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Friday, January 19, 2007

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


ricardo said...

you're the best!

Tin Woodsman said...

Josh -

Thanks for the thoughtful commentary. I find my self disappointed in your analysis of the short term events. You speak of the potential for 3-5" coming from the clipper now passing through, yet you make no mention of the wrap-around/upslope snow we we are certain to see over the next 36 hours. This is strange because the SB/MRG region already saw 2" form the primary coastal low this morning along with another 2" from the incoming clipper that has a long fetch of moisture to our west. Moreover, how do you neglect the impending upslope event entirely when by all accounts that will be the primary snow maker in our region throughout this weekend? I think your call is FAR to conservative, and this isn't just a matter of wishcasting. We're already at 4" and counting!

Joshua Fox said...

Tin Woodsman,

Thanks for your comments. My forecast called for 4" or more between Friday Night and Saturday and made no mention of Friday. I specifically didn't include Friday because it was already half over and by the time most readers see the update the first period in question will be Friday Night.

I am delighted to see MRG and the rest of Vermont do well Friday but its important to note that none of today's snow fell as a result of the coastal. Check out the intellicast 12-hour loop for today, its very revealing. The coastal did in fact shift the focus of precipitation to down-east maine by the afternoon but the decaying clipper used the unfrozen lakes to help bring snow back into Vermont. The oragraphy certainly enhanced the snowfall but with Burlington (elevation 400 feet) receiving what looks to be a few inches, I think its fair to say that there was a more synoptic force at work here.

Your comments regarding upslope flow over the next 36 hours. The 4 inches or more that I am predicting Friday Night and Saturday are a result of upslope enhancement. I specifically said that the NWS forecast has the best chance of working out at high elevations including MRG. Perhaps I should have spelled it out further.

Lastly, I know that there are, and you may be one, who are very sensitive about what I write here. The Vermont ski industry is in a precarious spot with the winter we have had to-date and my short term forecast may have downplayed the 4 inches that fell today. For this I apologize but since I do this voluntarily and do not work at the pleasure of the ski industry then I am not committed to hype weather fot its sake.

Your comments may simply be constructively critical which is fine. I freely admit that I am not the best short term forecaster in the world. Its simply not something I have a daily practice in such as an NWS employee would. My 6 years of experience in the energy industry though gives me more credibility when looking at the big picture and it is here where I hope to really add value to the MRG community. The medium and long range, the various forcing mechanisms whether they be hemispheric or more on a continental scale is something I have a lot of practice in since I work with natural gas and power traders on a daily basis. If your interested in weather, and it sounds like you are, I would certainly advise looking at the local NWS AFD's and combining this with some of the insight that I have to offer.

Have a good weekend and enjoy the powder if you can !

mark said...

Jesus tin....lighten up warden.... I think Joshua put together a pretty consise report ....lots of possibilities laid out and I enjoy his thoroughness .....thanks Josh
Im over in Portland ME and we got skunked on this last one....hopefully soon winter will come!