12Z Guidance Discussion 12/23/2010

[afvet89]

It says maybe we finally put to bed the notion that the Euro is a consistently superior model

Amen brother. Also, it seems whenever u need a NW trend from the models along the coast u dont get it.However when the storm is in the Ohio Valley or Midwest and u dont want a NW shift, u get it.Like 2 weeks ago when the storm went thru Minnesota.

[RUNNAWAYICEBERG]

some really terrible rants in here.....

i like the way the NAM is showing threw 48, and the GFS isnt bad either. id let the better model post 48hr (EURO) handle the phasing.

[wxtogo]

it says that people need to stop model hugging the one that shows the snow and be objective about the scenerios

Very Much Agree! You had to know that the Euro scenario would never play out when no other model was even close.

[WBRE Wx]

Here are my thoughts:

There are significant differences even at initialization for both the NAM and GFS at 12Z. Looking at the 500 hPa initialization charts, the NAM seems like everything is shifted a bit west compared to the GFS. With regards to the western Atlantic low, the NAM shows a stronger low with more of a elongated trough to the SW, the vorticity maxima around the low are stronger. The vorticity maxima in NW Arizona is displaced about 50 miles west of the GFS and it is stronger.

At H+24 the trend persists, the western Atlantic low is shifted west with the NAM but also a bit weaker than the GFS. The vort max has moved ESE to the Texas Panhandle where the NAM is a bit further west, a bit slower and a bit stronger.

At H+48 the trend persists, but not only that the GFS & NAM begin diverging significantly. In my view, the NAM has a perturbation problem at initialization which becomes a positive feedback loop throughout the entire model run. The NAM has the vort max southwest of Galveston Bay, TX and the northern stream energy around Kansas City, MO. Meanwhile, the GFS is a bit less amplified with both the southern and northern streams, however the vort max in the southern stream is much more progressive. At H+48 the 500 hPa vorticity maxima is around Baton Rouge, that is a difference of about 250 miles and is extremely significant in my view at H+48 when we consider the phasing need which others have discussed.

A lot happens after H+48 so I’ll go to H+60. The NAM is not phasing because it is slower with the southern stream vorticity max. The northern and southern streams are clearly separated with the vort max well south of New Orleans, while with the GFS the streams are beginning to phase, the separation of the northern and southern streams are clearly less identifiable, the trough is displaced further west and is beginning to become more amplified.

At H+72 the the NAM is beginning to phase put the initial piece of southern energy is driven down to West Palm Beach, FL? The GFS is more phased and the upper-level trough is more amplified.

After 72 hours I wouldn’t trust either model so I’ll patiently wait for the ECMWF ensembles to come out, but in a nut-shell I believe the NAM is suffering from initialization issues. I'm very interested to see the ECMWF's interpretation of the initialization and speed of the energy in the southern stream.

Good analysis. So can we read into this that the NAM may be too slow with the southern piece, the GFS a little too fast? Is the Euro falling somewhere in the middle? Looks to me as well like both the NAM and GEM are slower with the southern piece and bury it in the Gulf. On the optimistic side for the storm, the GFS does not bury it but it's taking it out a little faster than the other models. If we compromise on the timing are we threading the needle down there, ala the Euro??? Will be interesting to see the 12z Euro in a couple of hours.

[adelphi_sky]

what it tells me is this... The gfs is garbage 7+ days out b/c it teases us with multiple runs of a snowstorm then in the mid range the euro picks up on it - we all get excited in the 5-6 day range and then slowly the nam and gfs start to crummble. We all sit and hope that the euro is right as the American models begin to sniff out the fact that this isn't going to be the blizzard of the century. At the end of the day the euro is not king bur just a tease. Lastly we shouldn't get to excited over threats 100+ hours out.

I would argue that we shouldn't expect much past 48 hours out. I think we put too much trust in the people that build these models. They give us an idea about what's going to happen, but usually, their guess is as good as any human looking at maps. I'm not sure how much advantage a model gives over simple map analysis outside of 48 hours.

[Midlo Snow Maker]

lets take the model bashing here please

[Chagrin Falls]

Good analysis. So can we read into this that the NAM may be too slow with the southern piece, the GFS a little too fast? Is the Euro falling somewhere in the middle? Looks to me as well like both the NAM and GEM are slower with the southern piece and bury it in the Gulf. On the optimistic side for the storm, the GFS does not bury it but it's taking it out a little faster than the other models. If we compromise on the timing are we threading the needle down there, ala the Euro??? Will be interesting to see the 12z Euro in a couple of hours.

Well, I think the NAM is much too slow, too far south and too far west with the southern stream energy. The GFS, well...too early to tell. Many think the ECMWF has a southern/stream 4-corners bias. This will be a great test.

[Scarlet Pimpernel]

This is just an awful post. How are you going to congratulate models at this point? Today is Thursday, the event won't get started until Sunday. You can start handing out awards Friday night if you wish and please don't tell us what the Euro will do ~2 hours before it initializes...

Totally agree. Yes, this is highly disappointing of course for all of us. But to declare the Euro a piece of <bleep> just because it was giving us a dream storm for several straight runs but now that looks significantly less likely is just spouting off anger. Actually, the Euro still has a major storm, but it was more wide-right in last night's run such that mostly NY and New England get hammered but unfortunately the MA gets missed. It's not like it was showing the thing going out to Bermuda all of a sudden.

[WBRE Wx]

I would argue that we shouldn't expect much past 48 hours out. I think we put too much trust in the people that build these models. They give us an idea about what's going to happen, but usually, their guess is as good as any human looking at maps. I'm not sure how much advantage a model gives over simple map analysis outside of 48 hours.

Excellent point. In my days at Penn State they would make us forecast without looking at models... good old fashioned map analysis. My worry all week on this storm is just how far east that ridge in the west is. A ridge in the eastern Rockies is awfully far east to get a nice hit up and down the coast. Are there exceptions? Absolutely. But with that kind of energy crashing into the west coast and that ridge cruising east, it only make sense that 90% of the time or better that storm will be off the coast....

[afvet89]

I would argue that we shouldn't expect much past 48 hours out. I think we put too much trust in the people that build these models. They give us an idea about what's going to happen, but usually, their guess is as good as any human looking at maps. I'm not sure how much advantage a model gives over simple map analysis outside of 48 hours.

Ive seen times over the yrs where the models have absolutely nailed a storm, other times when it looks like they were programmed from Kmart and havent got a clue. I would hope as the yrs continue and thru more research , that more consistency would be given from the models instead of these hit and miss scenarios.

[rygar]

What does this say about the Euro if the NAM and GFS end up right?

Sorry, not exactly model analysis, but I want to thank all the experts last few days who have hammered home the point that while possible, a big storm has always been a very risky call in this situation. It really just says take 6+ day forecasts with a grain of salt - sure, there may be a threat showing, but that is all it is, a possibility..

[WBRE Wx]

Any word on the HM/New year's storm on the GFS?

Already looking ahead! Seems like the overwhelming consenus from both operational GFS and its ensembles past few days that the ridge is coming east with a nice warmup to end 2010 and start 2011. Strong storm heads into the western lakes around New Year's Day... Euro concurs.

[ohleary]

it says that people need to stop model hugging the one that shows the snow and be objective about the scenerios

Best post I've read in days.

[thegreatdr]

If the southern shortwave is able to emerge into the Gulf of Mexico, there's a chance there will be winter recon on this puppy when it gets there, like there was on the recent miss. If not, the recon would have to wait til the system is emerging offshore the East coast. This data gets into the NCEP and non-NCEP guidance alike. It seemed like the recon led to the model switch toward non-storm last time, so you never know. As they say, there is uncertainty. =)

[Guest someguy]

IF it turns out that the 12 NAM and 12z GFS Ukie are correct

THINK about that

while the operational Euro solution was extreme and fun to wacth and impressive in the way the model held it for 2 or 3 runs

right now even the euro ens mean forecast would turn out to be 100% wrong

ask yoruselves and be honest....

would you in a million years ever think the euro ensemble eman would turn to be totally wrong

after showing the same thing for 6 + runs ?

and that the Nam and GFS will be correct and there will be NO snow -- NONE -- over RIC DCA BWI PHL NYC BDL... and darn LItlte in BOS?

really?

[Midlo Snow Maker]

Here is the funny thing. My daughter's winter camp, in the Richmond area, was just cancelled for Monday because of "the impending snow storm". Absolutely ridiculous the hype and horn blowing around one model's solutions that were not backed up by any other model.

i love how the the storm has passed, and everything has verified great bashing folks

[ezweather]

Great post Dave..

IF it turns out that the 12 NAM and 12z GFS Ukie are correct

THINK about that

while the operational Euro solution was extreme and fun to wacth and impressive in the way the model held it for 2 or 3 runs

right now even the euro ens mean forecast would turn out to be 100% wrong

ask yoruselves and be honest.... would you in a million years ever think the euro ensemble eman would turn to be totally wrong

the Nam and GFS right and NO snow over RIC DCA BWI PHL NYC BDL... and darn LItlte in BOS?

really?

[ag3]

IF it turns out that the 12 NAM and 12z GFS Ukie are correct

THINK about that

while the operational Euro solution was extreme and fun to wacth and impressive in the way the model held it for 2 or 3 runs

right now even the euro ens mean forecast would turn out to be 100% wrong

ask yoruselves and be honest.... would you in a million years ever think the euro ensemble eman would turn to be totally wrong

the Nam and GFS right and NO snow over RIC DCA BWI PHL NYC BDL... and darn LItlte in BOS?

really?

Normally yes. This is a great point.

But the only thing that I can think of is the sw is being fully sampled for the 1st time in these 12z runs.

If euro still shows a hit with this sw sampling ingested, then this point is very valid.

[Brian5671]

IF it turns out that the 12 NAM and 12z GFS Ukie are correct

THINK about that

while the operational Euro solution was extreme and fun to wacth and impressive in the way the model held it for 2 or 3 runs

right now even the euro ens mean forecast would turn out to be 100% wrong

ask yoruselves and be honest.... would you in a million years ever think the euro ensemble eman would turn to be totally wrong

the Nam and GFS right and NO snow over RIC DCA BWI PHL NYC BDL... and darn LItlte in BOS?

really?

In this type of year, yes. The storm last week was out to sea so the pattern would hold....someone pointed out that there's never been a KU in a strong LA nina, so going with that alone would lead me to believe that this could be a miss or at best a graze job for the coast--obviously hoping for more, but the latest trends are not good... If Euro is further east next run, I'd say most are cooked.

[yhbrooklyn]

While it might be right, let's not pull all of our faith in a model that had the last 5 runs of QPF looks like this.

12z/18z/00z/06z

12z today

[SnowGoose69]

Normally yes. This is a great point.

But the only thing that I can think of is the sw is being fully sampled for the 1st time in these 12z runs.

If euro still shows a hit with these sw sampling ingested, then this point is very valid.

I think the Euro's bias in the SW bit it big time because of this raging La Nina we're in...I mentioned how it can usually still come out to the right end solution but given the flow to this pattern maybe it was a bit too much for it to be able to do so.

[Guest someguy]

In this type of year, yes. The storm last week was out to sea so the pattern would hold....someone pointed out that there's never been a KU in a strong LA nina, so going with that alone would lead me to believe that this could be a miss or at best a graze job for the coast--obviously hoping for more, but the latest trends are not good... If Euro is further east next run, I'd say most are cooked.

OK... But the euro had it that BIg coastal at day 8 and 9 then backed off

it brought it back for 1 run on 0z friday

AND ....AND ... the euro ensemble mean did NOT show that event for 6+ runs

[weatherwiz]

In this type of year, yes. The storm last week was out to sea so the pattern would hold....someone pointed out that there's never been a KU in a strong LA nina, so going with that alone would lead me to believe that this could be a miss or at best a graze job for the coast--obviously hoping for more, but the latest trends are not good... If Euro is further east next run, I'd say most are cooked.

The whole no KU in a strong Nina has pretty little merit, the sample size of strong Nina winter's isn't exactly relatively large...only dealing with about 7-9 years of data to work with.

[isnice]

IF it turns out that the 12 NAM and 12z GFS Ukie are correct

THINK about that

while the operational Euro solution was extreme and fun to wacth and impressive in the way the model held it for 2 or 3 runs

right now even the euro ens mean forecast would turn out to be 100% wrong

ask yoruselves and be honest....

would you in a million years ever think the euro ensemble eman would turn to be totally wrong

after showing the same thing for 6 + runs ?

and that the Nam and GFS will be correct and there will be NO snow -- NONE -- over RIC DCA BWI PHL NYC BDL... and darn LItlte in BOS?

really?

Good point, but it's not impossible and looking more and more likely that it was just the Euro's mistake. In all seriousness, I'd like to see GFS ensembles just to confirm what that model really thinks. I know it's premature, and don't bash me for it, but I don't see how the Euro will maintain what it showed last night. I saw a met say something about how the Euro adjusts in pieces. Maybe last night was a piece of the adjustment. We cannot deny that even though the threat is still there, it is disappating rather quickly. And, not only am I annoyed, but so should every meteorologist who has been following the Euro. This kind of solution would lead to a major bust for many mets.

[SnowGoose69]

The GEM is horrid at 48 hours..

[Ridingtime]

This is one of the most garbage threads I've read here in a while. I am amazed at how much stock people are putting both in the NAM past 48 hrs and the GFS also past 48 hours when both of these models up until now have been 1) extremely inconsistent with this storm and 2) always really sucky in general in the time range we are looking at.

What also makes this thread suck so much is that people are jumping ship before today's 12z Euro even came out, calling it a piece of s***, simply because the american models aren't looking good. Seriously? Let the damn Euro run first! It very well may be just as infallible as the other models with this storm, but no one has the right to say that yet!

In summation: this thread=

[PhineasC]

This is one of the most garbage threads I've read here in a while. I am amazed at how much stock people are putting both in the NAM past 48 hrs and the GFS also past 48 hours when both of these models up until now have been A) extremely inconsistent with this storm and always really sucky in general in the time range we are looking at.

What also makes this thread suck so much is that people are jumping ship before today's 12z Euro even came out, calling it a piece of s***, simply because the american models aren't looking good. Seriously? Let the damn Euro run first! It very well may be just as infallible as the other models with this storm, but no one has the right to say that yet!

In summation: this thread=

GGEM and UKMET also are not looking good. Euro has been alone for days and last night it moved towards the GFS, for sure. I don't see any of that as a good thing.

[Midlo Snow Maker]

[PhineasC]

Holy mama the GGEM is way south and terrible.

[SnowGoose69]

The GEM has the northern stream so fast that the Gulf Low might become its own storm!!!!