12Z Guidance Discussion 12/23/2010

[Guest someguy]

the writing was on the wall at 54 with the sw weakening and left behind in the w. gulf. It also causes the ridge out west and ahead to be less amplified.

strongly disagree

[Dcwx]

Doesn't anyone care the Ukie and Canadian are well out to sea? I mean these are not junk models. Seems to me that in torms of past they were always at least in the ballpark, often the kie a little too far east and GGEM west. But they are not in the zip code of a snowstorm here. No worries about that?

To me things are not very good right now. Almost going quickly the way of last week. Euro decent hit, GFS scraper, everything else is not even close.

These models have been conveniently "dismissed" because they have not shown the consistency as the Euro. But it seems they have been consistent in showing some form of OTS run for days. I think at this point there are few who are riding the Euro solution of yesterday hard. I am not saying its over, but if we do not get any trending back west for the 12z, I think it might be time to look ahead; at least for the southern MA.

[buckeye]

That sudden SE kick it takes is the problem after 36 hours, if it simply continued on a due east trajectory the thing would phase like the second coming of 1899.

but isn't the reason for that the fact that it starts to close off? I couldn't understand why some were thinking its a good thing to have the low closed off across the gulf states. To me it seems like the last thing you would want is the sw closing off outside the base of the trough. Wouldn't it be better for you to have a lot of energy sharpening the base of the trough as it moves east with more coming down the backside. The trough tilts neg and then a closed low drops in and bam.

[SnowGoose69]

The 12Z RGEM continues to agree with the NAM through 48 about as dead on as possible across the Midwest and South...we could really use an RGEM to 84 hours right about now.

[Quasievil]

well, NAM's been ots so far and the DGEX has followed suit

I have always said I'm a firm believer in pattern repetition

last weekend's storm was the first potential threat for the east coast this year and it went ots

one storm does not establish a pattern, but in my little wx world, 2 does

so I'll give it some time, but my gut on this storm has done a 180 in the past 20 hours

I'd hate to do it but I agree with this. It hasn't been difficult to figure out why Miller A's are difficult to get in a La Nina... we're seeing that now. The flow is too fast and by the time the phase happens ... see ya OTS.

[Joe4alb]

I think the whole issue here is that s/w coming from the 4-corners region. If that dives S/E rather than east we end up with almost no phase and a neutral trough at best. That is very similar to what the GFS was showing several runs ago. If that s/w moves into TX, and then across the gulf states rather than into the GOM we are back in business.

[stormtracker]

NAM might not be too far off..12z RGEM doing the same thing 48 hours

[WxClimate]

The problems I have with getting a major east coast storm out of the whole setup are:

1. The longwave trough is too far east

2. The 500 mb trough is too far tilted in the positive direction

3. The jet streak in the northern jet hasn't rounded the base of the trough by the time the low center is off Hatteras

It's gonna be awfully hard to get something to run up the coast close enough for it to have a big impact

[buckeye]

strongly disagree

well, when i saw that map all i could see was the disconnect.

[Dalfy]

NAM might not be too far off..12z RGEM doing the same thing 48 hours

Not necessarily... The big screw job occured outside of 48 hrs.. around 60-66... up until then the evolution seemed decent so we can never know what the rgem does with the storm as we cant really extrapolate it.

[SnowGoose69]

The problems I have with getting a major east coast storm out of the whole setup are:

1. The longwave trough is too far east

2. The 500 mb trough is too far tilted in the positive direction

3. The jet streak in the northern jet hasn't rounded the base of the trough by the time the low center is off Hatteras

It's gonna be awfully hard to get something to run up the coast close enough for it to have a big impact

Number one is the biggest problem and I've posted that too many times to count....its rare with this positioning to get a good storm and if you do the snow is only maybe going to be 50 to at most 80 miles inland most places.

[CT Rain]

Number one is the biggest problem and I've posted that too many times to count....its rare with this positioning to get a good storm and if you do the snow is only maybe going to be 50 to at most 80 miles inland most places.

Agreed for sure. This is also one of the setups that can really hammer I-95. If that trough is too far west we're obviously looking at an increased chance for this thing running up the coast and bringing in ptype problems.

High risk... high reward.

[Organizing Low]

when the NAM and RGEM agree, its pretty much a lock.....but the screwup looks to occur after the 48 hr period

EDIT see that was posted above already

[Clinch Leatherwood]

Not necessarily... The big screw job occured outside of 48 hrs.. around 60-66... up until then the evolution seemed decent so we can never know what the rgem does with the storm as we cant really extrapolate it.

Imo if the gulf s/w is in that position at 48 hrs with the rest of the trough where it is, this is bad news and I agree with the camp that says it's an ots solution. It's left behind. It seems suspect to me, the gfs seems to suffer less from big swings so I have some hope

[Guest someguy]

The problems I have with getting a major east coast storm out of the whole setup are:

1. The longwave trough is too far east

2. The 500 mb trough is too far tilted in the positive direction

3. The jet streak in the northern jet hasn't rounded the base of the trough by the time the low center is off Hatteras

It's gonna be awfully hard to get something to run up the coast close enough for it to have a big impact

alll very good points...

to point number -- made the very same point on the radio show a few days ago... BUT I think what is different is the extreme 500 low over nw atlantic/ se Canada

that feature is also UN common and extreme

2... that is why the southern s/w is track is important.

3. according to then GFS and GGEM.... but this is kind of circular reasoning no?

your point is right but you are looking at those Models that show storm or one that is not close enough ... to show thee is no storm that is close enough?

[SnowGoose69]

Imo if the gulf s/w is in that position at 48 hrs with the rest of the trough where it is, this is bad news and I agree with the camp that says it's an ots solution. It's left behind. It seems suspect to me, the gfs seems to suffer less from big swings so I have some hope

It seems to me it gets shunted SE because the northern energy forces it, so how do we win seriously? We need the northern energy slower? But then it doesn't phase in time...LOL...it seems this one is just too tough to get happen....here comes the 12Z GFS...no matter what it shows, east or west of its last run I can't wait for the reaction..

[psuhoffman]

There is one trend that is on all the guidance the last few runs and that is for the northern branch not to dig nearly as much and further east. The NAM and RGEM both look bad to me at 48 hours because the southern energy is behind the trough. The trough is way to progressive and its not digging south its diving in more SE'ward. If you go back and look at the euro runs that produced the moster storm that energy in the southern branch was where the models have it now, but the northern branch was digging in BEHIND it, not in front of it. The GFS has headed in that direction also which is why even with a nice cut off at h5 it amplifies the energy way too late because its not amplifying that southern energy. It washes that out and then sparks a storm along the trough on its own with northern branch energy, but this happens way too late for the mid atlantic. New England might have a shot in that scenario and perhaps NYC but certainly not the mid atlantic. I feel like some are looking at specific details and missing a HUGE change in the entire way this system is evolving now on models. That said the euro run last night looking at the H5 was not far from having a similar solution to its past 5 runs. it would not take much to pull it back west as the euro progression was still showing the older idea with the northern branch digging in behind, it just got things going about 3 hours too late to hook the low in for the mid atlantic. However, the other models are NOT trending towards this. They may show a run that looks close in sensible weather from time to time but they are getting there completely different. I have yet to see any guidance other then the euro showing a favorable H5 setup with the northern branch digging deep enough for what I would like to see for the mid atlantic.

[psuhoffman]

BTW, from what I see its not the speed of the STJ that changed, its the speed of the northern branch which is now getting out ahead of the southern branch. That disconnect is the problem IMHO>

[Clinch Leatherwood]

It seems to me it gets shunted SE because the northern energy forces it, so how do we win seriously? We need the northern energy slower? But then it doesn't phase in time...LOL...it seems this one is just too tough to get happen....here comes the 12Z GFS...no matter what it shows, east or west of its last run I can't wait for the reaction..

If the GFS is a miss it will be wait for the Euro, if the GFS is a hit and the Euro a miss it'll be ride the GFS.

Anyway, GFS is slower right away with both the sw s/w and the one coming down from north of MT early.

[chris87]

There is one trend that is on all the guidance the last few runs and that is for the northern branch not to dig nearly as much and further east. The NAM and RGEM both look bad to me at 48 hours because the southern energy is behind the trough. The trough is way to progressive and its not digging south its diving in more SE'ward. If you go back and look at the euro runs that produced the moster storm that energy in the southern branch was where the models have it now, but the northern branch was digging in BEHIND it, not in front of it. The GFS has headed in that direction also which is why even with a nice cut off at h5 it amplifies the energy way too late because its not amplifying that southern energy. It washes that out and then sparks a storm along the trough on its own with northern branch energy, but this happens way too late for the mid atlantic. New England might have a shot in that scenario and perhaps NYC but certainly not the mid atlantic. I feel like some are looking at specific details and missing a HUGE change in the entire way this system is evolving now on models. That said the euro run last night looking at the H5 was not far from having a similar solution to its past 5 runs. it would not take much to pull it back west as the euro progression was still showing the older idea with the northern branch digging in behind, it just got things going about 3 hours too late to hook the low in for the mid atlantic. However, the other models are NOT trending towards this. They may show a run that looks close in sensible weather from time to time but they are getting there completely different. I have yet to see any guidance other then the euro showing a favorable H5 setup with the northern branch digging deep enough for what I would like to see for the mid atlantic.

exactly....there is no southern stream phase in the NAM....the lead shortwave digs with way too much of an eastern trajectory....the euro monsters had that lead shortwave dig almost due south and phase with the southern stream....the NAM depiction just crushes the southern stream...it might as well not even be there...it's not doing any good in this setup

[buckeye]

There is one trend that is on all the guidance the last few runs and that is for the northern branch not to dig nearly as much and further east. The NAM and RGEM both look bad to me at 48 hours because the southern energy is behind the trough. The trough is way to progressive and its not digging south its diving in more SE'ward. If you go back and look at the euro runs that produced the moster storm that energy in the southern branch was where the models have it now, but the northern branch was digging in BEHIND it, not in front of it. The GFS has headed in that direction also which is why even with a nice cut off at h5 it amplifies the energy way too late because its not amplifying that southern energy. It washes that out and then sparks a storm along the trough on its own with northern branch energy, but this happens way too late for the mid atlantic. New England might have a shot in that scenario and perhaps NYC but certainly not the mid atlantic. I feel like some are looking at specific details and missing a HUGE change in the entire way this system is evolving now on models. That said the euro run last night looking at the H5 was not far from having a similar solution to its past 5 runs. it would not take much to pull it back west as the euro progression was still showing the older idea with the northern branch digging in behind, it just got things going about 3 hours too late to hook the low in for the mid atlantic. However, the other models are NOT trending towards this. They may show a run that looks close in sensible weather from time to time but they are getting there completely different. I have yet to see any guidance other then the euro showing a favorable H5 setup with the northern branch digging deep enough for what I would like to see for the mid atlantic.

bingo

[RUNNAWAYICEBERG]

GFS slower and better with the energy dropping from canada/dakotas.

[chris87]

12z GFS at hour 30....looks much better in terms of the interface between the southern stream and the northern stream shortwave...we'll see

[weathermanchild]

The 12z gfs so far has the ridge set up VERY identical to the Euro... and much more to than the 00z run.

00z EURO 24 hr forecast

00z GFS 24 hour forecast

12z GFS 12 hour forecast (FOCUS in on the height contours from TX into NW Canada... and especially the orientation of the ridge in NW Canada where it will push the nearby shortwave down the trough... stronger ridge there means a deeper trough (which I think digs faster and ends up phasing quickly with the shortwave, as the EURO insists will happen the the GFs has hinted at recently...

Also, the strength of the shortwave in the 12z GFS f012 is much closer to the 00z ECMWF f024 than the 00z GFS f024... Im expecting a major storm from the 12z gfs.

[Joe4alb]

s/w slightly further north at 30. Good sign so far. better chance of an early phase unlike if the s/w dives in the GOM (NAM)

[Clinch Leatherwood]

Compared to 0z there's some significant changes. The southern s/w is further west which makes the entire developing trough slightly more positively tilted as the energy in the midwest is faster. At the same time energy coming down into the Dakotas (well north of there) is even slower.

Overall I'd say probably not good, but It's early.

[Guest someguy]

made this point on the show last night the N s/w has GOT to drop into the southern stream ... anything less and its trouble

There is one trend that is on all the guidance the last few runs and that is for the northern branch not to dig nearly as much and further east. The NAM and RGEM both look bad to me at 48 hours because the southern energy is behind the trough. The trough is way to progressive and its not digging south its diving in more SE'ward. If you go back and look at the euro runs that produced the moster storm that energy in the southern branch was where the models have it now, but the northern branch was digging in BEHIND it, not in front of it. The GFS has headed in that direction also which is why even with a nice cut off at h5 it amplifies the energy way too late because its not amplifying that southern energy. It washes that out and then sparks a storm along the trough on its own with northern branch energy, but this happens way too late for the mid atlantic. New England might have a shot in that scenario and perhaps NYC but certainly not the mid atlantic. I feel like some are looking at specific details and missing a HUGE change in the entire way this system is evolving now on models. That said the euro run last night looking at the H5 was not far from having a similar solution to its past 5 runs. it would not take much to pull it back west as the euro progression was still showing the older idea with the northern branch digging in behind, it just got things going about 3 hours too late to hook the low in for the mid atlantic. However, the other models are NOT trending towards this. They may show a run that looks close in sensible weather from time to time but they are getting there completely different. I have yet to see any guidance other then the euro showing a favorable H5 setup with the northern branch digging deep enough for what I would like to see for the mid atlantic.

[SteveB]

GFS looks good so far but remember, the other models ran into issues after 42/48 hours....we'll see. I'm hopeful.

[mitchnick]

the problem, to my weenie eyes, is that although the Canadian vortex is moving NE, it has expanded, lowering heights along the east coast and killing our chances

the energy from the north and the s/w in the southern stream are too little too late to overcome the effects of the Canadian monster

[Joe4alb]

Don't see any significant changes at 42. s/w just a bit faster but that is about it.