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January 2016 Pattern Disco


Damage In Tolland

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Someone a while ago said, 'ho-hum' in deference to the pattern through mid month, and I couldn't disagree more.  i don't have to time go back through - just a statement i noticed. 

 

Ahh gotcha.  I thought it was about the cold air on the EURO that Will and I were talking about that you disagreed with.

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Ahh gotcha.  I thought it was about the cold air on the EURO that Will and I were talking about that you disagreed with.

 

heh, that's part and parcel to the excitability of it all... but, understood that some enthusiasts in weather are particular and don't share that fascination for broader spectrum of events - tru dhat. 

 

If we got a bear ground 0 F day tho - Wow!  ...heck, that'd be amazing at 9 F

 

although, we could be perfectly situated for something like that if continental snow is near the door step, and mother nature leaves the door open - nice

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We see it all the time...if you get an airmass that drops south into the lakes/OH Valley and then eastward, that's a much worse delivery for us. Straight out of Quebec or Eastern Ontario is optimal. The fact that the major mountain ranges run mostly north/south makes for much more optimal cold delivery when the airmasses run north/south parallel to the mountains.

Well there's a couple of different issues here:

 

(1) the average elevations of the source regions for our cold is pretty much 2000ft across the board, whether its the Praries, Quebec, etc.   

(2) but that's not the end of the inquiry.  the issue here is that the air has moisture.

(3) the single most important way that our arctic air masses get modified is the lakes.  The lakes modify the air masses in two ways.  First, and most importantly, they add moisture to the air (more on this later).  Second, and less importantly, they directly warm the air.

(4) The moisture added to the air ends up warming the airmass through latent heat release.  The N/S or NE/SW trending ranges between us and the Lakes squeeze out much of the lake moisture and that's why the downslope is warmer.  Adiabatic heating doesn't alter the characteristics of the airmass without a moisture source.

(5) The N/S or NE/SW trend of the ranges tends to encourage shallow drainage of cold air (and damming of cold air in certain conditions) but doesn't really modify our coldest airmasses. Pretty much any trajectory you can model involves a parcel of air sinking and rising and sinking 1500 feet between the source region and the coast.

(6) snowcover also prevents modification of airmasses from the reradiation of heat energy absorbed from insolation

(7) A NNW-NNE trajectory minimizes time over bare ground, mostly, and avoids the lakes.  That's why it delivers the best cold.  That would be true even if the mountains weren't there.  

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Well there's a couple of different issues here:

(1) the average elevations of the source regions for our cold is pretty much 2000ft across the board, whether its the Praries, Quebec, etc.

(2) but that's not the end of the inquiry. the issue here is that the air has moisture.

(3) the single most important way that our arctic air masses get modified is the lakes. The lakes modify the air masses in two ways. First, and most importantly, they add moisture to the air (more on this later). Second, and less importantly, they directly warm the air.

(4) The moisture added to the air ends up warming the airmass through latent heat release. The N/S or NE/SW trending ranges between us and the Lakes squeeze out much of the lake moisture and that's why the downslope is warmer. Adiabatic heating doesn't alter the characteristics of the airmass without a moisture source.

(5) The N/S or NE/SW trend of the ranges tends to encourage shallow drainage of cold air (and damming of cold air in certain conditions) but doesn't really modify our coldest airmasses. Pretty much any trajectory you can model involves a parcel of air sinking and rising and sinking 1500 feet between the source region and the coast.

(6) snowcover also prevents modification of airmasses from the reradiation of heat energy absorbed from insolation

(7) A NNW-NNE trajectory minimizes time over bare ground, mostly, and avoids the lakes. That's why it delivers the best cold. That would be true even if the mountains weren't there.

It's not that complicated. Lakes not the issue.

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It's not that complicated. Lakes not the issue.

 

OK.  FWIW, this was my final project in one of my atmospheric science classes back in grad school.  It's the lakes more than anything else, which is apparent if you spend more than a few second modeling parcel trajectories.

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It effects it to a point, but it's not the main reason for a deep layer airmass to modify in SNE.

Yeah I don't see how you could say which is the main reason with out significant studying of it. The last thing to modify an airmass would certainly be the terrain, but who knows how much it already modified upstream over the lakes. That still might have modified it quite a bit and then the terrain is the final variable.

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Yeah I don't see how you could say which is the main reason with out significant studying of it. The last thing to modify an airmass would certainly be the terrain, but who knows how much it already modified upstream over the lakes. That still might have modified it quite a bit and then the terrain is the final variable.

The Great Lakes are not a huge area filled with water. Maybe if you had a small pocket of cold right over the lakes, but air masses are large and would only get an influence from more westerly flow. When you look at the air masses that modify on west flow, it's usually from downsloping as the greatest influence. 850 temps won't modify much and you can actually lose the lake modifying influence as you move east, just like you would with a chinook wind.

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Yeah I don't see how you could say which is the main reason with out significant studying of it. The last thing to modify an airmass would certainly be the terrain, but who knows how much it already modified upstream over the lakes. That still might have modified it quite a bit and then the terrain is the final variable.

 

 

Having gone to school at Cornell in Ithaca, NY, we looked at airmasses all the time and how they modified over the lakes. I can tell you that on WNW or W advecting airmasses, the cold in ITH was significantly more impressive than, say, ORH despite ITH still being east of the lakes. The crossing of the Catskills and Berkshires is a significant hindrance to airmasses for SNE.

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Having gone to school at Cornell in Ithaca, NY, we looked at airmasses all the time and how they modified over the lakes. I can tell you that on WNW or W advecting airmasses, the cold in ITH was significantly more impressive than, say, ORH despite ITH still being east of the lakes. The crossing of the Catskills and Berkshires is a significant hindrance to airmasses for SNE.

Yeah. With all due respect to DRZ, I just don't agree.

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Yeah I don't see how you could say which is the main reason with out significant studying of it. The last thing to modify an airmass would certainly be the terrain, but who knows how much it already modified upstream over the lakes. That still might have modified it quite a bit and then the terrain is the final variable.

 

Cold air that builds up at, say, 60N and then reaches us after passing over Superior/Huron has traveled over 2,000 miles to get to my region.  That same airmass coming S or SSE from Quebec may travel less than half as far.  Less time at lower latitudes might be the biggest factor, at least to this amateur.

 

In any case, the cold is good, especially after the past few weeks, and if the cold becomes dominant, storms should follow.

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Yeah. With all due respect to DRZ, I just don't agree.

 

 

There's a compressional heating element you have to add in addition to just losing altitude...the parcel loses 2000 feet, but if you are compressing that loss into a smaller zone, then you dry out and heat the air at a greater rate.

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Cold air that builds up at, say, 60N and then reaches us after passing over Superior/Huron has traveled over 2,000 miles to get to my region.  That same airmass coming S or SSE from Quebec may travel less than half as far.  Less time at lower latitudes might be the biggest factor, at least to this amateur.

 

In any case, the cold is good, especially after the past few weeks, and if the cold becomes dominant, storms should follow.

 

 

The distance is definitely a huge factor.

 

The Great Lakes though only modify it so much...as I noticed when I was out in western NY how Ithaca would frequently get the better of an eastward advecting cold airmass...even if there was full snow cover between there and ORH.

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There's a compressional heating element you have to add in addition to just losing altitude...the parcel loses 2000 feet, but if you are compressing that loss into a smaller zone, then you dry out and heat the air at a greater rate.

Hence why westerly flow over the Berks is terrible. You can't just modify a deep layer cold airmass from conduction of heat over a small area of water.

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