Think Snow, Tweet Snow !!!

Tuesday, January 30, 2007

New snow for the weekend more cold for next week

The contents of the last post included a prognostication of what the contents of this post would be; specifically, talk of significant new snow in the days ahead. Indeed there is much to talk about in that regard. The recent cold weather has moved January of '07 well ahead of January '06 in terms of skiing quality but new snow remains in high demand. Using the Mt Mansfield snow depth graph as a reference (since it is readily available on the web at http://www.uvm.edu/skivt-l/?Page=depths.php ) there is certainly evidence of significant gains during the last two weeks, but we remain over a foot below average and in a pattern like this I would certainly like to make up that ground and then some. Today's update is going to get lengthy with all of the goings ons since new snow will come at us in varying forms and varying times. There is also more very cold weather on the horizon which is poised to impact the western High Plains then Midwest and deep south perhaps in record breaking fashion. It will take a bit longer but this cold will eventually push into northern New England early next week.

Tuesday/Wednesday
Short term details could really bog us down on a day like this but to summarize, we will have to accept a wide-right on Tuesday's alberta clipper system which should bring a few inches to southern New England. A much weaker disturbance will bring light amounts of new snow to the northern Greens later Wednesday yielding the possibility of a few inches of the fresh stuff by Thursday morning.

Friday's Winter Storm
So this is how the board will get set on Thursday. The massive western ridge positioned near the B.C. coast which was hyped in the last post because of its amplitude will trigger a massive intrusion of arctic air which will make U.S. entry in Montana. Meanwhile, a southern branch system gathers moisture and awaits Polar Jet interaction. The result is alot of speculation, banter and all-out debate amongst eastern U.S. snow enthusiasts over what may go down late this week. The southern feature has a head start and indications are that it will move way out ahead of the arctic push and allow a storm to gather in force over dixie. What is more critical however is that the southern branch will ultimately get flattened by the strength of the pattern or the magnitude of the polar jet. My flight from Kansas City to Baltimore, MD Monday took less than two hours thanks largely to the strength of this jet. What this means essentially, is that although moisture will move up the Atlantic coast in impressive quantities (thanks mostly to that westward trough shift discussed in last Thursday's post), the failure of the southern branch impulse to perturb the polar jet will prevent this moisture from wrapping itself deep into interior sections of New York and New England for a long duration as the storm proceeds up the New England coast and thus prevent a huge Friday snowfall in central and northern Vermont. Forecasters look for a storm to attain what is called a "negative tilt" which indicates how much moisture will is thrusted west of the track With that said, I do think some of the deep moisture makes its way into Vermont for at least a shorter period of time allowing for what would amount to a few hours of moderate to heavy snow early Friday and an initial guess of 3-7 inches.

A complete upcoming weekend synopsis
A subsequent update refining these ideas will be needed of course but a as of now, a break in the snowfall is anticipated later Friday as an area of subsidence in the wake of the aformentioned non-negatively tilted storm moves through. As this is occurring the flow will gradually align itself vertically and allow terrain induced snow to develop across the entire chain of the Green Mountains either Friday afternoon or Friday Night. The snowfall could enhance for a time as the upper air impulse marking the advance of the very cold arctic air approaches. Terrain/Mountain induced precipitation is difficult to forecast both in duration and amounts this far in advance but the shear, stability and boundary layer moisture parameters will be met for at least a time (all part of the Braeton checklist !) prior to and during opening of the single Saturday morning. What does this all mean ? To summarize the guess is for two periods of snow, one early Friday and one early Saturday enough to produce a pair of powder days and an initial guess of 10-20 inches of snow for the period Thursday night through Sudnay. Wind will become a factor Saturday as will the cold weather. High temperatures Saturday will be in the low teens followed by a Sunday where temps fail to make it out of the single numbers.

Cold takes center stage
The big story for next week is the cold weather. In terms of both expansiveness and intensity, the attack of cold this weekend into early next week across the nation is as impressive as anything we have seen since December of 2000, perhaps dating back to 1996. It will make some headlines especially across the deep south. New England is one place which as seen its share of cold in more recent years and I refer mostly to January of 2004. Whether or not we can challenge some of those 2004 numbers which exceeded -20 in many areas remains to be seen but if it were to happen, Tuesday and Wednesday (February 6th and 7th) would be the time frame. Just prior to the peaking of the cold over the north country, we will be watching another system track near or just off the southeast coast. This system, a product of the southern branch may prove to create headlines either in the Mid-Atlantic or Southeast but it does not stand a chance against next week's overwhelming polar jet which will at some point, shunt this system out to sea before it plays any role in determing the weather at MRG. The polar jet will in fact ensure a fairly dry week for MRG overall with snowfall through the middle part of next week limited to the high terrain and falling in small increments.

Longer Range
As we move toward the weekend of February 10th, the ensembles do clearly suggest a relaxing of the polar jet. Even as this is occurring the Arctic Oscillation will remain at its lowest levels of the winter (-1) which will suggest that Arctic air will remain on the playing field in some fashion. This type of evolution, if viewed optimistically, would be interpreted as a chance to get some of the southern branch's deep moisture in the form of a well developed storm system up this far north. Pessimestically speaking, if the longwave trough/ridge structure were to align in the worst possible way it would allow for the possibility of a rain event. The latter would not be my guess. Recall that our early winter struggles were largely forced by an AO of positive 4. If the AO were to maintain a negative state it will be difficult for low pressure centers to track north 50 N along the east coast, a track necessary to bring rain to MRG. I do think temperatures move from their much below status to slightly below in the period between the 10th and 14th of the month. It also seems reasonable to expect at least one snow event after the very cold but fairly dry period between February 6th and 10th.

The Quick Summary
Snow will fall for varying weekends between early Friday and the end of the weekend. This is followed by very cold weather next week and then closer to normal temperatures for the weeek beyond.

Thursday, January 25, 2007

Another solid weekend and a promising early February

New England's north country has been the focus of the latest U.S. outbreak of cold. By the end of the month, many places across Vermont which saw temperatures average 12 degrees above normal for the first half of January will finish only 3-5 above normal thanks the to the late month cold rally. We also have some much needed momentum heading into the all important skiing month of February, a month which appears will start in a big way and hopefully continue. This update will contain a quick and detailed look at the weekend and a glimpse into the next two weeks which will contain some important fundamental changes as we head toward the first weekend of February.

The Weekend
In the last post we discussed the weekend Alberta Clipper system which at this juncture is still on the radar screen. It will dive out of Canada as a powerful jet impulse but will lose some potentcy by the time its effects are felt over Vermont. The system will spread clouds into the Green Mountain chain during the day Saturday and light snow will develop during the afternoon. The many forecasts I have seen up here are saying a 50 percent chance of snow showers or a "few snow showers" but I expect a significant period of light snow out of this system in spite of its weakening. By Sunday morning the mountain itself should squeeze at least 2-5 inches out of the limited available moisture but check the local NWS forecasts for updates Saturday morning. There is the concern of course about the intense cold weather but this should peak across all of New England Friday with a temperature moderation for the weekend; in fact, both days should top out in the teens and with less wind relative to Friday.

Slight pattern shift and meaningful results
The pattern from the perspective of the wide-angle-lens will change little over the next 10-14 days but there is a subtle and important shift next week involving the position of jet stream features which will impact MRG greatly by the first weekend of February. The focus of the cold which determined by the mean position of the trough will shift from New England late this weekend and early next week to the Midwest by the first of February. The pattern will on the overall still be dominated by cold over a broad area of eastern North America but the extreme cold will focus on the upper Midwest while below normal temperatures are more "garden-variety-like" across New England. The shifting of the mean position of the trough will better make use of the baraclinicity created by the Atlantic Ocean which is a better way of saying that approaching storms will pull Atlantic Ocean moisture deep into New England more effectively. The end result ? Well, I think there will be one to two significant weather systems leading to snow which will prove worthy of discussion in the next update. The first will occur leading up the weekend as the initial Midwest trough amplification occurs around February 1st. Subsequent to that will be another chance for a significant storm system around the 4th or 5th. I am obviously getting a bit ahead of myself but its exciting to watch the pattern engineer what I hope will be a historic comeback for us.

The Quick Summary
Light snow leading to an accumulation this weekend and then a subtle shifting in the pattern should bring the chance for much bigger things in early February.

Monday, January 22, 2007

Polar Jet ready to show its ferocity !

This is my first ever update from the basement of the MRG basebox, no doubt a bit different then blogging in the safe confines of your own home. January 22nd marks the 20th anniversary of one of the great east coast storms, a poor mans version of the '93 superstorm dumping 1-3 feet of snow up the spine of the Appalachians into interior New England. The storm tracked up through eastern Massachusettes and precipitaiton in Boston actually went to rain while heavy snow continued to fall over most of Vermont. It was my hope that we might see something similar late this week but the southern branch would simply prefer to stay on the sideline, at least as it relates to the production of new snow in our neck of the woods this week. The pattern appears to be manifesting itself into a ferocious positive PNA regime, one dominated by frequent intrusions of very cold arctic air on the wings of a very powerful polar jet. Of more importance will be the not so infrequent powder days, which will come mostly from Clipper systems or terrain induced events such as what fell Friday night and Saturday We have gone over the catylists but the intensity of the pattern is beginning to really impress me since it is one I have not seen on this widespread of a scale since December of 2000 and to a smaller degree, January 2003.

Short-term-casting
I have to admit that the short term analysis leading up to this past weekend was a bit lacking. It wasn't overly wrong but did not do justice to Friday's snow event and the subequent high winds which hit northern Vermont on Saturday. Sometimes I just get a bit too far ahead of myself so I will try and put a bit more of an effort into the short term casts leading into the weekend. On that note I do have to credit Scott Braeten who writes an occasional column for "firsttracksonline.com" . His January 18th analysis of the upcoming "oragraphic" Friday/Saturday snow event was terrific and he has a very thorough checklist designed specifically to deal with terrain induced snow events. HIs blog can be found at the link below.

http://www.firsttracksonline.com/index.php?name=News&catid=&topic=9

I am not expecting much in the way of new snow Monday night. A dusting to a few inches would be my guess and most of Tuesday and Tuesday night will be dry. This leads us to the approaching clipper system Wednesday and our next chane for significant new snow. We had hoped for big things out of the trough amplification which is expected late this week but the southern branch does not want to cooperate and the trough will not deepen at the rate needed and at the longtitude needed for a major storm. Nonetheless, we still have the amplifying and stenghening clipper which will spread snow into the region Wednesday, and as this storm continues to strengthen upon moving east, mountain/terrain indueced snow will continue Wednesday night into Thursday bringing with it a real chance for more significant powder to a building MRG base. Very cold weather will also be moving in on the heals of his storm, enough to make Thursday night easily the coldest of the year across the north country.

Good news for the weekend
It may never make it above the symbolic "0-degree" barrier (-18 C) Friday on the moutain but the good news is that both the wind and the cold will subside somewhat by Saturday. Even better is that the next in a series of clipper systems will spread more and much-welcomed new snow to the mountain during the day Saturday. A major storm is not anticipated on Saturday but it is clearly a good set-up with a well-established warm-advection overrunning area which is closely associated with the very important "left-exit" region of the jet max. I should re-name this type of clipper the "left-exit" clipper in hopes of getting us all to feel the positive vibe while at the same time getting stuck in technicalities (which it appears I have already done). It is very early and snow amounts will depend heavily on the systems track (and the left exit track) but a broad 4-8 inche area of snow is very reasonable over northern Vermont with this system and this would add to the snow which has already fallen Wednesday and Thursday.

Polar Jetted
To best assess the intensity of a given cold pattern it is often not the depth of the trough which needs to be addressed (I like to say) but the height of the western ridge. We have discussed, at the risk of over-stating, the stagnant B.C. ridge which has helped fuel the recent pattern change. Originally the ridge formed over Alaska, extended to the pole and helped to bring record cold into the West. Since then we have continued to see the ridge play an influence, only it has assumed a more favorable eastward position and has not extended all the way to the pole. Ensembles however suggest this may change as a trough amplfies south of the western Aleutian Islands and has the effect of strengthening the ridge in Western Canada, perhaps so it reaches to within the vicinity of the pole. This will have ramifications, the most important of which will be the intensity of the cold which become more impressive and more widesread over eastern North America. It may also have the effect of allowing the Polar Jet to completely overwhelm the pattern, eminating the southern branch as a major influence. I am still skeptical and hopeful that we can somehow phase the two like we did in late January of '66 which may turn to be a similar season in many respects consisting of a slow start to winter and a much bigger finish. Assuming the end results are more in line with the "overwhelming polar jet" solution we still should be kept happy with plenty of clipper and terrain/mountain induced snow events.

The Quick Summary
Polar Jet dominates bringing plenty of cold and frequent light to moderate snowfalls. A polar jet domination does lessen the chance for the biggest storms but they can still happen and always worth watching for, even up the last second.

Friday, January 19, 2007

Short Term Friday Night/Saturday update

Based on some comments I have received and observations from today and this evening, it is fair to say that my forecast of 4 or more inches of snow between tonight and tomorrow is not doing this short term situation justice. Radar imagery shows moisture continuing to stream into Vermont and the snowfall is certainly getting enhanced by both the lakes and the mountains in loose association with the decaying clipper. 4-5 inches has already fallen Friday and there is every indication that much more will fall particularly Friday Night. At this point I would not hesitate to say that 6 more inches will fall Friday Night with some additional snow Saturday. This will certainly make Saturday the best ski day at MRG so far this year.

Nickles, dimes and then there is late next week

The models at face value have us reaching for the change jar and counting its contents on the living room coffee table. I am always surprised at how much money can be accumulated in change and even if one were to hug the medium range models, we would still be surprised how well we can do counting the nickles dimes and quarters this pattern yields us. I expect much more though in a regime such as this; otherwise, I would have not gone out and predicted 300 inches of snow at MRG this year, a prognostication which still seems ready for spontaneous combustion. The week of January 21st to January 28th continues to bear watching as a couple of potent southern branch weather systems lurk in a pattern ready for amplification. Beyond that I can only continue to hype a pattern dominated in North America by a nearly stagnant ridge situated over the Canadian province of British Columbia and marginally favorable teleconnection indices. Its a pattern that now appears will be with us through the early part of February which is very much needed good news for us skiers loyal to Vermont.

The update for the weekend
The New York city metropolitan got a taste of snow Friday but by this storm reaches its full maturation, it will be too far north and east of Vermont and will end up doing more harm than good, robbing both energy and moisture from the approaching clipper system to our west. NWS has "3-5" inches possible in its forecast for Friday night, an outcome which at least to me seems only possible at the higher elevations. I am willing to go with a loose prediction of 4 or more inches between Friday night and Saturday on the mountain itself with lesser amounts in the valley. Snow showers will linger into part of Saturday night before the atmosphere dries and Sunday evolves into a Sunny but chilly day. We certainly could have done better but with new snow to ski on at least one and possibly both days this weekend it certainly qualifies as the best so far this season.

Making some sense out of next week
As mentioned there are two systems in the southern branch of the jet stream that bear watching. At the same time, the polar jet will be busy trying desperately to take matters into its own hands and cook up the good stuff for us particularly Wednesday - Friday of next week. The first southern branch system moves into the plains Sunday but this is too fast since it comes between east coast trough re-amplifications. I have watched this system closely since I believed it had potential. Models however have disagreed and have been suggesting that I am making a mountain out of a mohill. The consensus, which I am forced to go along with, would be to bring Sunday's snow to the Mid-Atlantic Monday and then off the coast in rather benign fashion. A weaker disturbance rotating through the lakes early next week will ultimately be responsible for any snow Monday or Tuesday and that is that.

The potential for late next week
There are two options with the second southern jet feature and models, particularly the European have gone back and forth on the issue over the last two days. In short, the feature either gets stuck in New Mexico or becomes somehow involved in the major east coast trough re-amplification which is expected to take place late next week. The re-amplification will be triggered by the polar branch of the jet and the disturbance responsible will in and of itself prove very productive. So the argument really boils down to whether or not any snow late next week comes from a clipper turned coastal storm or a major east coast snow event. In snow amounts this translates into an argument between either a 6-12 inch event or a 1-2 foot storm. Its nickles and dimes vs crisp dollar bills.

Looking beyond
Ensemble forecasts strengthen the existing pattern by next weekend and beyond although teleconnection indices seem most favorable in the upcoming week. I am referring mainly to the block east of Greenland which is in the process of forming and is not only responsible for finally sending the NAO index into negative territory but the major changes in the weather across Europe starting with the destructive storminess of the last few days. All this aside, it is important to focus on the patterns most dominant feature which is the all-important ridge across British Columbia. So long as that remains in place in some form and at some intensity, the new snow will, in some form, continue to pile up over the Green Mountains and in many other places. There remains strong evidence that this above mentioned ridge will maintain its existence through the end of the month and into early February. The individual model simulations can get a little melodramatic when simulated out that far but the potential for new snow will be continuous in this pattern.

The Quick Summary
Our focus shifts to late next week for something big but smaller amounts of new snow can really add up in a pattern like this

Wednesday, January 17, 2007

New/improved pattern and plenty of sports analogies

The snow is starting to pile up as the new jet stream regime is firmly entrenched across North America. The how and the when regarding the new snow remains a question and it got me to thinking about offensive philosophy's of various NFL football teams. Its a borderline ridiculous analogy but I am a victim of my own thought process. Many times in recent years, the Mad River Valley plays the west coast offense which relies on "dink and dunk" 3-6 inch snows during favorable patterns instead of getting the big play or 2 feet of powder all at once. Since we are playing from behind and its getting close to halftime we are in need of a big play to even the score or at least to ensure that my rock ski's remain in the basement where they belong. It has been a decadal phenomenon, or so it seems. In the 90's, much of interior Pennsylvania, New York and interior New England were the focus of the heaviest snow yet for much of this decade, the big storms have hit coastal areas harder while in many cases missing the interior locations thus forcing us to play the west coast offense. I was hoping that the juicy southern branch El Nino-fueled systems might reverse this recent trend but in the case of this year there hasn't been any trend because there hasn't been much in the way of storms.

Friday/Saturday
The newly established ridge west/trough east scenario with arctic air on the playing field in an El Nino year is like pitching to David Ortiz in the 9th inning and throwing him all fast balls. At some point we got to connect ! The first opportunity comes Friday as an incoming Alberta Clipper system collides with a wave of low pressure moving up the coast. Models suggest that any phasing here occurs too late and that our new snow Friday will come from the more moisture-starved Clipper system. Once the phasing does occur, the storm will strengthen into quite a snow-producer across the Canadian Maritimes. One result of this will be that moisture gets wrapped around back into the St Lawrence Valley and down the northern half of the Green Mountain chain. Jay Peak often does very well off this type of set-up but areas farther south can also pick up a fair share fresh powder as well. Between Friday and Saturday, the mountain could easily pick-up 3-6 new inches of powder and no, there won't be any sleet mixing in. If the phasing can occur a bit sooner on Friday, our prospects for more snow would improve.

Still lots of potential with the early/middle part of next week
I have had my eyes on the early to middle part of next week for some time and for good reason. The southern branch is poised to spit a moisture-rich system out of the Rockies while at the same time, the polar jet is poised to re-amplify across the eastern United States. These two items may not be timed in perfect coordination but the ingredients for a major east coast system are in the mixing bowl. To further make the case for such an event would be to show how terribly the medium range models have dealt with the strength of the southern branch. The ice-storm in Texas, which is the major event of the winter so far was for the most part not on the medium range model radar screen at least not for 3 days in duration. It would be therefore easy to suggest that any southern branch system next week will also be mis-handled by guidance both in terms of strength and intensity. At this point the best way to look at the Monday-Wednesday time frame next week is in the form of best case/worst case. Best case being big storm and worst case being another Alberta clipper and a light accumulation. Hey, its another fast ball and another chance to hit one out.

Looking Beyond
Beyond the middle part of next week there are not any changes to discuss. The medium range models have oscillated on the intensity of the pattern but the ensembles which can act to filter out some of the statistical noise in the long range have remained consistent that the pattern remains golden at least through the rest of the month. Embedded within this period will be additional chances for storms but its difficult for me to speculate on what and when considering how much trouble we are having nailing this all down within a week. I always like to say, get the pattern right first and the rest takes care of itself and it certainly applies here.

The Quick Summary
New pattern to produce plenty of new snow, at least in small increments but the question remains can we hit one out and soon ?

Sunday, January 14, 2007

Our pot of gold is getting near

We are on the leading edge of a fantastic period of winter weather in the northeast with many powder days inevitable following the snowfall MLK day and Tuesday. The pattern, as discussed in previous posts will be dominated by upper air ridge in British Columbia which will be accompanied by a healthy southern branch of the jet. The medium range models have had an especially difficult time with this because the interactions between the Polar Jet and Southern Jet are very difficult to pin down more than a few days in advance. For the last few days models have in fact indicated a very dormant southern branch which I have taken with a grain of salt primarily because of the ENSO state. The last cycle of model runs just released was finally beginning to turn on this issue and show the potential for two partially significant to significantly significant events over the next 10 days. This not surprisingly would result from the southern branch.

1) First chance comes on Friday as the newly established baroclinic area over the southeast coast will be the focusing mechanism for the development of a coastal wave of low pressure. There is already an Alberta Clipper which is expected to impact the region that day so the question becomes whether the former and latter mentioned systems interact constructively or destructively. The result can vary by region so its difficult to know or make any determination. Certainly we can establish that there is a very good chance for new snow leading into the weekend of the 20th and 21st.

2) The southern branch could then make a more definitive impact in the period between the 23rd and 25th. The ensembles have shown that during this period the eastern trough weakens somewhat only to subsequently restrengthen for the last few days of the month. This is probably the reason why we have yet to see any indications of a phase and a major storm. Since the mean trough position is in the east however the threat is certainly there and will certainly be worthy of some speculation in the days to come.

Winter should make some big amends over the next few weeks.

Saturday, January 13, 2007

8-15 inches of snow and a little sleet from MLK storm

MLK storm details
Like a classic sibling rivalry, the European and American models continue to duke it out over the MLK storm. My opinion on the outcome hasn't changed much, just fine tuned a bit. I am not going to split the difference between the models but instead side more with the European which has more support now from the higher resolution NAM as of late this morning. The track of the surface storm in the above mentioned scenario would be from southern Illinois through extreme northern Pennsylvania and finally across southern New England to the coast. This would place much of central and northern Vermont in the heart of the QPF (geek speak term for moisture) and would involve healthy amounts of snow although precipitation might change to or mix with sleet later in the day Monday. Specifically speaking, I think anywhere between 1-3 inches falls by Monday morning followed by 3-6 inches of snow and sleet during the day Monday and then 4-6 inches of mostly snow Monday night. This would leave us with a grand total of 8-15 inches of snow and sleet before it turns much colder Tuesday. The American model suggests that all of the precipitation falls as snow only that there is is not as much. This solution assumes a much weaker system which tracks much further south which I don't agree with since I think the model is under-phasing the storm with the incoming polar branch of jet stream.

Champlain powder Tuesday Night
Hard to predict amounts but there does appear to be an extended period of time Tuesday night when winds are directed over the longer fetch of Lake Champlain to Stark Mountain yielding additional powder. Temps will be well below zero Wednesday morning but there will be fresh snow to ski at MRG.

Long Range
No changes right now but I will have a full update tomorrow evening when hopefully we can shed some more light on the weekend of the 20th and 21st.

Thursday, January 11, 2007

The great MLK day turn-around, GO GO GO

It gives me plenty of satisfaction to report on many exciting things in this update. The most dramatic of which will occur at the tail end of this weekend. For the few that have followed this story in its entirety, we knew that the pattern was changing for the better around this time but the few days embedded within the upcoming holiday weekend looked dicey. I knew that northern New England was quite capable of turning this potentially lousy situation in to something positive, particularly in an El Nino year but the consistency at which we have been thwarted was both alarming and emotionally scarring so far this winter. Speaking of the recent and very remarkable stretch of mild weather, I heard a great interview on NPR's "All Things Considered" yesterday where Robert Siegel asked Penn State (my alma mater) meteorology professor Dr. Michael Mann about the extent to which global warming played in to the mild weather. The question is certainly one that often gets thrown my way but his answer was better then any I have given. He analogized global warming's influence on individual weather patterns to "loading the dice". He said accurately that weather patterns are deterministic and form because of a set of random and chaotic events. The intensity and coverage of the mild weather this year was like rolling "snake eyes" although global warming can make snake eyes a bit more likely than it would be under normal circumstances. You might be able to find the interview on NPR.org but I thought it was worth mentioning.

The MLK weekend set-up
Rolling "snake eyes" has given us our 5 weeks of skiing infamy but we have rolled again and come up with a much better outcome so lets get too it. We have expected (or at least I expected) much better things from El Nino and its finally playing the role it was anticipated to play. The eastern upper ridge is in the process of rapidly forming but a southern branch, fueled by El Nino, is going to quickly destroy it before it comes a dominant influence on the weather pattern. In the process of its destruction, a fairly strong low pressure system will move from the southwest to what I think will be the New England coast. It will be a system containing a very broad shield of precipitation and will be a system which will prove to be of great assistance to those of us hoping that MRG can quickly build a skiable base. There are other very important things at play here as well. Arctic air, as discussed, is now on the playing field and the splitting of the trough in the west will allow a push of cold weather to quickly re-assume control Saturday after an afternoon of above freezing temperatures Friday. This sets the stage for the events of late Sunday and Monday (MLK day). Two days where no longer do we expect above-freezing temperatures and where significant additions can be made to the base.

MLK day storm
Sunday itself turns out cloudy but with little precipitation and temperatures will remain below freezing. The storm at that time will prove to make itself known at the Seattle vs Chicago NFC divisional playoff game. Precipitation will make its northern New England arrival Sunday night in the form of snow and will continue either in some form through a good part of Monday. There are disagreements amongst the models concerning the details and I should bring up the fact that the American model now tracks the storm so far south that much of northern Vermont misses the heaviest precipitation although the precipitation type remains all snow throughout the event. When it comes to the track of this storm I am still inclined to go more with the European (which has also shifted its track southward but not as much) model or at least a blend of both. This would mean several inches of snow Sunday night into early Monday followed by a period of sleet or a snow/sleet mixture during the day Monday. Precipitation would end as snow Monday night before it turns windy and much colder Tuesday. The sleet factor makes it very difficult to predict accumulations but 6-12 inches of snow and sleet is a very reasonable first guess. I know also that sleet isn't exactly powder but sleet also makes a very good foundation for a workable base.

New and improved
Winter as we formerly knew it will re-acquaint itself with the region Tuesday and Wednesday bringing below zero (F) temperatures to the region during the overnights and only single numbers during the day. At this point, the new and radically improved pattern will become entrenched and we will watch as the powder continues to fall, and it stays cold. The medium range models suggest that the next two chances for powder come Thursday and then more significantly on the weekend of the 20th and 21st. This assumes of course that the southern branch goes dormant next week which I am not entirely sure about. Even if this moisture-rich portion of the jet does quiet down for a time I doubt it will be that way for long.

The big turn-around, can it be done ?
Lastly I wanted to discuss a more broader view of the weather pattern for the balance of the month and it also is a very encouraging topic of conversation. Although the teleconnection indices are neutral, the new pattern's most dominant feature is a ridge which will oscillate in position between the extreme northeast Pacific Ocean and western Canada. This will be enough to maintain a healthy stream of colder temperatures over the region. The feature is shown to maintain its strength and even intensify over the course of the next two weeks. In addition to this are some of the ongoings in the southern latitudes of the Pacific. Between 10-25 N in the Pacific, the long range ensembles show negative jet stream anomalies. This is in effect an indication of a healthy southern branch but also a weakened or split mid-latitude Pacific Jet. The aforementioned happen to be some very fundamental ingredients to great periods of winter weather gone by such as '92-'93 or '77-78. The '92-'93 winter had many of these things along with a positive NAO similar to that of this year. So in concluding I will say that yes the pattern change could be limited to a few weeks but it could turn out to be one of the most dramatic mid-season turn-arounds in a while.

The Quick Summary
MLK weekend to prove productive before its done and mark what will hopefully be a memorable mid-season turn-around.

Tuesday, January 9, 2007

MLK Weekend or not, January to make a comeback

With winter gradually re-establishing itself across many parts of the country our hope is to quickly build off accumulations of new snow and avoid any additional warm-ups. The big pitfall as we have discussed is the potential ice situation and subsequent warm-up on MLK weekend. This outcome can still avoided but I am increasingly concerned. I am not pessimistic about the period following the holiday weekend which will mark the beginning of what I think will be a big finish to the month. The key feature is the ridge which has recently developed over the northeast corner of the Pacific Ocean and is expected to gradually migrate eastward and settle over the Canadian province of British Columbia. It will prove crucial in our effort to establish a pipeline of consistent colder weather across eastern North America. When you combine this with the more active southern branch of the Jet Stream this year, we will get the opportunity for a late January comeback.

New snow through Wednesday
Periodic bursts of snow over the high terrain will continue through Wednesday largely due to lingering instability across the northeast. There is stronger impulse rotating through the newly formed trough but this system, as mentioned in the last post, will pass south of the region taking the best dynamics with it. We can rely on the fact that temperatures have remained above normal in spite of the trough thereby increasing the low level instability which should in turn encourage the development of snow showers. Also, winds will turn from west to northwest tonight which is a more favorable trajectory for new snow at MRG since it comes from Lake Champlain as opposed to straight off the Adirdondack Mountains. Overall, another 3-6 inches by late Wednesday is a perfectly reasonable best guess.

MLK Weekend
Temperatures will again climb above freezing during the day Friday but the warm-up will be temporarily thwarted Saturday by clouds and a push of low level cold which should keep most of the north country below freezing for the first part of the weekend. It is here where models duke it out over what follows for Sunday and Monday.

1) The American version of events
The american model would suggest that much of the warm weather and much of the rain stays away from northern New England; instead, the low level push of cold Saturday would set the stage for a period of snow mixed with some sleet on Sunday. This precipitation would gradually change to a mixture of sleet and freezing rain Sunday evening before ending as above freezing temperatures assume control on Monday. This is certainly less than ideal but this scenario allows for a net gain of snow/sleet at MRG followed by much colder weather on Tuesday, January 16th.

2) European version of events.
The Europeaon model suggests that the low level push of cold is not as potent on Saturday. In addition. The storm, according to the European, tracks farther north into Quebec leaving much of northern Vermont in a precarious situtation Sunday night and Monday. This solution essentially means that an initial period of sleet and freezing rain (with minimal snow) would change to plain rain Sunday night before much milder temperatures take command for a day on Monday. The european also allows for the change to colder weather on Tuesday.

3) My thoughts
The American model, as inviting as it looks, isn't a solution I am inclined to believe. The model has a southern bias when tracking surface systems and thus the European usually outperms the American model in the 3-6 day time frame. In addition you have other factors that don't work the American model's favor such as the Great Lakes which are anomalously warm (for this time of year) and snow cover which is anomalously absent or very low. My guess right now is that Saturday's temps are in the high 20's or low 30's but its dry, Sunday's temps are near freezing with sleet and freezing rain and Monday is mild with a few showers. This is not set in stone so please root for me to be dead wrong.

Rest of January
In spite of whatever happens this weekend, I am very encouraged as to how things look for the latter half of the month. The teleconnection indices are neutral but features embedded within the jet stream will be positioned in a way which should allow for a consistent stream of colder weather as I mentioned in the opening paragraph. I also refuse to believe that the southern branch is neutralized as some of the models would have us believe. I will instead go out on a limb and predict a significant snowfall either during or just before the weekend of the 20th and 21st of January. Furthermore there are indications that the aforementioned ridge in the Jet Stream will remain in place somewhere in western Canada through a good part of the duration of the month thus setting the table for a comeback of sorts. The pattern may prove to fall short of perfect but in a relative sense it is very welcome.

A quick summary
Warm weather to what is perhaps its final January push into the region Monday following some ice but mother nature should be full of much more positive news thereafter.

Sunday, January 7, 2007

Some Sunday adjustments and an MLK update

Some adjustments need to be made to the short term prognosis and it never hurts to update the prospects for MLK weekend.

1. Update on new snow through Wednesday morning
Friday's post included a prediction of 1-2 feet of snow for the mountain in the period beginning Sunday Night and ending Wednesday morning. I had envisioned that 3-6 inches would fall from the system which will approach the region Sunday Night and exit Monday. Indications are that this system is both stronger and is also tracking farther inland which has ramifications on temperatures in critical lowest layers of the atmosphere. I looked at this situation closely this morning and it appears as if precipitation arrives early Monday morning with precipitation type, at least initially, highly sensitive to elevation. Valley locations in Vermont may see very little snow out of this, maybe just a few wet flakes. Areas above 2,000 and especially 2,500 feet may fair significantly better with a few inches of wet snow falling before precipitation changes to rain or tapers off later Monday. With virtually no base at MRG's base, the debate over a few inches of wet snow at 2,500 feet is irrelevant; furthermore, the colder weather Monday evening combined with the instability will be enough to bring new snow to the entire mountain Monday Night, Tuesday and Tuesday night. This brings us to the second part of the adjustment which involves the impulse rotating into the newly formed trough trough Tuesday. Indications are that the best dynamics with this moisture-starved system will be south of the region, over Pennsylvania and Maryland, as opposed to Vermont. We will still see some much needed new snow here just not as much. My guess now is 6-14 inches in the period between Monday and Wednesday morning with the big range accounting for the elevation sensitive snow.

2. MLK Weekend Update
We are starting to get a better resolution on the period beginning Friday the 12th to Monday the 15th. There remain plenty of question marks and a big range of possibilities. I had mentioned that the American Model was indicating a meridional and almost perfectly "symmetrical" solution placing all the cold air and snow in the West while allowing for a push of very mild weather in the eastern quarter of the United States. Not surprisingly, the model has trended away from that scenario, showing a very important trough split in the West and thus allowing cold weather to stay much closer and possibly stay mostly entrenched across northern New England. This above-mentioned idea seems to in fact represent a loose model consensus although plenty of slight but very consequential adjustments are sure to occur. This "loose consensus" would be to allow for a push of milder weather Friday and Saturday, enough to get northern Vermont back into the 40's during the day time. Colder weather would subsequently make a push back into New England Sunday as the "broken" piece of the trough knocks down part of the newly established eastern ridge. The more potent part of the trough trough would then push east Sunday and Monday in the El Nino-fueled southern branch of the jet stream. This system as it approaches would bring the threat of snow or ice to the region possibly as early as Sunday but most likely Monday. I am actually fairly confident in the basic premise here but the very important details are entirely up for grabs. The first "broken" piece of the trough must beat back the eastern ridge significantly. If it does so successfully, more successfully then currently progged, then significant amounts of new snow become possible in the late part of the holiday weekend. If the above does not occur we will be in big trouble again.

Still encouraged about what I see following the holiday weekend and I can touch on that more with Tuesday's update.

Friday, January 5, 2007

The Fight for MLK Weekend

With the first weekend in January overrun with mild weather and rain all eyes now shift to the weekend of the 13th-15th in search of hope. The weekend honoring the great civil rights leader often marks the commencement of Mad River Glen's peak, when the base becomes deep enough to support many off-the-groomer adventures. It is safe to say that we have somewhat lowered our expectations this year; nonetheless, with arctic cold invading North America next week, the opportunity at redemption has presented itself. Whether or not the opportunity is seized remains a big debate.

The first taste of a new beginning Sunday Night
The rain and the near-record warmth needs no further additional review. The move to colder temperatures, which will be a step-down process, begins Saturday night and the 30-degree above normal temps are replaced by readings closer to 15-above normal Sunday. The first forecast challenge then arrives for Sunday Night in the form of a developing weather system that will be moving northeast up the coast along the tail-end of the already-passed cold front. Temperatures by this time will be very marginal, but models have come to a consensus that moisture from this system will indeed reach Mad River Valley and beyond and should provide an opportunity for a few inches of wet snow.

Powder early next week
Whatever does fall Sunday night into early Monday will be the start of what should be a far more intriguing period of weather across New England. During the day on Monday, colder temperatures (categorically normal), make a push into New England but as this happens, the lower troposphere will remain unstable and will thus start the Stark Mountain induced snow machine. The snow showers which should begin during the day Monday and last through Monday night are certainly be capable of producing 3 or 4 inches but this precedes a very potent upper air impulse which arrives on the wings of the Polar Jet on Tuesday. Some of the models are actually suggesting that Tuesday's system may develop into a coastal snow producer for Maine. For most of the Green Mountains, the system should bring much needed snowfall, particularly to the high elevations. I don't want to get caught being too specific but the mountains of north central Vermont could easily see anywhere between 1-2 feet of new snow in the period beginning late Sunday and ending early Wednesday.

The MLK Weekend conundrum
The headaches begin as we push toward MLK weekend. I am a big fan of looking at the "hemispherics" of a pattern which is more or less analogous to simply saying I try to look at the big picture. I mentioned in previous posts that the catalyst for the arrival of arctic air is the ridge which will develop across the northern latitude Pacific Ocean and extending up 155 W poleward across Alaska and beyond. Its an important feature and should bring plenty of bitterly cold arctic air into North America. The problem is that this so called "catalyst" is too far west, and will allow the deepest penetration of cold next week to occur in the western United States, not the east coast by late next week. As the cold air plunges into the Rockies, we may very well be watching more news footage of snow in Denver. This presents a problem for us skiers in that any deep upper air trough across the Western U.S. will bring about a ridge in the eastern United States. Its the jet stream more or less acting out Newton's third law of physics.

Best and Worst case possibilies for MLK weekend
The american model is keying on the aforementioned scenario and therefore replaces all of next week's colder temperatures with very mild weather for MLK weekend and an eventual period of rain. This is nothing short of a massacre but it can be avoided and the situation could and might very well turn out a lot more positive. When the American model integrates out past 6-7 days it likes to produce these merdional and very symmetrical scenarios with a trough and very cold weather in one part of the country and a ridge and very mild weather in another. The final outcome often does not turn out that way. In this particular case the trough in the West is not likely to amplify as the American model suggests. Assuming it doesn't, we have to hope that it splits, sending a piece eastward to mitigate the effects of the eastern ridge and keep us within reach of the arctic cold (which will be close in any scenario) and even the overrunning snow. Even the most positive scenario would have a threat of ice but a snow/ice scenario is much better than rain. I would not at all be surprised to see 65-degree temperatures in Philadelphia on MLK weekend while it is simultaneously snowing or icing with 20 degree temperatures at MRG.

Beyond MLK
Beyond the MLK holiday there is reason for more hope. The ridge situated over Alaska is shown to migrate slightly eastward allowing for a continued delivery of arctic cold. The NAO is shown to remain positive which is an adverse factor although even a normal regime is significant improvement over what we have seen. In addition, and as i mentioned in previous posts, if we can combine the presence of arctic air with an active southern branch then we should enjoy the results.

Quick Summary
New snow and colder temperatures early next week should follow the weekend washout but then the fight for MLK weekend begins which could yield both negative and positive possibilities.

Wednesday, January 3, 2007

Arctic air ready to shake things up

There is so much to talk about today that it will take an extra effort to avoid turning this into a 5-page essay. Overall, I am happy to report that major changes are in store for the North American continent overall and although we in New England aren't exactly sitting on the winning lottery ticket, we should be able to share in some of the winnings. As mentioned in the last post, the catalyst and key to all this will be the happenings above the state of Alaska; specifically, the development of a ridge which is expected to extend poleward and beyond and allow a pipeline of very cold Arctic air to push deep into North America and parts of the United States next week. For anyone following the 3-5 forecast it is obvious that I am getting a bit ahead of myself. Mild weather is poised to advance deep into New England Thursday and into Friday accompanied by plain rain and the benefits of any of these so called "changes" won't be felt until early next week.

Mild Weather and rain ruin another weekend
I won't spend too much time on this since the drama of the uncertain is gone and the news isn't good. NWS Burlington will do at least as good of a job nailing down the specifics here but it appears as if the first batch of precipitation arrives sometime during the night Thursday or early Friday as freezing rain or plain rain. The moisture is associated with a weather system which will ultimately track deep into Quebec thus making a push of mild weather and an eventual period of plain rain inevitable. The heaviest precipitation will fall as plain rain Friday Night or early Saturday. NWS Burlington is then calling for 40's on Saturday but if the clouds were to break for a few hours of Sun and some of those very warm temperatures aloft were "mixed" down to the surface, readings could climb well into the 50's which is record territory. The gradual trend toward colder temperatures does begin on Sunday but it will still be well above normal with no new snow.

A much needed week new snow and colder temperatures
Next week gets a little dizzying for me as their are so many parts of this story to tell. After sifting through the details it appears as if two significant "clipper" impulses will bring the chance for significant new snow. The first comes late Sunday or early Monday, the second Tuesday or Wednesday. The former proves to be more of the forecast challenge. It is complicated by the fact that a wave on the tail-end of the weekend cold front may try to ride up the coast Sunday night. The result of such an occurrence could be good or bad but probably bad since if the two impulses work out-of-phase with each other then the coastal system will rob us of some of the moisture from the clipper. Once this weather system clears the region by Monday however, we should have at least a little new snow at the high elevations plus the introduction of below normal temperatures. The second clipper system should deliver some much needed new snow to the mountains, tough to tell how much since its 6 days out but whatever falls in that January 7th to January 10th period will be much needed relief.

Big Arctic cold to make a big Rocky Mountain plunge
As we are finally being re-introduced to winter in northern Vermont early next week, there will be a major league push of cold into the Rocky Mountain west and High Plains. This occurs because this upper air feature described in the opening paragraph is establishing itself over Alaska or 155 W longitude as opposed 130 W which is over the Northwest Territories of Canada. Its a significant difference and creates a looming issue for us next weekend. If everything were progress as many of the numerical models are suggesting, it would mean another push of milder temperatures and possibly a snow to ice situation for the weekend of the 13th and 14th of January. This is where the debate begins and i have been watching it rage on amongst those in the weather community.

The 1998-1999 scenario
It was a year where in January, the prevailing upper air pattern was unfavorable but with the competing force of arctic air made for continuing drama. There was snow, bouts of very cold temperatures followed by freezing rain and even rain. It was not the year of the famous Quebec ice storm, it was the year after, a year which featured not just one big ice storm but many smaller ones. The medium range models are essentially showing most of this scenario but its important to note that 1998-1999 was a strong La Nina winter, this is certainly not which in my opinion should prove to have serious ramifications on the actual outcome.

The 1992-1993 and 2002-2003 scenario
I think it is safe to say that we have not exactly followed the template of these exceptionally great snow winters. I bring the two years up however because both were "El Nino" winters like this one (02-03 was weak) and in both cases, significant east coast ridges in the Jet Stream were advertised by the models only to be busted up by the southern branch of the Jet which in the end led to more east coast snow and cold. In the case of 92-93, the busting up of the ridge occurred in the middle of February and preceded an absolutely legendary period of snowfall lasting through late March. The 02-03 case occurred at Christmas time which was also a great period of snow for Vermont.

So how do I think this plays out ?
This winter has been so lackluster (to put it mildly) that it seems almost ridiculous to make comparisons to 92-93 or 02-03. Still, in an El Nino winter, getting arctic air on the playing field is the hardest part and so long as we can do that next week, which I think we will, it will prove to be a big step in the right direction. A 3-week period of very favorable weather is not guaranteed beginning next week but very possible in my opinion in spite of what the skeptics might say. The teleconnections, specifically the AO is expected to be neutral within 5-6 days and then at least slightly negative in a week. Thereafter, the outcome with the AO is still inconclusive but its still a major shift when you add the Alaska to North Pole ridge into the mix.

The Quick Summary
Mild weather and rain set to ruin another weekend but arctic air ready to shake things up next week.