As expected, heavy precipitation is advancing northeast as below freezing temperatures gradually get scoured out of most of Vermont. Forecast atmospheric cross sections through the day Tuesday reveal that temperatures will simply be too warm to support snow in most locations and instead will see rain with some occasional sleet mixed in. The above freezing layer will hover close to the surface and should extend up between 3,000 and 5000 feet. This means that some of the high summits could still see some wet snow through the day tomorrow but even in these elevated locations, temperatures could challenge or exceed the freezing mark. Precipitation will become less intense and more sporadic Tuesday evening and night but also turn to snow as temperatures slowly move back toward the freezing mark.
I'll have a more complete update Tuesday evening but there is another intense storm late this week that is destined to impact the region. This system will amplify across the Midwest and over-amplify thus allowing a destructive swath of very warm temperatures to advance deep into New England Thursday night into early Friday. Unless there are some miraculous 11th hour changes regarding this system, the mountain is getting a period of rain, perhaps even a short period of heavy rain and thunderstorms. This is a powerful system that could very well bring blizzard conditions to portions of the Upper Midwest. The silver lining with this storm involves what is expected to be an eventual stalling this weekend over the Canadian Maritimes after the occlusion occurs. This sets the stage for several days of snow showers capable of yielding accumulations over a multi-day period
Monday, December 17, 2012
Saturday, December 15, 2012
Lots of storminess, lots of precipitation types
As they like to say, let the games begin !!! In what should be one of the more active weeks of weather this calendar year, the region will see a bit of everything. The news is not all good but there is certainly plenty of news and after what should be a true roller coaster ride of weather conditions through Christmas Eve, the mountain should be much closer to an opening.
As of Saturday afternoon, there were not too many places in the U.S. that were seeing below-freezing temperatures but interior New England was one of those places. The culprit was a decaying but at one time quite intense piece of Arctic air centered over Quebec. The cold, dry airmass slipped into the region just ahead of the first round of precipitation expected to arrive in the form of snow during the middle of the day Sunday. I know the weather forecasts for Sunday have been all over the map and even as of now, models have yet to agree completely on a precipitation type through Sunday night. Various forecast sources seemed to have formed a consensus (that I agree with) calling for a period of snow through Sunday night. The snowfall intensity will be mainly in the light to occasionally moderate range allowing for snowfall totals to to be in the modest 2-5 inch range. With temperatures only a few degrees away from the freezing mark, snowfall will generally be wet.
4 days ago, we discussed a second and more vigorous piece of upper air energy which will act as a potent steroid (for lack of a better word) in this whole weather situation. The upper air support, described in the meteorology community as a "shortwave", will commence its impact early Tuesday. Prior to this, the loosely entrenched area of cold weather over New England will continue battling it out with a push of milder weather from the south. The result will be the periodic continuation of either mixed precipitation or snow depending on what package of model guidance you believe. For the most part however, temperatures should stay at or below freezing in spite of whatever precipation falls Monday. This vigorous injection of upper air support will unfortunately begin to tilt the scale of this cold vs warm battle in the wrong direction. This is a situation I discussed somewhat in the previous update. As exciting as some of these amplifications look in a medium range model, and as much upside potential in terms of snowfall they can bring, the lack of a reliable supply of cold air can lead to some lousy results, especially early in the season. In this case, we will see an exploding area of precipitation Tuesday probably get wasted as cold air slowly gets scoured out of northern Vermont allowing for a period of rain Tuesday. This remains a tenuous situation and a few slight changes in the evolution of Tuesday's system could yield a different result. The storms amplification will ultimately allow colder temperatures and some snow to return for Wednesday although temperatures will remain near to just below the freezing mark through Wednesday and into Thursday.
When it comes to weather, it seems everything comes in streaks. It is largely analogous to a baseball player who has hitting slumps and periods when he hits lots home runs in a short period of time. The upcoming period can certainly be described this way. After the the snow, mixed precipitation and rain in the Sunday-Tuesday time frame, another even feistier weather system will move out of the Rockies and into the Plains and Midwest Wednesday into Thursday. This is yet another system capable of amplifying the jet stream in a profound way but do so with only limited cold air and probably do so too early. By Thursday evening, cities like Chicago north through much of Wisconsin could see near blizzard conditions if some of the medium range models are correct, but an amplification so far to the west allows warmer temperatures and rain to again threaten New England for a period beginning Thursday night or during the day Friday. Fortunately this situation is fluid and the ridging in eastern Canada will prevent this storm from tracking too far into the Canadian provinces before transferring some of its energy to the New England coast. This means that rain will turn to snow and snow showers and could persist through the weekend into Christmas Eve with some significant snowfall accumulations and colder temperatures. By the end of all the storminess, there should be a good amount of snow on the mountain and hopefully we have an opening day in our sights.
The end of 2012 should continue to feature temperatures that are in the above normal category but not excessively so. A few runs of the European ensembles have indicated a storm around the time of the 27th and 28th. That weather system is a long way off still but has promise at least as of now. The pattern as a whole should continue to be a ruled by a ridge in the west-central Pacific (near the dateline) and a ridge in eastern or central Canada. This is not the most ideal situation in the world but it is not totally adverse either. We have yet to see anything resembling an upper ridge in the western part of Canada which is necessary for a sustained outbreak of arctic cold and below normal temperatures.
As of Saturday afternoon, there were not too many places in the U.S. that were seeing below-freezing temperatures but interior New England was one of those places. The culprit was a decaying but at one time quite intense piece of Arctic air centered over Quebec. The cold, dry airmass slipped into the region just ahead of the first round of precipitation expected to arrive in the form of snow during the middle of the day Sunday. I know the weather forecasts for Sunday have been all over the map and even as of now, models have yet to agree completely on a precipitation type through Sunday night. Various forecast sources seemed to have formed a consensus (that I agree with) calling for a period of snow through Sunday night. The snowfall intensity will be mainly in the light to occasionally moderate range allowing for snowfall totals to to be in the modest 2-5 inch range. With temperatures only a few degrees away from the freezing mark, snowfall will generally be wet.
4 days ago, we discussed a second and more vigorous piece of upper air energy which will act as a potent steroid (for lack of a better word) in this whole weather situation. The upper air support, described in the meteorology community as a "shortwave", will commence its impact early Tuesday. Prior to this, the loosely entrenched area of cold weather over New England will continue battling it out with a push of milder weather from the south. The result will be the periodic continuation of either mixed precipitation or snow depending on what package of model guidance you believe. For the most part however, temperatures should stay at or below freezing in spite of whatever precipation falls Monday. This vigorous injection of upper air support will unfortunately begin to tilt the scale of this cold vs warm battle in the wrong direction. This is a situation I discussed somewhat in the previous update. As exciting as some of these amplifications look in a medium range model, and as much upside potential in terms of snowfall they can bring, the lack of a reliable supply of cold air can lead to some lousy results, especially early in the season. In this case, we will see an exploding area of precipitation Tuesday probably get wasted as cold air slowly gets scoured out of northern Vermont allowing for a period of rain Tuesday. This remains a tenuous situation and a few slight changes in the evolution of Tuesday's system could yield a different result. The storms amplification will ultimately allow colder temperatures and some snow to return for Wednesday although temperatures will remain near to just below the freezing mark through Wednesday and into Thursday.
When it comes to weather, it seems everything comes in streaks. It is largely analogous to a baseball player who has hitting slumps and periods when he hits lots home runs in a short period of time. The upcoming period can certainly be described this way. After the the snow, mixed precipitation and rain in the Sunday-Tuesday time frame, another even feistier weather system will move out of the Rockies and into the Plains and Midwest Wednesday into Thursday. This is yet another system capable of amplifying the jet stream in a profound way but do so with only limited cold air and probably do so too early. By Thursday evening, cities like Chicago north through much of Wisconsin could see near blizzard conditions if some of the medium range models are correct, but an amplification so far to the west allows warmer temperatures and rain to again threaten New England for a period beginning Thursday night or during the day Friday. Fortunately this situation is fluid and the ridging in eastern Canada will prevent this storm from tracking too far into the Canadian provinces before transferring some of its energy to the New England coast. This means that rain will turn to snow and snow showers and could persist through the weekend into Christmas Eve with some significant snowfall accumulations and colder temperatures. By the end of all the storminess, there should be a good amount of snow on the mountain and hopefully we have an opening day in our sights.
The end of 2012 should continue to feature temperatures that are in the above normal category but not excessively so. A few runs of the European ensembles have indicated a storm around the time of the 27th and 28th. That weather system is a long way off still but has promise at least as of now. The pattern as a whole should continue to be a ruled by a ridge in the west-central Pacific (near the dateline) and a ridge in eastern or central Canada. This is not the most ideal situation in the world but it is not totally adverse either. We have yet to see anything resembling an upper ridge in the western part of Canada which is necessary for a sustained outbreak of arctic cold and below normal temperatures.
Tuesday, December 11, 2012
Winter storm speculation begins
Exciting times have finally arrived making the colder weather feel that much more invigorating. Finally, we have storms (plural) to discuss and real winter weather to talk about. Lets also preface some of the details by saying that it is especially nice to see a succession model guidance cycles trend colder and snowier as opposed to what dominated last years SCWB headlines - warmer and rainier or just warmer and warmer.
Over the next five days there will be two important big picture developments. The first and I will say critical, is the westward progression of the "evil empire" in the Pacific. This large and destructive ridge will move west toward the date line and will allow the onslaught of storminess to shift south. The second is the westward movement and enhancement of a large upper ridge, almost a block, across eastern Quebec, Newfoundland and Labrador. Although this combination doesn't necessarily encourage widespread very cold weather, it does promote an active and southern storm track capable of producing moist systems which can ultimately get trapped along the New England coast or in the Canadian Maritimes. This is precisely what we can expect with the weather as we head toward next week. We still have significant concerns regarding the amount of available cold air but we are headed in the right direction and lets hope this continues.
This is a one-two punch scenario with the first system tracking through the plains and Midwest this weekend as cold air across Canada weakens with the remaining chunk settling over Quebec. The building ridge over eastern Canada will allow this lingering cold to ooze south ahead of the approaching initial weather system and it looks for now that potential precipitation should begin as snow Sunday evening the 16th. With several days still remaining before the start of this potential weather situation, a lot can still change, but there are good indications of a healthy moist conveyor with this initial system that could allow for an extended period of light to moderate snows into Monday. Such a scenario would certainly mean the first real significant accumulation of snow for the winter were it to hold.
The second part of the one-two punch is a much more dynamic system and could involve a large east coast amplification Tuesday into Wednesday (18th-19th). I consider this type of system a high risk/high reward event at this point because the potential, given an absolute ideal situation is for a massive snowfall. The risk however is that when such a powerful amplification occurs, with minimal cold air, so close to the warm Atlantic, there is little resistance to the eventual envelopment of warm air and a transition to rain. For now, I will be happy to see this first system evolve in the way it is forecast to evolve right now and hope the powerful ridge in eastern Canada works to flatten out this second storm somewhat,
Aside from the potential over-amplification next week, there are fewer if any threats for warm weather going forward to Christmas. The pattern does not support below normal temperatures but for the most part, respectable temperatures through Christmas day consisting of generally below freezing temperatures, at least in the high country.
Over the next five days there will be two important big picture developments. The first and I will say critical, is the westward progression of the "evil empire" in the Pacific. This large and destructive ridge will move west toward the date line and will allow the onslaught of storminess to shift south. The second is the westward movement and enhancement of a large upper ridge, almost a block, across eastern Quebec, Newfoundland and Labrador. Although this combination doesn't necessarily encourage widespread very cold weather, it does promote an active and southern storm track capable of producing moist systems which can ultimately get trapped along the New England coast or in the Canadian Maritimes. This is precisely what we can expect with the weather as we head toward next week. We still have significant concerns regarding the amount of available cold air but we are headed in the right direction and lets hope this continues.
This is a one-two punch scenario with the first system tracking through the plains and Midwest this weekend as cold air across Canada weakens with the remaining chunk settling over Quebec. The building ridge over eastern Canada will allow this lingering cold to ooze south ahead of the approaching initial weather system and it looks for now that potential precipitation should begin as snow Sunday evening the 16th. With several days still remaining before the start of this potential weather situation, a lot can still change, but there are good indications of a healthy moist conveyor with this initial system that could allow for an extended period of light to moderate snows into Monday. Such a scenario would certainly mean the first real significant accumulation of snow for the winter were it to hold.
The second part of the one-two punch is a much more dynamic system and could involve a large east coast amplification Tuesday into Wednesday (18th-19th). I consider this type of system a high risk/high reward event at this point because the potential, given an absolute ideal situation is for a massive snowfall. The risk however is that when such a powerful amplification occurs, with minimal cold air, so close to the warm Atlantic, there is little resistance to the eventual envelopment of warm air and a transition to rain. For now, I will be happy to see this first system evolve in the way it is forecast to evolve right now and hope the powerful ridge in eastern Canada works to flatten out this second storm somewhat,
Aside from the potential over-amplification next week, there are fewer if any threats for warm weather going forward to Christmas. The pattern does not support below normal temperatures but for the most part, respectable temperatures through Christmas day consisting of generally below freezing temperatures, at least in the high country.
Monday, December 10, 2012
Another week of generally uninteresting weather but what about after ?
The sleet, freezing rain and rain will all be a memory as of Monday evening and this leaves us waiting and hoping for some good news before the holiday. Unfortunately it will not come from the "third wave" of low pressure, which will confine its impact to coastal communities Wednesday. We will see a few days of seasonable temperatures, generally below freezing but no major snowfall. Meanwhile, the cold weather will continue to intensify across Canada and act to freeze the Hudson Bay entirely within a few days - certainly a good development and the earliest freeze since 2007. The "evil empire" or the east-central Pacific Ocean upper ridge however will be the dominant player on our playing field and because of this, the bitterly cold arctic air will be forced more east rather than south and will have a difficult time being a major force in Vermont's weather over the next week.
As indicated in previous posts, another mild push of air will impact the region late in the week and into the weekend. The trend over the last few cycles of model runs has actually been a good one, lessening the intensity of the mild weather during the upcoming weekend and even hinting at a little pushback from colder air in eastern Canada. The concern however relates to the first in what should be a series of storm systems after December 16th. This first storm system is not likely to take a very favorable track and we might do best just hoping for a flatter, weaker storm that comes and goes with little notoriety. A stronger storm system, like the one the last European model is showing, is likely to bring another round of sleet, freezing rain and rain and perhaps a lot of it.
As we move beyond next weekend, it gets much more interesting. The "evil empire" shifts west allowing the jet stream in the eastern Pacific to weaken and the storm track as a whole to shift south. Meanwhile the ridge and potential block across Greenland should finally give us a long awaited assist. This feature should help to keep the NAO negative and keep things active and intriguing along the east coast. There are indications of at least two major storm systems between the 17th and Christmas Day and one or both could yield some significant snows, at least somewhere. There will be ongoing concern regarding the amount of available cold air by then. Much of what is so available now, will be scoured out of Canada by the 17th so we potentially could use some help in that department.
As indicated in previous posts, another mild push of air will impact the region late in the week and into the weekend. The trend over the last few cycles of model runs has actually been a good one, lessening the intensity of the mild weather during the upcoming weekend and even hinting at a little pushback from colder air in eastern Canada. The concern however relates to the first in what should be a series of storm systems after December 16th. This first storm system is not likely to take a very favorable track and we might do best just hoping for a flatter, weaker storm that comes and goes with little notoriety. A stronger storm system, like the one the last European model is showing, is likely to bring another round of sleet, freezing rain and rain and perhaps a lot of it.
As we move beyond next weekend, it gets much more interesting. The "evil empire" shifts west allowing the jet stream in the eastern Pacific to weaken and the storm track as a whole to shift south. Meanwhile the ridge and potential block across Greenland should finally give us a long awaited assist. This feature should help to keep the NAO negative and keep things active and intriguing along the east coast. There are indications of at least two major storm systems between the 17th and Christmas Day and one or both could yield some significant snows, at least somewhere. There will be ongoing concern regarding the amount of available cold air by then. Much of what is so available now, will be scoured out of Canada by the 17th so we potentially could use some help in that department.
Thursday, December 6, 2012
Storminess on the way, just not exactly how we would want it
Although not under the most ideal circumstances, there is some very active weather on the immediate horizon. The storminess will stem from what will be a highly amplified jet stream and all the ingredients that typically come with it like mild and moist air from the Gulf of Mexico and Arctic chill from Canada. I was almost expecting that a massive storm would be churned up out of all this; but were that to happen in this set up, it would suck very mild weather deep into interior New England. Instead of one big storm however. this massive baraclinic zone will produce not one, but two and quite possibly three separate storm systems. Cold air is in short supply but it's better than no supply.
The first and weakest of the series of potential weather systems arrives Saturday into a stale and deteriorating airmass. Precipitation will mostly occur early Saturday and will be in the form of rain with a few pockets of freezing rain. As completely useless as this weather system would seem, its passage will help allow some arctic air to jam its way into the Green and White Mountains in spite of a very adverse upper air weather pattern. The cold will arrive late Saturday and will be firmly in place on Sunday as the next system gathers strength in the Great Lakes and tracks toward the St Lawrence Valley. This track, unless it changes, will make it tough for any significant to snow fall when precipitation recommences Monday, but a period of mixed precipitation including a little snow is becoming likely. Ultimately, the mild push of air later Monday could prove to be too much and change all precipitation to rain but we could see some significant icing and if we are lucky, a nice base layer of concrete to build on. I had mentioned the possibility of a third wave in this series. Such a storm would be more of a snow producer Tuesday into Wednesday. Most of the model guidance has downplayed this possibility but the most recent run of the Euro showed some support for this.
Ensembles continue to show hints of another warm up beginning around the 13th of the month and persisting for a few days. The constant pushes of warmth still stem from Pacific ridge or the "evil empire" as we have been calling it. This ridge will migrate westward and set up an interesting dichotomy as we proceed toward Christmas with the PNA and NAO contradicting each other. With the Pacific ridge out of play however, the door will open for Arctic air to make its way into the northern part of the country and for the storm track to get pushed well to the south. In the end, some very positive developments should result. Stay tuned.
The first and weakest of the series of potential weather systems arrives Saturday into a stale and deteriorating airmass. Precipitation will mostly occur early Saturday and will be in the form of rain with a few pockets of freezing rain. As completely useless as this weather system would seem, its passage will help allow some arctic air to jam its way into the Green and White Mountains in spite of a very adverse upper air weather pattern. The cold will arrive late Saturday and will be firmly in place on Sunday as the next system gathers strength in the Great Lakes and tracks toward the St Lawrence Valley. This track, unless it changes, will make it tough for any significant to snow fall when precipitation recommences Monday, but a period of mixed precipitation including a little snow is becoming likely. Ultimately, the mild push of air later Monday could prove to be too much and change all precipitation to rain but we could see some significant icing and if we are lucky, a nice base layer of concrete to build on. I had mentioned the possibility of a third wave in this series. Such a storm would be more of a snow producer Tuesday into Wednesday. Most of the model guidance has downplayed this possibility but the most recent run of the Euro showed some support for this.
Ensembles continue to show hints of another warm up beginning around the 13th of the month and persisting for a few days. The constant pushes of warmth still stem from Pacific ridge or the "evil empire" as we have been calling it. This ridge will migrate westward and set up an interesting dichotomy as we proceed toward Christmas with the PNA and NAO contradicting each other. With the Pacific ridge out of play however, the door will open for Arctic air to make its way into the northern part of the country and for the storm track to get pushed well to the south. In the end, some very positive developments should result. Stay tuned.
Tuesday, December 4, 2012
Weather to remain on the milder side through mid-December
I do not have the news most were looking for 3 weeks before Christmas. The dominant chess piece through mid-December will indeed be the upper air ridge in the mid-latitude Pacific. This will make life very difficult for those of us hoping for some good early skiing this December. I had hoped that other pieces on the chess board might mitigate the pain but we will instead be forced to deal with a few rounds of milder weather, rain and a minimal build-up of snow through the next 10-12 days. This is not to say that wintry weather is completely out of the picture through this period. The storm I had alluded to in the previous post could still provide a bit of that Monday, but that is a best case scenario at this point.
Temperatures should get a little closer to seasonable levels late this week but only for about 36-48 hours. Thereafter, another surge of milder temperatures is expected as the pattern turns more meridional. This essentially means that colder weather advances south across the western half country while the milder weather pushes north across the eastern United States. There will be a rather intense clash of airmasses in between which sets the stage for some very active weather across the Midwest this weekend into early next week. Interior New England could also be a part of this clash if we can get a little push-back from the building cold across Canada. This is a big "if" right now however and I would expect more in the way of rain or perhaps some freezing rain Saturday from the first wave of low pressure. The second wave brings precipitation late Sunday or Monday and could have a bit more cold air to work with but only in a very limited variety. Snow or mixed precipitation is a bit more likely in this period but the models have been trending toward this warmer scenario I have been detailing and we would need to reverse this soon if we were to get any love from this.
Temperatures will turn colder for a brief time during the middle of next week but the pattern will fail to break down. In fact, a vigorous disturbance over the Yukon will drop south and re-invigorate the trough over the western states. This is one of those really unwanted byproducts of what we should refer to as the "evil empire" or the mid-latitude Pacific upper ridge. As a result, we should see another round of milder temperatures between the 13th-16th of the month. After that, there is some evidence that the "evil empire" will migrate northwestward allowing the Pacific Jet to loosen somewhat. There is even some evidence of some splitting in the flow and would thus make it considerably more interesting right around the time of the holiday.
Sorry about the crap news. It is very east to lose heart especially after a year like 2011-2012 but it's very early and there are plenty of reasons to remain optimistic. If we get another 10 days of lousy weather we might as well get it now because it can be much more disruptive once the season begins.
Temperatures should get a little closer to seasonable levels late this week but only for about 36-48 hours. Thereafter, another surge of milder temperatures is expected as the pattern turns more meridional. This essentially means that colder weather advances south across the western half country while the milder weather pushes north across the eastern United States. There will be a rather intense clash of airmasses in between which sets the stage for some very active weather across the Midwest this weekend into early next week. Interior New England could also be a part of this clash if we can get a little push-back from the building cold across Canada. This is a big "if" right now however and I would expect more in the way of rain or perhaps some freezing rain Saturday from the first wave of low pressure. The second wave brings precipitation late Sunday or Monday and could have a bit more cold air to work with but only in a very limited variety. Snow or mixed precipitation is a bit more likely in this period but the models have been trending toward this warmer scenario I have been detailing and we would need to reverse this soon if we were to get any love from this.
Temperatures will turn colder for a brief time during the middle of next week but the pattern will fail to break down. In fact, a vigorous disturbance over the Yukon will drop south and re-invigorate the trough over the western states. This is one of those really unwanted byproducts of what we should refer to as the "evil empire" or the mid-latitude Pacific upper ridge. As a result, we should see another round of milder temperatures between the 13th-16th of the month. After that, there is some evidence that the "evil empire" will migrate northwestward allowing the Pacific Jet to loosen somewhat. There is even some evidence of some splitting in the flow and would thus make it considerably more interesting right around the time of the holiday.
Sorry about the crap news. It is very east to lose heart especially after a year like 2011-2012 but it's very early and there are plenty of reasons to remain optimistic. If we get another 10 days of lousy weather we might as well get it now because it can be much more disruptive once the season begins.
Saturday, December 1, 2012
Competing forces battle for control of Vermont's weather after the eary month thaw
After a nibble of the white stuff and a bigger taste of some single digit temperatures, the mountain will be forced to endure a significant stretch of above freezing temperatures and some rain. All of this has been in the cards for some time so there is nothing too surprising or alarming. All of the big questions and potential concerns relate to the period beyond Thursday. There are reasons to be optimistic but there are also reasons to be nervous. The weather pattern confronting the region involves many competing variables and which ever one wins the day will largely determine whether or not the mountain can be set up with an early opening.
It's not worth spending significant amounts of time on what amounts to a meaningless thaw. Temperatures should surge into the 50's Tuesday and the combination of mild weather and rain Tuesday night should essentially wipe out most of the snow below 3,000 feet.
More seasonable temperatures and even a bit of terrain-induced snow should prevail later in the week which is where much of the uncertainty exists in our forecast timeline. As mentioned there are competing features on our playing field. The big concern, at least from my vantage point, is that the medium range ensembles are showing the return of the dreaded upper ridge in the east-central Pacific. My personal loathing for this feature has been on full display for well over a year now and my reaction is a mix of both dismay and skepticism. The preseason prognostication mentioned that the ridging in the mid-latitude Pacific has really not been an issue this fall and the disappearance of La Nina certainly discourages its development this year, at least for an extended period of time. Yes, it still could prove to be another tease, but we have to be honest, such a feature works to tighten the jet in the pacific, encourage zonal flow, and all but eliminate the ability of cold air to sustain its coverage of mid-latitude geography over the eastern United States.
There is a brighter side of this possibility spectrum so I hope I have not completely killed the mood. The hemispheric picture consists of much more than a east-central Pacific ridge. In fact, there is clear evidence of ridging in the Jet Stream extending from the Aleutian Islands northward over the north pole and southward to Greenland and the Davis Strait. Essentially, the ridging forms a ring-around-the-rosie encompassing an area of very cold air across Alaska and western and central Canada. The cold has allowed for a rapid expansion of snow and ice across North America as a whole and most importantly for us, the Hudson Bay. Look at the coverage of ice on the Hudson Bay this year compared to the last 5.
2012 - http://www.natice.noaa.gov/pub/ims/ims_gif/ARCHIVE/AK/2012/ims2012335_alaska.gif
2011 - http://www.natice.noaa.gov/pub/ims/ims_gif/ARCHIVE/AK/2011/ims2011335_alaska.gif
2010 - http://www.natice.noaa.gov/pub/ims/ims_gif/ARCHIVE/AK/2010/ims2010335_alaska.gif
2009 - http://www.natice.noaa.gov/pub/ims/ims_gif/ARCHIVE/AK/2009/ims2009335_alaska.gif
2008 - http://www.natice.noaa.gov/pub/ims/ims_gif/ARCHIVE/AK/2008/ims2008335_alaska.gif
The freezing of this large body of water, and freezing it early is monumental in getting a good build up of cold over eastern Canada so it ultimately can become an asset in our crucial winter weather scenarios.
Cold weather across Canada is not the only reason to be optimistic. The two major ensemble packages largely disagree with one another on how this all plays out by next weekend. The American GFS package depicts a scenario that hinges on the aforementioned Pacific feature. Two additional and significant surges of milder weather are likely in such a pattern which would be dominated by a negative PNA and more minimal high-latitude blocking. The European package paints a much more optimistic evolution which would have cold weather returning by the end of next weekend and remaining in place for an extended period there after. This set-up hinges more on what is indicated to be a negative AO and a broader extended reach of the bitter chill across Canada. Most interestingly, the European also depicts the potential for our first major snow producer around the 10th of the month. We have not seen evidence of such a storm until today we would love to see it.
I thought it was interesting to see how similar this year is matching 1984-1985. November of 1984 was a touch below normal on the east coast (same as this year) but more significantly below across western Canada, much like this year. The December that followed featured cold weather across the U.S. and mild weather covering much of the east coast, much like the GFS ensemble depicts. The ensuing January was then bitterly cold featuring the coldest Presidential Inauguration ever recorded when Ronald Reagan was sworn in for his second term. I am closely watching how this plays out, and whether we continue to follow the 1984 scenario in accordance with the American ensemble or whether we diverge like the European suggests.
It's not worth spending significant amounts of time on what amounts to a meaningless thaw. Temperatures should surge into the 50's Tuesday and the combination of mild weather and rain Tuesday night should essentially wipe out most of the snow below 3,000 feet.
More seasonable temperatures and even a bit of terrain-induced snow should prevail later in the week which is where much of the uncertainty exists in our forecast timeline. As mentioned there are competing features on our playing field. The big concern, at least from my vantage point, is that the medium range ensembles are showing the return of the dreaded upper ridge in the east-central Pacific. My personal loathing for this feature has been on full display for well over a year now and my reaction is a mix of both dismay and skepticism. The preseason prognostication mentioned that the ridging in the mid-latitude Pacific has really not been an issue this fall and the disappearance of La Nina certainly discourages its development this year, at least for an extended period of time. Yes, it still could prove to be another tease, but we have to be honest, such a feature works to tighten the jet in the pacific, encourage zonal flow, and all but eliminate the ability of cold air to sustain its coverage of mid-latitude geography over the eastern United States.
There is a brighter side of this possibility spectrum so I hope I have not completely killed the mood. The hemispheric picture consists of much more than a east-central Pacific ridge. In fact, there is clear evidence of ridging in the Jet Stream extending from the Aleutian Islands northward over the north pole and southward to Greenland and the Davis Strait. Essentially, the ridging forms a ring-around-the-rosie encompassing an area of very cold air across Alaska and western and central Canada. The cold has allowed for a rapid expansion of snow and ice across North America as a whole and most importantly for us, the Hudson Bay. Look at the coverage of ice on the Hudson Bay this year compared to the last 5.
2012 - http://www.natice.noaa.gov/pub/ims/ims_gif/ARCHIVE/AK/2012/ims2012335_alaska.gif
2011 - http://www.natice.noaa.gov/pub/ims/ims_gif/ARCHIVE/AK/2011/ims2011335_alaska.gif
2010 - http://www.natice.noaa.gov/pub/ims/ims_gif/ARCHIVE/AK/2010/ims2010335_alaska.gif
2009 - http://www.natice.noaa.gov/pub/ims/ims_gif/ARCHIVE/AK/2009/ims2009335_alaska.gif
2008 - http://www.natice.noaa.gov/pub/ims/ims_gif/ARCHIVE/AK/2008/ims2008335_alaska.gif
The freezing of this large body of water, and freezing it early is monumental in getting a good build up of cold over eastern Canada so it ultimately can become an asset in our crucial winter weather scenarios.
Cold weather across Canada is not the only reason to be optimistic. The two major ensemble packages largely disagree with one another on how this all plays out by next weekend. The American GFS package depicts a scenario that hinges on the aforementioned Pacific feature. Two additional and significant surges of milder weather are likely in such a pattern which would be dominated by a negative PNA and more minimal high-latitude blocking. The European package paints a much more optimistic evolution which would have cold weather returning by the end of next weekend and remaining in place for an extended period there after. This set-up hinges more on what is indicated to be a negative AO and a broader extended reach of the bitter chill across Canada. Most interestingly, the European also depicts the potential for our first major snow producer around the 10th of the month. We have not seen evidence of such a storm until today we would love to see it.
I thought it was interesting to see how similar this year is matching 1984-1985. November of 1984 was a touch below normal on the east coast (same as this year) but more significantly below across western Canada, much like this year. The December that followed featured cold weather across the U.S. and mild weather covering much of the east coast, much like the GFS ensemble depicts. The ensuing January was then bitterly cold featuring the coldest Presidential Inauguration ever recorded when Ronald Reagan was sworn in for his second term. I am closely watching how this plays out, and whether we continue to follow the 1984 scenario in accordance with the American ensemble or whether we diverge like the European suggests.
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