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Feb Long Range Discussion (Day 3 and beyond) - MERGED


WinterWxLuvr
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9 minutes ago, high risk said:

         Agreed, Bob.    This one has high-impact potential for a lot of people here, although the 12z Canadian now has a very different solution, so I don't think that the synoptic details are totally locked in yet.

Truth. Nailbiters and living on the edge is our predefined specialty in the mid range.

The overrunning stripe is quite narrow in all guidance and it's a club sandwich of ptype south to north. Staying all snow requires someone to be on the tiny slice of the already narrow slice thru the duration. Tall order as the stripe will wobble up and down as slp influences flow. 

CMC is different but still shows the W-E aligned boundary like the other globals. That orientation is very encouraging. If it morphs to sw-ne it will quickly take the wind out of our sails and the ice out of our yards. Fun week on tap!

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Larry Cosgrove = Pants Tent :lol:

 

“There is no fighting the notion that most of the lower 48 states are going to get swept up by the Arctic regime now descending from Canada. But there are questions about storm potential, especially regarding track and type of precipitation. Let me remind you that all of the numerical models show at least one massive disturbance passing out of the southern Rocky Mountains in the 6 - 10 day range. The ECMWF scheme is reluctant to allow the intense cold to reach the southern and eastern tier of the nation, which the GFS series is more aggressive and brings the forward edge of the cAk readings all the way into the Interstate 10 and 95 corridors. In effect, only California and Florida dodge the proverbial bullet.
 
It has been my experience that the American scheme handles cold advection much better than its European counterpart, particularly when a true Arctic air mass is involved. It is a judgment call, but the regime over North America is arguably the coldest in the Northern Hemisphere and will continue with that dubious title for the rest of the calendar winter. This is important because the path of storms in the medium range will likely be suppressed into the northern Gulf of Mexico and then up or off of the eastern Seaboard. I can see a scenario where the southern rim of the U.S. has a rain ending as an ice event, while snow deepens from the Great Plains into the Mid-Atlantic and New England states. Much of this is up for grabs, mind you, but the emergence of renewed blocking in Greenland, agreed upon by all of the computer models, will favor a lower latitude trajectory of impulses in the Arctic, polar, and subtropical jet streams. And the most obvious candidate is the broad cyclonic circulation below the Aleutian Islands
 
I note that most of the ensemble packages show yet another shortwave from the northern Pacific Basin getting caught up in the deviated jet stream configuration, with another deepening storm in the Southwest seven days from now. We have to watch this feature carefully! I can see a track scenario taking shape where the system drops into northern Mexico, then moves along the Gulf Coast,m and then close to and likely just to the right of the Eastern Seaboard. around February 14 - 17. This is the type of set-up that -could- produce a true monster winter weather event, with the Arctic motherlode being pushed into the Great Lakes region and phasing with the low pressure area. The vast expanse of cold is worrisome since actions like overrunning and cold instability will interact, with a wider coverage of precipitation types than is normal”

 

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7 minutes ago, WinterWxLuvr said:

Question, when you get these boundaries separating warm arid from very cold air, does the converging winds at 850 as illustrated in that map above create a zone of enhanced lift/precip or is that level too low for that?

It's def part of it. The deeper/bigger the cold dome the more lift isentropic upglide/lifting. In this case it's not a front line battle like it could be if the arctic boundary divded the warm/moist flow. That's way up north in NY this go around. Ingredients are still certainly there but mixy messy instead of deep deep winter. 

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4 minutes ago, Scraff said:

Larry Cosgrove = Pants Tent :lol:

 

“There is no fighting the notion that most of the lower 48 states are going to get swept up by the Arctic regime now descending from Canada. But there are questions about storm potential, especially regarding track and type of precipitation. Let me remind you that all of the numerical models show at least one massive disturbance passing out of the southern Rocky Mountains in the 6 - 10 day range. The ECMWF scheme is reluctant to allow the intense cold to reach the southern and eastern tier of the nation, which the GFS series is more aggressive and brings the forward edge of the cAk readings all the way into the Interstate 10 and 95 corridors. In effect, only California and Florida dodge the proverbial bullet.
 
It has been my experience that the American scheme handles cold advection much better than its European counterpart, particularly when a true Arctic air mass is involved. It is a judgment call, but the regime over North America is arguably the coldest in the Northern Hemisphere and will continue with that dubious title for the rest of the calendar winter. This is important because the path of storms in the medium range will likely be suppressed into the northern Gulf of Mexico and then up or off of the eastern Seaboard. I can see a scenario where the southern rim of the U.S. has a rain ending as an ice event, while snow deepens from the Great Plains into the Mid-Atlantic and New England states. Much of this is up for grabs, mind you, but the emergence of renewed blocking in Greenland, agreed upon by all of the computer models, will favor a lower latitude trajectory of impulses in the Arctic, polar, and subtropical jet streams. And the most obvious candidate is the broad cyclonic circulation below the Aleutian Islands
 
I note that most of the ensemble packages show yet another shortwave from the northern Pacific Basin getting caught up in the deviated jet stream configuration, with another deepening storm in the Southwest seven days from now. We have to watch this feature carefully! I can see a track scenario taking shape where the system drops into northern Mexico, then moves along the Gulf Coast,m and then close to and likely just to the right of the Eastern Seaboard. around February 14 - 17. This is the type of set-up that -could- produce a true monster winter weather event, with the Arctic motherlode being pushed into the Great Lakes region and phasing with the low pressure area. The vast expanse of cold is worrisome since actions like overrunning and cold instability will interact, with a wider coverage of precipitation types than is normal”

 

Yeah the models have been flirting with some big moisture coming up from the gulf for a bit and it has piqued my interest for sure over the past couple days paired with the cold coming. Classic case of give me the ingredients and let the details work themselves out.

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If even remotely correctly fun times are ahead. Keep in mind,  this snowfall extends out beyond the 7 day just a bit.  

Attempting to see where the baroclinic, arctic air mass jackpot zone may be, we certainly appear to be in the game. 

 

 

60201ef245301.png

 

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