Think Snow, Tweet Snow !!!

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.

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