February/March 2021 - Frigid or Flop? Pattern/Longterm Forecast Thread.

[AMZ8990]

33 minutes ago, Holston_River_Rambler said:

If you liked that gray, you'll surely like the National Blend of Models:

Thanks for all you do brotha, and I really appreciate you sharing all these maps with us!  It doesn’t go unnoticed or unappreciated I assure you!

[MSSnow]

38 minutes ago, Holston_River_Rambler said:

If you liked that gray, you'll surely like the National Blend of Models:

Could you post that for on down in Mississippi?

[Holston_River_Rambler]

6 minutes ago, MSSnow said:

Could you post that for on down in Mississippi?

Here ya go:

[MSSnow]

Thanks, Holston!

[MSSnow]

Just now, Blue Moon said:

Hope that's a good event for y'all down there.

Looks to be mostly freezing rain for my side of the State. Not looking forward to that! 

[Carvers Gap]

For eastern folks, I do have at least give mild attention to this 12z CMC look for Tuesday.  The slp(as is) is likely too weak.  However, if that strengthens even a little...that is not benign for the eastern valley IMHO.  That is different from what we have seen recently.  Modeling has trending towards this inland runner during the past few runs.  The para has a similar look but runs a shadow up through the eastern valley which is no good.  If the CMC consolidates, that is good.  Might just be a hiccup, but the RGEM was pretty much there as well at 84.

[Carvers Gap]

I was thinking that as much as we like to give modeling a hard time(me included), they have been remarkably steady for this.  Obviously, I am hoping for a shift for MBY....but they aren't moving much.  The CMC is the first hiccup which I have seen.

[PowellVolz]

Trying to keep up.... hasn’t mods vs reality been to far NW this year? Seems like I remember this and I believe I read on here that someone felt the same way.


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[Carvers Gap]

The 18z RGEM is tracking an areas of weak slp from the Panhandle of FL through the Carolina Piedmont with seemingly little energy transfer.  Back side of the slp switches to light snow in ETN.  It is on the eastern envelope of storm tracks not implausible.  The EPS at 12z moved several of its slp member tracks into the same vicinity as the RGEM.

[CG2]

Not calling for a storm IMBY yet, but I think the jury is still out on how this SLP system develops on Tuesday.  Here are the comparison runs for the 12z EPS 90 and 96 time frames compared to 6z.  Notice the shift south and east.  New is on the left.  There has been a trend towards moving this area of weak slp to our SE and reducing or eliminating energy coming west of the Apps.  May or may not hold, but that is the trend on some modeling.  Notice that at 6z many SLPs went through E TN and into WVA.  At 12z, many went from central Georgia and into the Carolina Piedmont.

[Utvols235]

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[CG2]

Just now, Utvols235 said:

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I would place that in the storm thread.  Great find.

[Utvols235]

I would place that in the storm thread.  Great find.

Yup just realized i posted in the wrong thread


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[CG2]

Just now, Utvols235 said:

Yup just realized i posted in the wrong thread


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I do it all the time!  LOL.  Just whichever threat is at the top!  LOL.  Great to have you posting!  

[Holston_River_Rambler]

18z Para getting a little closer to with and Apps runner or keeping the LP east of the Apps:

 

such a good looking HP, and holding its own instead of skidootchling east. 

[Holston_River_Rambler]

Ole Ragl'r 18z GFS actually keeps the LP east of the Apps. 

[codgator]

Nice would love it just east and stronger

[Holston_River_Rambler]

Just now, codgator said:

Nice would love it just east and stronger

I think you'll like the 18z GEFS members I just posted in the other thread, lol, if you are in Franklin. 

[codgator]

Looks much better for middle Tenn - some real nice bumps for this area- still need more wiggle room. But for a novice like me some good trends are occurring. 

[codgator]

Might be a late night to see the Euro !

[Olhausen]

28 minutes ago, codgator said:

Might be a late night to see the Euro !

Didn’t the 12z euro look a bit better for middle Tennessee snow sleet wise?

[codgator]

I believe you are correct! 

[CG2]

18z GFS SLP location is east of the Apps.  Not sure how much more east it can actually trend.  At some point, it trends back west - I think.  However, the ensemble does hint that a mixed bag IMBY is not out of the possibility on Tuesday.  Not gumming up the middle/west TN storm thread with this though.  LOL.

[codgator]

Yeah hope that is not an over reach- love that location not needing a west trend at this point for personal reasons. 

[John1122]

Not looking at the model outputs long range because I've been focused on the short term. I did look at the indices and see +NAO/-PNA/MJO looping towards 6 on the Euro. So basically get what you can this week then get ready to welcome spring if all those come to pass. 

[Carvers Gap]

Looks like the NAO tries to refire after d10.  The Euro MJO continues to forecast a move into the COD - dives out of 7, head fakes to 8, moves to 6, and then moves back to colder phases.  Larry Cosgrove who has done a fantastic job this winter hinted that he thinks we may see the current pattern repeat again during March.  The MJO is hinting at that as well.  He also has stated that when we break to spring that it will be quite abrupt.  He is calling for a scorcher of a summer as well.   March can hold a surprise or two.  If the NAO re-fires that is a good thing for March...we don’t want that index negative for summer as all.

[CG2]

Long Range Ideas and Short/Mid-Range Commentary:

Here are the 0z EPS NAO and the 6z GEFS NAO forecasts from earlier today.  All three current global ensembles are depicting the NAO to re-fire around the 25th.   This does signal an at least temporary eastern ridge after this week(as the pattern waits for a -NAO reload), and then the potential exists for a return to a colder pattern towards the end of February and/or the beginning of March(likeliest is early March).  This has been the pattern this winter.  We see cold, we get a few weeks break, and then it returns.  Would not surprise me if the cold returns one last time relative to March norms.  I hate to quote Cosgrove without his permission, so I will simply state that he thinks the relaxation of the pattern during late February is simply the pattern recharging for one more cold shot similar to what we have now but maybe excluding the Deep South.  I would note that when the NAO changes phases to negative (or leaves negative) that is when we might see another round of storms.  I could be wrong, but would be very surprised if winter is over.  I think we see a relaxation coming up very similar to what we saw in January(just shorter) and then maybe one last bout of winter. 

 I think the -NAO has more than proven its value this winter as western(and hopefully middle as well!) subforum areas of the TN Valley Region are possibly about to experience one of the great winter patterns of recent memory for this subforum and for their local.  If the NWS verifies for Memphis this week, this pattern could well be the best winter pattern for them during the past two decades.  Their temps are not forecast to rise above freezing until next Saturday!   They are modeled to have two winter storms.  Just because the NAO does not deliver IMBY, does not mean it is not a signifiant pattern driver for winter weather for this region - even on its own.  It is also worth noting that this maturing of the trough occurred right at the end of the current negative phase of the NAO.  That is worth remembering if the NAO goes negative once again (if LR modeling is correct) later this month.  As a final caveat, the NAO is a tricky animal to forecast...so keep that in mind when looking at LR forecasts showing it re-firing.  I think it likely, but not a certainty. I am also adding the EMON from the 11th.  The Euro MJO looks nearly identical today.  Notice the dive back to cooler phases after the jaunt towards six.  For posterity(and for future reference regarding the NAO), I am attaching the Memphis forecast for the week. They are simultaneously under a wind child advisory and winter storm warning with yet another winter storm modeled for mid-week.  Also, it is worth noting that the MJO is at mid-amplitude phase 7(nearly 6).  The NAO has overcome warm phases of the MJO as well.  

Lastly, I think this forum has done a great job with pattern recognition this winter.  That doesn't mean we nail every storm, but I think folks have done a great job of weighing the possibilities "for" and "against" winter weather.  Hopefully, after the warm up set to unfold after 6-7 days, we see one more bout of winter.  Good luck(meaning lots of snow and not as much ice) to those in middle and western forum areas this week!!!  

Addendum note: Some modeling is also hinting that the EPO may go briefly negative right as the NAO block potentially reforms later this month and early March.

 

[Carvers Gap]

One other thing to watch in the LR, the Euro and GFS again both set a really nice boundary just after d8.  To me that is a little bit early.  However, maybe we get one more system to run an east/west boundary prior to a brief warm-up to end the month and more winter later during the first week of March.  Seems like two years ago, we hit 80 during February here at TRI.  LOL.  

[Carvers Gap]

Reposting as I failed earlier to put a time stamp on this comment....

Something to keep an eye on for NE TN and SW VA folks...the 12z Euro is implying that there could be a mix at TRI and snow/sleet in SW VA before the cold is scoured out.  edit: Thursday morning!

[AMZ8990]

5 hours ago, CG2 said:

Long Range Ideas and Short/Mid-Range Commentary:

Here are the 0z EPS NAO and the 6z GEFS NAO forecasts from earlier today.  All three current global ensembles are depicting the NAO to re-fire around the 25th.   This does signal an at least temporary eastern ridge after this week(as the pattern waits for a -NAO reload), and then the potential exists for a return to a colder pattern towards the end of February and/or the beginning of March(likeliest is early March).  This has been the pattern this winter.  We see cold, we get a few weeks break, and then it returns.  Would not surprise me if the cold returns one last time relative to March norms.  I hate to quote Cosgrove without his permission, so I will simply state that he thinks the relaxation of the pattern during late February is simply the pattern recharging for one more cold shot similar to what we have now but maybe excluding the Deep South.  I would note that when the NAO changes phases to negative (or leaves negative) that is when we might see another round of storms.  I could be wrong, but would be very surprised if winter is over.  I think we see a relaxation coming up very similar to what we saw in January(just shorter) and then maybe one last bout of winter. 

 I think the -NAO has more than proven its value this winter as western(and hopefully middle as well!) subforum areas of the TN Valley Region are possibly about to experience one of the great winter patterns of recent memory for this subforum and for their local.  If the NWS verifies for Memphis this week, this pattern could well be the best winter pattern for them during the past two decades.  Their temps are not forecast to rise above freezing until next Saturday!   They are modeled to have two winter storms.  Just because the NAO does not deliver IMBY, does not mean it is not a signifiant pattern driver for winter weather for this region - even on its own.  It is also worth noting that this maturing of the trough occurred right at the end of the current negative phase of the NAO.  That is worth remembering if the NAO goes negative once again (if LR modeling is correct) later this month.  As a final caveat, the NAO is a tricky animal to forecast...so keep that in mind when looking at LR forecasts showing it re-firing.  I think it likely, but not a certainty. I am also adding the EMON from the 11th.  The Euro MJO looks nearly identical today.  Notice the dive back to cooler phases after the jaunt towards six.  For posterity(and for future reference regarding the NAO), I am attaching the Memphis forecast for the week. They are simultaneously under a wind child advisory and winter storm warning with yet another winter storm modeled for mid-week.  Also, it is worth noting that the MJO is at mid-amplitude phase 7(nearly 6).  The NAO has overcome warm phases of the MJO as well.  

Lastly, I think this forum has done a great job with pattern recognition this winter.  That doesn't mean we nail every storm, but I think folks have done a great job of weighing the possibilities "for" and "against" winter weather.  Hopefully, after the warm up set to unfold after 6-7 days, we see one more bout of winter.  Good luck(meaning lots of snow and not as much ice) to those in middle and western forum areas this week!!!  

Addendum note: Some modeling is also hinting that the EPO may go briefly negative right as the NAO block potentially reforms later this month and early March.

 

This is a great breakdown Carver!!!  I appreciate you going into detail on this stuff.