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Mid to Long Term Discussion 2021


jburns
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Anyone taking the dramatic warming shown on this run as gospel has not lived here long. Wedges ALWAYS stick around longer and are stronger than forecast. The density of the cold air and our geographic orientation make it almost impossible to dislodge that airmass especially with precip falling into it. A couple weeks ago our highs were forecast in the mid 60’s but most of us stayed in mid 40’s through the day. It can definitely warm enough to change to liquid and not freezing rain, but it ain’t getting out of the mid 30’s triangle north and west in this setup 

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Euro is still an absolute classic cold air damming scenario. The combination of squashing/dissolving the Canadian vortex quickly as it ejects East and over amplifying the southern stream wave leads to a warmer outcome in the mid levels... but would be a catastrophic ice storm as depicted for cad regions of nc/sc. 

the models will waffle on the strength of those two features but they all are in agreement on the perfect placement of the damming high and timing of the southern wave. If they’re correct in that timing we will get a major ice storm.

 

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1 minute ago, NorthHillsWx said:

Anyone taking the dramatic warming shown on this run as gospel has not lived here long. Wedges ALWAYS stick around longer and are stronger than forecast. The density of the cold air and our geographic orientation make it almost impossible to dislodge that airmass especially with precip falling into it. A couple weeks ago our highs were forecast in the mid 60’s but most of us stayed in mid 40’s through the day. It can definitely warm enough to change to liquid and not freezing rain, but it ain’t getting out of the mid 30’s triangle north and west in this setup 

The issue with this, is that while often they are stubborn to be scoured out in environments where wind aloft isn't very strong, it's a different story when winds aloft are screaming in response to a strong cyclone. I think this is a case where I wouldn't lay my hat on it persisting longer.

That all being said, that was a mixed Euro run. The good:

It was encouraging to see the lead shortwave hold more of it's integrity as it went through the SE, which lead to a stronger, more amped, beefier storm. 

The CAD signal is robust and at this point I like the consistency of it's depiction. Overall, I think that there's a good chance that the Euro is not rendering the evolution of cyclogenesis correctly and it's likely we have lower pressures off the coast than what it's depicting, which would keep cold air around longer. 

The bad:

The TPV getting strung out is not a great trend. Hopefully future cycles build it back up again, or else a more inland storm track is on the table. 

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18 minutes ago, wncsnow said:

Look at the difference, its still ice for some but way warmer 

prateptype_cat_ecmwf.us_ma (14).png

prateptype_cat_ecmwf.us_ma (13).png

 

The big reason the 12z Euro is 'warmer' than the 0z for Tuesday is that the 500mb energy goes negative tilt over the central Gulf Coast, and the surface low matures and is much stronger, much sooner on the 12z compared to the 0z. 

The overall signal has not changed, and there are going to be tons of changes as the models resolve:

- the depth of the cold, arctic air

- the strength, orientation of individual short waves

- the strength, placement of the CAD-inducing high

- many other moving pieces.

 

I strongly suggest folks to check their emotions with the wild swings that are sure to come. 

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45 minutes ago, msuwx said:

 

The big reason the 12z Euro is 'warmer' than the 0z for Tuesday is that the 500mb energy goes negative tilt over the central Gulf Coast, and the surface low matures and is much stronger, much sooner on the 12z compared to the 0z. 

The overall signal has not changed, and there are going to be tons of changes as the models resolve:

- the depth of the cold, arctic air

- the strength, orientation of individual short waves

- the strength, placement of the CAD-inducing high

- many other moving pieces.

 

I strongly suggest folks to check their emotions with the wild swings that are sure to come. 

Excellent post. I think negative tilt is pretty hard to forecast, especially this far out. This solution is factoring it in, but it's one detail of the whole picture that has a drastic effect on the outcome. If that tilt were not part of this particular run, think about how that might change the output of the storm. The low may be much father south, weaker, and allow the cold high confluence to remain longer and stronger. The model could easily change that particular detail in a future run and then we have an icy and colder solution again. Way too much time to go on this one. The ingredients are there, but we likely won't have a good idea till Sun or Monday, if not even go time. I still don't think we have a great picture of this weekend's system.

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7 minutes ago, Iceagewhereartthou said:

Excellent post. I think negative tilt is pretty hard to forecast, especially this far out. This solution is factoring it in, but it's one detail of the whole picture that has a drastic effect on the outcome. If that tilt were not part of this particular run, think about how that might change the output of the storm. The low may be much father south, weaker, and allow the cold high confluence to remain longer and stronger. The model could easily change that particular detail in a future run and then we have an icy and colder solution again. Way too much time to go on this one. The ingredients are there, but we likely won't have a good idea till Sun or Monday, if not even go time. I still don't think we have a great picture of this weekend's system.

Agree.  I'm focusing more short range...this weekend and Monday.  Anything further out is still fuzzy and likely to change.  But I will admit that the models this far out are fun to look at!

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13 minutes ago, Iceagewhereartthou said:

Excellent post. I think negative tilt is pretty hard to forecast, especially this far out. This solution is factoring it in, but it's one detail of the whole picture that has a drastic effect on the outcome. If that tilt were not part of this particular run, think about how that might change the output of the storm. The low may be much father south, weaker, and allow the cold high confluence to remain longer and stronger. The model could easily change that particular detail in a future run and then we have an icy and colder solution again. Way too much time to go on this one. The ingredients are there, but we likely won't have a good idea till Sun or Monday, if not even go time. I still don't think we have a great picture of this weekend's system.

Yes but the cold air retreating allows the LP amplification in my view not the other way around.  Modeling this cold vortex has and remains to be problematic. 

If I were a betting man...we will not see this brutal cold in the triangle...or only for a very short-lived period of time.  It will still be chilly (not warm) for sure but this is February after all

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8 minutes ago, CaryWx said:

Yes but the cold air retreating allows the LP amplification in my view not the other way around.  Modeling this cold vortex has and remains to be problematic. 

If I were a betting man...we will not see this brutal cold in the triangle...or only for a very short-lived period of time.  It will still be chilly (not warm) for sure but this is February after all

I agree.  Models have been struggling with the cold all along.   

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34 minutes ago, PackGrad05 said:

 

I agree.  Models have been struggling with the cold all along.   

And as I said days ago, models corrected colder in the Friday to Monday window after they torched things for awhile.  It may not be brutally cold but no question seeing ATL go from a high on models 3 days ago Friday of 68 to probably a 2am high now before the wedge of 55 is quite a change 

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3 minutes ago, Tealsnowball said:

Well the NAM certainly has made things interesting for Thursday Night along I-81 & Highway 460 for the New River Valley and Roanoke. Teetering the line of rain and snow.  I am curious to see what transpires.  Agreed that Friday night looks nasty:yikes:

12k and 3k Nam are worlds apart. Go figure... lolll

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