Re: Long Range Thread 29.0

[heehaw453]

I don’t necessarily disagree with anything you mention heehaw. My opinion is that given the PNA/EPO/AO triplet, that’s a strong mechanism to drive cold air into the eastern CONUS. Added to the fact that the southern stream is lagging as a tail to the main trough, I think the models are under-representative of the speed with which the true northern stream can get out ahead of the southern stream and essentially erode the western flank of that Atlantic ridging before the southern stream starts gaining latitude, therefore over-representing the western periphery of the western Atlantic positive anomalies. So, those are the adjustments I’m looking for in current modeling, because verbatim, you’re 100% right.

Without a true 50/50 low you will need a clipper like s/w to be ahead of, but not too far ahead, of any energy ejecting out of the SW to act as some sort of confluence to prevent the inevitable height rises out ahead of said SW energy and trap the cold to force the storm Track S&E of LI.   We are going to need this little guy in the middle in order to have all these pieces to come together just right.  IMHO not dead, but odds are not in our favor.  

GFS made steps today at 12z. Not a trend, but I’d rather a change in the direction it went than another lol I don’t know what the GEM is doing, honestly, and I don’t think it knows what it’s doing either aha

Agreed. GEFS basically I81 and westward is the spot where cold air meets the moisture. 7 days and model variability can still be quite high. Lack of Atlantic trough in early/mid December for snow on the 95 makes me very cautious w/out a big dome of H pressure parked over Quebec/NNE. But on the other hand the NAO/AO are - whilst the PNA is + which are normally very correlated to sig snow in the I95. Also, inflection points of the teleconnections tends to be associated with bigger storms. We'll see next few days...

all of the above...

Food for thought, heehaw, regarding your “lack of a dome of high pressure parked over Quebec/northern New England”…..

Today’s 12z GFS:



These are changes I expect to continue. But that’s feeding fresh Arctic air into this thing from the north and northwest, and it’s pressing HARD.

I agree with that. What i meant is something already established though. It's a race here and believe further westward is much better position to benefit. If we had the Atl trough this would be much much easier as we'd minimize the warm air and it'd slow this bad boy down some.

This is def cold air on the move.

[rb924119]

I don’t necessarily disagree with anything you mention heehaw. My opinion is that given the PNA/EPO/AO triplet, that’s a strong mechanism to drive cold air into the eastern CONUS. Added to the fact that the southern stream is lagging as a tail to the main trough, I think the models are under-representative of the speed with which the true northern stream can get out ahead of the southern stream and essentially erode the western flank of that Atlantic ridging before the southern stream starts gaining latitude, therefore over-representing the western periphery of the western Atlantic positive anomalies. So, those are the adjustments I’m looking for in current modeling, because verbatim, you’re 100% right.

Without a true 50/50 low you will need a clipper like s/w to be ahead of, but not too far ahead, of any energy ejecting out of the SW to act as some sort of confluence to prevent the inevitable height rises out ahead of said SW energy and trap the cold to force the storm Track S&E of LI.   We are going to need this little guy in the middle in order to have all these pieces to come together just right.  IMHO not dead, but odds are not in our favor.  

GFS made steps today at 12z. Not a trend, but I’d rather a change in the direction it went than another lol I don’t know what the GEM is doing, honestly, and I don’t think it knows what it’s doing either aha

Agreed. GEFS basically I81 and westward is the spot where cold air meets the moisture. 7 days and model variability can still be quite high. Lack of Atlantic trough in early/mid December for snow on the 95 makes me very cautious w/out a big dome of H pressure parked over Quebec/NNE. But on the other hand the NAO/AO are - whilst the PNA is + which are normally very correlated to sig snow in the I95. Also, inflection points of the teleconnections tends to be associated with bigger storms. We'll see next few days...

all of the above...

Food for thought, heehaw, regarding your “lack of a dome of high pressure parked over Quebec/northern New England”…..

Today’s 12z GFS:



These are changes I expect to continue. But that’s feeding fresh Arctic air into this thing from the north and northwest, and it’s pressing HARD.

[rb924119]

I don’t necessarily disagree with anything you mention heehaw. My opinion is that given the PNA/EPO/AO triplet, that’s a strong mechanism to drive cold air into the eastern CONUS. Added to the fact that the southern stream is lagging as a tail to the main trough, I think the models are under-representative of the speed with which the true northern stream can get out ahead of the southern stream and essentially erode the western flank of that Atlantic ridging before the southern stream starts gaining latitude, therefore over-representing the western periphery of the western Atlantic positive anomalies. So, those are the adjustments I’m looking for in current modeling, because verbatim, you’re 100% right.

Without a true 50/50 low you will need a clipper like s/w to be ahead of, but not too far ahead, of any energy ejecting out of the SW to act as some sort of confluence to prevent the inevitable height rises out ahead of said SW energy and trap the cold to force the storm Track S&E of LI.   We are going to need this little guy in the middle in order to have all these pieces to come together just right.  IMHO not dead, but odds are not in our favor.  

GFS made steps today at 12z. Not a trend, but I’d rather a change in the direction it went than another lol I don’t know what the GEM is doing, honestly, and I don’t think it knows what it’s doing either aha

Agreed. GEFS basically I81 and westward is the spot where cold air meets the moisture. 7 days and model variability can still be quite high. Lack of Atlantic trough in early/mid December for snow on the 95 makes me very cautious w/out a big dome of H pressure parked over Quebec/NNE. But on the other hand the NAO/AO are - whilst the PNA is + which are normally very correlated to sig snow in the I95. Also, inflection points of the teleconnections tends to be associated with bigger storms. We'll see next few days...

all of the above...

Food for thought, heehaw, regarding your “lack of a dome of high pressure parked over Quebec/northern New England”…..

Today’s 12z GFS:



These are changes I expect to continue. But that’s feeding fresh Arctic air into this thing from the north and northwest, and it’s pressing HARD.

I agree with that. What i meant is something already established though. It's a race here and believe further westward is much better position to benefit. If we had the Atl trough this would be much much easier as we'd minimize the warm air and it'd slow this bad boy down some.

This is def cold air on the move.

But that’s what I’m saying - it SHOULD BE in place prior to the onset of precipitation, even if only by six hours. My point is that the fresh injection should get her before the precipitation associated with the southwestern energy. It’s not going to be the other way around where we are waiting for a changeover mid-storm or later. Even if there is a changeover, it would be early on and limit any potential accumulation loss.

[sroc4]

I don’t necessarily disagree with anything you mention heehaw. My opinion is that given the PNA/EPO/AO triplet, that’s a strong mechanism to drive cold air into the eastern CONUS. Added to the fact that the southern stream is lagging as a tail to the main trough, I think the models are under-representative of the speed with which the true northern stream can get out ahead of the southern stream and essentially erode the western flank of that Atlantic ridging before the southern stream starts gaining latitude, therefore over-representing the western periphery of the western Atlantic positive anomalies. So, those are the adjustments I’m looking for in current modeling, because verbatim, you’re 100% right.

Without a true 50/50 low you will need a clipper like s/w to be ahead of, but not too far ahead, of any energy ejecting out of the SW to act as some sort of confluence to prevent the inevitable height rises out ahead of said SW energy and trap the cold to force the storm Track S&E of LI.   We are going to need this little guy in the middle in order to have all these pieces to come together just right.  IMHO not dead, but odds are not in our favor.  

GFS made steps today at 12z. Not a trend, but I’d rather a change in the direction it went than another lol I don’t know what the GEM is doing, honestly, and I don’t think it knows what it’s doing either aha

Agreed. GEFS basically I81 and westward is the spot where cold air meets the moisture. 7 days and model variability can still be quite high. Lack of Atlantic trough in early/mid December for snow on the 95 makes me very cautious w/out a big dome of H pressure parked over Quebec/NNE. But on the other hand the NAO/AO are - whilst the PNA is + which are normally very correlated to sig snow in the I95. Also, inflection points of the teleconnections tends to be associated with bigger storms. We'll see next few days...

all of the above...

Food for thought, heehaw, regarding your “lack of a dome of high pressure parked over Quebec/northern New England”…..

Today’s 12z GFS:



These are changes I expect to continue. But that’s feeding fresh Arctic air into this thing from the north and northwest, and it’s pressing HARD.

I agree with that. What i meant is something already established though. It's a race here and believe further westward is much better position to benefit. If we had the Atl trough this would be much much easier as we'd minimize the warm air and it'd slow this bad boy down some.

This is def cold air on the move.

But that’s what I’m saying - it SHOULD BE in place prior to the onset of precipitation, even if only by six hours. My point is that the fresh injection should get her before the precipitation associated with the southwestern energy. It’s not going to be the other way around where we are waiting for a changeover mid-storm or later. Even if there is a changeover, it would be early on and limit any potential accumulation loss.

Ehhhh but your assuming ever single s/w in both the southern and northern streams plays out perfectly in timing and strength leading up to hours 175-195. I can see 36 ways to sunday that could screw up the fresh injection of cold air.

[rb924119]

I don’t necessarily disagree with anything you mention heehaw. My opinion is that given the PNA/EPO/AO triplet, that’s a strong mechanism to drive cold air into the eastern CONUS. Added to the fact that the southern stream is lagging as a tail to the main trough, I think the models are under-representative of the speed with which the true northern stream can get out ahead of the southern stream and essentially erode the western flank of that Atlantic ridging before the southern stream starts gaining latitude, therefore over-representing the western periphery of the western Atlantic positive anomalies. So, those are the adjustments I’m looking for in current modeling, because verbatim, you’re 100% right.

Without a true 50/50 low you will need a clipper like s/w to be ahead of, but not too far ahead, of any energy ejecting out of the SW to act as some sort of confluence to prevent the inevitable height rises out ahead of said SW energy and trap the cold to force the storm Track S&E of LI.   We are going to need this little guy in the middle in order to have all these pieces to come together just right.  IMHO not dead, but odds are not in our favor.  

GFS made steps today at 12z. Not a trend, but I’d rather a change in the direction it went than another lol I don’t know what the GEM is doing, honestly, and I don’t think it knows what it’s doing either aha

Agreed. GEFS basically I81 and westward is the spot where cold air meets the moisture. 7 days and model variability can still be quite high. Lack of Atlantic trough in early/mid December for snow on the 95 makes me very cautious w/out a big dome of H pressure parked over Quebec/NNE. But on the other hand the NAO/AO are - whilst the PNA is + which are normally very correlated to sig snow in the I95. Also, inflection points of the teleconnections tends to be associated with bigger storms. We'll see next few days...

all of the above...

Food for thought, heehaw, regarding your “lack of a dome of high pressure parked over Quebec/northern New England”…..

Today’s 12z GFS:



These are changes I expect to continue. But that’s feeding fresh Arctic air into this thing from the north and northwest, and it’s pressing HARD.

I agree with that. What i meant is something already established though. It's a race here and believe further westward is much better position to benefit. If we had the Atl trough this would be much much easier as we'd minimize the warm air and it'd slow this bad boy down some.

This is def cold air on the move.

But that’s what I’m saying - it SHOULD BE in place prior to the onset of precipitation, even if only by six hours. My point is that the fresh injection should get her before the precipitation associated with the southwestern energy. It’s not going to be the other way around where we are waiting for a changeover mid-storm or later. Even if there is a changeover, it would be early on and limit any potential accumulation loss.

Ehhhh but your assuming ever single s/w in both the southern and  northern streams plays out perfectly in timing and strength leading up to hours 175-195.  I can see 36 ways to sunday that could screw up the fresh injection of cold air.  

Thanks for the words of encouragement lmfaooooo

You’re right, Scott. But isn’t that what the point of a forecast and being a meteorologist actually is; trying to figure out what the real weather is going to be? lol I’m laying out a blueprint for where I think models are currently wrong, how I think they will adjust, and why, using knowledge that I’ve acquired over the years. I could always just default to “It might snow or rain, I don’t really know yet and have to see how models change over the next week before I can really give an accurate forecast.” but that isn’t a forecast, it’s an excuse for not making a forecast and not taking a stand to avoid the hazards that come with making such a forecast lol

[heehaw453]

There's a big difference in the EPS to the op in terms of the cold air push. I think we need a few days to see where this is going.  

[rb924119]

There's a big difference in the EPS to the op in terms of the cold air push. I think we need a few days to see where this is going.  

They’re not going to look exactly alike for Day 8 forecast of 50 ensemble members - you’re going to have spread, which is why it looks like it does. But if you look more closely, you’ll see the darker shades of blue within the ensemble mean indicating one low center over/near Hudson Bay, and one near the Virginia Capes, with a relative lack of lower pressure in between. This is not dissimilar, and the changes at H5 were in line with what I would expect - faster/stronger northern stream, relatively unchanged southern stream, which also aligns with the changes the Operational run made. As long as the changes were there, that’s all I’m focused on when it comes to guidance, because the rest will follow if they continue/hold.

[rb924119]

Granted, it’s an 18z run of the GFS, BUT, it is MUCH MORE REPRESENTATIVE of my current thinking than anything else in terms of overall appearance and evolution, though still displaced a bit too far to the northwest.

[amugs]

Granted, it’s an 18z run of the GFS, BUT, it is MUCH MORE REPRESENTATIVE of my current thinking than anything else in terms of overall appearance and evolution, though still displaced a bit too far to the northwest.

It made a massive jump to the 12Z EURO

A decent high over SE CAN - A little faster set up by about 6 hours stronger(5 mb) and about 75 -100 miles S and its snow to the coast

[dkodgis]

33 degrees and three inches and so on. Still lightly snowing. Not sticking to the roads.

It's pretty out there.

[rb924119]

If the 12z ICON is any indication of how the rest of today’s 12z suite is going to go, it should be an interesting day

[rb924119]

GFS and GEM were underwhelming; close but no cigar. Then there was the Euro which almost went nuclear. The 12z EURO is closest to me at H5 this time around, but there’s not much consistency yet. Still following the ensembles and trusting the process for now.

[sroc4]

The one thing I don't like even in the ensembles is as our mean trough, northern and southern stream energy propagates along towards the EC, The beautiful ridging along the west coast of NA seen at the beginning of the loop collapses at the most inopportune time; replaced with the negatives along the WC of Canada that moves south into the SW CONUS.  This is not what we want to see if we want cold air is to stick around, and S & N energy are to come together in any sort of meaningful way.  Im still really skeptical Ray.  I want to buy in but Im having a hard time.  Below are links to the loop of the EPS then GEFS between 10th-14th

https://maps.api.weatherbell.com/gif/temporary/ecmwf-ensemble-avg-namer-z500_anom-1733400000-1733810400-1734199200-20.gif

https://maps.api.weatherbell.com/gif/temporary/gfs-ensemble-all-avg-namer-z500_anom-1733400000-1733810400-1734199200-20.gif

[heehaw453]

The h5 looks great for 12/12 PNA/NAM state. What bugs me is the poleward EC ridge and we are trying to time cold air. I've been monitoring EC snow storms for over 30 years and on the I-95 and coastal plain in early/mid December you almost always need confluence (troughing) OR moisture running into an anonymously cold air mass for bigger snows. I feel the former is not going to happen and the latter I think favors I81 Scranton northward.

Hate to be a debbie downer on this as I'd like nothing more than 6"+ of the white gold. I'd love to be wrong and I am rooting for Rb's scenario 100%!

[Dunnzoo]

Cold and dry, warm and wet. CFS weeklies showing AN temps until after New Year's so not expecting anything white until then. There is a chance of some white stuff as a storm leaves on the 12th, but not getting my hopes up. It's tough for NENJ to get any accumulations in transitional December, so I'll keep my expectations low until we get sustained cold next year.

[dkodgis]

“ Cold and dry, warm and wet”

Yep

[rb924119]

Bunch of Grinches trying to steal my Christmas, the lot of you! Haha jk. But! I like the look of today’s 12z GFS, and think it’s under-representative of the precipitation shield on the western side. We’ll see, but I continue to hold for now.

[rb924119]

For the record, the Euro is also in my camp, though on the outskirt.

[rb924119]

And here comes the GEM…..

[rb924119]

It’s not going to show on the precip maps, but there’s a definite trend in today’s 12z operational runs so far to tilt the southern stream trough negative sooner. That’s important because it will allow more forcing for ascent to be focused in the cold sector behind the frontal boundary that continues to press eastward.

[rb924119]

Let’s give this a chance, gang. It ain’t over yet.

[rb924119]

It’s not going to show on the precip maps, but there’s a definite trend in today’s 12z operational runs so far to tilt the southern stream trough negative sooner. That’s important because it will allow more forcing for ascent to be focused in the cold sector behind the frontal boundary that continues to press eastward.

Also gets a coupled jet structure going toward the end. Bottom line, the precip maps on the GEM under-done, and this would be a significant snow north and west of I-95. We need 50 miles to get the bullseye into the Corridor, and I still think we get there.

[amugs]

Cold and dry, warm and wet. CFS weeklies showing AN temps until after New Year's so not expecting anything white until then. There is a chance of some white stuff as a storm leaves on the 12th, but not getting my hopes up. It's tough for NENJ to get any accumulations in transitional December, so I'll keep my expectations low until we get sustained cold next year.

Crap Forecast Sysem?? Euro's show cold swinging back by around Xmas with the MJO phase going into null phase. CFS shows phase 7 which would have the man trough over the midwest

[amugs]

It’s not going to show on the precip maps, but there’s a definite trend in today’s 12z operational runs so far to tilt the southern stream trough negative sooner. That’s important because it will allow more forcing for ascent to be focused in the cold sector behind the frontal boundary that continues to press eastward.

Also gets a coupled jet structure going toward the end. Bottom line, the precip maps on the GEM under-done, and this would be a significant snow north and west of I-95. We need 50 miles to get the bullseye into the Corridor, and I still think we get there.

Posted on X and another board this reminds me of the anafront storm of 2014 that the 1st cutter, apps runner, sets up the 50/50 and buckles the flow behind it dragging the cold air press east more. Even 25 miles would be an absolute paste job for NNJ and a the HV.
Clipper helps sets up the 1st storm that sets up this one. Two days ago no 50/50, now we see the semblance of a 50/50 - why you never know what weather will do ESPECIALLY in a transitional month as Zoo alluded to.

[Dunnzoo]

Cold and dry, warm and wet. CFS weeklies showing AN temps until after New Year's so not expecting anything white until then. There is a chance of some white stuff as a storm leaves on the 12th, but not getting my hopes up. It's tough for NENJ to get any accumulations in transitional December, so I'll keep my expectations low until we get sustained cold next year.

Crap Forecast Sysem?? Euro's show cold swinging back by around Xmas with the MJO phase going into null phase. CFS shows phase 7 which would have the man trough over the midwest

lol we'll see. I just don't trust the models for our area in December until we are within a few days. The climate is too transient, no sustained cold, and the marine layer dashes most chances of decent snow around here. NWNJ, Hudson Valley and NEPA, no problem. But NENJ? I'll hang out on OTI for a few more weeks.

[rb924119]

Telling you right now, the 12z Euro is a warning-criteria snow for the I-95 Corridor. The reason it’s not showing? Because it has 925mb temps between 0-2°C. IGNORE THAT. Once the forcing is realized, it will snow. This is another very steep front, so once it goes through, you snow. Cold air arrives as the precipitation does. I fully expect the precip maps to play catch-up yet again. Game on, folks. The negative tilt of the southern stream earlier is a real trend. If that continues, which it very well could, arguably should, you’re golden.

[heehaw453]

It’s not going to show on the precip maps, but there’s a definite trend in today’s 12z operational runs so far to tilt the southern stream trough negative sooner. That’s important because it will allow more forcing for ascent to be focused in the cold sector behind the frontal boundary that continues to press eastward.

Also gets a coupled jet structure going toward the end. Bottom line, the precip maps on the GEM under-done, and this would be a significant snow north and west of I-95. We need 50 miles to get the bullseye into the Corridor, and I still think we get there.

Posted on X and another board this reminds me of the anafront storm of 2014 that the 1st cutter, apps runner, sets up the 50/50 and buckles the flow behind it dragging the cold air press east more. Even 25 miles would be an absolute paste job for NNJ and a the HV.
Clipper helps sets up the 1st storm that sets up this one. Two days ago no 50/50, now we see the semblance of a 50/50 - why you never know what weather will do ESPECIALLY in a transitional month as Zoo alluded to.

Give me that 50/50 or anything to slow the Atlantic flow down and let this energy consolidate and I will beat that drum with you all.

12Z Canadian
h5 digging trough tilting negative is always intriguing, but there's not consolidation here on the mid-levels. Which IMO means it scoots on out and is more anafrontal which I don't think works too well here (I95) for bigger snows. Again my observations are my opinions and not saying this cannot work out. I respect Rb's analysis.