By the new year, we are expecting a ridge to develop over British Columbia and this will focus much of the unmoderated arctic cold over Vermont and other nearby areas.


Of course, we need snow to go along with this cold. Another clipper system, which will arrive late Sunday into early Monday, will bring the next chance for snow to the mountain. This system marks the first big intrusion of cold in the newly aligned pattern. After that, much of the energy in the jet stream will shift south as will the storm track. If it doesn't shift too far south, it opens the door for future clipper systems to continuously deposit additional snow and one of those could evolve into a more significant  snow producer given some constructive interaction with the Atlantic Ocean.  To get a big monster storm, we need the flow to split underneath the positive PNA in the west. This would allow southern branch energy to undercut part of the pattern (without destroying it) and the result would be a steady stream of 1-2 footers like we saw in 1993-1994. No indication of that, at least as of yet but we do still have the door open for terrain induced and Champlain induced events that will also make a contribution during the early part of 2014. 

Saturday, December 21, 2013

Ice and more yuck through Monday but sustained cold weather takes the wheel after that

The front is oscillating up and down through Vermont Saturday. Unfortunately, the warmth pushed just far enough, north and I mean just far enough north, to allow the warm inversion to mix down to the surface and push temperatures close to 50. This boundary between warm and cold was literally positioned across I89, extending west southwest across the southern Adirondacks. Burlington's temperatures remained in the high 20's Saturday and temperatures remain in the high teens near the Canadian border. Oh well, chalk that up to some first class misfortune.

As of late in the day Saturday, the colder air is making a push south behind the first wave of low pressure and ahead of the stronger storm advancing toward us from the Ohio Valley. Temperatures will again be near the freezing mark Sunday morning while rain or freezing rain is falling. Looking at the temperature cross-sections, it looks like some sections of the mountain might see significant icing while other areas might remain a touch above freezing, it is literally that close and temperatures will for much of the day be within a degree of the freezing mark on either side. Saturday's temps will be the warmest we will see in some time but we will see another period on Monday where temperatures hover around 40 for a time before falling back below freezing by the evening.

The mountain will be back in the firm grasp of arctic chill Tuesday morning with readings near 10 for much of the day. Without much in the way of new snow to speak of through Christmas day, it will leave things a bit crusty, a good time to test the sharpened edges on the groomers. We had talked about our next chance for snow coming the day after Christmas as temperatures moderate in advance our next reenforcing shot of cold. The European model continues to drive the snowiest train on this particular system since it allows a relatively strong clipper system to gather limited amounts of Atlantic even some Gulf moisture and deposit a much needed 4-8 inches of snow to the VT high country. The Canadian and American model packages seem less intent on doing much of anything with this clipper, and the result would be more along the lines of a dusting to 2 inches of snow.

It once again gets chilly late Thursday into Friday which sets the stage for a rinse and repeat situation with questions regarding another clipper and another reenforcing shot of cold around the time of the 29th. The Arctic Oscillation is going to take this critical turn toward negative country around the new year or just before it. Specific results are a bit hard to make sense of this early, but generally speaking, we should the polar jet overwhelm a good part of the United States and lots of very cold weather through the first 7-10 days of 2014. When the polar jet is too overwhelming, in can prevent organized storm systems from having a big influence on interior New England but at the same time, sustained cold can never hurt and clipper systems can gradually fluff the mountain back into shape.

Thursday, December 19, 2013

A tough weekend lies ahead

Lots of stuff to sort out as we head toward the Christmas holiday and as of early Thursday morning, we are beginning to get some better clarity on the coming weekend. There is a lot to cover and could make the update seem a bit long-winded but bear with me. Unfortunately, the mountain will have to play some defense against a weather pattern that wants to push very mild temperatures into New England. Barring a late inning change, we  have have to endure some less than ideal stuff (Perhaps we should call in the 2013 vaunted Red Sox bullpen or David Ortiz for some heroics) Arctic cold will put up a massive big fight on our behalf to maintain some control on our weather; in fact, by Sunday I can almost envision one of those epic battlefield scenes in a movie as the appropriate metaphor for the clashing of these air masses. The big consequence of all this is of course, a lot of weather. 
 
A decaying wave of low pressure will provide the region with the initial taste of precipitation Friday. The boundary responsilbe for the upcoming warm push will reach central and northern Vermont but will stall during the day and precipitation is likely going to be a wintry mix, starting as snow and going to a sleet/freezing rain mixture. At some point we could get a period of plain rain also but at least on Friday, this problem will be minimal. Mountains such as Jay Peak and points north will be positioned north of this aforementioned boundary and are likely to get mostly snow and minimal sleet/freezing rain from Friday's more benign system.
 
I expect some occasional light freezing rain/drizzle or some light rain or drizzle but much of the day Saturday will just feature clouds and some areas of fog.  As this is happening our bigger storm will move out over the southern plains, gather moisture from the Gulf and begin to head northeast toward the eastern Great Lakes. Since the last update, models have suggested that this storm will deepen (strengthen) quicker and track farther north right into the heart of the St Lawrence Valley. This will put the onus on a potent artic high pressure center in northern Quebec to dam  whatever is left of the cold air across interior New England, a challenging task considering the track of this storm.  There is time for some late inning changes, and even a slight shift south in the trajectory of this strorm could have a serious impact impact on the results. As it stands now however, a major of intrusion mild air between 5,000 and 10,000 feet in the atmosphere takes out the possibility of snow. The inversion is so strong in fact, that it could create a situation where many of the summits on the Green Mountain chain are noticeably warmer than valley locations. It could, during a significant part of the precipitation event, be the difference between ice or plain rain.
 
Precipitaiton over the mountain becomes more intense Saturday night and there is a threat for some serious icing if temperatures are at or below the freezing mark. It is very close call but since we are anticipating 1-2" of liquid precipitation, the icing situation could rival anything we have seen in the last decade or so if temperatures stay below freezing. If the storm would track over Vermont, it would open the door for more sleet with is a much more ideal early season scenario since it would provide a big anchor to our early season base. Although this is still a remote possibility, I think the more likely scenario is freezing rain or rain. Even this less than ideal situation should not become a complete debauchery, temperatures across most of the mountain should stay in the 30's, mostly in the low 30's so although there will be some melting, it will not be a total melting. The rain or ice should end during the afternoon Sunday and temperatures will gradually return to normal by Monday afternoon along with some some snow flurries.
 
The Christmas holiday week will feature a cold day Christmas Eve followed by moderating temperatures Christmas Day and the 26th. This could go one of two ways  at this point. Around the time of the 26th, we could see a weaker storm system, maybe even a clipper, spread some light snow into the region ahead of what should be a reenforcing shot of cold weather very late next week or into the the last weekend of 2013. We could also see something more along the lines of what the recent European model indicated which was a more organized storm system another round of a wintry mixture of snow sleet or freezing rain. After a glance at the ensemble data, i didn't get the sense that the Euro solution was a true representation of the model conensus so I would expect that the 26th is our next chance for at least a light accumulation of plain snow followed by colder temperatures on the 27th.
 
There are signs around the new year that the Arctic Oscillation will finally turn negative but this will compete somewhat with the evil empire in the Pacific. We saw a lot of this in 2012-2013 and the results are all over the place. For the time being though, the upcoming weekend represents the only major elongated threat of above freezing temperatures and in the end, temperatures may not get above freezing by too much.

Monday, December 16, 2013

Late December Christmas outlook - lots to cover !!

We have one solid blanketing of snow and a memorable opening day in the books at MRG, but time keeps on ticking into the future and there is a lot to contend with in this future. The first half of this December is one of the coldest starts to the month we have seen in a decade and the cold has occurred in spite of a pattern not entirely supportive of sustained cold or big snow. The prevailing upper air feature in the jet stream has been a blocking ridge in the Bering Sea. This is hardly the ideal position for such a feature but it nonetheless sent such an onslaught of arctic cold into North America that the pattern was more or less overwhelmed with cold much like it was in my favorite winter of 1993-1994. It is such an encouraging sign going forward (at least this winter) to witness arctic cold battle the prevailing pattern with this type of ferocity. In spite of this, we still have to deal with some of the variability that such a pattern was inevitably going to produce. 

We will see this variability manifest itself during the upcoming weekend but in the meantime there is plenty of cold air in place and an incoming clipper system that promises to bring some light snow to the Green Mountains later Tuesday. Light snow from Tuesday afternoon into the evening might amount to a very fluffy 2-5 inches, enough for a few fresh turns Wednesday but the density of this snow will be noticeably less than the almost 2 feet of snow already on the ground. This particular clipper system will have its energy swallowed by a developing coastal system which promises to bring eastern Maine some nice powder Wednesday. Mad River Glen might see some snow showers or at least flurries Wednesday and some more lighter snows Thursday as a boundary representing the warm push of air makes its way toward VT. I don't expect much in the way of accumulation after Tuesday night. 

This brings us to Friday and the weekend which could feature all kinds of weather, possibly lots of weather and as of yet medium range models have failed to develop any sort of believable consensus. We do know that the northern half of our Bering Sea ridge will get chopped off leaving a pattern closely resembling that of the dreaded "evil empire". This being a upper ridge in the mid-latitude Pacific. Lots of mild air will thus make it's way northward, particularly Friday and although some of the aging arctic cold in eastern Canada will fight for control of interior New England, it could get dicey for sure. At this point it seems like there will be an initial push of warm air which will reach parts of VT for Friday. Parts of the mountain could see several hours of above freezing temperatures and perhaps some rain or freezing rain although precipitation on this day appears to be minimal. Colder temperatures will make a rather feeble push south Saturday ahead of what could be a very powerful storm system which will gather strength in Texas Saturday and head in our direction. In this particular situation, it will prove very difficult for this weak area of cold to play defense against a storm heading for the St Lawrence Valley. That being said there are hints on the last round of model output that the storm will travel south of Canada and perhaps right over Vermont allowing the cold weather, at least at the surface, to maintain a precarious grip on the region. There will be copious amounts of moisture sent in our direction and precipitation Sunday is unlikely to be snow but rather sleet, freezing rain or just plain rain. A significant icing event is actually possible in such a set-up but hard to pinpoint for sure how possible as of now. If we do get accumulating snow out of this storm, it would be Sunday night or early Monday. 

This brings us to the all important Christmas week which has yet to get extensive coverage from SCWB (it  has been overshadowed by our recent storm). A somewhat moderated arctic air mass should envelop the region in the wake of our big weekend weather producer. The ensembles however seem to be keying in on another weaker push of warmth around Christmas day. The American ensemble package has been downplaying this repeatedly and has suggested a relatively normal week of weather with a chance for some of the white stuff around Christmas day as opposed to any milder temperatures. I hope the American is right but another mild day and maybe another rain/ice event is possible around Christmas day. I would be more confident of a more serious push of cold weather and possibly some snow in the days following Christmas and into that last weekend of December.  

Saturday, December 14, 2013

What a nice looking December winter storm !!

Opening day is upon us in what looks to be a very promising start to the season. Even the Champlain induced, terrain induced snow shower machine has chimed in with some help this week in front of one of the better early season storms we have seen in VT in a few years. Yes we have seen some stronger storms and this one shouldn't become part of any New England folklore; but nonetheless, this is a beautiful noreaster for us. The track of this storm will ultimately be right over Cape Cod, the ideal scenario for the MRG powder freaks such as myself and many others. Snow will begin Saturday evening and some very intense snow is possible between midnight and dawn Sunday. This is a fast moving system that should make it's way into the Gulf of Maine by midday Sunday and the snow should taper to flurries by the early afternoon. In the last few days it actually has been quite unnecessary to provide updates. Last Monday it looked like we could get a 1-2 footer and it looks like that now, 1-2 feet of noreaster powder, and hopefully a critical part of the MRG base for weeks to come this season. 

I want to provide a more detailed update on what we might expect for the Christmas holiday, seeing as the ski season will be in full swing and I will do so tomorrow. In the shorter term however, there is a nice little follow-up to the weekend storm that will arrive later Tuesday in the form of a clipper system. This system represents a fight between arctic air and pacific air, both competing for control of eastern North America. The result should be some fluffy snow Tuesday and Tuesday night and some additional powder for the Wednesday ski day. We still have at least one and maybe two pushes of warm air to deal with in the weekend prior to Christmas. We can talk about that tomorrow but for now enjoy the storm, its a beauty. 

Wednesday, December 11, 2013

Storm musings and the weather in the week that follows

Winter is blooming at Mad River Glen. Cold temperatures, snow showers and squalls has the MRG community itching for opening day. The only thing that might be better is some big storm excitement and it just so happens that we have some of that as well. We can't ask for a much better set up either. We have a reenforcing fresh short of arctic chill clashing with a viable southern branch system. The Low pressure system will strengthen in the Ohio Valley and make the jump to the southern New England coast, ultimately moving in the near vicinity of Cape Cod before exiting into the open Atlantic. Snow from this system will arrive Saturday evening and persist through midday Sunday with the heaviest snow likely falling in the pre-dawn hours Sunday. If there was a trend in the cycle of model runs today it was that the storm has a somewhat flatter and weaker appearance. The last American model released Wednesday evening strengthened the storm to a shade under 1000 mb while the European model Tuesday showed a storm close to 980 mb walloping Vermont with 2 feet of snow. This somewhat fickle behavior in the models is very typical a few days from the storm and is a big reason to not sell your soul to the snowiest model. At face value, models today showed a modest 8-12 inch event with some of the heaviest snow falling falling across southern Vermont, the Berkshires and much of New Hampshire. I would not sell my soul to this solution either, at least not yet. It is still possible to get a stronger storm and upwards of 20 inch snowfall totals. Stay tuned !!

The amplification in the jet stream associated with the weekend storm will help keep temperatures on the chilly side of average through about Tuesday or Wednesday. After that, things could get really crazy. If you have been following the blog at all at this early date in the season, we had discussed the Bering Sea upper ridge and its tendency to produce volatile weather across the eastern U.S. including wild swings in temperatures from warm to cold and vice versa. As we move toward late next week, we could be faced with just such a scenario. The jet stream will again amplify but do so over the western and central part of North America thus sending a huge surge of warm temperatures up the eastern seaboard. Arctic air will try to fend off a chunk of this warm push late next week and next weekend (12/21 and 12/22 ) but this could evolve into a thaw or an ice storm or a rain to ice to snow situation. After our big storm, I am hoping for none of the above honestly and maybe we can find a way out of all those scenarios. Time will tell. This battle between some warmth along the eastern seaboard and arctic cold over Canada should continue into Christmas week and could result in a noteworthy event near the Christmas holiday.


Monday, December 9, 2013

More details on potential weekend storm !

I wasn't going to do any detailed update but with the MRG opening bell nearing and the weather this weekend "evolving", a brief one is warranted. On sunday we had discussed the possibility of snow on Sunday before more arctic chill encompasses the region early next week. The situation is a bit more intriguing however since a split in the jet stream and southern branch energy will be capable of incorporating more moisture into the equation. The last 1 or 2 cycles of models have clarified somewhat  the "if", the "when" and the "how" regarding the phasing of this system. And yes, we absolutely want this system to phase, we want it to phase a little earlier and we ultimately want a coastal low to absorb the systems energy off the New England coast. Although this is not etched in stone, it was certainly the trend in some of the last few bits of information. This system has a lot of the right ingredients to be a big snow producer, one certainly capable of getting winter mountain activities up and running.

Precipitation, we hope snow, would arrive late Saturday evening and persist through much of Sunday. More cold air then invades for Monday. Snowfall totals ? A bit too early for that speculation but we should at least up the range of expected snowfall for the next 7 days which should include some snow from snow showers and snow squalls Wednesday.

Much improved expectations for the middle of December

The first potential decent winter storm deposited much of its snow on southern Pennsylvania and managed largely fizzle as its depleted moisture overspread Vermont. Still, the limited snow provides the setting for a wintry scene which will prevail through much of this week and even into early next week. There is little doubt in my mind that the ferocity and expansiveness of the arctic chill so far this winter has been impressive, specifically how the arctic cold has managed to defy some of the less than optimal upper air configurations. It is vital to note that this is a very empirical observation yet an important one that must invariably be incorporated into our medium and long term expectations. In spite of the fact that the pattern has yet to favor cold or snow of any real magnitude over New England, it has favored cold and snow across the central and western United States and the result has been widespread areas of 20-25 degree below normal temperatures. We actually haven't seen much of this the last few years; in fact, we probably have to go back to 2003-2004 or maybe even prior to that since we have seen cold weather of that magnitude in the United States. Needless to say, when the pattern does align itself for cold across the northeast, the cold weather is likely to be considerably more intense than anything we have seen in the recent decade or so.

In the near term and specifically over the next week, we are actually set up for some very chilly December temperatures. A wave of low pressure will bring some mixed precipitation to coastal areas of New England Tuesday but will mostly miss interior areas like the Green and White Mountains of Vermont and New Hampshire.  On Wednesday, the Polar Vortex will take aim at New England and upper level impulse marking the leading edge of this surge of arctic chill should spread snow showers and a few snow squalls to the high country Wednesday and Wednesday night. It then turns bitterly cold by Thursday morning and this chill persists through Friday before modifying slightly before the weekend.

The "slightly" part of the last sentence is noteworthy since we had expressed some concern about a big warm-up for the middle of the month or maybe even a ugly pre-holiday thaw. Ensembles over the last two days have suggested that is much less likely which marks a big shift in the medium range guidance and certainly changes some of my expectations in the important week leading up to Christmas.  A reenforcing shot of arctic air is expected in the latter part of next weekend and this may or may not be accompanied by some snow. The European model is actually hinting at a significant snow producer for the Mid Atlantic while the American and Canadian model packages of hinted at a light to moderate snow event for the likes of us. I no longer expect a big move toward above normal temperatures after the 15th of the month and instead expect normal and even a few days of below normal temperatures with 1 or 2 chances for snow. This is a big improvement and some very good news in spite of the disappointing results from our Sunday Night-Monday event.

Thursday, December 5, 2013

Widespread snow/sleet event for Monday will be part of a very wintry week

Our first significant widespread snow event across the northern part of Vermont will arrive Sunday night or Monday morning. This will be one small part of a very volatile temperature forecast over the next two weeks. The pattern is being anchored by a giant omega blocking ridge over the Bering Sea. This is sending plenty of strong arctic air southward, but most of it is going into the Plains and Rocky Mountains where many spots will see temperatures near record levels during the coming week. Some of this arctic air will move eastward but we will not be the focal point of cold in this pattern. 

We are set up to have a somewhat wintry upcoming week however beginning over the weekend when the first batch of arctic cold displaces the mild air that will dominate the region Thursday into early Friday. A dusting to as much as two inches of snow is possible by Saturday morning but the real system of note is a loose conglomeration of low pressure centers which will gradually move out of the Rocky Mountains later this weekend. Arctic cold will be well entrenched as this system approaches. One of the systems two centers will move toward the eastern Great Lakes while another cranks up along the Atlantic coast. This is a very garden variety storm but it will impact a broad area of interior New England with snow across both mountains and valley locations. Snow should arrive late Sunday evening or early Monday with the heaviest snow lasting not more than a few hours. Precipitation could end as some sleet or freezing rain later Monday. I would put this in the category of a 6-12 inch event with the mixed precipitation adding some density or possibly some crust to whatever falls. Quite possibly a good base-building event !

Another batch of the some of the intense cold centered across western North America will then build across the region during the middle of next week but will likely be rather short-lived. The Polar Vortex could actually get rather close to Vermont for a day or so, perhaps sending temperatures well below zero for the first time this winter season. A clipper system could add a light accumulation of snow to the region as well. The Bering Sea ridge and the lack of any downstream blocking in the Davis Straits or Greenland will allow the cold to escape rather quickly and this could set the stage for another mild week beginning around the 14th or 15th of December. A few days ago I was more concerned about a widespread outbreak of mild temperatures but I think lingering cold in Canada will compete for control of the weather in spite of the overall expected jet stream configuration. At the very least however, it is likely we see some more above freezing days in the week preceding the Christmas holiday. 

Sunday, December 1, 2013

Variable pattern to dominate first half of December

The big finale to November has many giddy about the upcoming month and why not, it has been a momentous week to ten days. In reality though, the first half of December is typically erratic and more recently a big struggle. This one appears that it will conform to this norm since in spite of some promising looking possibilities in isolated parts of the forecast period, the next two weeks as a whole is fraught with trouble.

Arctic cold still, as we speak, encompasses much of Canada and is helping to rapidly freeze the Hudson Bay (now ~ 60 percent frozen). Unfortunately, it's influence has someone subsided across New England and points south. Were it to be more pronounced, a developing coastal system Tuesday might have had a greater chance of manifesting itself into something significant. As it is, the system will develop and it will mainly be a mixed rain and snow producer for coastal New England, exiting the region Tuesday evening. The duration of the week will generally be free of any new snow. Arctic cold and snow will descend on the Rocky Mountain region while the east coast will see a warming trend. Precipitation, if it falls at all, will be rain Thursday night (although nothing more than a period of a few hours).

Speaking fundamentally, the pattern in front of us is being anchored by a strong blocking ridge in the Bering Sea. Blocking, in general is a positive thing and the jet stream in the Pacific will be "loose" as opposed to "tight" which is also a positive thing. Longitudinally speaking however, the Bering Sea blocking ridge still presents some problems since it is a mechanism for focusing cold on the western half of North America while there is no mechanism to hold the cold in place over New England or eastern North America. The result is a highly variable pattern with intrusions of cold, some significant followed by quick warm-ups. New snow, maybe even a significant snow is possible as well but a thaw might quickly follow.

After a day or two of above freezing temperatures later this week, there will the first move toward colder temperatures by the weekend but this turn to colder weather does not look like it will accompanied by any snow. The next best chance for good snow comes around the 9th or 10th of the month as a potential system exits the Rocky Mountain and gets catapulted northeastward toward the eastern Great Lakes by another big jet amplification across the west. Actually, the track of this system is still very much in question and if the amplification across the west is a bit more imperfect, it might generate a flatter system. The snowiest solution would probably involve some compromise of the above solutions. The potential storm (or no storm) will be followed by a more significant chunk of cold for the middle of the week but this to will be short-lived. By the 13th of the month there is some strong evidence to suggest a more significant push of warmer temperatures, perhaps even a significant thaw since the Bering Sea ridge may in face bottle up much of the cold in western Canada or at least that is what some of the ensembles are indicating.