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Big Snow Threat Disco Jan2/3


Damage In Tolland

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Doesn't really change that closer to home the synoptic setup was similar. This one looks like a stronger high to the north if we're getting picky and who knows if this one has a secondary that ends up wraaping up more than guidance shows (minus the Euro).

disagree. this system looks colder, digs more, and has better ridging in the west with a more favorable atlantic for the coastal plain

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The signal's been out there for a long while in the runs, but now the American teleconnectors are being douchy about it, too.   The PNA spike has backed off in the GFS ensemble member mean the last two nightly computations, which doesn't lend too well as cross-guidance support.   It is not absolutely necessary to have that cross support, but about half the time it is a red flag when you don't. 

 
I have a general rule of thumb that heights over Miami should not exceeed 582 dm, and the balanced geostrophic wind should not exceed 35kts, ...and here is the key, PRIOR to the amplification coming into the rough longitudes of the Mississippi Valley region.  In this case, the Euro violates both rules of thumb.  
 
The reason this is a limitation has to do with mechanics and is complicated to explain.  Let me just put it simply as, "shear."  Or rather, if you can bear it, when the wind maximum core in the jet stream tries to enter a domain that is already highly compressed (big geopotential gradient with already high-ish wind) then the wind max associated with the S/W is no longer as differentiating on the flow.  If it is not differentiating, this lowers jet responses (inflow of WAA to feed cyclogenesis with latent heat ... etc).   The way it works is called q-vector forcing, where q vectors relate to the amount of Upward Vertical Motion that is "forced".   Less differentiation = less upward forcing = less UVM = weak WAA response = weak storm.  
 
To me that is a very simple chain of logic, but when I have tried to explain this rather fundamental principle to people ... it's like a scene out of a sitcom where the room goes silent for 6 seconds, then squabbling re-ensues where no one even acknowledges what was just said.  I'm not sure, but for some reason, people have a tough time getting it...   I only get a little frustrated by the lack of perceived comprehension, because the principle is clad and can be employed during deterministic/operational weather prediction, but people just slip right back into autopilot when they see a trough coming E.  For those on the blogosphere, we then have to suffer a "blizzard" of TK and MN tweets...  
 
But I digress... anyway, seeing the GFS suite backing off the +PNA may just be related to why in this case ... both variables are being violated in order to get to the Euro's exotic solution. But, then again, we also notice that the GFS has maintained more progressive character to the flow, and a more sheared out system, so it is good within it's own processing.   
 
What it all boils down to is a bit of a model battle.  The Euro can overcome the Miami heights and wind rule of thumb, by dumping and absolute monstrosity into the flow (so in order to establish the greater differentials), but that would be the rarefied solution -- because to do so approaches the upper bounds of Terra physical extremes, so inherently it is less likely to achieve those degrees of intensity.  We'll just have to see if this week is one of those rarer times.
 
Btw, no other guidance pulls that off, either.   On the other hand, the Euro is now inside of D5, and that's really when the model is almost impossible to beat.  Oy vay
 
This 12z Euro run will be really interesting... 
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disagree. this system looks colder, digs more, and has better ridging in the west with a more favorable atlantic for the coastal plain

 

Objection: relevance?

 

Nitpicking analogs is for sad people. Get down to brass tacks and make me an early first guess map for snow accumulations in the northeast US this Thrusday into Friday, and be sure to have your color scheme based only on the photo in your signature.

 

THANK YOU

 

HOTMAIL

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Objection: relevance?

 

Nitpicking analogs is for sad people. Get down to brass tacks and make me an early first guess map for snow accumulations in the northeast US this Thrusday into Friday, and be sure to have your color scheme based only on the photo in your signature.

 

THANK YOU

 

HOTMAIL

i'm nitpicking it because i think using analogs is silly

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Euro has no choice, but to back down from its ridiculous 00z solution.

 

hahaha.....  oh man.   It's like, remember the histrionics and melodrama prior to that February blizzard last year?  That Euro solution would trump that drama with actual, factual required panic this time. 

 

Although, it seems modern times has a way of limiting the impact of these bigger winter storms.  True -   It almost gets difficult to imagine a 1978 scenario having the same impact of turning I-95 into an abandoned visage akin to an apocalyptic siege in this day and age, but who knows...  

 

But IMO, I do think that high wind and powdery bombs are not as society impacting as the 31.5F S++ thunder freaks that stall and last for 2.5 days -- that was 1978; we have not regionally experienced, objective (not subjectively) anything that really hearkens to that, other than brief encounters, since then.  And there are knee-jerk responders that try to argue it, because for some reason, to even merely suggest otherwise is some kind of a violation upon their winter-sensibilities.  But that's all bullcrap.     One day, we will be tested again. 

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