January 12-14 Potential storm

[PatrickSumner]

Nobody look at the 06Z GFS. Ouch is a good for it...

[baroclinic_instability]

Nobody look at the 06Z GFS. Ouch is a good for it...

yeah I just glanced at it. That was a disaster run. Had a weak southern stream anomaly...fast, weak northern stream, no phase. Ugly all the way from the northern plains to the lakes. I am not buying into any guidance yet though...especially with the northern stream features.

[Harry]

Nobody look at the 06Z GFS. Ouch is a good for it...

Probably wont be till we get this thing fully inside of 120hrs that we see the OP models start to get a better grip on what is going on. This is where the ensembles come in very handy. Thus don't jump for joy or get majorly dissapointed with any run yet. 12z could show a triple phase and the 00z could turn around and show what the 06z run is showing.

[Harry]

yeah I just glanced at it. That was a disaster run. Had a weak southern stream anomaly...fast, weak northern stream, no phase. Ugly all the way from the northern plains to the lakes. I am not buying into any guidance yet though...especially with the northern stream features.

That was ugly.

I wont lie.. That 00z euro run made my heart skip a beat. But yeah i'll contain my excitement for now till i see a few runs show that especially once we get inside of 120hrs.

[PatrickSumner]

On a positive note, the long term sure looks frigid if the 06Z GFS has anything to say about it. Puts virtually entire U.S. in a ice box by hour 312. BRRRR...

[IWXwx]

I wish I could be excited for something big like Harry, but I've got a bad feeling about this. I can foresee the SW cutoff spitting out a couple of weak waves as it progresses east giving the GL/OV some rain to light snow, followed by a couple of clippers as the cold air seeps east, so we go from torch to winter with no big storm to show for it.

The good thing is that hopefully this is sign that we will end the progressive split flow crap no matter how this plays out.

[snowstormcanuck]

I believe the issue you bring up with the ECWMF model over the SW US has more to do with long-duration, cutoff type events (I don't think it is accurate to say that the model is always "not progressive enough" with any low over the SW US). In fact, I'm not certain this is even an issue with recent versions of the model (they do very regular, fairly frequent upgrades) "

Thanks for that quote B_I. That does seem to clear up my question of whether the supposed bias is exclusive (or prevalent) to cutoff lows. dtk seems to be suggesting it is. He doesn't rule out though the possibility that the bias still exists. I know your anecdotal experience suggests that the bias is more fiction than fact, however, I have, as recently as this season, found the opposite. Obviously, you're interpretations carry more weight than mine, but it seems to me there have been several occasions where the EURO has incorrectly failed to kick out or phase energy in the desert SW. In fact, I think I've read as much in an AFD or two this fall/winter.

I'm not going to live and die with this interpretation but I'll definitely keep a closer eye on it from this point forward to get a better sense as to whether it's true or false.

[snowstormcanuck]

If this thing phases, I think you, Bowme, and Alek (whether he wants to admit it or not) are looking good. The other possibility is that this storm follows the seasonal trend and stays disjointed, with the southern wave moving off the EC with a lot of juice but little snow while the northern stream wave stays up near Lk Superior. That would suck doubly because it would likely delay the pattern change as well.

Looks like that's the models' choice du jour. Although I'm not certain the last sentence will pan out. I thought a big phased storm would act as a quasi-block when it reached the upper latitudes, the absence of which in a neutral/-PNA pattern would allow the dominant flow to return to being zonal after a brief intrusion of arctic air.

0z EURO though seems to be indicating a pattern change can happen without the big initial phase. Looks like it partially phases the northern stream upper low with the PV around D9, which is an alternative way to create a bit of block. Actually has the faintest hint of ridging over southern Greenland by D10.

[baroclinic_instability]

Thanks for that quote B_I. That does seem to clear up my question of whether the supposed bias is exclusive (or prevalent) to cutoff lows. dtk seems to be suggesting it is. He doesn't rule out though the possibility that the bias still exists. I know your anecdotal experience suggests that the bias is more fiction than fact, however, I have, as recently as this season, found the opposite. Obviously, you're interpretations carry more weight than mine, but it seems to me there have been several occasions where the EURO has incorrectly failed to kick out or phase energy in the desert SW. In fact, I think I've read as much in an AFD or two this fall/winter.

I'm not going to live and die with this interpretation but I'll definitely keep a closer eye on it from this point forward to get a better sense as to whether it's true or false.

I think what dtk is saying was this was an issue in the past. I tend to agree. I think the big probklem here is when the EC does have this issue (and any model can certainly have this exact issue), it is chalked up as being a "bias". Never once has there been any type of actual research of any type to suggest this bias is actually true. I am not saying it very well may be there, but I find it difficult to believe unless someone can actually post some type of reasoning that suggests it may very well be true (i.e., maps, statistics, etc.).

[baroclinic_instability]

Thanks for that quote B_I. That does seem to clear up my question of whether the supposed bias is exclusive (or prevalent) to cutoff lows. dtk seems to be suggesting it is. He doesn't rule out though the possibility that the bias still exists. I know your anecdotal experience suggests that the bias is more fiction than fact, however, I have, as recently as this season, found the opposite. Obviously, you're interpretations carry more weight than mine, but it seems to me there have been several occasions where the EURO has incorrectly failed to kick out or phase energy in the desert SW. In fact, I think I've read as much in an AFD or two this fall/winter.

I'm not going to live and die with this interpretation but I'll definitely keep a closer eye on it from this point forward to get a better sense as to whether it's true or false.

I think what dtk is saying was this was a possible issue in the past (and the past discussion revolved around long duration cutoff lows). I tend to agree. I think the big problem here is when the EC does have this issue (and any model can certainly have this exact issue since all numerical guidance struggles with cutoff features), it is chalked up as being a "bias". Never once has there been any type of actual research of any type to suggest this bias is actually true. I am not saying it very well may not be there, but I find it difficult to believe unless someone can actually post some type of reasoning that suggests it is a true "bias" with the latest version of the ECMWF. (i.e., maps, statistics, etc.).

[baroclinic_instability]

^^Regarding the above, an actual "bias" and not a tendency for it to happen on occasion, as, by nature, this type of scenario may happen without it being an actual bias.

[snowstormcanuck]

I think what dtk is saying was this was an issue in the past. I tend to agree. I think the big probklem here is when the EC does have this issue (and any model can certainly have this exact issue), it is chalked up as being a "bias". Never once has there been any type of actual research of any type to suggest this bias is actually true. I am not saying it very well may be there, but I find it difficult to believe unless someone can actually post some type of reasoning that suggests it may very well be true (i.e., maps, statistics, etc.).

The way I understand what dtk was saying was that he was uncertain about the bias existing, and thus didn't preclude it from possibly being true. You're right, I've never seen anything concrete being established about this potential bias (although, I'm not a regular peruser of meteorological scholarly literature anyway ). There is stuff like this, which appears to be written by a meteorologist with some skill at model diagnostics, but obviously, not exactly a peer-reviewed article.

[baroclinic_instability]

The way I understand what dtk was saying was that he was uncertain about the bias existing, and thus didn't preclude it from possibly being true. You're right, I've never seen anything concrete being established about this potential bias (although, I'm not a regular peruser of meteorological scholarly literature anyway ). There is stuff like this, which appears to be written by a meteorologist with some skill at model diagnostics, but obviously, not exactly a peer-reviewed article.

Yeah that seems pretty old (the page says it was last updated 2008....who knows when that article was updated), and it sounds like the exact same over-used phrases still used today. I think the big contributor here is the fact cutoff lows are quite common across the intermountain W, and by nature, there are some that are going to eject faster than modeled (and some slower too). But is it really actually happening more often than the other scenario (ejecting too slow)?

[dtk]

I actually don't have much to add and I stand by my previous comments on the issue (which have been interpreted correctly). I'm hesitant to say flat out that such a bias does not exist, since I do not myself look at these things closely on a regular basis. But to summarize:

• Slowly propagating, cut-off type features can be notoriously difficult to model (and forecast, for that matter). In this regard, most models will exhibit some type of behavior that will be perceived as a "bias"
  
• It is entirely possible that the ECMWF model use to exhibit the behavior of ejecting such features too slowly out of the SW US
  
• Most evidence to support such claims are usually old, or anecdotal at best
  
• This supposed "bias" is exclusive to cut-off type features, and not every piece of energy in the SW US
  
• People hold onto notions about numerical models WAY too long. The major operational centers (NCEP, UKMet, ECMWF) frequently upgrade the global systems, including modifications to things like physical parameterizations model resolution which can have profound impacts on the model behavior.
  

[A-L-E-K]

I actually don't have much to add and I stand by my previous comments on the issue (which have been interpreted correctly). I'm hesitant to say flat out that such a bias does not exist, since I do not myself look at these things closely on a regular basis. But to summarize:

• Slowly propagating, cut-off type features can be notoriously difficult to model (and forecast, for that matter). In this regard, most models will exhibit some type of behavior that will be perceived as a "bias"
  
• It is entirely possible that the ECMWF model use to exhibit the behavior of ejecting such features too slowly out of the SW US
  
• Most evidence to support such claims are usually old, or anecdotal at best
  
• This supposed "bias" is exclusive to cut-off type features, and not every piece of energy in the SW US
  
• People hold onto notions about numerical models WAY too long. The major operational centers (NCEP, UKMet, ECMWF) frequently upgrade the global systems, including modifications to things like physical parameterizations model resolution which can have profound impacts on the model behavior.
  

Love this, thanks

[A-L-E-K]

loving the run to run volatility...potential remains potential. Significant shift north from 6z.

6z

12z

[snowstormcanuck]

I actually don't have much to add and I stand by my previous comments on the issue (which have been interpreted correctly). I'm hesitant to say flat out that such a bias does not exist, since I do not myself look at these things closely on a regular basis. But to summarize:

• Slowly propagating, cut-off type features can be notoriously difficult to model (and forecast, for that matter). In this regard, most models will exhibit some type of behavior that will be perceived as a "bias"
  
• It is entirely possible that the ECMWF model use to exhibit the behavior of ejecting such features too slowly out of the SW US
  
• Most evidence to support such claims are usually old, or anecdotal at best
  
• This supposed "bias" is exclusive to cut-off type features, and not every piece of energy in the SW US
  
• People hold onto notions about numerical models WAY too long. The major operational centers (NCEP, UKMet, ECMWF) frequently upgrade the global systems, including modifications to things like physical parameterizations model resolution which can have profound impacts on the model behavior.
  

Thanks for this. Although there's some uncertainty remaining, I feel your submissions (along with Jason's) provide sufficient evidence, for me at least, to conclude that the bias is not apparent. That being said, I'll definitely pay closer attention in the coming months to how the models handle SW cutoff lows to see if any tendencies can be discerned.

[snowstormcanuck]

Definitely an earlier phase this run of the GFS. Still not excited.

[A-L-E-K]

Definitely an earlier phase this run of the GFS. Still not excited.

I'm taking what i can get tracking wise and i just can't help but feel a minor (like 6-12 hr) change in ejection timing and things change in big way. I'm going to remain in the game until we start seeing the ensembles trend en masse towards a swing and a miss. Until then, too much understandable uncertainty to punt.

[kab2791]

GGEM shows 995 SLP over southern L. Huro Hr 144

[A-L-E-K]

GGEM shows 995 SLP over southern L. Huro Hr 144

I hate the GGEM b&w's but it sounds like a shift back west after 0z went way east.

[kab2791]

FWIW, the UKMET shows 997 SLP over North Central IN at Hr 120, then 991 SLP over Boston at Hr 144.

I hate the GGEM b&w's but it sounds like a shift back west after 0z went way east.

[A-L-E-K]

The differences on the Canadian's handling of the SW vort by 84 on 12z and 96 on 0z are massive. The variability with these setups is massive.

[A-L-E-K]

_{12z Canadian much slower with the SW vort allows heights to crank and low to cut far west, rain for most, northern piece still late to the party.}

[Chicago Storm]

seasonal trends.

[Geos]

The cold air and northern energy needs to slide further east or the low needs to hang back a little longer. - to move that high pressure off to the east and out of the way for phasing.

[Hoosier]

Some substantial spread on the 18z GFS ensembles but several offer a better outcome than the OP run.

[cyclone77]

I just got done looking at the 12z runs for the first time. Just like yesterday you can tell we're pretty close to seeing a nice phase. The fact that many of the various ensemble members look promising is more than enough to keep it interesting.

[baroclinic_instability]

The cold air and northern energy needs to slide further east or the low needs to hang back a little longer. - to move that high pressure off to the east and out of the way for phasing.

That is ultimate :weenie:

[Baum]

A year ago Aleking you would not have farted in this thread. A clear commentary on the winter.