18z Models 12/21/2010

[Eskimo Joe]

I have been watching the upper air presentation for the UKMET/EURO/CMC/GGEM for this particular threat, and comparing it to the NAM/GFS/NAEFS. Perhaps it is the weenie in me, but it appears as though the 200/300mb setup is being better handled by the foreign regime, versus the American models, especially the beginnings of the amplified western ridge and Atlantic trough. Am I the only one who is seeing this?

[bluewave]

I admittedly do not yet have the knowledge and understanding needed to properly interpret model data and post in these threads, therefore I lurk for the most part.

Based on the way this discussion has largely gone, more members should adopt this practice IMHO...Maybe met only model analysis threads? Let gen pop have one too, but have another for some continuous, thoughtful posts by people who know what they are talking about. Just a thought, sorry for OT...

It would probably be good for you to familiarize yourself with known model biases and recent performance so you can make you own decisions as to what

you think is correct.

[Mitchel Volk]

Here we go again it looked like a lock yesterday and now the GFS speaks, sounds fimilar? This is what happen with the last storm kinda. I know the ECMWF drop it then GFS keep it then the ECMWF said blizzard and the GFS said it is not true. This time it is just the GFS and UKMET that drop the storm, to me this means there are divergent solutions and this decreases the chances for an I-95 storm. The low to our NE is also a main concern too and makes me take the GFS seriously, however it is still to early and will wait for more models runs before I drop it all together.

[Mitchel Volk]

Like 1978 and 1996 total model agreement and an excellent set up.

[vinylfreak89]

GFS "rushes" it due to the open H5 setup.

which is due to the flow further upstream.... look to the pacific!

[Dr No]

So the members are rolling out on Ralieghs site- all 12 in good agreement until about 72.

Then it's all kind of solutions. As stated, it seems to tie directly to the strength and speed of the short wave.... slower/stronger provide the better solution. (only 1 has a solid 95 hit) ... others are decent storms but near misses.

weaker/faster... well, you know, including some getting sheared out all together. The sheared out solutions are dragging the mean down. Kinda disconcerting... 5/12 No pretty much no LP center after 96. (although they do reform eventually well OTS)

http://raleighwx.ame...rs/18zf096.html

[Paweatherguy1]

Wouldn't the fact that the ensemble mean for the gfs being in line and slightly west of the op seeing as the ensemble mean is usually well south and east? Not to mention that the gfs is usually far more progressive?

[WhiteoutWX]

Wouldn't the fact that the ensemble mean for the gfs being in line and slightly west of the op seeing as the ensemble mean is usually well south and east?

I havent seen the mean maps, but the individual member are definately NOT in line with the OP. Most of them are weak to nonexistent with the storm, with only a couple wrapping the storm up more than the OP and even these are fairly weak and a miss up the coast.

[Paweatherguy1]

I havent seen the mean maps, but the individual member are definately NOT in line with the OP. Most of them are weak to nonexistent with the storm, with only a couple wrapping the storm up more than the OP and even these are fairly weak and a miss up the coast.

However, from what I have read, I have gathered that the gfs op is closer to some of those more sheared out solutions, which would be opposite of what is usually true, correct?

[ohleary]

I have been watching the upper air presentation for the UKMET/EURO/CMC/GGEM for this particular threat, and comparing it to the NAM/GFS/NAEFS. Perhaps it is the weenie in me, but it appears as though the 200/300mb setup is being better handled by the foreign regime, versus the American models, especially the beginnings of the amplified western ridge and Atlantic trough. Am I the only one who is seeing this?

The NAEFS is a blend of the NCEP and CMC ensembles.

[ArtRosen]

Only 30 more minutes til 0z nam!

[WxUSAF]

Seems to me on a quick glance that the 18z GFS ensembles show LESS uniformity than the 12z did. A couple members show a solution similar to the 12z GEM and one is almost Euro-esque. Could be a good sign that the surprising (and confusing) uniformity of the 12z ensembles with the Op might be breaking down and future GFS runs will provide yet another solution.

If the Euro was completely alone in its mega-storm solution, I'd be nervous. The reason the big storm can happen is because the Euro is slower and gives the big low in the Canadian maritimes time to lift out and weaken. This could be the Euro's bias of hanging s/w energy in the SW US too long. But, since the NAM, GEM, and UKIE are all slower (even if they provide somewhat different outcomes) than the GFS, that improves the confidence in those solutions.

[WhiteoutWX]

Seems to me on a quick glance that the 18z GFS ensembles show LESS uniformity than the 12z did. A couple members show a solution similar to the 12z GEM and one is almost Euro-esque. Could be a good sign that the surprising (and confusing) uniformity of the 12z ensembles with the Op might be breaking down and future GFS runs will provide yet another solution.

If the Euro was completely alone in its mega-storm solution, I'd be nervous. The reason the big storm can happen is because the Euro is slower and gives the big low in the Canadian maritimes time to lift out and weaken. This could be the Euro's bias of hanging s/w energy in the SW US too long. But, since the NAM, GEM, and UKIE are all slower (even if they provide somewhat different outcomes) than the GFS, that improves the confidence in those solutions.

I took a little time to compare the three main other models besides the Euro (18z GFS, 12z CMC, and 12z UK) to try and pick out the timing differences with the southern s/w out west. Looks like the UK is the slowest through hr 60, GFS a little behind that, and the CMC is actually the fastest with the shortwave. Only reason the CMC ends up with a coastal is it breaks down the atlantic PV faster allowing the wave to amplify. GFS, even being slower with the wave initially, does not do this and it ends up out to sea. UK im assuming is in between the two with the atlantic low, as I only have the detailed maps to 72 hrs off e-wall. How the atlantic PV breaks down is the key here IMO, even more so than the quickness of the southern wave.

Also of course having it close off in Texas like the Euro and Ukie (NAM to some extent) helps as it allows time for the PV to decay.

[Midlo Snow Maker]

18z ukie color/ 18z gfs lines hr 72

[psuhoffman]

just a thought...the location of the h5 block up in Canada is well west of where it was for the 12/19 miss, the ridge axis out west is much more amplified and west, this should translate to a closer to the coast scenario this time just from telleconnecting the main h5 features I would think.

[varicweather]

Seems to me on a quick glance that the 18z GFS ensembles show LESS uniformity than the 12z did. A couple members show a solution similar to the 12z GEM and one is almost Euro-esque. Could be a good sign that the surprising (and confusing) uniformity of the 12z ensembles with the Op might be breaking down and future GFS runs will provide yet another solution.

If the Euro was completely alone in its mega-storm solution, I'd be nervous. The reason the big storm can happen is because the Euro is slower and gives the big low in the Canadian maritimes time to lift out and weaken. This could be the Euro's bias of hanging s/w energy in the SW US too long. But, since the NAM, GEM, and UKIE are all slower (even if they provide somewhat different outcomes) than the GFS, that improves the confidence in those solutions.

Good point. Both the Euro and the GFS handle the big H5 low in the maritimes differently. The12z Euro at 120hr. has a sharper trough on the Eastern seaboard and the H5 low is further North and East, than the 18z gfs at 114hr. The gfs seems to be setting up a +NAO regime with little blocking behind the large maritime low, whereas the Euro maintains more blocking (-Nao) regime. I don't know which is right, but the low in the maritimes will have to be watched.

http://www.meteo.psu.edu/~gadomski/ECMWF_12z/ecmwfloop.html#picture

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/carib/gfs/18/fp0_114.shtml

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/npac/gfs/18/fp0_114.shtml

[snowdude]

18z ukie color/ 18z gfs lines hr 72

Since the 18z models are pretty much done I hope it's ok to say this, if not, I'll take my first warning...but nice rack on that map. Sorry that's the first thing I noticed when I saw it.

[eduggs]

Seems to me on a quick glance that the 18z GFS ensembles show LESS uniformity than the 12z did. A couple members show a solution similar to the 12z GEM and one is almost Euro-esque. Could be a good sign that the surprising (and confusing) uniformity of the 12z ensembles with the Op might be breaking down and future GFS runs will provide yet another solution.

Yeah, it looks like we have 1.5 members giving a slight nod to the Euro/GGEM solutions. I've been watching the individual ensembles for several days, and overall they have looked steadily worse. The past few cycles have offered 1 member on average that resembled the slower, more wound-up solutions.

I'll be watching to see if a period of transition in s/w timing from the GFS toward the Euro camps leads to high volatility in the ensembles. Thus far, I haven't really seen it.

[psuhoffman]

wow UKMET looking rather HECSY there

[ravensrule]

Since the 18z models are pretty much done I hope it's ok to say this, if not, I'll take my first warning...but nice rack on that map. Sorry that's the first thing I noticed when I saw it.