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Thursday, March 27, 2008

No rain this weekend but new snow will be limited

And it's somewhat disappointing to watch what was a borderline rain/snow event turn into a non-event. We have entered a pattern however where, with the help from the mostly negative NAO, most of the our potential weather makers have tracked further south verses some initial indications. As frustrating as this may be for the weekend, we are going to once again call on the NAO for some first aid next week as it looks like a couple of systems will need to track a bit further south in order to deliver us our much needed goods.

What our weekend storm will do
The weekend system in question exists as a result of a rather intense temperature contrast which stretches right across the middle of the country. The temperature contrast is often referred to by Meteorologists as a natural zone of "baroclinicity" and a baraclinic zone can be described as an area ripe for storm system development. And yes a storm will develop, but from an organizational standpoint it will fail to mature and will merely move east in disjointed fashion. Moisture from this system will arrive on the east coast as early as Thursday but will struggle to push north into Vermont. A period of snow is possible early Friday, perhaps enough for a light accumulation but later on Friday much drier air will prevail across the state and precipitation will be forced southward. The outcome for the weekend appears cold relative to normal and much drier relative to a few days ago. There is still enough low level instability for flurries throughout the day Saturday but the snow should not amount to much. Temperatures will struggle to reach the freezing mark on Saturday but should do so and then some on Sunday allowing for a bit of softer snow in the afternoon.

The next week looking glass
There are some competing forces in the pattern as we head into early April. We will see a substantial block develop across Greenland which will help to amplify the already negative NAO. At the same time however will be for the formation of a large trough across the west coast. The result will be a zone of above normal temps across the Plains which will at times try and extend eastward. One of these times will be during the arrival of another storm system early next week. This is why the NAO could prove to be instrumental here since this particular storm will need to trend south in order to provide us with any snow. We will be dealt a similar hand regarding yet another system which will impact the region in the time frame of next weekend. In between, I would expect temperatures to be a little below normal but in early April this can still mean well above freezing for afternoon high temperatures.

Sunday, March 23, 2008

Our "big event" is way out to sea but we still are good for at least one powder day this week

And now that we finally have some support from our teleconnection indices, the east coast is seeing its most widespread outbreak of cold air since the middle of January. As it turned out, MRG didn't actually need this support but we nonetheless had to live on the edge with every storm and snowfall totals for the nothern part of the state this season were much greater than the southern part. As for the system early in the week, no part of the state is going to come out on the winning end of that one. The axis of the upper air support is simply too far east and changes in the pattern across the northwest part of the nation are going to force any storm on the playing field to continue moving east rather than north. The Greenland Block (-NAO) which was an important factor in the powder we received on Thursday and Friday is actually expected to weaken early this week but return in a weaker state next weekend. This would mean that winter is not quite finished with us yet.

The Powder Day - Wednesday is your best shot
More instability flurries and even a few snow showers are still possible Sunday and Monday although accumulations will be minimal if any and there will be intervals of sunshine through it all. On Tuesday we should see any morning sun give way to an overcast sky as a clipper system moves quickly through the Great Lakes. This system, as far as clippers go, actually does have some moisture and will begin depositing it on the mountain Tuesday evening in the form of snow. The pattern will continue to be progressive through the mid-part of the week meaning that the system will say good-bye almost before it says hello. The storm will however leave a pocket of instability in its wake and snow should continue for at least half the day on Wednesday. Between the 3-5 inches that falls Tuesday night and the additional 2-4 which is possible during the day on Wednesday, it seems that Wednesday is our winner as far the choice of ski days is concerned.

Next Weekend
There is yet another more significant storm or even a series of storms on the weather map late this week and into the weekend. The weather map actually has a very familiar look to it as the set-up appears oh so similar to the many systems which have impacted Vermont this winter. An amplifying trough in the west, a tight north-south gradient of temperatures in the east and a storm which could either track over southern New England and deliver us some snow or across the St Lawrence Valley which would thus yield a much less appetizing result. One encouraging aspect is the NAO which will be in the process of moving back into negative territory at this time and may help push this storm to the south. At this time, it does appear as if clouds and a period of snow is likely during the day Friday; thereafter, we could see a wide range of outcomes depending on the eventual track of the system). By Sunday, a return to colder weather is likely which would include the chance for TIS snow showers.

Early April continues to look on the chilly side of normal, at least until April 3rd or 4th. MRG's grand finale was April 7th and 8th last year and there are no spring thaw's on the horizon that would prevent the season from extending at least that far this year.

Wednesday, March 19, 2008

Friday's our best shot for a powder day

The NAO did its best and our midweek storm is now indicated to track over southern Vermont as opposed to the St Lawrence Valley. Still, we have the glaring lack of fresh cold air on the front flank of this system and this will hurt us as far as Wednesday is concerned. As advertised, the storm will slow its eastward progress over Nova Scotia and this will allow for the extended period of enhanced TIS activity I was hoping for.

The specifics
After a few inches of wet snow early Wednesday, we get a period mixed sleet and rain which will persist into the evening. After that the precipitation becomes more showery (in the form of rain) until the passage of the storms associated front and the arrival of our long awaited supply of cold. The snow showers will intensify gradually and temperatures will become cold enough during the evening for an accumulation of powder. It is easy to land yourself way off course when trying to predict amounts in these situations but my best guess is anywhere from 4 to 10 inches between late Thursday and late Friday. Low level instability is actually indicated to linger through the weekend although the depth of the unstable layer is expected to gradually decrease. This essentially means the snow showers will become less frequent and will be less intense. Still, we could see flurries all the way through Sunday.

Still watching early next week for the possibility of a big system

The system for early next week appears to be a "snow or no" situation which is rarity in this winter season. Most of the model guidance has been indicating that the trough may be too overwhelming to allow the storm to track close enough to the coast. That being said, the last run of the European model was flashing big event and the American model had the storm much closer to the coast verses its own prior indication. This will be worth a close watch as we do tend to see longwave troughs with shorter wavelengths in March as opposed to December in January. The timing of all this would have the impact of the storm beginning late Monday and persisting through Tuesday. Plenty of questions remained unanswered however and our chances for a big dump are still somewhat less than 50 percent.

A worst case scenerio for early next week would still allow for some new snow from a clipper system. There remains strong indications for a temperature moderation later in the week as the strength of the negative NAO and associated blocking begins to subside.

Monday, March 17, 2008

Midweek storm to start as rain and will hopefully end as snow

Its time to focus on what looks to be a powerful midweek storm system. In this La Nina year we have at times been dealt very little in the way of cold air as the many storms have approached. This is yet another case where the cold weather will remain focused on the western flank of the storms center. Precipitation will arrive Wednesday and any remaining cold from the weekend will by then be quite stale and allow precipitation to be a mix of sleet and freezing rain by around first tracks time. After that it is likely we are going to have to brave a period of rain.

Some details
Fortunately we have the NAO and a strong block at the southern tip of Greenland to help us. There is still time in fact for the storm which is currently indicated to travel through New York and into Quebec to track further south and thus improve the outcome. If that fails the aforementioned block will allow our storm to intensify while it slows its eastward progress across the Canadian Maritimes. This provides an extended opportunity for terrain induced snow as cold and instability combine with the lingering plume of wrap-around moisture. This outcome if it does occur would have the rain turn to snow showers late on Thursday and persist into Friday. In summary, it is going to be hard to turn Wednesday into a powder day as this appears to be the wet period for us. Thursday into Friday are a different story and a subsequent update will detail amounts and timing.

A cold weekend with another storm to watch
We are still on target for a period of below normal temperatures through the upcoming weekend. This is in association with a large upper trough which will allow the cold to extend fairly deep into the south. Models have been back and forth regarding our chances for precipitation. Specifically, there is another system that bares watching as it tracks through dixie over the weekend and prepares to make some sort of left turn on Sunday. Its eventual interaction with the Atlantic Coast and movement thereafter will have, as you might be able to guess, a profound impact on the big snow potential as we head into the early part of next week. At the very least, it appears as if the colder weather will remain in place through the middle of next week with a modification to follow during the middle of the week.

Friday, March 14, 2008

Some snow for the weekend and it gets more interesting next week

The developing block in the North Atlantic Ocean, the catylist for the sinking NAO, appears to be doing its job. Our weekend storm will get deflected to the south thus eliminating the chance for a prolonged period of rain or ice. Instead, the snowflakes should be flying through the early morning Saturday and should leave us with a few inches by first tracks time (3-6 for a storm total). Now we are not working with much when it comes to the cold air. Temperatures will be within a few degrees of freezing through Friday night and into Saturday and this means the snow will be of the more wet variety, particularly at the low elevations. The various pieces of this storm (and there are a few) will fail to align themselves until the system is well off the New England coast. This means that a big event is not likely for any of the Vermont ski areas. That being said, the storms upper air support will swing though Vermont on Sunday and should act to enhance the TIS activity. Sunday will also be blustery and colder and should allow for accumulations to be more powdery in character. It doesn't appear as if any of this snow sunday will be available for first tracks time but its hard to say for sure.

The snow on Sunday will continue into Sunday night and with the help of strong winds, should allow for at least a minimal amount of untracked powder Monday. The winds will subside by Tuesday and the cold will also modify but the questions and uncertainty begin to mount as we head into later Tuesday and the middle part of the week.

Mid-week storm or a crap-out
There is agreemeent next week on a split flow situation in the jet stream and by the end of the week, the formation of a large eastern U.S. trough along with a widespread area of below normal temperatures. The disagreement involves the handling of a very strong feature in the southern branch of the jet stream and it particularly relates to the speeed of this feature. If it successfully speeds into Texas by late on Tuesday then a phase with a developing trough is likely and would thus mean a big mid-week event MRG and surroundings. If this critical southern branch feature lolli-gags in the southwest then the pieces won't fit. Either I think some snow is likely with a powder day later in the week. The "big event" scenario would actually include some rain or mixed precipitation at the onset with a change-over to snow. What is particularly encouraging is that the NAO-block would force any storm to linger in the Canadian Maritimes and allow for a longer period of TIS activity. What is discouraging is that the American Model seems convinced on the big event while the European says "no dice". The European has the better track record in the 5-7 day forecast period but every dog has its day and nothing in the prognostication game is ever certain.

Long Range Notes
The period from the 20th to the 25th which includes a weekend will be a cold one relative to normal thanks largely to our NAO teleconnection. The eastern trough will in fact be large enough to allow cold air to envelop quite a large area of the eastern United States and eliminate the southern branch as a producer of storms. Precipitation which may be somewhat limited but will fall as all snow in this period and will fall as a result of clipper systems and other TIS enhancers. Winter is certainly not over and next weekend will prove it.

Monday, March 10, 2008

NAO on its way down and we hope for results sooner as opposed to later

Some help does arrive Wednesday in the form of a classic Alberta Clipper which will dive southeast into interior New England. Clouds from the system arrive Tuesday night and snow should begin to fall just before dawn Wednesday. This system is limited in its supply of moisture but we will do our best at MRG with an inch or so by first tracks time an an additional few inches during the ski day. I might add that we will get some help Wednesday by TIS and will thus allow accumulations in the mountains to be higher than the dusting to an inch that is likely to fall in Burlington.

Questions remain for the weekend

We will see a gradual erosion of the cold air as we progress into the late part of the week. The trend toward milder temperatures will precede the approach of a more significant storm system. The events surrounding the storm will get kicked off with a bit of wet snow on Friday which may turn to some rain early Saturday. At this point however we hope the NAO begins to intercede on our behalf. A negative NAO can act as an effective mechanism for deflecting systems to the New England coast and thus allowing the would-be rain event to become snow. Since most of the cold air associated with the weekend system sits behind the storm in the Midwest we will have to hope that the storm pulls the cold into Vermont while the system intensifies as it interacts with the Atlantic Coast. This would result in a change to snow on Saturday and some accumulations both during the day and at night. Models have been hinting at such an occurrence sporadically but have yet to provide any definitive answers. Lets just say this could go either way.

Another system, another chance - the active weather continues

A repeat performance appears to be the setup for the middle part of next week and let me just say there is no rest for the weary on the SCWB. Very incredible the active weather which has prevailed which includes one system after another and all with varying impacts on the mountain. That is the best excuse I have for some of the wrong turns I have made in the forecasting game. In the case of next week, there remains much in the way of potential but with most of the cold air to the west of the system we will need a track close to or off the coast. I put a lot of faith in the NAO in terms of its ability to scratch out a few victories for us and it will have another chance to do just that during the middle of next week.

Friday, March 7, 2008

The board is set for the weekend...

and it does not appear as if the storm will track far enough to the east for an all snow event. Precipitation may begin as a bit of snow Friday evening before going over to a sleet/freezing rain mixture overnight. This is a very powerful storm although appears that it will occlude before reaching interior New England. This means that the very warm temperatures will get pinched off well to the south and temperatures will be limited to within a few degrees of freezing Saturday. There will be nasty squall line which will include some heavy precipitation and even thunderstorms. I think this will begin impacting Vermont late in the day Saturday as either rain and/or rain and some sleet. At around midnight on Sunday, we will finally get the necessary cold weather to turn it all to snow. The snow should be of the steady variety for a while and then become more sporadic in intensity during the day Sunday. As damp as Saturday could be, Sunday can still be powdery and my very rough guess has the mountain getting 4-8 inches between midnight Sunday and the evening. This will be accompanied by the wind and sub-20 degree temperatures that I had mentioned in the last post.

So to summarize, no significant new snow for Saturday and we will instead get a sleet/freezing rain mixture that will eventually become a rain/sleet mixture. The precipitation will be heavy late in the day.

Sunday features some fresh powder to ski in and snow showers for a good chunk of the day. Obviously much will depend on the amount of powder we get Sunday as it relates to the quality of the skiing. That rough guess of 4-8 inches is what it is "rough".

Wednesday, March 5, 2008

Major jet phasing for the weekend but the news isn't all good

If you can remember back to your days in Physics class (or for some of you that may still be yet to come), recall the lesson on interacting waves and the meaning of destructive and constructive interference. When jet phasing is mentioned in the blog the analogy is most appropriate and it refers particularly to the constructive interference part. Jet phasing is often times very exciting to us skiers as talk of a big storm is often a big part of the discussion. The jet phase this weekend is certainly no exception as the amplification this weekend will spawn the rapid development of a low pressure system along the Gulf Coast. This storm system will be a big and in some cases violent weather producer as I fully expect a major severe weather outbreak in portions of the southeast including damaging tornadoes.

The storm and its possibilities

By the time this storm begins impacting northern Vermont it will quite a beast but size is not everything, we still need a somewhat favorable track and an adequate supply of cold air. In this case both leave something to be desired. Model guidance, with the exception of the Canadian model seems convinced that the center of the storm will take dead aim at interior New England. Meanwhile, the cold weather continues its 2007-2008 Midwest bias and is not where we need it to be while precipitation is the heaviest. In spite of all this, it will not take a major shift in the track to greatly improve the outcome. If the current consensus has the the storm tracking from Harrisburg, PA to Fryeburg, ME and the ideal track would have the storm tracking from Atlantic City, NJ to Boston, MA then we are not talking about a great distance. A shift of less than 200 miles to the east would in fact make all the difference.

More specifically
So now to the specifics which are of course contingent on some of the above lingering questions. Thursday and Friday at MRG will both consist of some pleasant afternoon skiing as temperatures warm to well above freezing along with light winds. Clouds will be on the increase late on Friday and precipitation will arrive late on Friday evening. If the storm were to follow its current indicated course then any initial snow would change to a sleet/freezing rain mixture during the overnight and to plain rain or drizzle by first tracks time Saturday. The precipitation on Saturday would be showery in nature and could include a clap of thunder as the front associated with this powerful storm nears MRG. A storm track more to the east would include more snow of course and much less of what was detailed above. Even the more adverse track however would include the eventual invasion of much colder temperatures and a significant period of wrap-around precipitation. Would it be enough to turn Sunday into a powder day even if we crap-out on Saturday ? Absolutely yes although Sunday will be quite blustery and as I mentioned much colder (temps in the teens).

Long range notes
A clipper system of uncertain significance will be the next weather item of note during the middle of next week and this will be followed by milder weather and perhaps another non-snow precipitation producer around the time of March 15th. With that said the long range is starting to take on a different look as for the first time this season we are seeing indications of what could turn out to be a major block over Greenland. Such a feature could be the catalyst for a big finish to the end of March and easily could push the seasonal snow total to over 300 inches. And yes I am aware that there are those mocking the seasonal forecast of 200 inches and would prefer to revert back to the farmers almanac which is fine with me btw. Just remember that I have said many times that the seasonal outlooks are about 55 to 60 percent accurate which means rolling the dice is almost as good (this is pretty much what is done at the farmers almanac).

Sunday, March 2, 2008

Big time icing a real possibility Wednesday

And I know a lot of us in Vermont eye the first Tuesday in March as not only a way to honor the great tradition of Town Meeting Day but to also sneak out to MRG and enjoy a powder day. If memory serves, the last few Town Meeting Tuesday's have been of the powdery variety and it brings out the crowds. The one exception would be last year where it was -20 all day which proves to be a bit rough for even the most hardiest of us skiers. Give credit to Ben Hewitt however who did the great feature on the coop in Ski Magazine and was willing to make a few turns with me on that very cold day last year. This year will be quite different and certainly not powdery. After a cold start to the day Monday, temperatures will warm dramatically and should be several degrees above freezing during the afternoon. Tomorrow could be a great spring skiing afternoon so long as the area of clouds and even mixed precipitation which could prevail in the morning, move away during the afternoon. This is my expectation anyway and the morning clouds (and possible precipitation) should give way to sunshine which should fuel the snow softening.

Town Meeting Tuesday

The problem with Tuesday is not the mild weather but rather the rain which should begin falling in the early morning and continue through the early portion of the ski day. If we can somehow dodge the rain, which seems very unlikely right now, we would have an additional day of good spring skiing but at this point it is fair to expect at least a quarter of an inch of rain followed by a period of dry weather beginning in the afternoon.

Icing on Wednesday ?
The period of active weather continues into Wednesday as a moist system approaches from the Gulf States. I had mentioned in the previous post that we are in desperate need of some cold air to inject itself into this system. There is a minimal amount of arctic cold in interior Quebec and it will make a low level push southward late on Tuesday. As this is happening however, we will see conditions in some critical mid-layers of the troposphere warm. The set-up is thus very good for some significant icing on Wednesday. Precipitation will begin, perhaps as a little snow or sleet, very early in the day Wednesday and continue into the early afternoon mostly in the form of freezing rain.

The weekend of the 8th ad 9th

The pattern does take a turn for the more favorable later in the week in response to a deepening eastern U.S. trough. This turn however appears more gradual as opposed to abrupt and it may take a few days before we see new natural snow. There are series of impulses within this trough and the passage of each of these will bring colder weather to the region. The first such "post ice-storm event" arrives Thursday and precipitation from that will be of the rain or wet snow shower variety. Colder weather Friday and the arrival of yet another disturbance should at that point bring some snow although its difficult to envision amounts. Additional TIS type snow is possible Friday night into early Saturday and with the colder weather in place, it could set us up for a decent day of skiing.

Long Range
The ridge west/trough east regime should get one more re-enforcement early next week which offers the possibility of some additional new snow. The teleconnection indices are not favorable however and with no mechanism in place to keep existing cold in place or force new cold weather southward, we should see a trend toward significantly milder weather by the end of next week. Any system toward the middle or end of next week could still bring snow but it might be asking a lot to say that it looks good for powder since the snow could be wet in nature.