Christmas Storm V

[msuwx]

I feel like I need a shower after sitting through that....good grief. Somebody said it....NAM is basically a cold frontal passage. yikes.

[Cold Rain]

One thing we can say for certain is that this run is VASTLY different than the 0Z run in terms of the strength of the STJ s/w and the interaction between the two streams.

The NAM has never shown a bomb with this system so far. But it looks like with a few changes, it could.

It's starting to seem like this is going to be an all or nothing storm.

[burgertime]

Just putting this out there, we knew the models would flip at some point. There is no need to cliff dive just yet or say this storm isn't going to happen. I think 00z tonight will be the most important runs. We've all seen this plenty of times (granted climo was different) where it shows something, disappears then shows back up with in 36 hours. Just last year it looked wonderful for me for every storm only to strongly shift NW and put me out of the game at the very last minute. Not saying it will do that this year but that's the way weather is, you just never know until the day for 100% certainty.

[WidreMann]

Just putting this out there, we knew the models would flip at some point. There is no need to cliff dive just yet or say this storm isn't going to happen. I think 00z tonight will be the most important runs. We've all seen this plenty of times (granted climo was different) where it shows something, disappears then shows back up with in 36 hours. Just last year it looked wonderful for me for every storm only to strongly shift NW and put me out of the game at the very last minute. Not saying it will do that this year but that's the way weather is, you just never know until the day for 100% certainty.

Also, the GFS and the Euro still have a storm. Yes, it's not the perfect bomb that we had a day ago, but it's up to a half foot for some people and at least a solid 2-4" across a lot of NC. So to get all worried because the flip-flop NAM can't get it's act together is probably unnecessary.

[SnowNiner]

Am I missing something in regard to the strength of the system out west right now? It's supposed to be real strong but I don't see much radar/precipitation with it right now on the radar. Is it still a beast or could the NAM be right just crushing it like it was a wee little girl?

[Poimen]

The 12Z NAM looks an awful lot like last nights GGEM. Not the trend we were looking for.

[QC_Halo]

One more post like this in this thread and you're done.

I understand the rule, thinks its smart, and have been following it, but it seems some people are excluded from having to follow it..

[msuwx]

Indeed. I liked the trends overall in the 6z GFS. We will see if the 12z follows suit.

Also, the GFS and the Euro still have a storm. Yes, it's not the perfect bomb that we had a day ago, but it's up to a half foot for some people and at least a solid 2-4" across a lot of NC. So to get all worried because the flip-flop NAM can't get it's act together is probably unnecessary.

[iceman]

Also, the GFS and the Euro still have a storm. Yes, it's not the perfect bomb that we had a day ago, but it's up to a half foot for some people and at least a solid 2-4" across a lot of NC. So to get all worried because the flip-flop NAM can't get it's act together is probably unnecessary.

LOL @ a half a foot. Doubtful.

[NCWeSU]

HPC has all but disregarded the NAM up to this point. I don't see any reason why that would change unless the rest of the 12z suite follows along.

[WidreMann]

LOL @ a half a foot. Doubtful.

Check the 06z GFS ensembles, which remain stronger and to the west of the OP. They're even better than 00z and honestly, the best we've seen out of the GFS ensembles in the last few days.

[WidreMann]

And the UKIE, JMA.

UKMET still pops a decent storm, just a bit too far offshore. With a NW trend, we'd do okay, at least central and eastern NC.

[Shawn]

The issue here is, the models were locking onto something yesterday morning at this time slowly but surely and now since 18z & 00z last night they are backing off of anything major for the Southeast since the shortwave has come on shore. Looking at the current maps it definitely already seems North of even the Euro guidance at this time. I don't even think it entered as far South as it was supposed to? This trend is not good for anyone honestly, and the closer we get, the more accurate these models become!

[Poimen]

And the UKIE, JMA.

Yes, those too. At this point I'd rather be back on the OBX. But we shall see what the rest of the 12Z guidance has for us.

[iceman]

The precip also seems to be arriving later. How does that effect things?

[packbacker]

Also, the GFS and the Euro still have a storm. Yes, it's not the perfect bomb that we had a day ago, but it's up to a half foot for some people and at least a solid 2-4" across a lot of NC. So to get all worried because the flip-flop NAM can't get it's act together is probably unnecessary.

Only concern is we needed a phase at hour 54-60 so you would think the NAM can handle that.

[iceman]

The issue here is, the models were locking onto something yesterday morning at this time slowly but surely and now since 18z & 00z last night they are backing off of anything major for the Southeast since the shortwave has come on shore. Looking at the current maps it definitely already seems North of even the Euro guidance at this time. I don't even think it entered as far South as it was supposed to? This trend is not good for anyone honestly, and the closer we get, the more accurate these models become!

Best post of the day so far. The trends suck and anyone thinking any part of NC is getting close to a half a foot of snow at this point is dreaming.

[WidreMann]

Only concern is we needed a phase at hour 54-60 so you would think the NAM can handle that.

You'd think a lot of things about the NAM.

[Shawn]

Only concern is we needed a phase at hour 54-60 so you would think the NAM can handle that.

We need the s/w to really intensify like previous runs on the Euro/NAM a couple days ago and for the energy in the Northern Stream to stay more consolidated in a 3-punch scenario like Euro depicted yesterday. I'm not the best at reading these maps but it does look like the s/w is a little bit weaker and the Northern Stream is faster and less favorable for a phase at the right time even on the Euro now.

[WidreMann]

Best post of the day so far. The trends suck and anyone thinking any part of NC is getting close to a half a foot of snow at this point is dreaming.

Except for the GFS trends, the GFS ensemble trends, the Euro. Even the UKMET isn't terrible. So we have the NAM sucking, as usual, and the Canadian popping a low too late. We'll see what the later Canadian runs show. I wouldn't hang my hat on the NAM until we are at 24-36 hours ahead of the event HERE.

[BullCityWx]

I understand the rule, thinks its smart, and have been following it, but it seems some people are excluded from having to follow it..

We definitely don't have a perfect system but we're doing our best. I am trying to weed out the worst offenders though.

[Poimen]

Best post of the day so far. The trends suck and anyone thinking any part of NC is getting close to a half a foot of snow at this point is dreaming.

Perhaps, but I think the issue is not so much with the CA shortwave as it is with the various northern stream shortwaves.

[WidreMann]

We need the s/w to really intensify like previous runs on the Euro/NAM a couple days ago and for the energy in the Northern Stream to stay more consolidated in a 3-punch scenario like Euro depicted yesterday. I'm not the best at reading these maps but it does look like the s/w is a little bit weaker and the Northern Stream is faster and less favorable for a phase at the right time even on the Euro now.

Southern s/w looks better on the 12z NAM than it did on the 00z NAM. It just doesn't phase. Since the NAM seems to be wavering a great deal on how it handles the northern stream, I don't know if I'd pin any NAM changes on a "trend".

[Weather Czar]

Best post of the day so far. The trends suck and anyone thinking any part of NC is getting close to a half a foot of snow at this point is dreaming.

The last three runs of the GFS have been the best so far. Including the GFS ensembles.

[NCSNOW]

Heres a current look at the players on the field. I have better links, but they take up to much space. You can tell just by looking at water vapor our southern stream isnt to shabby, but its easy to see that the northern stream is the big boy on the block. You folks want a motion sat view of what a phase looks like then click this 1st link. I think after you watch it, you can see how unpredictabel it is for man or model to forecast these type of synoptic events. This link is the Jan 2000 Carolina Crusher. It also shows you why folks west of Augusta/Charlotte/RDU are best served with a phase to originate in the GOM as opposed to The NEcorner of Florida, Jacksonville. There is also a image of what the ETA(Current Nam) displayed right up to the event and what actually took place. The model showed a phased solution happening way later and futher east, than what actually occured.

radar loop from 00Z January 24 (700 PM January 23) through 11Z January 26 (600 AM January 26)

Model Error

In general, forecast models preformed very poorly during this event. An example of this is shown in the image below which compares the 48 hour, observed liquid equivalent precipitation with the Eta model 48 hour forecast valid at the same time (click on the image to enlarge, image provided by Michael Brennan, NC State University). The model failed to capture the significant precipitation over the Carolinas and Virginia; in fact the Eta forecast had no precipitation over Raleigh and Richmond where over an inch of liquid equivalent was observed.

</IMG>

As forecasters scrambled to adjust forecasts to reflect the unfolding snowstorm, there was little time to analyze the full reason why the forecast had gone bad. In the wake of the storm, many were left wondering how nearly two feet of snow could have fallen in less than 24 hours with very little warning. Was there something that could have been analyzed ahead of time that would have lead to questioning of model precipitation forecasts? Or was there a physical mechanism that was misunderstood, or missed by the models? Below is a brief summary of some of the forecast errors and research topics that arose from this case.

Current View of our system: Hopefully the above info gives newbies and others an insight as to how precise things have to be in order to get a phased winter storm to work out just right.

[Shawn]

Southern s/w looks better on the 12z NAM than it did on the 00z NAM. It just doesn't phase. Since the NAM seems to be wavering a great deal on how it handles the northern stream, I don't know if I'd pin any NAM changes on a "trend".

I understand totally what you're saying. The ensembles even from the 06z GFS are not the worst in the world. This all comes down to how this thing will phase if at all.

[msuwx]

Yeah, I have zero confidence in the NAM. 12z GFS will indeed be interesting....curious if it can keep stepping a bit westward.

[weatherfide]

Just putting this out there, we knew the models would flip at some point. There is no need to cliff dive just yet or say this storm isn't going to happen. I think 00z tonight will be the most important runs. We've all seen this plenty of times (granted climo was different) where it shows something, disappears then shows back up with in 36 hours. Just last year it looked wonderful for me for every storm only to strongly shift NW and put me out of the game at the very last minute. Not saying it will do that this year but that's the way weather is, you just never know until the day for 100% certainty.

I believe you are correct in some of this. It does appear that the players are so very close to harmonizing. It wouldn't take much to get the phase that is needed. In this situation, substantial uncertainty may continue very close to 48 hours before the event, maybe even 36 hours.

[WidreMann]

I understand totally what you're saying. The ensembles even from the 06z GFS are not the worst in the world. This all comes down to how this thing will phase if at all.

For me, the 06z GFS ensemble mean is a nice Christmas snow. I'd take 4-6" in a heartbeat.

[Cold Rain]

Southern s/w looks better on the 12z NAM than it did on the 00z NAM. It just doesn't phase. Since the NAM seems to be wavering a great deal on how it handles the northern stream, I don't know if I'd pin any NAM changes on a "trend".

I agree. If you look at the facts over the last few cycles, you will see the following:

Euro still shows a nice storm but has trended away from the apocalypse.

GFS has trended away from nothing toward a storm.

Ukie has trended from super suppressed to a little bit suppressed.

Canadian has trended toward more suppression.

Nam has trended all over the place.

The data is hopefully being sampled better, so hopefully the models will converge. But at this point at least, the likelihood of convergence toward the Euro is probably greater than the likelihood toward the Nam.