January 2012 Storm Threats and Discussion

[usedtobe]

One other thing. I for one look at the ukmet pretty much every time there is an interesting forecast in which the gfs and euro differ. It was one of the reasons I thought the recent euro megastorm solution was wrong. It is the second best model in the world so it is a good model to use as a very skillful ensemble member. HPC also looks at it. I'm not as enamored with the GGEM though I like it when Yoda posts it and think it is also a model to look for when trying to confirm a solution you just don't weight it as much as the ukmet.

[usedtobe]

Wes seems to only look at the GFS and Euro, with the SREFs and NAM sometimes close in. That is all I need even if the UKMET is kicking ass at the upper levels over Siberia.

Wes looks at teh gEFS and euro ensembles and ukmet despite rarely showing the latter.

[nw baltimore wx]

Other than -18C 850s over DC Tuesday night there's not much to talk about. Raw 2m temps fall into the mid to upper teens north of DC (though the ensembles would suggest that gets bumped up a couple of degrees).

Thanks. I'm looking forward to the cold even if it's only temporary.

Also, in my previous post, I forgot to mention that Alan's site has a new "previous model cycle comparison" link. I wasn't sure if others had seen it because only noticed it a couple of days ago, but it could have been there for awhile. It makes me wonder if there's something like that but compares a run to itself and over a longer period of time for verification purposes. Of course, if I was not such a slacker, I suppose it wouldn't be too hard to design one on my own.

[dtk]

Wes looks at teh gEFS and euro ensembles and ukmet despite rarely showing the latter.

Wes, have you spend much time looking at NAEFS products? I get the impression that it tends to be especially helpful in situations where the GEFS seems to lack spread (since it also includes Canadian members, which is itself a multi-model/physics ensemble, substantially increasing the diversity).

[usedtobe]

Wes, have you spend much time looking at NAEFS products? I get the impression that it tends to be especially helpful in situations where the GEFS seems to lack spread (since it also includes Canadian members, which is itself a multi-model/physics ensemble, substantially increasing the diversity).

Lol, I was almost ready to post the new experimental temp forecast based on the NAEFS. I do some but probably not as much as I should.

[eurojosh]

Sorry for derailing the thread by sticking up for the JMA of all things. First, I was referring to relative recent history (on the order of months to the past year, not 5 years). These days, because of computing power, models tend to change fairly rapidly (we do a major upgrade on the time scale of once a year, or every other year).

As has been stated, the biggest issues with models like UKMet, JMA, etc. is access to timely data and nice graphics; as well as lack of familiarity. The GFS is the first model available, it is generally a decent model (not at good as the EC), and has a very long history (for folks to develop familiarity). Anyone that says the UKMet is a terrible model is clueless. The difference between the UKMet and GFS at day 5 for the past month or two is significant at the 95% confidence level.

Maybe this deserves a separate thread altogether in the main forum - and apologies if this question has already been asked at some point, but what role, if any, does location bias play in the models.

That is to say, the UKMET, for example, emerged out of local weather modeling based around the UK, in which features like gulf stream, transatlantic jet stream, etc, play a role. Is it more accurate in dealing with those features? Similarly, is NOGAPS better at modelling oceanic weather? Does origination/original purpose bias play a role in the model accuracy?

[usedtobe]

Maybe this deserves a separate thread altogether in the main forum - and apologies if this question has already been asked at some point, but what role, if any, does location bias play in the models.

That is to say, the UKMET, for example, emerged out of local weather modeling based around the UK, in which features like gulf stream, transatlantic jet stream, etc, play a role. Is it more accurate in dealing with those features? Similarly, is NOGAPS better at modelling oceanic weather? Does origination/original purpose bias play a role in the model accuracy?

All the models essentially have the same data as it is shared internationally. The differences in the models has to do with how they assimilate the data into the models. The euro and Ukmet both I beleive have a little more sophisticated method of doing that and in differences in how they handle the physics (for example convection). The NOGAPS is not better over the oceans. The Ocean Prediction Center relies more on the GFS and probably euro than on the NOGAPS. if it scores worse at the surface and 500mb, it's wind and wave forecasts are probably not goign to be as good as algorithms based on a better scoring model. DTK probably can answer you in a more comprehensive manner. If there was any real storm threat to talk about, this might be a derailment but with the pattern so dull, it's probalby not.

[ravensrule]

This is an excellent discussion, and thank you DTK for helping me try to understand how the models work. I never knew that you guys considered the UKMET a good model because everyone usually trashes it around here so i never pay it any attention. If you would be willing to start a seperate thread about how the models work and attain their verification scores i would love that. Thank you for all your insight.

[JERSEYSNOWROB]

Wasn't the NOGAPS recently upgraded to 4DVAR? I would assume it has gotten a bit better no?

[ORH_wxman]

I've found the UKMET to be pretty poor with east coast storms...it loves extreme solutions. So while its 5h score might be 2nd best over the northern hemisphere, its a tough model to rely on when you are forecasting east coast storms...and unfortunately we live on the east coast. It can sometimes catch into a big shift before other models, and I will use it as a tiebreaker sometimes like Wes mentioned, but I rarely ever decide to use it as a big piece of the puzzle if it disagrees with other guidance.

[Ian]

I think a lot of people get lost in the models. For most purposes the Americans and the Euro will get you what you need. It's one thing for a met to look at all the options it's another for a weenie.

[chris87]

All the models essentially have the same data as it is shared internationally. The differences in the models has to do with how they assimilate the data into the models. The euro and Ukmet both I beleive have a little more sophisticated method of doing that and in differences in how they handle the physics (for example convection). The NOGAPS is not better over the oceans. The Ocean Prediction Center relies more on the GFS and probably euro than on the NOGAPS. if it scores worse at the surface and 500mb, it's wind and wave forecasts are probably not goign to be as good as algorithms based on a better scoring model. DTK probably can answer you in a more comprehensive manner. If there was any real storm threat to talk about, this might be a derailment but with the pattern so dull, it's probalby not.

This is an excellent discussion, and thank you DTK for helping me try to understand how the models work. I never knew that you guys considered the UKMET a good model because everyone usually trashes it around here so i never pay it any attention. If you would be willing to start a seperate thread about how the models work and attain their verification scores i would love that. Thank you for all your insight.

Here are some excellent resources on NWP models and data assimilation:

http://www.ecmwf.int...ions/index.html

As Wes mentioned, all models mainly use the same observations in their assimilation system. One difference between systems is the handling of assimilated satellite data, for example, differences in the radiative transfer model used to "convert" an observed satellite radiance to actual atmospheric state variables (such as temperature or moisture).

On a fundamental level, NWP is an initial condition problem, in theory, a better initial condition should lead to a better forecast, assuming you can accurately simulate the processes within the model. So NWP performance is a function of the initial condition (data assimilation) and model physics/parameterizations (which simulates processes such as convection, cloud microphysics, radiation, land surface processes). The ECMWF model uses 4DVAR for its data assimilation system, a process which is more accurate (yet much more computationally expensive) than 3DVAR which is currently used in the GFS [as dtk has mentioned previously, the GFS will eventually be moving to a hybrid variational-EnKF assimilation system, which has shown a lot of promise]. However, as the initial condition is important, without good model physics/parameterizations is does not necessarily lead to a better forecast. For example, the NOGAPS now uses 4DVAR for its assimilation system, but still suffers from rather crude model physics (in some cases), thus its continued poor performance [i'm not sure of any quantifiable improvement in the NOGAPS after its upgrade, although I'm sure there was improvement].

[JERSEYSNOWROB]

Here are some excellent resources on NWP models and data assimilation:

http://www.ecmwf.int...ions/index.html

As Wes mentioned, all models mainly use the same observations in their assimilation system. One difference between systems is the handling of assimilated satellite data, for example, differences in the radiative transfer model used to "convert" an observed satellite radiance to actual atmospheric state variables (such as temperature or moisture).

On a fundamental level, NWP is an initial condition problem, in theory, a better initial condition should lead to a better forecast, assuming you can accurately simulate the processes within the model. So NWP performance is a function of the initial condition (data assimilation) and model physics/parameterizations (which simulates processes such as convection, cloud microphysics, radiation, land surface processes). The ECMWF model uses 4DVAR for its data assimilation system, a process which is more accurate (yet much more computationally expensive) than 3DVAR which is currently used in the GFS [as dtk has mentioned previously, the GFS will eventually be moving to a hybrid variational-EnKF assimilation system, which has shown a lot of promise]. However, as the initial condition is important, without good model physics/parameterizations is does not necessarily lead to a better forecast. For example, the NOGAPS now uses 4DVAR for its assimilation system, but still suffers from rather crude model physics (in some cases), thus its continued poor performance [i'm not sure of any quantifiable improvement in the NOGAPS after its upgrade, although I'm sure there was improvement].

Thanks.

[ravensrule]

Here are some excellent resources on NWP models and data assimilation:

http://www.ecmwf.int...ions/index.html

As Wes mentioned, all models mainly use the same observations in their assimilation system. One difference between systems is the handling of assimilated satellite data, for example, differences in the radiative transfer model used to "convert" an observed satellite radiance to actual atmospheric state variables (such as temperature or moisture).

On a fundamental level, NWP is an initial condition problem, in theory, a better initial condition should lead to a better forecast, assuming you can accurately simulate the processes within the model. So NWP performance is a function of the initial condition (data assimilation) and model physics/parameterizations (which simulates processes such as convection, cloud microphysics, radiation, land surface processes). The ECMWF model uses 4DVAR for its data assimilation system, a process which is more accurate (yet much more computationally expensive) than 3DVAR which is currently used in the GFS [as dtk has mentioned previously, the GFS will eventually be moving to a hybrid variational-EnKF assimilation system, which has shown a lot of promise]. However, as the initial condition is important, without good model physics/parameterizations is does not necessarily lead to a better forecast. For example, the NOGAPS now uses 4DVAR for its assimilation system, but still suffers from rather crude model physics (in some cases), thus its continued poor performance [i'm not sure of any quantifiable improvement in the NOGAPS after its upgrade, although I'm sure there was improvement].

Alot to read through i will try to start this weekend, thank you very much for the info.

[H2O]

I think a lot of people get lost in the models. For most purposes the Americans and the Euro will get you what you need. It's one thing for a met to look at all the options it's another for a weenie.

I only like the model that shows me what I want it to show.

[Huffwx]

I only like the model that shows me what I want it to show.

Here here!

[stormtracker]

If there is not something on the models to track by next week, I'm going to start just randomly banning people.

I see you Wes.

[Scuddz]

So, when do we switch this from a storm thread to wish-casting that LES makes it over the Apps?

[snowfan]

Maybe we can just start tracking the cold. Lows are expected to be around 40-45 below on Saturday night near Prudhoe Bay. Anyone up for a "quick" roadtrip?

[Ian]

the 12z gfs is pretty horrid but i guess that's to be expected at this point

[Kmlwx]

If there is not something on the models to track by next week, I'm going to start just randomly banning people.

I see you Wes.

Start with Ian.

[WinterWxLuvr]

Yes I was just thinking that same thing, just how much that looks like any given Sunday over the course of this near warmly historic recent December.

Not sure what the worth of the following is beyond commiseration... but, 4 days ago ... when the Euro operational developed that odd looking monsters storm from cutting off of an actual long wave trough (as opposed to the more typical model of short wave scaled events ....), there was actually some support via that product of the PSU E-Wall site. At that time, two runs, back-to-back, that Euro mean painted a huge western ridge and coupled fairly deeply carved out low heights in east centered on the same time. Meanwhile, the GEFs derived PNA was forecast to modestly spike to +2 standard deviations or so. So basically, the idea of "some sort" of event appeared very plausible - most thought the extremeness of the Euro was over-the-top, if perhaps wisely... Point being, there was cross-model type support both spatially and temporally for an era of cold amplitude, so things appeared pointed in a certain direction.

It's just bemusing, though, how no sooner was all that correlative assurance established, only then did the house of card come-a crumblin' down. It was an illusory romp perpetrated by the forces of chaos, we're left to suppose...

Be that as it may, what do we now have to show for the course? First of all...obviously nothing. But, the GEFs derived PNA is still trying to spike between the 2-6th of January; yet the Euro mean ... has gone ahead and submarined it's verification score card for that particular D6-10 range by opting for the opposite appeal, abruptly, like that which you provided. Granted, every night tacks another day on the end of that 8-10ness. There was, however, a 2 -day period, though, where they recently overlapped.

The hidden lesson in all this is

1), the Euro is not an infallible tool (nor its constituencies);

2), "anything" Euro in general is just as indictable as a piece of shyt tool as any GFS/GEFs derived product, period. I'm not forgetting this, nor that inland cutter in January last year, where at D4 or 5 the Euro had a bomb over Cleveland, and the GFS handed that model its hat in a rare defeat when what verified was a nice 6-12" resulting coastal.

Concerning the latter notion. I am not sure what it is really about the 4-D initialization thing, but it certainly does pay dividends to accuracy but only up to a certain lead time. I believe it is somewhere between D4-5 **(and yes the numbers are readily available); after which chaos roars in and bares its ugly presence with rapidity.

This sort of leads me loosely into the only comment I have regarding the pattern over the longer haul heading on into the month of Cantuary. There are some albeit thin for the time being, interesting signals coming from the western Pacific, and disparately so, from the AO, that might converge and force changing things regardless of the "infallible" Euro Weeklies.

The MJO is just entering the western Pacific Basin as it is now continuing its eastern propagation through Phase 6. Its weak to moderate in intensity, but since there is an utter and complete abandonment (apparently) of any polarward exertion on the flow, that leaves the Pac domain very prone to the advances of the tropical boner. I think it certainly possible (perhaps demonstrated via some kind of re-analysis/eval study) that the failed original Euro meridional flow may have been because the MJO wave sort of phoenix from the COD/incoherency grave, and rose to moderate strength midway through Phase 4, and then assumed a steady eastward propagation through Phase butt-bangin' 5. The end result "might" just have been rather abrupt insert of large scale destructive wave interference *(I've discussed this a few times in the recent past, but feel it prudent presently to bring it up again). I am not sure of that ... again, that's supposition. Either way, SOMETHING caused the entire Euro cluster to waver on the entire mass of the Milky Way Galaxy seemingly violating physical laws in getting there... You provide an explanation - I dunno.

Anyway, with the wave progressing now deeper eastward through the western Pac, the dispersive influence down stream should spatially favor the kind of Pacific orientation that folks are inclined to wanting to see ... eventually. Right now - of course - the GEF says the PNA neutralizes and gets rather dicey/incoherent around -.5; I honestly don't see that as significant. If we look across December, the PNA (according to both the CDC/CPC) in fact appears to have averaged slightly positive. How's that working for us? Again, it really more and more appears to be the complete and utter red-headed step child neglect by the alcoholic AO step dad that doomed us to the ennui that most are complaining about, when taking all into retrospective.

There's the rather tentative rub... The warm node I was mentioning in the upper altitudes of the stratospheric PV is gaining some strength. The very recent analysis, take on the 29th of the month, shows both the temperature +flux combined with a Wave 1 (geopotential height) bullying a presence:

What we don't know is whether or not this already verifying warm intrusion/flux will be downward propagating or not. What is interesting is that I did see some recent EP Flux diagrams that suggested it would not be; yet, when observing the other sudden onset warm events in the data set spanning the last 30 or so years...the ones that did have a subsequent propagation behavior were associated with a stronger Wave 1 geopotential signature such as that provided above. So there's some conflicting notions there...

Barring the EP Flux' accuracy (and if some warm events have an extraterrestrial orginin ( hmmm (interestingly, there has been some recent CME( maybe there somehow a polarity link to the airs of the upper PV that is realized through the variable temperature in the electroconductivity of a fluid medium) ) ) ) than a partial disconnect with EP could almost be assumed)

...Let's see who succeeds in parsing that out...

The short version, perhaps the AO begins to fall off, concurrent with a more favorable Pac orientation in about 2, 3 weeks.

Up until then, it can snow...sure, or not. Smaller time scale what-nots in the flow ...it's January. I don't see a blow torch like the whiners are chanting though. Of course, I am not even sure what defines a "torch". I scanned around in the Glossary over at AMS ... they don't have f clue. I figure it's "anything that is outside the box of winter intent", period, should be labeled a torch, and that ought to about cover it. So given that logical pre-requisite I suppose, yeah - torch. But imnsho, i find the broad spectrum oscillatory pattern that ranges from lewd run-ins with +12C, 850mb day in half warmth, followed by smack in the face -20C, 850mb day and half cold incursions (with no storms intervening the separation of those exotically differing mass fields) to be more maddening and annoying to look at then a torch. But that's just me.

Copied from the New England thread. I thought it was pretty good given the recent discussion in this thread.

I'm just a watcher, but I thought the bolded was hard to argue.

[Ian]

looks like the outer banks could get one inch or three from the dt one run wonder storm. that would be fitting.

[snownut]

So, when do we switch this from a storm thread to wish-casting that LES makes it over the Apps?

sounds like a whole new thread and maybe a few "JEB like" lets blow up the mountains rantings and JON JON posting about 4 and 5 foots drifts at Canaan Valley.

[eurojosh]

looks like the outer banks could get one inch or three from the dt one run wonder storm. that would be fitting.

Hey now. It was two runs.

[J.Mike]

If there is not something on the models to track by next week, I'm going to start just randomly banning people.

I see you Wes.

Ji hijacked Randy's account

[J.Mike]

BTW, I've been talking with my landscaper - this would look nice in my front yard:

I'm serious.

[Wonderdog]

looks like the outer banks could get one inch or three from the dt one run wonder storm. that would be fitting.

Looks like dt's storm has started the retrograde process. By Sunday morning, we should be back estimating snowfall amounts.

[Ian]

And in looking at the latest European weeklies, I'd swear they've been reprinted from the winter of 2001-2002. I know they are brand spanking now, but after next week, there's an awful lot of warmth being forecast for the REST of January.

http://www.accuweather.com/en/weather-blogs/lundberg/by-the-first-we/59689

[JoMo]

Brett Anderson says:

"After a brief visit early next week the ECMWF says that winter goes on another extended hiatus in the East through the end of the month, while the cold gradually takes hold out in western Canada."

And he's going to post his interpretation of the Euro weeklies tonight, they sound ugly for your part of the world

http://www.accuweather.com/en/weather-blogs/anderson/random-thoughts/59695