12Z Model Thread

[mattinpa]

A question: do we need the mid-week storm to be south in order to to help the next storm, or doesn't it matter?

[dtk]

An ensemble system takes a "control" model run and perturbs the initial conditions of the numerical model to consider the effects of errors in the data assimilation system. Think chaos theory...tiny initial condition errors can result in massive forecast errors with time. The GFS ensemble has I believe 11 perturbed members and 1 control run, and you can take these different solutions and develop a "mean" as well as look at each individual member. So, for instance, if 2-3 members show a large storm and 7-8 don't, the mean will reflect those members showing the storm. In this case I find the individual members more informational than the mean. Height field maps and vorticity maps will help a lot in this case too.

It's not just to sample initial condition error, but also attempts to account for model/parametrization error/uncertainty. The GEFS is a 20 member ensemble (plus control)....all run at much lower resolution than the operational GFS (also, it's not the exact same version of the model).

[Weather Czar]

Anyone got the ukie yet?

[baroclinic_instability]

It's not just to sample initial condition error, but also attempts to account for model/parametrization error/uncertainty. The GEFS is a 20 member ensemble (plus control)....all run at much lower resolution than the operational GFS (also, it's not the exact same version of the model).

Thanks, I didn't know they varied parameterizations/physics in the GEFS as well. Any info on the various physics/parameterization settings for each member?

[dtk]

Thanks, I didn't know they varied parameterizations/physics in the GEFS as well. Any info on the various physics/parameterization settings for each member?

They don't actually use different physics packages for different members (they use essentially the operational physics.....though they lag in their implementations, so they are currently still using the pre-July 2010 version of the GFS), but they do use a 'stochastic parameterization' scheme. Basically, the scheme just adds quasi-random noise to the physics tendencies (I don't think the scheme is as quite as sophisticated as the EC scheme, which uses something called "stochastic backscatter", such that the perturbed tendencies are less random"). I'd honestly have to ask around to get more information....

[stormtracker]

GFS individual ensembles are rather impressive. At least 6 of them are northwest of the OP and more amplified, and 5-6 show a snowstorm depending on your location.

I honestly don't understand the pessimism at this stage in the game. I think the threat is still very much on the table and at 144+ hours out, we gotta like where things stand. There is still PLENTY of time for important changes to get this thing closer to the coast. Ensembles are there still and if the Euro can come around, I think we'd be doing pretty well.

[baroclinic_instability]

They don't actually use different physics packages for different members (they use essentially the operational physics.....though they lag in their implementations, so they are currently still using the pre-July 2010 version of the GFS), but they do use a 'stochastic parameterization' scheme. Basically, the scheme just adds quasi-random noise to the physics tendencies (I don't think the scheme is as quite as sophisticated as the EC scheme, which uses something called "stochastic backscatter", such that the perturbed tendencies are less random"). I'd honestly have to ask around to get more information....

Thanks, I found this. I am reading it now to get the latest info on GEFS. http://www.emc.ncep.noaa.gov/gmb/yzhu/imp/i200811/NAEFS_GEFS_Implementation_briefing_for_science_post.pdf

[baroclinic_instability]

I honestly don't understand the pessimism at this stage in the game. I think the threat is still very much on the table and at 144+ hours out, we gotta like where things stand. There is still PLENTY of time for important changes to get this thing closer to the coast. Ensembles are there still and if the Euro can come around, I think we'd be doing pretty well.

Pessimism just because of the somewhat low probability of this type of phasing to occur. Still see potential, I don't think many have written it off yet, just going off probability alone it seems to be on the lower end both due to the multi-phasing and the small scale nature of the low...could be a good noreaster that doesn't hit anyone, for instance.

[kurtstack]

Yep this threat is still very much on the table, and the devil will be in the details in how the 500 mb level evolves. If anything the vorts have become more amped and phased as we approach each storm this season, which is why the last storm ended up blasting Minnesota in the end, so I wouldn't be surprised if the models start to trending deeper and stonger with the vort as the event approaches. Look for a west trend in next day or two of model runs.

[yoda]

Anyone got the ukie yet?

Only out to 72. It has a 1002 L right on the AR/MO border (more SW MO area)

[Allsnow]

hr 78 12z euro for the first wave has light snow from south central VA-DC...all rain south of that

[Weather Czar]

Only out to 72. It has a 1002 L right on the AR/MO border (more SW MO area)

Thanks.

[yoda]

hr 78 12z euro for the first wave has light snow from south central VA-DC...all rain south of that

At 72 the 12z EURO has the low in C AR... so I guess the low moves ENE?

[Allsnow]

hr 84 froze preciep for south central VA.....light snow central VA-Dc

[usedtobe]

I honestly don't understand the pessimism at this stage in the game. I think the threat is still very much on the table and at 144+ hours out, we gotta like where things stand. There is still PLENTY of time for important changes to get this thing closer to the coast. Ensembles are there still and if the Euro can come around, I think we'd be doing pretty well.

Of course there is time but my opinions haven't really changed much from yesterday, it's still alow probably type situation because of the timing and phasing issues. It's always been a thread the needle type situation. Possible but more likely not to occur than occur. I wouldn't be surprised to see the euro swing back towards the coast but also wouldn't be surprised to see is it hold serve. Fairly small differences in initial conditions can make a big difference on the ultimate outcome. I think much of the pessimism in in response to some getting overly excited yesterday but the woofing.

[Allsnow]

hr 90 some very light preciep left in central va-south.

prob close to .10 for DC...... and .10-.25 for central Va on first wave

[yoda]

12z EURO

hr 90 the other vortex in the western great lakes is a lot further south on this run.

hr 96 that vortex over the lakes continues to drop south towards the low in the plains....hgts starting to rise on the coast.

hr 102, vortex continues dropping south alot more amplified than 0z last night

[Inudaw]

Plymoth maps for day 4...

PV dropping further south this run.. ^^;

[psuhoffman]

I have seen this game before

models have storm day 7-10

models lose storm day 6

storm pops back up around 72-100 hrs

We all know this has happened before, of course more often once the storm is gone it never comes back, but sometimes they disapear due to models digesting bad information or sparse data in a critical region then the storm pops up again as those issues are resolved. People acting like its over are a little crazy.

THe models are still trying to resolve the overrunning event day 3 and some think they are locked in stone for a day 6 storm... really???

[Allsnow]

trof is more amplified then 00z and preciep buliding in se...at hr 120 broad area of low pressure just off HSE

[yoda]

hr 108 precip building in the southeast, trof continues to be more amplified and vortex is dropping in..this should be good....

hr 114 low pressure developing by hatteras, precip breaking out in nc and southern va

[Allsnow]

HR 132 its justa bit to late with the phase....but improvement from 00z... light to mod preciep from eastern NC and se VA

[Inudaw]

Day 5 Plymouth maps..

[Ridingtime]

Damn, the poor servers here are just not handling the traffic well when the major models come out. Hope we can donate enough and get it fixed before this winter really gets under way.

[stormtracker]

Good enough for me. The threat is still there and as usual, its pretty much about timing. Its good to see the players on the field at this stage of the game.

[stormtracker]

Damn, the poor servers here are just not handling the traffic well when the major models come out. Hope we can donate enough and get it fixed before this winter really gets under way.

What? Its been loading fine here.

And we are well on our way to upgrading.

[PhineasC]

Looks fine for 130+ hours.

[Allsnow]

hr 138 low 992 150 miles south of the BM....hr 144 988 100 miles off the coast of maine.....boston gets brush with light preciep....

[mattinpa]

What? Its been loading fine here.

And we are well on our way to upgrading.

It's been slow for me, too.

Euro is close, and guess that's ok at this point.

[Inudaw]

Day 6