No need to beat around the bush with a big storm bearing down the east coast. By now, I had hoped we would have reached some sort of decisiveness regarding this event but for now, it remains very much on the fence between a garden variety, easily forgotten weather system and a more memorable early December winter storm. The pieces are coming together as expected with the storm, as of Saturday, spinning its way through the upper Midwest. The emergence of a coastal low pressure center by Sunday evening will ultimately make this a big east coast precipitation producer but the track of this coastal system is expected to stay south of Long Island and south of Cape Cod, at least for the time being. This would keep the heaviest zone of snow south of the northern half of Vermont, especially since the well-established jet stream level support for this storm, otherwise referred to as an upper level low, is expected to move due east and take the east coast "escape hatch" out over the Delmarva. This feature is then expected to take a turn northeastward but it would be too late for the Mad River Valley to procure an epic snow event; instead, it would be a smaller event. It is very close however and between Friday afternoon and Saturday afternoon, models have been suggesting that the zone of best snow would be a little farther north. Southern Vermont is in fact in one of those "best zone" areas and if the storm would track another 50 miles farther north, it could really turn the outcome. So I can throw out some expectations as it stands now and simply throw it out there that things could certainly change for the better.
So with the big picture situation established the particulars are as follows. Snow should begin Sunday evening and fall moderately for a time before midnight. As the coastal low pressure center intensifies and assuming it tracks as predicted, the precipitation will consolidate over southern and central New England and the snow will dissipate somewhat over northern Vermont. By Monday morning, the zone of heaviest snow is expected to be situated over the Catskills, extreme NE Pennsylvania and eventually extending into southeast New Jersey. As both the surface and upper level features associated with this big east coast storm move northeast, the heavier snow will also push northeastward and again impact much of Vermont, especially the southern half of the state. Mad River Glen will get some of this as well with the heaviest snow falling Monday afternoon and evening. Total snowfall with this storm track is likely to be in the 8-16 inch territory. Snowfall totals could reach two feet over the high country of southern Vermont and certainly over the Catskills of New York state. The intensity of the storm will certainly allow for very blustery conditions through Tuesday.
Sub-freezing temperatures are expected to continue for the balance of the week but significant snow is unlikely. Flurries are expected to continue through Tuesday and weather disturbance passing to the region's south will spread some snow showers into the state Wednesday night and those will continue into Thursday. A more intense shot of arctic chill is expected to arrive Friday evening and with that could come some more light snow or snow showers through early Saturday.
The longer range outlook, beyond next weekend looks more mediocre as of now. The two most glaring things is the lack of high latitude blocking quantified by a rising AO index. The EPO, which for much of November remained largely negative and was defined by a loose Pacific Jet, will neutralize, allowing the Pacific jet to become more active. These two changes will limit the influence of arctic cold in mid-latitude North America. That said, there are no indications we are moving into full blown "el torchy" mode. I would expect 2-3 fairly mild days between December 8th and 18th which is not atypical in a Vermont December. The pattern also continues to look stormy and snowfall will thus remain a possibility in spite of a more zonal jet stream pattern.
Saturday, November 30, 2019
Tuesday, November 26, 2019
Upcoming week is very active and December 1st and 2nd looks especially interesting
With the seasonal outlook delivered, it is time to quickly shift gears and talk about what is an active looking week of weather even if it's not especially cold. We are about to finish the coldest November so far this century, colder even than last year's Snowvember. Much of the arctic air responsible for this very cold month has retreated an active jet stream is poised to deliver two major weather systems to the east coast, both of which are likely to be elevation sensitive but significant events - especially #2.
The storm responsible for over a foot of snow early Tuesday over portions of the Colorado front range will move northeast toward the eastern Great Lakes bringing a push of milder temperatures up the eastern seaboard. For a time, this milder air appeared also headed for Vermont but a re-aligning polar jet stream in Canada will help turn this storm eastward preventing the state from getting blow-torched. It will be warm enough for precipitation to begin as rain up and down many of the green mountains, even at the highest elevations but as we head toward the evening precipitation will begin changing to snow at the summits. During the overnight hours, we should see some snow even in the lower valleys while the ski areas receive 4-8 inches. Light snow should persist over the high country for a decent portion of Thanksgiving day as well with temperatures just below the freezing mark. This basically means that much of what falls Wednesday night into Thanksgiving Day will be pretty wet, except above at least 3000 feet.
A moderated polar air mass will build across the state late Thursday into Friday drying it out and providing a couple of days of sunshine both Friday and Saturday. Friday will be a bit on the blustery side, Saturday will be relatively calm. Both days should feature temperatures below the freezing mark throughout the day.
While the Thanksgiving event was a storm that originated in the southern Rockies, the storm poised to impact the east coast in the Dec 1-3 time frame is a powerful area of jet energy that will slowly migrate its way into California in the coming days, bringing heavy snow to a huge swath of heavy snow to a broad area of western ski country (both north and south) and proceed into the northern plains this upcoming weekend. Under many circumstances the storm would become a spent force while occluding across the north-central part of the country but the jet stream is poised to re-amplify across the east coast setting the east coast snowfall potential through the roof. The fresh supply of cold air is somewhat lacking, as it often is in early December, but the interior high country is positioned extremely well for a very big event given the right track. We've seen some good consistency from the European model the last several runs which makes me extremely optimistic. The Canadian model is also on board as of midday Tuesday but the American did shift the track of this storm pretty far south. In any case, the event remains 5-6 days off so we can't quite lock it in yet.
Normal early December temperatures will follow in the wake of this storm, whether we get the full impact or not. Some light snow is again possible later in that week.
Glancing toward the middle of December, the pattern does not appear arctic but not torchy either. A positive Arctic Oscillation is likely to keep wintry weather combined to Canada and the far northern latitudes of the US. Fortunately Vermont makes the cut there so wintry conditions remain possible through the 15th .
The storm responsible for over a foot of snow early Tuesday over portions of the Colorado front range will move northeast toward the eastern Great Lakes bringing a push of milder temperatures up the eastern seaboard. For a time, this milder air appeared also headed for Vermont but a re-aligning polar jet stream in Canada will help turn this storm eastward preventing the state from getting blow-torched. It will be warm enough for precipitation to begin as rain up and down many of the green mountains, even at the highest elevations but as we head toward the evening precipitation will begin changing to snow at the summits. During the overnight hours, we should see some snow even in the lower valleys while the ski areas receive 4-8 inches. Light snow should persist over the high country for a decent portion of Thanksgiving day as well with temperatures just below the freezing mark. This basically means that much of what falls Wednesday night into Thanksgiving Day will be pretty wet, except above at least 3000 feet.
A moderated polar air mass will build across the state late Thursday into Friday drying it out and providing a couple of days of sunshine both Friday and Saturday. Friday will be a bit on the blustery side, Saturday will be relatively calm. Both days should feature temperatures below the freezing mark throughout the day.
While the Thanksgiving event was a storm that originated in the southern Rockies, the storm poised to impact the east coast in the Dec 1-3 time frame is a powerful area of jet energy that will slowly migrate its way into California in the coming days, bringing heavy snow to a huge swath of heavy snow to a broad area of western ski country (both north and south) and proceed into the northern plains this upcoming weekend. Under many circumstances the storm would become a spent force while occluding across the north-central part of the country but the jet stream is poised to re-amplify across the east coast setting the east coast snowfall potential through the roof. The fresh supply of cold air is somewhat lacking, as it often is in early December, but the interior high country is positioned extremely well for a very big event given the right track. We've seen some good consistency from the European model the last several runs which makes me extremely optimistic. The Canadian model is also on board as of midday Tuesday but the American did shift the track of this storm pretty far south. In any case, the event remains 5-6 days off so we can't quite lock it in yet.
Normal early December temperatures will follow in the wake of this storm, whether we get the full impact or not. Some light snow is again possible later in that week.
Glancing toward the middle of December, the pattern does not appear arctic but not torchy either. A positive Arctic Oscillation is likely to keep wintry weather combined to Canada and the far northern latitudes of the US. Fortunately Vermont makes the cut there so wintry conditions remain possible through the 15th .
Monday, November 25, 2019
Can't really complain if we get more of the same ! Winter 2019-20 has many of the same 2018-19 characteristics
2019-2020 marks the 16th year of weather blogging for Mad River Glen, a sweet sixteen of sorts. Though I am proud of the duration, what is more remarkable is taking a step back to realize all the changes that have occurred relating to weather dissemination online. Back in 2004 it was a new thing, now it is a very "evolved" thing. Raw data is more readily available, model data has improved and become more readily available, many amateur weather fanatics have fined tune their skill sets and have become excellent resources (some have not but I like to keep it positive) and social media happened and it really became crazy. Yet our beloved weather blog stays mostly the same again, retaining its look and format much like Mad River Glen, a place that truly does skiing justice by staying true to its best traditions.
With all that said however, I am ready to take this whole thing off "blog.spot". If there are web development people that can help me do that, send me an email.
Another winter is upon us and yet another winter outlook leads the way. With that comes the usual disclaimer, proclaiming how utterly unreliable these long term outlooks are. I can actually claim to have graded out fairly decently on temperatures over the many years, but snowfall has been an up and down experience and I can promise that will continue. Adding to that disclaimer is the promise that if I truly find a reason to be pessimistic, it will be conveyed. Some sugarcoating can be expected because I like to keep conform to the optimistic prevailing tone of the blog but bad news is still important news and is always included on the blog, as uninvited as it certainly is.
ENSO/PDO
I am going to combine our yearly examination of ENSO (El Nino/La Nina) and Pacific Decadal Oscillation into one section this year. These two variables enjoy an imperfect relationship with each other, meaning that positive (El Nino) and negative (La Nina) ENSO events are usually associated with a PDO of a similar positive or negative sign. "Usually" however is not synomous with "always" and this appears to be one of those years, much like last year, where the signs will differ. Most importantly regarding El Nino, there were repeated (same as last year) fears that we were moving toward a more signifcant El Nino this autumn. Just like last year however, those fears have abated. SST's in those critical equatorial regions of the Pacific strengthened toward a moderate El Nino situation for a time but have weakened in recent weeks and forecasts going forward don't indicate that a big El Nino is unlikely. From our perspective that relagates ENSO to a more tertiary paramater in the equation though not a non-factor entirely.
Meanwhile the PDO, which appeared to be trending toward a positive phase earlier this year, has taken an autumnal plunge back into negative territory. The PDO describes the more general configuration of sea surface temperatures in the mid-latitude Pacific while ENSO refers to the region around the equator. Most interesting is the large red blob south of the Gulf of Alaska which appears to be the most dominant anomalous feature in the Pacific from a sea surface temperature standpoint.
So we have differing signs on the ENSO/PDO front, somewhat like what we had last year, which can be argued was one of the strongest Vermont ski seasons of the decade. When I saw this evolve, once again, it was my hope that I could glean a more clear cut cause and effect relationship from all this but saying that would be a reach. 1965-66, 1968-69, 1975-1976 and last year were all either very good or excellent snow years on the mountain. 1991-92 and 1994-95 were not. 4-2 isn't bad but not overwhelming. The large blog of SST warmth south of the Gulf of Alaska is probably the most disconcerting element of the outlook as a whole. It's stronger than the same feature last year and capable of tightening the Pacific Jet and limiting negative EPO episodes (such as the one we just experienced) and thus the amount of arctic air across mid-laititude North America. Later in the outlook, I will focus on a different but perhaps equally important SST feature that might counter that for the early part of the upcoming winter.
Land Area Snow Expansion
The expansion of snowcover has been very impressive once again in October across the northern latitudes. The arctic has made a lot of news, as well it should, for the dwindling amounts of sea ice that have been observed late in the summer or early in the autumn, and the impact that it's had on various, though sparsely populated climate zones. In this analysis, we are looking more specifically at land areas and how snowcover is differing from the near 50-year mean. So while sea ice continues to make news by continuing to melt away, the last 7 October's have featured a very strong expansion of snow cover, 3 of which, including this most recent October, have been over a full standard deviation above this 50 year mean of 18.51 millions of square KM. There are obvious limitations to a 50-year data set but the recent trends certainly begs the question of how might the expansion of open water in the arctic be impacting this data. I am no climatologist and would not pretend to be able to answer this question better than some, but at this point I have to guess that there is an impact. Keeping our proverbial eye on the ball however, the rapid expansion of snow cover this October is a positive as far as cold air "pooling efficiency" is concerned and would suggest that arctic air will be a powerful ally this winter, as it was for much of the winter last year, even when the overall jet stream pattern was not.
Chukchi Sea
From a bigger picture standpoint, the loss of sea ice is not in any way, a positive in the long term. It's hard to imagine the impact on our Nothern Hemisphere winter, as a whole if, 100 or so years from now, the arctic is struggling re-freeze as opposed the typical ritual of expanding to areas such as the Hudson Bay, the Bering Sea or the Baffin Bay. There can be little doubt we are headed in that direction. In the near term, it has been the Chukchi Sea which has raised some alarms this year because of the exceedingly slow rate of autumn ice expansion. Zack Labe is a terrific follow on twitter, handle -@Zlabe, for all things arctic sea ice. He and many others have been monitoring and reporting on the unprecented (in recorded history) sea ice situation in the Chukchi Sea which is a small subset of arctic water north of the Bering Straight but part of the larger Arctic Ocean. Though the loss of ice here underscores a larger overall (and not a good) trend regarding sea ice it has created a large area of warm ocean water in a key location. Can such a feature have an impact on the prevailing weather pattern by encouraging a high latitude jet stream block in such a location. If so, it would support some of the prevailing theories that exist regarding the effects of climate change in relation to redefining pathways of arctic cold and sustaining prevailing weather patterns for a longer duration than they might otherwise, both good and bad. I am not skeptical about the impacts of anomalous ocean water but I remain a little skeptical of statements such as the one I made above. I understand the logic certainly but would like to see more data.
I understand there is a lot of overly scientific hypothesizing in the above two paragraphs. From the standpoint of our winter outlook, the expansion of snow and ice is obviosly a good thing for our winter , the Chukchi Sea ice anomaly certainly could be a good thing for our upcoming winter and this would counter the other large area of warm water south of the Gulf of Alaska which I do not consider to be such a good thing.
Atmospheric "Tells"
In a final bit of analysis, I would like to stay true to more recent tradition and spend some time discussing possible atmospheric "tells" - the phrase of course borrowed from common poker lingo. There has been quite a bit of anomalous weather over the past few months across North America, particularly anomalous cold. In October, a large area of anomalous cold focused itself over western North America and represented one of the largest areas of colder than average temperatures across the entire globe. In November, this area shifted eastward thanks largely to a very negative EPO (weakened Pacific Jet). Much of the Great Lakes region, eastward to Vermont are in the midst of one of the coldest November's ever recorded. It will likely fall short of the coldest thanks to a milder final 10 days of the month but could still be in the top 5 or 10 cold Novembers. What I find to be especially noteworthy is the intensity of the recent cold outbreaks, particularly the ability to reach daily anomalies of 25 and even 30 degree below normal over mid-latitude sections of North America. This first happened in the Rocky Mountain region in October and more recently over the Great Lakes in November. If the atmosphere is capable of aligning once to produce such outcomes it indicates the potential for a repeat later in the year. Were it not for the negative PDO and specifically some of the SST anomalies in the Pacific associated with it, I would probably be willing to go "all in" (more poker lingo) on a Polar Vortex style 1976-77 or 2013-2014 winter.
Summary/Outlook 2019-20
If you're smart and skipped down to this paragraph, well done ! Our little collection of variables that typically contribute to the winter outlook look, largely, very much the same as they did at this time last year. El Nino is present but, at the more preferable subdued intensity. We had a very healthy expansion of hemispheric land-area snow. We've been able to exhibit the ability to produce both sustained and intense periods of cold even early this season and I might mention that this rather impressive outbreak of November cold has helped to cool both the Great Lakes aggregate and the immediate waters off the northeast coast. Very much like last year, the Pacific Decadal Oscillation will enter the winter season in negative territory which is unique during any kind of El Nino, even the weaker variety. The nature of this particular negative PDO is the one big concern because the most prevalent associated feature is the aforementioned warm blob south of the Gulf of Alaska. So while I think the upcoming winter will exhibit some similarities to the very exciting 2018-19 season, we will experience 1-2 extended bouts of adverse conditions lasting a couple of weeks. But although the PDO is a net-negative as far as being a force for sustaining cold, it will keep the storm track from going too far south. This will, again make interior New England one of the more favored locations for heavy snows, at least along the east coast. This means another year of what I think will be above average snowfall and I have a funny feeling that a healthy chunk of that snowfall comes in the upcoming month of December (we will just see about that) ! Temperatures last year during the ski months averaged 2-3 degrees below average and we managed to freeze Lake Champlain for the third time this decade. In spite of one of the coldest November's since at least 1996, I don't think the upcoming winter will feature those kind of temperatures. Instead, I would expect temperatures closer to normal overall which means we are unlikely to see the sustained blowtorch conditions that we saw during the Super Nino of 2015-16 or the snow-torch winter that followed in 2016-17. With that, let the blogging efforts begin for another season, I hope it's a good one for everyone.
With all that said however, I am ready to take this whole thing off "blog.spot". If there are web development people that can help me do that, send me an email.
Another winter is upon us and yet another winter outlook leads the way. With that comes the usual disclaimer, proclaiming how utterly unreliable these long term outlooks are. I can actually claim to have graded out fairly decently on temperatures over the many years, but snowfall has been an up and down experience and I can promise that will continue. Adding to that disclaimer is the promise that if I truly find a reason to be pessimistic, it will be conveyed. Some sugarcoating can be expected because I like to keep conform to the optimistic prevailing tone of the blog but bad news is still important news and is always included on the blog, as uninvited as it certainly is.
ENSO/PDO
I am going to combine our yearly examination of ENSO (El Nino/La Nina) and Pacific Decadal Oscillation into one section this year. These two variables enjoy an imperfect relationship with each other, meaning that positive (El Nino) and negative (La Nina) ENSO events are usually associated with a PDO of a similar positive or negative sign. "Usually" however is not synomous with "always" and this appears to be one of those years, much like last year, where the signs will differ. Most importantly regarding El Nino, there were repeated (same as last year) fears that we were moving toward a more signifcant El Nino this autumn. Just like last year however, those fears have abated. SST's in those critical equatorial regions of the Pacific strengthened toward a moderate El Nino situation for a time but have weakened in recent weeks and forecasts going forward don't indicate that a big El Nino is unlikely. From our perspective that relagates ENSO to a more tertiary paramater in the equation though not a non-factor entirely.
Meanwhile the PDO, which appeared to be trending toward a positive phase earlier this year, has taken an autumnal plunge back into negative territory. The PDO describes the more general configuration of sea surface temperatures in the mid-latitude Pacific while ENSO refers to the region around the equator. Most interesting is the large red blob south of the Gulf of Alaska which appears to be the most dominant anomalous feature in the Pacific from a sea surface temperature standpoint.
So we have differing signs on the ENSO/PDO front, somewhat like what we had last year, which can be argued was one of the strongest Vermont ski seasons of the decade. When I saw this evolve, once again, it was my hope that I could glean a more clear cut cause and effect relationship from all this but saying that would be a reach. 1965-66, 1968-69, 1975-1976 and last year were all either very good or excellent snow years on the mountain. 1991-92 and 1994-95 were not. 4-2 isn't bad but not overwhelming. The large blog of SST warmth south of the Gulf of Alaska is probably the most disconcerting element of the outlook as a whole. It's stronger than the same feature last year and capable of tightening the Pacific Jet and limiting negative EPO episodes (such as the one we just experienced) and thus the amount of arctic air across mid-laititude North America. Later in the outlook, I will focus on a different but perhaps equally important SST feature that might counter that for the early part of the upcoming winter.
Chukchi Sea
From a bigger picture standpoint, the loss of sea ice is not in any way, a positive in the long term. It's hard to imagine the impact on our Nothern Hemisphere winter, as a whole if, 100 or so years from now, the arctic is struggling re-freeze as opposed the typical ritual of expanding to areas such as the Hudson Bay, the Bering Sea or the Baffin Bay. There can be little doubt we are headed in that direction. In the near term, it has been the Chukchi Sea which has raised some alarms this year because of the exceedingly slow rate of autumn ice expansion. Zack Labe is a terrific follow on twitter, handle -@Zlabe, for all things arctic sea ice. He and many others have been monitoring and reporting on the unprecented (in recorded history) sea ice situation in the Chukchi Sea which is a small subset of arctic water north of the Bering Straight but part of the larger Arctic Ocean. Though the loss of ice here underscores a larger overall (and not a good) trend regarding sea ice it has created a large area of warm ocean water in a key location. Can such a feature have an impact on the prevailing weather pattern by encouraging a high latitude jet stream block in such a location. If so, it would support some of the prevailing theories that exist regarding the effects of climate change in relation to redefining pathways of arctic cold and sustaining prevailing weather patterns for a longer duration than they might otherwise, both good and bad. I am not skeptical about the impacts of anomalous ocean water but I remain a little skeptical of statements such as the one I made above. I understand the logic certainly but would like to see more data.
I understand there is a lot of overly scientific hypothesizing in the above two paragraphs. From the standpoint of our winter outlook, the expansion of snow and ice is obviosly a good thing for our winter , the Chukchi Sea ice anomaly certainly could be a good thing for our upcoming winter and this would counter the other large area of warm water south of the Gulf of Alaska which I do not consider to be such a good thing.
Atmospheric "Tells"
In a final bit of analysis, I would like to stay true to more recent tradition and spend some time discussing possible atmospheric "tells" - the phrase of course borrowed from common poker lingo. There has been quite a bit of anomalous weather over the past few months across North America, particularly anomalous cold. In October, a large area of anomalous cold focused itself over western North America and represented one of the largest areas of colder than average temperatures across the entire globe. In November, this area shifted eastward thanks largely to a very negative EPO (weakened Pacific Jet). Much of the Great Lakes region, eastward to Vermont are in the midst of one of the coldest November's ever recorded. It will likely fall short of the coldest thanks to a milder final 10 days of the month but could still be in the top 5 or 10 cold Novembers. What I find to be especially noteworthy is the intensity of the recent cold outbreaks, particularly the ability to reach daily anomalies of 25 and even 30 degree below normal over mid-latitude sections of North America. This first happened in the Rocky Mountain region in October and more recently over the Great Lakes in November. If the atmosphere is capable of aligning once to produce such outcomes it indicates the potential for a repeat later in the year. Were it not for the negative PDO and specifically some of the SST anomalies in the Pacific associated with it, I would probably be willing to go "all in" (more poker lingo) on a Polar Vortex style 1976-77 or 2013-2014 winter.
Summary/Outlook 2019-20
If you're smart and skipped down to this paragraph, well done ! Our little collection of variables that typically contribute to the winter outlook look, largely, very much the same as they did at this time last year. El Nino is present but, at the more preferable subdued intensity. We had a very healthy expansion of hemispheric land-area snow. We've been able to exhibit the ability to produce both sustained and intense periods of cold even early this season and I might mention that this rather impressive outbreak of November cold has helped to cool both the Great Lakes aggregate and the immediate waters off the northeast coast. Very much like last year, the Pacific Decadal Oscillation will enter the winter season in negative territory which is unique during any kind of El Nino, even the weaker variety. The nature of this particular negative PDO is the one big concern because the most prevalent associated feature is the aforementioned warm blob south of the Gulf of Alaska. So while I think the upcoming winter will exhibit some similarities to the very exciting 2018-19 season, we will experience 1-2 extended bouts of adverse conditions lasting a couple of weeks. But although the PDO is a net-negative as far as being a force for sustaining cold, it will keep the storm track from going too far south. This will, again make interior New England one of the more favored locations for heavy snows, at least along the east coast. This means another year of what I think will be above average snowfall and I have a funny feeling that a healthy chunk of that snowfall comes in the upcoming month of December (we will just see about that) ! Temperatures last year during the ski months averaged 2-3 degrees below average and we managed to freeze Lake Champlain for the third time this decade. In spite of one of the coldest November's since at least 1996, I don't think the upcoming winter will feature those kind of temperatures. Instead, I would expect temperatures closer to normal overall which means we are unlikely to see the sustained blowtorch conditions that we saw during the Super Nino of 2015-16 or the snow-torch winter that followed in 2016-17. With that, let the blogging efforts begin for another season, I hope it's a good one for everyone.
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