A large upper air "block" has certainly established itself across Greenland over the past week. It has tag teamed with another high latitude blocking feature centered over the Bering Sea to allow arctic air to flood the country and will ensure a generally favorable early season pattern for the beginning of December. The benefits of the negative NAO will unfortunately not be felt until after the 2nd or 3rd of the month. The Bering Sea block has allowed a large trough to form across the inter-mountain west and this in turn will allow a large fetch of mild southerly to flow to establish itself across the east and this will flood the region with mild air very quickly on Tuesday. The rain will soon follow and rain it will to the tune of 1-2 inches. We might as well get this out of the way now because an event like this would have a devastating impact on skiing were it to come prior to the Christmas holiday.
So speaking from the standpoint of the MRG "base" we will be starting from scratch on December 2nd but a sustained period of cold weather will begin on that day. Temperatures will be seasonable through the upcoming weekend and by the looks of it, we will not have the instability for a big terrain induced snow event. There will be a lingering "baraclinic" area (you could say front) in the Gulf of Maine and this has the chance to stir up a bit of snow though the chances for accumulations will be best over coastal regions though much is left to be determined. The combination of better instability and even weak weather systems should result in some new snow early next week and hopefully by then we can start discussing a opening day party.
There is evidence that the block over Greenland will begin to break down around December 10th but our Bering Sea blocking feature will remain. The pattern will thus turn more variable but we should begin to churn out a few weather systems as we approach the middle of the month. There are a few additions or side features which should help to provide more of a numerical summary. Included will be seasonanal and 7-day snowfall totals at MRG and expected snowfall over the upcoming 7-day period. I will also include a favorability index. This will be a very generic, cumulative measure of the three teleconnection indices: the Arctic Oscillation (AO) the North Atlantic Oscillation (NAO) and Pacific-North American (PNA index. The AO and NAO index is favorable when negative while the PNA is favorable when positive. Thus for the purposes of the "favorability index", the signs of the AO and NAO will be flipped and added to the PNA index for a final total. This approach has weaknesses but it will be a simple non-subjective and numerical way of looking at the next two weeks since our newly devised "FI" will be calculated at 7 and 14 days.
Sunday, November 28, 2010
Thursday, November 25, 2010
Winter 2010-2011: The revenge of La Nina !!!
It is the middle of November and the weather has been excruciatingly mild so it must be time to kick off the seventh season of Single Chair Weather Blogging. Preseason forecasts can be a mess to evaluate in hindsight for their inexactitudes, inaccuracies and unquantifiable subjectivities. It can generate some excitement an for me induce a sudden craving for Magic Hat's Single Chair ale, which seems to be in short supply during Vermont's stick season (someone will have to clue me in on where to find some out of season SCA).
The emails I have gotten, which can now be sent to josh.aaron.fox@gmail.com (as opposed to yahoo) suggest that the SCWB reader continues is getting more and more weather literate asking the tough questions months ahead of the time when they usually get answered. We have an impressive audience of "in the closet" and "out of the closet" weather geeks and this helps to make running the SCWB a lot more fun. The talk this year has mostly revolved around La Nina and rightly so. It has blossomed quickly, decisively and promises to be a dominating force throughout the winter months. Its development also underscores how sharply the upcoming winter promises to deviate from the outcome last winter which featured a moderate El Nino, a vigorous and very moist southern branch of the jet stream and a season that I will now referred to as "the great inversion of 2009-2010" for its tendency to provide snow and cold to our friends down south and agony due to the lack of snow in Vermont. Preseason forecasts may be mostly famous for vagueness (I confess to share the guilt on this) but I can stress, even in mid November that the upcoming winter will be a striking contrast to the last and will quickly display a very different personality. If nothing else, it will keep the prognosticators on our toes, since frequent updates will be required to what should be a rapidly changing and volatile weather pattern. It will prove to be fun and challenging if nothing else.
La Nina's return
The ENSO conversation is typically the easiest part of the preseason discussion. Its associations and relationships are known and a ENSO event is easily quantifiable. This years La Nina has already received a ton of discussion and for good reason. As an aggregate measure, the current La Nina in September-October (-1.59 SST anomaly)is the strongest since 1955. I was somewhat surprised that we didn't blow right through the tropical storm alphabet since La Nina's of such ferocity usually are associated with very active hurricane seasons (this year's actually was but we did not see any major land falling storms in the U.S. and we didn't blow through the alphabet, at least not yet). Two other La Nina event that comes close developed in 1988 a winter we would just assume forget and 2007 a winter where I was pleasantly surprised. The winter of 1970-71 also featured a strong La Nina (although one that developed very late) and this winter turned out like a dream with incredible snowfall amounts across northern Vermont. This may seem like a pointless range of possibilities to discuss (since the range includes seemingly everything) but La Nina winters have a distinct personality that ties them together as opposed to specific snowfall amounts. Two features that seem most persistent and most influential tend to be a large and potent ridge across the Gulf of Alaska and a persistent ridge across the southeastern United States. This often dreaded southeast ridge can make winter's non-existent in our southern mid-latitudes below 38-40 north. Ski areas that received the high snowfall amounts last year like Seven Springs in PA or Snowshoe in West Virginia will not be so lucky this year. It is a different ball game up north however. Storm systems, and many of them, get deflected up through the Ohio or Mississippi Valleys toward the eastern Great Lakes and then often proceed to split New England into pieces in terms of the weather that results including heavy snow across northern areas, ice, ice and more ice across southern interior areas and rain along the coasts. This line of rain to ice to snow is by no means a constant and tends to fluctuate from north to south based on the storm track or readily available fresh supply of cold air. During some winters, MRG is on the favorable side of all the uncertainty (70-71), some they are not and most fall in between. This means some weeks turn out very snowy but there are several where ice and rain can greatly damage our skiing enjoyment. It is often unfortunate because there is not much even a little elevation can do to stop surges of mid-level warmth that often become so prevalent during these type of winters. Latitude does greatly help however and we do have that working for us (44 north thank you very much !!
2007-2008 winter forecast got suffocated much to our delight !!
The discussion about the current La Nina should also include a look at the 2007-2008 winter. That season was predicted to be a poor one since it was thought that the La Nina strength combined with the slow autumn buildup of northern hemisphere snow cover would be tough to overcome. That forecast was terrible but in retrospect revealing. For one, it is another in an invariable string of reminders of how inaccurate these forecasts can be. Secondly, it did provide a bit of inspiration for some preseason research. The results are interesting in a study that involved looking at strong ENSO events (strong La Nina's or strong El Nino's) and snowfall and temperatures across northern New England. The temperature results are not surprising. The strong El Nino events are dominated by milder temperatures and strong La Nina events feature above normal temperatures of a lesser degree. Snowfall in winters featuring significant ENSO events was a bit suprising. Both strong La Nina's and El Nino's featured above normal snow which to some might seem like a counter-intuituve result. It would be healthy to maintain a bit of cynicism regarding the results since the sample size which spanned 60 years and 21 qualifying winters is rather small. Still it is fair to suggest that the winter forecast made in 2007-2008 was a bit too pessimistic. The premises were right and many of those premises will remain this year.
The build up of snow and a further look at other strong La Nina winters
Looking at the buildup of snow across the northern hemisphere is our empirical method for assessing the hypothetical magnitude of cold airmasses through the upcoming winter. It is very inexact and can change over the course of the season. Snow cover area however often proves to be an important thermal feedback especially when trying to predict the sign of temperature. It helps cold air pool more efficiently especially early in the season when large expanses of high latitude land can either be covered in snow or snowless. The 10 most recent strong La Nina winters featured the following coverage of snow (in millions of square km) across the northern hemisphere during October and November. The end result of each winter is included on the right.
Year Snow Result
1970-71 28.6 Very cold, much above normal snow
1973-74 27.6 Slightly mild and above normal snow
1975-76 23.8 Slightly cold and above normal snow
1984-85 25.4 Slightly cold and above normal snow
1988-89 22.1 Slightly mild, way below normal snow
1998-99 26.6 Very mild, normal snow
1999-00 25.5 Very mild, below normal snow
2007-08 24.4 Mild, much above normal snow
2010-11 ~25.3 ??
The average snow cover area for the northern hemisphere during this period is 25.3. The period ending this November 30th will come in just at or slightly over that number. It is interesting that that the year with the highest autumn snow cover turned out to be the best and the year with the lowest (1988) turned into the worst as far as skiing goes. Somewhat circumstantial perhaps but probably not entirely so. This winter has seen a healthy buildup of snow and a rapid expansion in the last week or two across the North America but its not much better than average over a two month period so therefore difficult to draw any conclusions.
Our friend the PDO
The Pacific Decadal Oscillation (PDO) is another variable we have factored in to the preseason forecasts. The PDO refers to the configuration of temperatures across the mid-lattitude Pacific Ocean as opposed to the ENSO which refers to the equatorial Pacific. A positive or warm phase is often but not always teamed up with an El Nino and tends to feature a long-wave or jet stream pattern consisting of a trough in eastern North America and a ridge in western North America. A negative phase of the PDO is often prevalent during a La Nina and has the opposite effect. Data in recent years suggests that we have moved into a prevailing negative PNA and that last years strong El Nino was tag teamed with a very weak positive PDO. This year the PDO has swung back to negative and it appears it will remain there through the winter. This comes as no surprise and supports a pattern we are already expecting given the strength of the current La Nina.
The Quasi-Biennial Oscillation
Just like with the PDO, 10 years ago, there has been work and increased discussion over the last several years regarding the Quasi-Biennial Oscillation and its relationship to the behavior of weather patterns in the northern hemisphere winter. I hope to keep most of the in-season discussions focused on more benign terminology but I did learn enough from emails and other discussions to provide a brief blurb. The QBO refers to the oscillation of the equatorial zonal wind in the stratosphere and is measured as an westerly or easterly index with westerly having a positive index and easterly negative. Some work has been done to establish a relationship between the phase of the QBO and Sudden Stratospheric Warming Events (another lengthy term). The SSWE have their own lengthy description and definition but they are associated with mid latitude jet stream blocks that are often the cause of sustained periods of cold weather. The easterly phase of the QBO for instance last year was said to encourage the persistent negative NAO. It has since moved to westerly perhaps suggesting less frequent negative NAO events and a more zonal pattern. None of this really contradicts anything that we might expect in a strong La Nina year such as this.
A summary and a prediction
So in summary, La Nina will win the day and win it decisively. It will mean that temperatures will average above normal but not as much as they did last winter - lets call it 1-2 degrees above for the ski season. Many places south of 40 degrees north latitude will experience a winter dramatically milder than last and dramatically less snow. We will get outbreaks of some severe cold but they will be interrupted and very abruptly by intrusions of milder weather. The milder weather will in many cases be accompanied by rain or ice which will at times be damaging. On the flip side there will be many other storm systems that bring snow and we should see a few epic periods. The southern branch of the jet stream will not be as influential and we will instead see a consolidated west to east jet stream send storm systems in our direction and few should miss. This should be enough to allow snowfall to come in above average - lets say 290 inches. This is around 110 percent of average at the mountain. The winter will require our full attention since many of the best periods will be simply wet or icy along the coast and conditions will change very quickly. Enjoy the thanksgiving holiday and think snow.
The emails I have gotten, which can now be sent to josh.aaron.fox@gmail.com (as opposed to yahoo) suggest that the SCWB reader continues is getting more and more weather literate asking the tough questions months ahead of the time when they usually get answered. We have an impressive audience of "in the closet" and "out of the closet" weather geeks and this helps to make running the SCWB a lot more fun. The talk this year has mostly revolved around La Nina and rightly so. It has blossomed quickly, decisively and promises to be a dominating force throughout the winter months. Its development also underscores how sharply the upcoming winter promises to deviate from the outcome last winter which featured a moderate El Nino, a vigorous and very moist southern branch of the jet stream and a season that I will now referred to as "the great inversion of 2009-2010" for its tendency to provide snow and cold to our friends down south and agony due to the lack of snow in Vermont. Preseason forecasts may be mostly famous for vagueness (I confess to share the guilt on this) but I can stress, even in mid November that the upcoming winter will be a striking contrast to the last and will quickly display a very different personality. If nothing else, it will keep the prognosticators on our toes, since frequent updates will be required to what should be a rapidly changing and volatile weather pattern. It will prove to be fun and challenging if nothing else.
La Nina's return
The ENSO conversation is typically the easiest part of the preseason discussion. Its associations and relationships are known and a ENSO event is easily quantifiable. This years La Nina has already received a ton of discussion and for good reason. As an aggregate measure, the current La Nina in September-October (-1.59 SST anomaly)is the strongest since 1955. I was somewhat surprised that we didn't blow right through the tropical storm alphabet since La Nina's of such ferocity usually are associated with very active hurricane seasons (this year's actually was but we did not see any major land falling storms in the U.S. and we didn't blow through the alphabet, at least not yet). Two other La Nina event that comes close developed in 1988 a winter we would just assume forget and 2007 a winter where I was pleasantly surprised. The winter of 1970-71 also featured a strong La Nina (although one that developed very late) and this winter turned out like a dream with incredible snowfall amounts across northern Vermont. This may seem like a pointless range of possibilities to discuss (since the range includes seemingly everything) but La Nina winters have a distinct personality that ties them together as opposed to specific snowfall amounts. Two features that seem most persistent and most influential tend to be a large and potent ridge across the Gulf of Alaska and a persistent ridge across the southeastern United States. This often dreaded southeast ridge can make winter's non-existent in our southern mid-latitudes below 38-40 north. Ski areas that received the high snowfall amounts last year like Seven Springs in PA or Snowshoe in West Virginia will not be so lucky this year. It is a different ball game up north however. Storm systems, and many of them, get deflected up through the Ohio or Mississippi Valleys toward the eastern Great Lakes and then often proceed to split New England into pieces in terms of the weather that results including heavy snow across northern areas, ice, ice and more ice across southern interior areas and rain along the coasts. This line of rain to ice to snow is by no means a constant and tends to fluctuate from north to south based on the storm track or readily available fresh supply of cold air. During some winters, MRG is on the favorable side of all the uncertainty (70-71), some they are not and most fall in between. This means some weeks turn out very snowy but there are several where ice and rain can greatly damage our skiing enjoyment. It is often unfortunate because there is not much even a little elevation can do to stop surges of mid-level warmth that often become so prevalent during these type of winters. Latitude does greatly help however and we do have that working for us (44 north thank you very much !!
2007-2008 winter forecast got suffocated much to our delight !!
The discussion about the current La Nina should also include a look at the 2007-2008 winter. That season was predicted to be a poor one since it was thought that the La Nina strength combined with the slow autumn buildup of northern hemisphere snow cover would be tough to overcome. That forecast was terrible but in retrospect revealing. For one, it is another in an invariable string of reminders of how inaccurate these forecasts can be. Secondly, it did provide a bit of inspiration for some preseason research. The results are interesting in a study that involved looking at strong ENSO events (strong La Nina's or strong El Nino's) and snowfall and temperatures across northern New England. The temperature results are not surprising. The strong El Nino events are dominated by milder temperatures and strong La Nina events feature above normal temperatures of a lesser degree. Snowfall in winters featuring significant ENSO events was a bit suprising. Both strong La Nina's and El Nino's featured above normal snow which to some might seem like a counter-intuituve result. It would be healthy to maintain a bit of cynicism regarding the results since the sample size which spanned 60 years and 21 qualifying winters is rather small. Still it is fair to suggest that the winter forecast made in 2007-2008 was a bit too pessimistic. The premises were right and many of those premises will remain this year.
The build up of snow and a further look at other strong La Nina winters
Looking at the buildup of snow across the northern hemisphere is our empirical method for assessing the hypothetical magnitude of cold airmasses through the upcoming winter. It is very inexact and can change over the course of the season. Snow cover area however often proves to be an important thermal feedback especially when trying to predict the sign of temperature. It helps cold air pool more efficiently especially early in the season when large expanses of high latitude land can either be covered in snow or snowless. The 10 most recent strong La Nina winters featured the following coverage of snow (in millions of square km) across the northern hemisphere during October and November. The end result of each winter is included on the right.
Year Snow Result
1970-71 28.6 Very cold, much above normal snow
1973-74 27.6 Slightly mild and above normal snow
1975-76 23.8 Slightly cold and above normal snow
1984-85 25.4 Slightly cold and above normal snow
1988-89 22.1 Slightly mild, way below normal snow
1998-99 26.6 Very mild, normal snow
1999-00 25.5 Very mild, below normal snow
2007-08 24.4 Mild, much above normal snow
2010-11 ~25.3 ??
The average snow cover area for the northern hemisphere during this period is 25.3. The period ending this November 30th will come in just at or slightly over that number. It is interesting that that the year with the highest autumn snow cover turned out to be the best and the year with the lowest (1988) turned into the worst as far as skiing goes. Somewhat circumstantial perhaps but probably not entirely so. This winter has seen a healthy buildup of snow and a rapid expansion in the last week or two across the North America but its not much better than average over a two month period so therefore difficult to draw any conclusions.
Our friend the PDO
The Pacific Decadal Oscillation (PDO) is another variable we have factored in to the preseason forecasts. The PDO refers to the configuration of temperatures across the mid-lattitude Pacific Ocean as opposed to the ENSO which refers to the equatorial Pacific. A positive or warm phase is often but not always teamed up with an El Nino and tends to feature a long-wave or jet stream pattern consisting of a trough in eastern North America and a ridge in western North America. A negative phase of the PDO is often prevalent during a La Nina and has the opposite effect. Data in recent years suggests that we have moved into a prevailing negative PNA and that last years strong El Nino was tag teamed with a very weak positive PDO. This year the PDO has swung back to negative and it appears it will remain there through the winter. This comes as no surprise and supports a pattern we are already expecting given the strength of the current La Nina.
The Quasi-Biennial Oscillation
Just like with the PDO, 10 years ago, there has been work and increased discussion over the last several years regarding the Quasi-Biennial Oscillation and its relationship to the behavior of weather patterns in the northern hemisphere winter. I hope to keep most of the in-season discussions focused on more benign terminology but I did learn enough from emails and other discussions to provide a brief blurb. The QBO refers to the oscillation of the equatorial zonal wind in the stratosphere and is measured as an westerly or easterly index with westerly having a positive index and easterly negative. Some work has been done to establish a relationship between the phase of the QBO and Sudden Stratospheric Warming Events (another lengthy term). The SSWE have their own lengthy description and definition but they are associated with mid latitude jet stream blocks that are often the cause of sustained periods of cold weather. The easterly phase of the QBO for instance last year was said to encourage the persistent negative NAO. It has since moved to westerly perhaps suggesting less frequent negative NAO events and a more zonal pattern. None of this really contradicts anything that we might expect in a strong La Nina year such as this.
A summary and a prediction
So in summary, La Nina will win the day and win it decisively. It will mean that temperatures will average above normal but not as much as they did last winter - lets call it 1-2 degrees above for the ski season. Many places south of 40 degrees north latitude will experience a winter dramatically milder than last and dramatically less snow. We will get outbreaks of some severe cold but they will be interrupted and very abruptly by intrusions of milder weather. The milder weather will in many cases be accompanied by rain or ice which will at times be damaging. On the flip side there will be many other storm systems that bring snow and we should see a few epic periods. The southern branch of the jet stream will not be as influential and we will instead see a consolidated west to east jet stream send storm systems in our direction and few should miss. This should be enough to allow snowfall to come in above average - lets say 290 inches. This is around 110 percent of average at the mountain. The winter will require our full attention since many of the best periods will be simply wet or icy along the coast and conditions will change very quickly. Enjoy the thanksgiving holiday and think snow.
Sunday, April 4, 2010
Warm weather ends an uneven season
Uneven would be a generous way of putting it, disappointing might be the blunt way. There were some high expectations going into the year as it appeared we would have the right mix of high octane jet energy in the south and cold weather from the north to produce some big things. In fact, that is exactly what we saw, but all the fun was well to Vermont's south. The snow would have been more welcomed in our neck of the woods since it caused unprecedented disruptions in air traffic and costly clean-up projects in our major U.S. cities.
It is funny to look at the compiled data and how it illustrates how 2007-2008 got turned upside down thanks largely to a flip in the ENSO from La Nina to El Nino. Take a look at how we left 2007-2008 at the SCWB.
"Montreal, Quebec - 142 inches (169 % of average)
Burlington, VT - 100 inches (131 % of average)
Boston, MA - 51 inches (113 % of average)
Philadelphia, PA - 6 inches (25 % of average)
In the language of anomalies that is quite a contrast. In other words, some pain and suffering had to be endured by skiers/riders who stayed at Seven Springs or Snowshoe WV this year. Lattitude was key at we had it at MRG and this proved to save our season."
Pain and suffering is not the word to describe the season at Seven Springs or Snowshoe this past winter. Both mountains received over 200 inches of snow which in the case of Seven Springs was a record. Most importantly, the conditions were epic for the first three weeks of February in all of those locations as record snow was combined with consistent cold.
At Mad River Glen, we did not have a winter as futile as 2005-2006 or 2001-2002. We were pleasantly surprised early in the season as several storms pronged to move well to our south took an 11th hour turn northward to yield some powder. The mountain missed the Megalopitan storm "I" but did get a multi-day powder fest on New Years as a storm retrograted westward out of the Gulf of Maine. This was arguably the best event of the season for the mountain and was meteorologically fascinating since the event caused Champlain induced powder to fall over Burlington to the tune of 3 feet.
There was much anticipation after a quiet end to January since the pattern in early February looked as stormy as any I have ever seen in winter. The pattern was fueled by a plethora of blocking mechanisms across the high latitudes and an extremely energetic southern branch of the jet stream. The blocking was so ferocious that the storm track was forced unusually far to our south. Interestingly, so was the cold weather. Florida was not the place to visit during the winter as frequent outbreaks of intense cold resulted in the coldest winter in over 30 years. At Mad River glen, the cold weather never reached a level we would consider "intense" and although the winter was free of large scale "thaws" temperatures averaged above normal for the season. It was an unusual combination of circumstances to say the least but one that caused back to back major storms across the Mid-Atlantic States in early February. The seasonal snowfalls in cities like Baltimore, MD and Philadelphia climbed to 400 % of normal but much of Vermont continued to be plagued with a snow drought. Not only did MRG miss both Megalopitan events in February, but terrain induced events were non-existent as northern branch jet energy was locked up across Canada and southern branch energy was causing unprecedented snow farther south.
The big event of the winter at MRG occurred late in February. It was a very convoluted system flush with moisture but initially disorganized and ultimately quite mighty but very occluded. The initial burst of snow resulted in a swath of 50 inch totals up the spine of the Berkshires and Green Mountains but as the storm matured, it brought a conveyor of warmth into interior New England while cold advanced east into areas like Maryland, Pennsylvania and New Jersey. There were several hours during this event where you could've driven south on the New York State Thruway and the weather would have transitioned from heavy rain to heavy snow. In many ways it underscored the personality of the entire winter as an imaginary line within a few degrees of 40 north seemed to divide areas that received record snow from areas that consistently seemed to receive little snow. The storm in late February was a great one for MRG and would have been epic were it not for that warm intrusion which made conditions very changeable as you moved down the mountain.
In the end an El Nino of moderate strength such as the one that was present for much of the season, combined with the consistent presence of mid latitude cold are certainly the ingredients necessary for a winter such as the one we received. My conventional wisdom was perhaps wish casting for a winter more similar to 1992-1993 or 1977-1978 but the winter turned out to be a more exaggerated version of 1986-1987 or 1987-1988. The year perhaps most similar was 1957-1958. In that winter, record snow hit portions of Maryland and Pennsylvania late in the season in another year where the El Nino was very prevalent.
On a more personal note, I once again enjoyed the opportunity to talk weather to the greatest weather audience perhaps in the world. I felt the quality of the blog perhaps suffered at times since at times I found it challenging to combine my work load with blogging responsibilities. To make a long story short, it was easier to maintain the blog when you are unemployed and in search of things to do. I got a lot of emails, mostly positive and many I never got a chance to respond to. I appreciate the comments even if I never got a chance to craft a response. Enjoy the summer, stay safe think big snow for next winter.
-Josh Fox of the SCWB
It is funny to look at the compiled data and how it illustrates how 2007-2008 got turned upside down thanks largely to a flip in the ENSO from La Nina to El Nino. Take a look at how we left 2007-2008 at the SCWB.
"Montreal, Quebec - 142 inches (169 % of average)
Burlington, VT - 100 inches (131 % of average)
Boston, MA - 51 inches (113 % of average)
Philadelphia, PA - 6 inches (25 % of average)
In the language of anomalies that is quite a contrast. In other words, some pain and suffering had to be endured by skiers/riders who stayed at Seven Springs or Snowshoe WV this year. Lattitude was key at we had it at MRG and this proved to save our season."
Pain and suffering is not the word to describe the season at Seven Springs or Snowshoe this past winter. Both mountains received over 200 inches of snow which in the case of Seven Springs was a record. Most importantly, the conditions were epic for the first three weeks of February in all of those locations as record snow was combined with consistent cold.
At Mad River Glen, we did not have a winter as futile as 2005-2006 or 2001-2002. We were pleasantly surprised early in the season as several storms pronged to move well to our south took an 11th hour turn northward to yield some powder. The mountain missed the Megalopitan storm "I" but did get a multi-day powder fest on New Years as a storm retrograted westward out of the Gulf of Maine. This was arguably the best event of the season for the mountain and was meteorologically fascinating since the event caused Champlain induced powder to fall over Burlington to the tune of 3 feet.
There was much anticipation after a quiet end to January since the pattern in early February looked as stormy as any I have ever seen in winter. The pattern was fueled by a plethora of blocking mechanisms across the high latitudes and an extremely energetic southern branch of the jet stream. The blocking was so ferocious that the storm track was forced unusually far to our south. Interestingly, so was the cold weather. Florida was not the place to visit during the winter as frequent outbreaks of intense cold resulted in the coldest winter in over 30 years. At Mad River glen, the cold weather never reached a level we would consider "intense" and although the winter was free of large scale "thaws" temperatures averaged above normal for the season. It was an unusual combination of circumstances to say the least but one that caused back to back major storms across the Mid-Atlantic States in early February. The seasonal snowfalls in cities like Baltimore, MD and Philadelphia climbed to 400 % of normal but much of Vermont continued to be plagued with a snow drought. Not only did MRG miss both Megalopitan events in February, but terrain induced events were non-existent as northern branch jet energy was locked up across Canada and southern branch energy was causing unprecedented snow farther south.
The big event of the winter at MRG occurred late in February. It was a very convoluted system flush with moisture but initially disorganized and ultimately quite mighty but very occluded. The initial burst of snow resulted in a swath of 50 inch totals up the spine of the Berkshires and Green Mountains but as the storm matured, it brought a conveyor of warmth into interior New England while cold advanced east into areas like Maryland, Pennsylvania and New Jersey. There were several hours during this event where you could've driven south on the New York State Thruway and the weather would have transitioned from heavy rain to heavy snow. In many ways it underscored the personality of the entire winter as an imaginary line within a few degrees of 40 north seemed to divide areas that received record snow from areas that consistently seemed to receive little snow. The storm in late February was a great one for MRG and would have been epic were it not for that warm intrusion which made conditions very changeable as you moved down the mountain.
In the end an El Nino of moderate strength such as the one that was present for much of the season, combined with the consistent presence of mid latitude cold are certainly the ingredients necessary for a winter such as the one we received. My conventional wisdom was perhaps wish casting for a winter more similar to 1992-1993 or 1977-1978 but the winter turned out to be a more exaggerated version of 1986-1987 or 1987-1988. The year perhaps most similar was 1957-1958. In that winter, record snow hit portions of Maryland and Pennsylvania late in the season in another year where the El Nino was very prevalent.
On a more personal note, I once again enjoyed the opportunity to talk weather to the greatest weather audience perhaps in the world. I felt the quality of the blog perhaps suffered at times since at times I found it challenging to combine my work load with blogging responsibilities. To make a long story short, it was easier to maintain the blog when you are unemployed and in search of things to do. I got a lot of emails, mostly positive and many I never got a chance to respond to. I appreciate the comments even if I never got a chance to craft a response. Enjoy the summer, stay safe think big snow for next winter.
-Josh Fox of the SCWB
Sunday, March 28, 2010
Another east coast storm brings all rain to VT followed a season ending thaw
In the end, the storm early this week will be a microcosm of the season. The cold air which returned in time for the recent weekend has become stale and will receive little re-enforcing help. As a result the storm which will refuel along the North Carolina coast will have little cold air to work with and will spread rain into Vermont Monday and lots of it. There is in fact legitimate concern about flooding when you combine the nearly 2 inches of rain that is expected to fall Monday and Tuesday with the snow that will melt across the high country. The periods of rain should persist through Tuesday with temperatures generally in the low 40's. On Tuesday, the summits could see some limited snow before precipitation moves east and out of the region Wednesday.
Once the sunshine returns the weather will turn spectacular as promised late last week. It is a mammoth upper ridge which is expected to build across the eastern third of the country and this will allow for weather more typical of early June in Vermont as opposed to early April. The only competing force will be some marine air which could back in to interior New England sporadically; otherwise, temperatures will surge into the 70's on at least 2 and probably 3 days in the period between Friday of this week and Tuesday of next week. The warm air will be accompanied by some great visibility and plenty of sunshine. So long as the snow survives, the skiing will be great but the warmth is strong enough to put a mortal dent into the snow cover and will likely render parts of MRG unskiable by April 5th or 6th. With all that in mind the SCWB will probably get one more update before we call it a season.
Once the sunshine returns the weather will turn spectacular as promised late last week. It is a mammoth upper ridge which is expected to build across the eastern third of the country and this will allow for weather more typical of early June in Vermont as opposed to early April. The only competing force will be some marine air which could back in to interior New England sporadically; otherwise, temperatures will surge into the 70's on at least 2 and probably 3 days in the period between Friday of this week and Tuesday of next week. The warm air will be accompanied by some great visibility and plenty of sunshine. So long as the snow survives, the skiing will be great but the warmth is strong enough to put a mortal dent into the snow cover and will likely render parts of MRG unskiable by April 5th or 6th. With all that in mind the SCWB will probably get one more update before we call it a season.
Thursday, March 25, 2010
Winter makes a brief return but will fade quickly by late next week
Cold air has made its southward push in time for the weekend and a brief period of snow will whiten the mountain by Friday first tracks. The weekend however will be a dry one and will be preceded by a rare day of below freezing temperatures (Friday) and single digit temperatures in the morning Saturday. Light winds and full sunshine during the day Saturday should allow for a rapid recovery and slightly above freezing temperatures by Saturday afternoon. Sunday morning will be considerably warmer and the day should feature more clouds but relatively light winds and temperatures slightly above freezing during the afternoon hours.
As one of the warmer and snowless March's I can remember moves forward, the SCWB updates have gotten more sporadic but we continue (consistent with the last update) to watch a weather system on Monday. It is a potent southern branch piece of jet energy which will exit the central Rockies Sunday and make its way to the east coast by Monday. Its track is favorable for some MRG powder but the amount of cold air remains a question. The European model indicates a rather stale supply of cold air and thus limits the accumulating snow to the high elevations of the Green Mountains and the snow itself would be of the wetter variety. The American GFS model indicates that a fresher surge of cold air will become entrained in this system and we would thus look forward to several inches of powder across the entire span of the mountain Monday. The differences between the two models might seem small but have huge consequences. It involves a small piece of energy in the polar jet, a branch of the jet which has largely been confined to Canada this month. The GFS model however allows some arctic air from this branch of the jet to get involved in Monday's system while the European simply confines all the polar jet energy to the north. We can settle for a compromise for it too would yield snow on Monday.
If Monday's system fails to materialize it will be lights on the the winter. Not to say we can't get more snow in Vermont come later in April but the thaw that is to come by late next week will be massive. It will result from ridging in the Central Pacific and unsettled weather across the west. This will allow a Bermuda high to form and the warm air to surge northward. And when I say warm I mean "warm" not "mild". Temperatures in the valley locations will surge to 70 degrees and beyond across the low lying areas by late next week and into the weekend. It will make for incredible spring skiing so long as the snow survives but those temperatures will obliterate the base and likely put an end to the MRG season in short order. I would take advantage of the warm temps early while the snow lasts. It will also be a terrific time to head up to Tuckermans Ravine as there should be several days of fantastic visibility and tolerable winds to accompany the soft snow.
As one of the warmer and snowless March's I can remember moves forward, the SCWB updates have gotten more sporadic but we continue (consistent with the last update) to watch a weather system on Monday. It is a potent southern branch piece of jet energy which will exit the central Rockies Sunday and make its way to the east coast by Monday. Its track is favorable for some MRG powder but the amount of cold air remains a question. The European model indicates a rather stale supply of cold air and thus limits the accumulating snow to the high elevations of the Green Mountains and the snow itself would be of the wetter variety. The American GFS model indicates that a fresher surge of cold air will become entrained in this system and we would thus look forward to several inches of powder across the entire span of the mountain Monday. The differences between the two models might seem small but have huge consequences. It involves a small piece of energy in the polar jet, a branch of the jet which has largely been confined to Canada this month. The GFS model however allows some arctic air from this branch of the jet to get involved in Monday's system while the European simply confines all the polar jet energy to the north. We can settle for a compromise for it too would yield snow on Monday.
If Monday's system fails to materialize it will be lights on the the winter. Not to say we can't get more snow in Vermont come later in April but the thaw that is to come by late next week will be massive. It will result from ridging in the Central Pacific and unsettled weather across the west. This will allow a Bermuda high to form and the warm air to surge northward. And when I say warm I mean "warm" not "mild". Temperatures in the valley locations will surge to 70 degrees and beyond across the low lying areas by late next week and into the weekend. It will make for incredible spring skiing so long as the snow survives but those temperatures will obliterate the base and likely put an end to the MRG season in short order. I would take advantage of the warm temps early while the snow lasts. It will also be a terrific time to head up to Tuckermans Ravine as there should be several days of fantastic visibility and tolerable winds to accompany the soft snow.
Sunday, March 21, 2010
Storm system to bring lots of moisture to Vermont but cold air is lacking
The cold air has been lacking for much of the month and the first 21 days has averaged an astounding 10 degrees above normal. The warmth has certainly corned up the snow quite nicely and the sun and relative lack of wind has made it pristine for outdoor activities. The snow, however is melting fast and a storm is very much needed in order to extend the winter season.
A storm is on the way and one which could have very much extended the season with the support of any cold air. Unfortunately, the cold more or less spent itself into bankruptcy across the western U.S. and will do little more than return temperatures to within the ballpark of normal. Meanwhile we have a storm system in the southern half of the U.S. which is spinning eastward and bringing rain to the 2010 snowbelt (Washington D.C.). This storm will grab Atlantic moisture as it moves northeast and spill it on much of Vermont and interior New England. Temperature profiles reveal a relatively warm lower 6000 feet of the troposphere and I would expect nothing more than rain below 2,500 feet. The rain will begin rather lightly on Monday but gain intensity by early Tuesday and should fall moderately and occasionally heavy through much of the morning. Above 2,500 feet we could see some snow mix in but temperatures should remain slightly above freezing so it will be a wet day for sure. As the storm continues to gain intensity and pull away to the northeast, colder weather will allow for more snow at the summits and for rain to change to snow at the base. This could lead to a few inches by Wednesday but the accumulations will be very wet at the base with only the summits having any chance for real powder. This is another storm which could have been a real winner for MRG but this winter has produced a litany of events where at least one puzzle piece always goes missing. In this case we have the moisture and we have a relatively favorable track but have little cold air. The event could bring 1-2 inches of rain to much of the Green Mountain spine which will damage the remaining bases to a degree but should not eliminate them entirely, particularly across the summits.
Snow showers and flurries will continue most of Wednesday and into Thursday although temperatures at the base should remain above freezing for the most part and any precipitation could be rain in the valleys. Late on Thursday, we should see a fairly good "punch" of cold air make a push into New England. This could bring a burst of snow to the mountain and finally bring temperatures universally below freezing on Friday. We will be watching a more organized storm system by the weekend but I don't think its impacts (rain or snow) will be felt until later on Sunday leaving the weekend free of any big precipitation. Temperatures will rebound to above freezing levels during the day and 20 degree readings at night.
The storm mentioned above does have some cold air as an ally but it track is a question mark and thus so is the precipitation type. At the very least we should see some terrain induced powder in the wake of whatever does evolve. It will mark a 3-4 day stretch of relative cold but it won't last as ridging in the central Pacific will again shift the storminess into the Western United States. It will thus likely be a rather mild end of March and early April and should set the region up for more spring conditions on whatever snow remains.
A storm is on the way and one which could have very much extended the season with the support of any cold air. Unfortunately, the cold more or less spent itself into bankruptcy across the western U.S. and will do little more than return temperatures to within the ballpark of normal. Meanwhile we have a storm system in the southern half of the U.S. which is spinning eastward and bringing rain to the 2010 snowbelt (Washington D.C.). This storm will grab Atlantic moisture as it moves northeast and spill it on much of Vermont and interior New England. Temperature profiles reveal a relatively warm lower 6000 feet of the troposphere and I would expect nothing more than rain below 2,500 feet. The rain will begin rather lightly on Monday but gain intensity by early Tuesday and should fall moderately and occasionally heavy through much of the morning. Above 2,500 feet we could see some snow mix in but temperatures should remain slightly above freezing so it will be a wet day for sure. As the storm continues to gain intensity and pull away to the northeast, colder weather will allow for more snow at the summits and for rain to change to snow at the base. This could lead to a few inches by Wednesday but the accumulations will be very wet at the base with only the summits having any chance for real powder. This is another storm which could have been a real winner for MRG but this winter has produced a litany of events where at least one puzzle piece always goes missing. In this case we have the moisture and we have a relatively favorable track but have little cold air. The event could bring 1-2 inches of rain to much of the Green Mountain spine which will damage the remaining bases to a degree but should not eliminate them entirely, particularly across the summits.
Snow showers and flurries will continue most of Wednesday and into Thursday although temperatures at the base should remain above freezing for the most part and any precipitation could be rain in the valleys. Late on Thursday, we should see a fairly good "punch" of cold air make a push into New England. This could bring a burst of snow to the mountain and finally bring temperatures universally below freezing on Friday. We will be watching a more organized storm system by the weekend but I don't think its impacts (rain or snow) will be felt until later on Sunday leaving the weekend free of any big precipitation. Temperatures will rebound to above freezing levels during the day and 20 degree readings at night.
The storm mentioned above does have some cold air as an ally but it track is a question mark and thus so is the precipitation type. At the very least we should see some terrain induced powder in the wake of whatever does evolve. It will mark a 3-4 day stretch of relative cold but it won't last as ridging in the central Pacific will again shift the storminess into the Western United States. It will thus likely be a rather mild end of March and early April and should set the region up for more spring conditions on whatever snow remains.
Sunday, March 14, 2010
Quiet weather to encompass region in the wake of the departing storm
Consistent with March traditions the weather has gone from very quiet to very stormy and will again go back to quiet. It has been a weekend of wind swept gails which have not only impacted many east coast locations but also the beloved single chair at MRG which is ashame but it yet again proves nothing is as effective at closing the single as the wicked east wind.
The duration of this storm will feature snow at high elevations and rain in valley locations. With little available cold air this is a system that is ever so sensitive to elevation and the threshold elevation for snow as opposed to rain will lower late Sunday into early Monday. This will allow the mountain to pick up a few inches of snow although the "powdery" stuff will be confined to the upper half of the mountain. All precipitation will be over with by the middle of the morning Monday and clouds may give way to a bit of sun. Monday should be the only real blustery day but temperatures should still creep above the freezing mark across most of the mountain.
The only disturbance of note for the upcoming week will pass well to our south west and this will set the state for a dry and "quiet" week as I mentioned above. Temperatures will climb to above freezing levels every day of the week and in most cases get well into the 40's. We should see an additional surge in temperatures Friday afternoon setting the stage for a very mild and spring-like weekend on the 20the and 21st of March. The push of warmth is a direct result of surge of upper level energy which will dive into the eastern Rockies late in the week. A weather producing system will develop as a result of all this along with an accopanying push of colder weather. Until this system reaches MRG, it will remain mild and the storm is not expected to impact Vermont until early in the week of March 22nd.
The NAO will remain negative but the effect of this teleconnection will be mitigated by blocing across western Alaska. This will allow cold and unsettled weather to focus itself in the Rockies while cold an unsettled weather although not totally absent from Vermont will transition through the region only to give way to milder temperatures. This is more or less what I expect March 22nd and beyond. Rain followed by some colder weather and perhaps a bit of snow followed again by a quick return to milder weather. I don't think unsettled weather of any sort will "persist" across the region until very late in the month or in April.
The duration of this storm will feature snow at high elevations and rain in valley locations. With little available cold air this is a system that is ever so sensitive to elevation and the threshold elevation for snow as opposed to rain will lower late Sunday into early Monday. This will allow the mountain to pick up a few inches of snow although the "powdery" stuff will be confined to the upper half of the mountain. All precipitation will be over with by the middle of the morning Monday and clouds may give way to a bit of sun. Monday should be the only real blustery day but temperatures should still creep above the freezing mark across most of the mountain.
The only disturbance of note for the upcoming week will pass well to our south west and this will set the state for a dry and "quiet" week as I mentioned above. Temperatures will climb to above freezing levels every day of the week and in most cases get well into the 40's. We should see an additional surge in temperatures Friday afternoon setting the stage for a very mild and spring-like weekend on the 20the and 21st of March. The push of warmth is a direct result of surge of upper level energy which will dive into the eastern Rockies late in the week. A weather producing system will develop as a result of all this along with an accopanying push of colder weather. Until this system reaches MRG, it will remain mild and the storm is not expected to impact Vermont until early in the week of March 22nd.
The NAO will remain negative but the effect of this teleconnection will be mitigated by blocing across western Alaska. This will allow cold and unsettled weather to focus itself in the Rockies while cold an unsettled weather although not totally absent from Vermont will transition through the region only to give way to milder temperatures. This is more or less what I expect March 22nd and beyond. Rain followed by some colder weather and perhaps a bit of snow followed again by a quick return to milder weather. I don't think unsettled weather of any sort will "persist" across the region until very late in the month or in April.
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