Think Snow, Tweet Snow !!!

Friday, December 30, 2011

Less enthused about New Years eve Clipper and about the pattern overall starting next weekend

Unfortunately, we are going to have to lower expectations with the polar pacific clipper system. It has some moisture with it as it passes through the Midwest but much of this moisture, according to some of the latest high resolution models, will get rung out over the Great Lakes. In the end, occasional light snow Friday night and Saturday will amount to 1-4 inches. This will be followed of course by the push of milder weather which is expected to impact the region on one afternoon. It will actually be a rather pleasant late December day with temperatures in the 40's but we are in much greater need of both more snow and more cold.

Much of the eastern United States will get its biggest blast of cold so far this winter. The front will arrive late in the evening of New Years Day and we are not expecting much in the way of any rain. Enough low level instability in the wake of the frontal passage should set the stage for a period of terrain induced snow showers throughout January 2nd and into January 3rd. A little too early to tell about the potential for accumulations in this time frame except to say at least an inch or two. Later in the week the large upper trough, responsible for the widespread outbreak of cold will get re-enforced briefly by a clipper system that is expected to drop into the eastern Great Lakes around the time frame of Wednesday the 4th. This system may bring some snowfall to Vermont or may bring the bulk of its effects to areas farther south.

The concern expressed a few times on the blogs relates to the lack of blocking associated with next week's cold outbreak. You can think of this as a ship reaching port without an anchor. Jet stream blocking at high latitudes is this anchor and although the North Atlantic and Arctic Oscillations have been neutralized they have yet to resemble the picture that we need to turn this thing completely around. The result will be the erosion of cold weather by next week and perhaps even another 1-2 day stretch of unneeded milder weather. I have been watching the upper level pattern in the Pacific closely for signs of a change; indeed, there are some changes but not all of them good. It will be another coupling of upper ridging in the Pacific/Polar Vortex over Alaska which will drive the cold out next weekend. The vortex of cold in Alaska however will move out of that region toward western North America allowing a somewhat more tradional La Nina set up to establish itself by January 10th or so. The result ? cold weather in western North America, warm weather in the southeastern United States and anything goes across the Great Lakes and Northeast. My guess is that temperatures between the 8-14th of the month will be above normal. We could however see slight above normal temperatures with a few snow/ice events or we could see more substantial above normal temperatures with ice and rain events. Our friends in the western United States should do very very well in this set-up.

Wednesday, December 28, 2011

We need more where that came and we may just get it !!

A very much needed foot of snow fell across parts of the central and northern Green Mountains yesterday. A terrain induced event aided by wrap around moisture from the departing storm and lake moisture from everywhere. Its nice to get surprised with more than expected snows but I also like to see the cold weather exceed some expectations since the winter so far has exhibited the opposite personality of failing to meet expectations from both a cold weather and snowfall perspective.

After a dry Thursday, Friday December 30th will feature the arrival of a fast moving but intriguing clipper system. Its a system featuring two pieces of polar pacific jet energy with enough vigor to bring an extended period of light to occasionally moderate snows to Mad River and company for New Years Eve. If parts of the mountain do indeed open as expected, it will be a nice way to start the season. Overall snowfalls Friday into Saturday could total in the 5-10 inch range and should be of the low density-fluff variety.

The warm weather I was concerned about will be confined to one afternoon - New Years Day. Temperatures will make a push toward above-freezing levels but balmy conditions will not be nearly as intense or prolonged as I had feared. Better yet, no significant rain or ice should occur when a sharp cold front ushers in much colder weather for next week. This is a week which will be dominated by the polar branch of the jet which means below normal temperatures (FINALLY), snow showers for Monday and Tuesday and perhaps some clipper snows later in the week. Undoubtedly this is a much more encouraging appearance !!

Monday, December 26, 2011

Variable upcoming week but a better outlook after Jan 2

We did get a few days where it did truly feel like winter and the outlook appears more wintry going forward but the next week or so will be very hit and miss. The big weather system Tuesday is a big miss. The phasing of southern stream moisture and polar jet energy will not bring us much as cold weather is simply incapable of holding its ground in this pattern. The system will bring its precipitation to the region Tuesday evening as a mixture of rain, snow and sleet but ultimately the mountain will get another several hours of rain. The system will indeed bomb out as it approaches the Canadian Maritimes and this will help usher cold back into Vermont early Wednesday accompanied by some snow but we could've used a better result from this and we simply won't get it. Overall it looks like about an inch of liquid will fall from this system with 70-80 percent of it rain and 20-30 percent snow Wednesday thus about 3-4 inches.

From Wednesday onward the outlook is more optimistic and significantly snow after the New Year. A series of clipper systems between Thursday and New Years Eve will yield some fruitful results. Products of the very intense Polar/Pacific jet stream, the first of such systems should arrive later Thursday and spread a light accumulation of snow to most of Vermont and New Hampshire and a second could spread additional snows to the region Friday night into Saturday. Put together, the accumulations from these two systems could total as much as 10 inches. The snowfall will be very fluffy in nature and the 10 inches is the optimistic side of the range but we will take that in what has been a very tough month. The now frozen Hudson Bay is also finally lending a hand since it appears some cold in eastern Canada is finally showing signs of fighting its way into the region since it can't seem to make any progress anywhere else in the U.S. right now.

The warm-up promised for New Years Day (plus or minus a day or two) is still evident on the forecast weather maps but not quite as intense in magnitude or duration. It will begin with a warmer, above freezing afternoon on New Years Day and will hopefully end with a minimal amount of rain on the 2nd. Maybe the trend toward removing this from the forecast picture will continue but for now I would continue to expect it.

The better news involves manifestations upstream of the region after the New Year. The Pacific has, as mentioned many times, been very problematic so far this winter season with the upper ridging in the Mid-latitude regions clashing with a polar vortex over Alaska for much of the month. At around the time of the New Year, the jet energy across Alaska will at least temporarily win this clash and allow a deeper trough to form in the eastern Pacific and consequently a ridge to develop in western North America. The upper ridge now appears as if it may be one of the stronger features on the Northern Hemisphere weather map in about a week or so. This type of pattern is much more amplified and should allow for a period of much colder and wintry weather across a broad area of the eastern United States after the 2nd. It does not mark a switch in some of the major teleconnection indices that we track but we should a neutralization of these indices and hopefully - game on.

Friday, December 23, 2011

Wintry through the 27th, rain and wet snow the 28th and warm weather for New Years

The ground is white, the trees are white thanks to the warm and wet weather that preceded our light snowfall and at least it looks a bit wintry out there. It will also stay wintry for the next few days with some single digit overnights and daytime temps in the 20's. The weather itself will remain dry through Christmas Day but a clipper system will bring its clouds to the region late Sunday and snow showers Sunday night into Monday. This clipper system is potent enough to temporarily carve a nice little trough along the northeast coast and there are some indications that instability as a result of this will allow for snow showers through much of Monday, enough for a terrain induced accumulation of a few inches.

The weather evolution next week appears a bit different than it has the last few days. Most of the changes are less than desirable, but Tuesday could be an interesting event although it if lives up to the tradition of December 2011 it will simply be another rain event. The changes involve southern branch Gulf of Mexico moisture and energy that will be grabbed by the collar by a faster moving clipper system. The result will be a significant precipitation producing weather system for the entire northeast beginning later Tuesday and none of this appeared likely even 36 hours ago. The cold which is expected to persist through Tuesday morning will erode very quickly and a fresh supply of cold will far removed from the weather picture. The southern energy however allows the storm to take a more southern track so temperatures should be close to freezing when the precipitation begins Tuesday evening. What appears most likely is period of both rain and snow, with precipitation beginning as a mixture before changing to rain then perhaps back to a heavy snow before ending midday Wednesday. With any weather system of this nature though, slight changes in the forecast variables could push the result in either direction. We could certainly use a surprise heavy snow. It is possible, if it does happen it could be of the "sierra cement" variety but us skiers know how desperately the Vermont high country needs a boost to the snowpack right now.

The less than desirable part of the forecast change will take place around New Years Day where it appears models are converging on yet another warm-up for the east coast. The mild push would begin Friday after semi-seasonable temperatures late Wednesday into Thursday. How fast this occurs remains uncertain but much above normal temperatures are now very likely in the New Years Eve to New Years Day time frame and with that will come the increased risk for more rain.

Beyond the first looks slightly more promising. Much will depend on the ability to break down the jet stream ridge in the central mid-latitude Pacific. There is not a lot of evidence of this as of yet and with that we will continue to struggle. That being said both ensembles indicate a ridge west/trough east jet stream configuration and such an outcome would still be better verses what the previous month has wrought.

Wednesday, December 21, 2011

Hoping we go one for two this weekend

Snow is at least part of the discussion this go round. It will be worth thinking about in the midst of what should be a mostly rainy or freezing rainy Wednesday across the Green Mountains of Vermont. The situation sets up as follows. The mainly wet system Wednesday will exit and leave with it one extra day of above freezing temperatures Thursday. The front associated with Wednesday's system is a very weak one initially but the entrainment of some polar energy will give this front some legs and invite a wave of low pressure to develop near the Gulf Coast and track very quickly northeast toward the New England coast Friday. It is less than 72 hours away and the track of impact from this storm remains unclear; in fact, the much more reliable European model is suggesting no impact at all (although the European wants to tell a whole different yet interesting story Christmas weekend, more on that later). The system however does have some potential and also has the benefit of a fresh supply of what limited cold is available from this deplorable weather pattern. The cold will drain gradually southward out of Canada as the wave of low pressure approaches Thursday night. Snow could be moderate to heavy for a time if the storm tracks close to Long Island or attains a stronger intensity than models suggest. Its quick movement however would keep snowfall totals generally in the light to moderate category if at all.

The European model, which has been eating the American Model's lunch all month is suggesting not at all. That being said, the European model maintains that storm development along the aforementioned front will be later in the forecast period. Christmas Day to be exact. The supply of cold air will be more stale but the pattern will be in the process of turning more amplified and could allow for major storm to take shape and one that could deal interior areas the bulk of the snow. The American model will have none of this however and is putting all its eggs in Friday's basket.

My best guess is that we go one for two here. If Friday's wave of low pressure fails to materialize it will leave the door open for the ignition of the second and potentially more potent wave Sunday. A stronger system and a snowier Friday could act to drive the front farther offshore by Sunday. I can't see two events in the 3-4 day stretch.

No reason to doubt any of the thinking beyond Christmas Day. The temporary amplification of the eastern trough is no match for the furious jet action in the Pacific. This is just been such a demoralizing scenario to start the ski year and there are stronger indications it will try and re-assert itself after the 27th of the month. This will mean another mild of push of air after the 27th and potentially another non-snow event before the new year. Ensembles are then suggesting the potential for temporary pushes of cold around New Years Day and beyond but it is vital we break the positive Arctic Oscillation and we have yet to see evidence of that.

Saturday, December 17, 2011

Change we can believe in ?? Not quite

We have made it to "the reprieve". The warm weather has finally given way to more seasonable temperatures but it remains extremely difficult to get excited about the outlook going forward. In short, the pattern continues to be plagued by many of the same problems discussed in the blog in previous entries. The repetition of these features, particularly in the Pacific is making me feel like a boxer against the ropes getting his head beat in as he tries to avoid a knock down. The next 10 or so days should be better verses what we have seen so far this December but I want "change I can believe in" to borrow the Obama slogan and I have yet to see it.

We finally have our hands on some arctic cold which is a start. As we move into Monday the cold will get re-enforced as a clipper system moves through the eastern Great Lakes and spreads what should be a light accumulation of snow to the region late Monday the 19th. This is not the system we have been watching however, that system will begin its journey in the southern Rockies, move into the Red River Valley later Monday and track across the rest of the country Tuesday. We should see precipitation from this feature either late Tuesday into Wednesday but although the track of this system is not nearly as unfavorable as previous, our supply of cold air will quickly become stale and will struggle to hold its ground. At best we can expect a wet snow out of this but it is possible for a changeover to mixed precipitation, freezing rain or even a period of rain. Everything should be over and done with by Wednesday evening and a gradual return to colder conditions.

The return to chill late in the week should be the start of another stretch of at least seasonable temperatures and possibly even below normal temperatures for a day or two. The return to chill late in the week might also include some type of mixed precipitation to snow event. This would likely take the form of a wave of low pressure energizing a slow moving cold front. This however along with the cold weather that follows should preserve the period between the 24th and 28th of the month which i know is a big one for vacation planners. During this period, there is no evidence of a major snow event but clipper systems and weaker features could certainly provide some fresh powder to the region Christmas Day or the two days that follow.

The brief amplification of a western North American upper ridge will play its hand in that aforementioned 24th-28th period but there continues to be a lack of evidence that this change will be of a permanent. Instead, the broader weather map reverts back to the features that have hurt us. Height rises and upper ridging in the Mid-latitude Pacific coupled with the potential redevelopment of an poler vortex over Alaska. These are the main ingredients to the zonal flow scenario we have seen now for 5 weeks. The Arctic Oscillation and North Atlantic Oscillation continue to run positive revealing the lack of blocking at high latitudes and it is only the PNA providing some support over the next 10 days that is providing any real aid.

Tuesday, December 13, 2011

Encouraging signs in some of the Ensemble data

Yet another round of mild weather and rain is poised to invade interior New England and specifically the northern Green Mountain chain. Temperatures will soar well into the 40's Thursday and we will have to endure a period of rain during the middle of the day. The weather system responsible for the rain will bring colder weather, much colder weather in its wake. We will finally start to benefit from the 80 percent frozen Hudson Bay and colder air will thus be able to access eastern Canada more freely and more vigorously and can push southward from there. Temperatures over the weekend will stay well below freezing through the weekend and a clipper system Sunday should spread a fluffy accumulation of powder to the mountains.

Our pivotal pre-holiday moment will come early next week, likely Tuesday, as the cold air relinquishes its grip on the region and a stronger storm system approaches from the southwest. There are questions about both the track of this system and the available cold air and I am certainly concerned about both. We have as you know, no blocking mechanism to keep cold air in place and the prevailing pattern and warm Great Lakes has constantly pulled these systems farther north and farther west. It is very possible if not likely that next Tuesday sees this very result. With all that said, models are still odds and have yet to settle on a solution and are allowing for the possibility of a more wintry scenario.

Tuesday is important because if we can get some snow or even sleet out of that system, the stage will get brighter. The European Ensemble which has been accurately predicting almost tropical weather for the northeast over the past 3-4 weeks is finally showing some key changes starting in the middle of next week. It is not total vindication but the pattern will get an important boost from at least the temporary establishment of a western North American upper ridge. This should send some rather impressive shots of cold deep into the U.S. as we approach Christmas. The polar vortex in Alaska will also weaken at this point allowing the Jet in the Pacific to relax. The pattern in the Pacific is still disconcerting. It will still feature a lot of this Jet Stream level warmth referred to as ridging. Last year the Pacific was surprisingly unstable at mid-latitudes and this was attributed to the highly negative AO which dominated the weather pattern for December and January. Going a little deeper into the world of "geek speak" meteorologists talk about the formation of a high latitude "block' as a stratospheric warming event. A sudden warming of the stratosphere signals the formation of a high latitude block and thus signals that there will be a major southward transport of arctic air somewhere. The stratosphere which has been very cold so far this winter is expected to see such an event in the next 7-10 days. The phenomenon can only be viewed in general terms and does not reveal specifics. All we know is that the atmosphere will get shaken up, at least a little as we get toward the holidays. Given what has happened so far, we have little too lose from such a shake-up.

Saturday, December 10, 2011

In search of the lost cold - extended version

In short we are continuing to get really hurt by jet stream level warmth in the mid-latitude Pacific. It continues to be one of the biggest features on the globe and it continues to haunt MRG and surrounding Vermont encouraging frequent warm-ups, rain events and an inability to build an early season snow-pack. These struggles will continue through the holidays thanks largely to the Pacific issues and the Arctic Oscillation which will remain mostly positive for the next two weeks.

The next few days will remain mostly below freezing, at least in the high country. By Thursday however, another push of mild weather will precede what appears to be a rain event. A better track might allow for a period of snow with this system but the Great Lakes aggregate continues to be warm relative to average, 7-10 degrees warmer than average in fact and that often induces low pressure centers in the center of the country to track toward the Great Lakes and thus bring milder weather ahead of the track and deep into New England. We will find some lost cold behind this system, a legitimate shot of arctic air in fact by next weekend and the coldest weather of the season so far. The Ensembles beyond this time frame however are not painting a pretty picture however. Specifically one that still includes the above-mentioned features. I would thus guess that although we may see some snow between the 17th and 19th of the month we are likely to see another warm-up prior to the holidays

Monday, December 5, 2011

Its looking better, at least a little

For one thing, we will get a reprieve from the sustained warmth which has plagued the region throughout November into the early part of this month. More generally speaking the teleconnection indices which have been quite disruptive particularly in recent weeks will also take a break There is no evidence of a decisive shift toward a "blocking" pattern of some variety, but a relatively neutral AO and slightly positive PNA will be just enough to at least get the ball rolling in the right direction. The first chance for significant snow is a very long shot. If it happens it will come from a wave of low pressure forming along the slow moving front to the regions south. If any real snow is to occur from this, the storm will need to intensify much quicker than what is currently indicated; otherwise, the storm will bring precipitation, and mainly rain to coastal cities.

A clipper system will arrive late Friday in advance of a much more substantial shot of chill, the first chance we will have of seeing temperatures lower than 10 F. A few inches of snow are possible from this before temperatures take this plunge. Thereafter, the pattern will be anchored by a classic La Nina style upper ridge in the Gulf of Alaska which is traditionally a dangerous place for such a feature. Thus, the risk remains for a early week warm up and non-snow type of event between the 12th and 14th of the month. Recent medium range model runs however have suggested that cold weather will grip a large portion of southern Canada and will keep us in the game so to speak. Any warm-up next week will likely be brief and my not occur at all. Cold weather will then overtake the region again after 15th and should grip the region for at least a 4-6 day stretch. It may not be a home-run forecast but at least an improvement over what we have seen.

Another positive development is the speed at which the Hudson Bay is freezing. Cold weather has gripped that region of Canada and that large body of water is on pace to freeze in a week to 10 days. This would be several weeks earlier than last year and will allow unmodified cold weather to move into eastern Canada a lot more freely. This is a critical thermal feedback that we will need to work in our favor if we are to proceed into the heart of this winter without any high latitude "blocking" to assist us.

Saturday, December 3, 2011

Another week of mild weather coming

A few days ago I broke down and bought "The Last Waltz" on blu-ray. This is a concert/documentary by Martin Scorsese on The Band's last performance in late 1976 at the Winterland Ballroom in San Francisco. I can't claim to be a die-hard fan of "The Band", admittedly it seemed far removed from my generation but in the end I was completely blown away. It really is an organic music experience like no other I think. The incredible collection of musicians, the assortment of musical styles and influences ranging from jazz to country/bluegrass to blues to straight up rock and the sincerity of the interviews and performances are really hard to match. Sadly it all especially rings true in an environment watered down with the likes of Katie Perry or the other mass-produced pop music filling the airwaves. Especially for those generation Y2k's looking for something "real", go out and get your hands on "The Last Waltz", its a real piece of musical Americana. The irony there is that "The Band" is Canadian and the concert includes American musicians paying tribute to their contributions to music.

I can't speak so positively about the weather at MRG over the next week. Mild air will work its way back into the region later Sunday and into Monday. With that will come the rain which will in association with a slow moving front. The rain will be off and on between Monday and Tuesday night totaling between .50 and 1 inch total. Colder weather then arrives Wednesday night with flurries and snow showers but even this cold will fail to bring temperatures back to normal and might also give way to another mild push and rain for next weekend although this remains a question mark right now.

About the only thing we do know for sure beyond a week is that we will see a more serious punch of cold weather late next weekend after another rain or mixed precipitation event next weekend. Several runs of the European Ensemble have suggested that the very positive AO will continue to rule the day allowing the cold weather next weekend/early next week to lift and opening the door for more mild temperatures and potentially more rain. The GFS and its ensembles suggest otherwise; in fact, the GFS is so dramatically different beyond the 12th of December allowing arctic cold to completely overwhelm the pattern. This evolution is supported by a developing La Nina style ridge in the Gulf of Alaska and allowing the downstream trough to become expansive enough to cover most of Canada. It defies my sense of reality but it is nonetheless encouraging. It would be realistic enough to expect cold weather to expand its influence across Canada and at least become somewhat accessible to northern New England. I would not expect cold weather to be as persistent as what the GFS suggests beyond the 12th of the month.