Weekend Storm Discussion 2/18-2/19

[Ian]

Id love to see a lobe of that pv come down and phase in.. But I'm getting greedy

banter

[Dr No]

The 50/50 was weaker and more "split" this run... slow the kicker down a little and you are now dealing with a Miller B with a primary in TN/KY. I'm not sure that's a bad thing as there's a limit to how far west it can go...Good thing for the HP to our north too.

[Isopycnic]

http://fortysouthwx.com/index.php?/topic/2446-what-we-have-this-time/

For now and into Thursday, I would suggest, remain confident with the fact that it really does look like we have a Georgia passing low of good intensity, some cold high...

[WinterWxLuvr]

If anyone is going to give cred to the 18z op, then, at still 114-126 hours out, I'd think you have to give some to the ensembles. 4 of those, not including the op, have a solution that is better than the op. But, then again, those things are doing a bit of flip-flopping as well. Hard to know what to think at this point.

[Wonderdog]

That's a nice run of the GFS. And the day 11-15 time range shows us getting colder. Pattern change?

[mitchnick]

If anyone is going to give cred to the 18z op, then, at still 114-126 hours out, I'd think you have to give some to the ensembles. 4 of those, not including the op, have a solution that is better than the op. But, then again, those things are doing a bit of flip-flopping as well. Hard to know what to think at this point.

remember, as someone posted, they changed the programming or something with the GEFS at 12Z

I'm not certain if we can trust them as they may be better or worse than before

[chris87]

remember, as someone posted, they changed the programming or something with the GEFS at 12Z

I'm not certain if we can trust them as they may be better or worse than before

there is absolutely no reason to believe they will not be an improvement...what do you think EMC does...plans a random update and implements...in reality, these updates are tested and verified off-line for months before the public ever sees them.

[WinterWxLuvr]

remember, as someone posted, they changed the programming or something with the GEFS at 12Z

I'm not certain if we can trust them as they may be better or worse than before

Yeah. You'd think they'd get better, but you wouldn't know that for a long time I suppose.

[dtk]

Yeah. You'd think they'd get better, but you wouldn't know that for a long time I suppose.

Not true at all. This particular upgrade has been run for a LONG evaluation period. The service centers (HPC, NHC, SPC, AWC, CPC, etc.) as well as NWS regions (who can then coordinate with WFOs if desired) are involved in the process, get to see experimental data leading up to the implementation, take part in an official evaluation, and have veto power if planned upgrades aren't good enough.

NCO used to distribute graphics from our pre-implementation evaluation runs on the old MAF, but that has since been lost with the transition to the MAG (unfortunately). Data is made readily available in near-real time, but not many in the private sector (some do though), take part.

[WinterWxLuvr]

Not true at all. This particular upgrade has been run for a LONG evaluation period. The service centers (HPC, NHC, SPC, AWC, CPC, etc.) as well as NWS regions (who can then coordinate with WFOs if desired) are involved in the process, get to see experimental data leading up to the implementation, take part in an official evaluation, and have veto power if planned upgrades aren't good enough.

NCO used to distribute graphics from our pre-implementation evaluation runs on the old MAF, but that has since been lost with the transition to the MAG (unfortunately). Data is made readily available in near-real time, but not many in the private sector (some do though), take part.

I didn't know that, dtk. I had posted my reply before seeing Chris' post. It makes sense though. Isn't that the same thing that was done with the GFS para runs before they switched them?

Thanks for the info.

[mitchnick]

there is absolutely no reason to believe they will not be an improvement...what do you think EMC does...plans a random update and implements...in reality, these updates are tested and verified off-line for months before the public ever sees them.

the Edsel was supposed to be a better car, but we know how that turned out

seems to me we have to wait and see, that's all I'm suggesting because people will/may use them assuming the same issues as prior GEFS program

also, all the computer programs have their strengths, weaknesses and biases

I believe NCEP has a page with those characteristics of each model

have they done that with the new GEFS?

[dtk]

I didn't know that, dtk. I had posted my reply before seeing Chris' post. It makes sense though. Isn't that the same thing that was done with the GFS para runs before they switched them?

Thanks for the info.

Yeah, we have to go through a formal procedure for any "big" implementation. For example, we have a huge change to the GFS/GDAS data assimilation (model initialization) coming up (I think it's been delayed to May now)....which has required extensive testing. We already have over a year's worth of simulated days done (and more on the way). I'll point people to data/graphics once it is caught up to real-time again or when the official 30-day evaluation begins.

[dtk]

the Edsel was supposed to be a better car, but we know how that turned out

seems to me we have to wait and see, that's all I'm suggesting because people will/may use them assuming the same issues as prior GEFS program

also, all the computer programs have their strengths, weaknesses and biases

I believe NCEP has a page with those characteristics of each model

have they done that with the new GEFS?

If you are referring to the page that I think you're referring to, it is totally subjective and most of the information is outdated.

And yes, extensive testing was done with the new GEFS. Evaluations were performed by the service centers. I have access to some of the measures of skill comparing the new versus old system if people are that interested (though I don't want to clutter this thread with ensemble verification metrics).

[Clinch Leatherwood]

If anyone is going to give cred to the 18z op, then, at still 114-126 hours out, I'd think you have to give some to the ensembles. 4 of those, not including the op, have a solution that is better than the op. But, then again, those things are doing a bit of flip-flopping as well. Hard to know what to think at this point.

The GFS and GEFS were attrocious up here with the last coastal. In reality all models grossly underestimated the strength of the southern s/w until the last day or two, with the NCEP models not doing well even inside of 24. The OP GFS and to an extent some of the GEFS members continually tried to develop a low under convective elements in NC in the D1-2 range, and prior to that about a thousand miles offshore.

The GGEM was by far the superior model, FWIW, for whatever reason in that particular event where we had interaction between a deeper southern s/w and a slower, broader northern system.

[ravensrule]

If you are referring to the page that I think you're referring to, it is totally subjective and most of the information is outdated.

And yes, extensive testing was done with the new GEFS. Evaluations were performed by the service centers. I have access to some of the measures of skill comparing the new versus old system if people are that interested (though I don't want to clutter this thread with ensemble verification metrics).

Can you post it in the banter thread please.

[Midlo Snow Maker]

this is from the 12z gfs run 500mb analogs at forecast hour 120 one of the analogs is 1/24/2000 lol.

coop snowfall for the 72 hour period

[Amped]

With this pattern, I think that will be very tough to get and don't see this as a storm likely to get much farther north than us. I also composited all the 4 inch or greater events since 1950 during la nina years and the composite does not look like this pattern. That doesn't mean we can't see snow but is sort of a flag about getting too excited about the potential for a big one. I know you know that but Rob G whoever he still has higher probabilities than I think is warranted.

The Nogaps disagrees with you. This time it's progressiveness of the northern stream acually lets the ridge get ahead of the storm and force it north.

[nw baltimore wx]

The Nogaps disagrees with you. This time it's progressiveness of the northern stream acually lets the ridge get ahead of the storm and force it north.

I'm sure that you didn't mean your post to sound the way I took it initially, but to be sure, Wes vs the Nogaps? It's a gimme. Even for Wes and his putter.

Again, I don't think you meant it the way I first read it.

[yoda]

FWIW, which isn't much at all, the 84 hr 00z NAM has closed 552DM h5 low just west of TX... and a 516DM closed h5 low in Quebec

[Amped]

I'm sure that you didn't mean your post to sound the way I took it initially, but to be sure, Wes vs the Nogaps? It's a gimme. Even for Wes and his putter.

Again, I don't think you meant it the way I first read it.

Now it's 00z NAM and NOGAPS vs Wes. Double N rule.

[nw baltimore wx]

Now it's 00z NAM and NOGAPS vs Wes. Double N rule.

Huh? What do you know? Damn. You might be right. But my nam only goes out 84 hours so I can't see the final solution. Maybe I should get the pay version.

[Amped]

Huh? What do you know? Damn. You might be right. But my nam only goes out 84 hours so I can't see the final solution. Maybe I should get the pay version.

The Nam 00z 84 looks similar to Nogaps 12z 96. So I extrapolating

I was just pointing out that this storm does have the opportunity to cut if the southern energy hangs back in NM until the troff digs over Idaho. Not saying it will happen, although I am thinking it to myself.

[usedtobe]

If you are referring to the page that I think you're referring to, it is totally subjective and most of the information is outdated.

And yes, extensive testing was done with the new GEFS. Evaluations were performed by the service centers. I have access to some of the measures of skill comparing the new versus old system if people are that interested (though I don't want to clutter this thread with ensemble verification metrics).

I agree, it is subjective and outdated.

[PhineasC]

I don't see this being a cutter. Suppression is the far more likely risk.

[WinterWxLuvr]

Speaking of the nam, how would that play out? Isn't that look getting close to the look of two weeks ago? It almost looks like it would send a storm way west at least initially. Somebody give their interpretation. I'd like to learn something here.

[usedtobe]

The Nogaps disagrees with you. This time it's progressiveness of the northern stream acually lets the ridge get ahead of the storm and force it north.

It's the nogaps and it takes it to the lakes. That's the one model I tend not to look at as I think it is so far below the others in skill that it is not very good. I don't see it going up the coast as a amjor storm but some of the ensembles do so of course I could be wrong. In any official forecast the best call is just to say a chance of rain or snow. As Don Sutherland noted. with a positive AO and a La NIna there has only been one KU storm and not many 4 inch or greater but then I really don't know. That's a large part of why I think it doubtful we see a major snowstorm plus there are the temp issues.

[Inudaw]

Extropolating the nam is really pointless. But it would suggest a further north track.. but the kicker will eventually send it ene..... I don't expect a low to go to far north givent he 50/50 low. I expect it would still go ene because of the set up in the Atlantic. Things of note... unless it takes longer to eject out allowing the 50/50 low to escape and relax the flow out east. That would mess up a lot of things really. But that really stretching things. x.x;

[PhineasC]

Speaking of the nam, how would that play out? Isn't that look getting close to the look of two weeks ago? It almost looks like it would send a storm way west at least initially. Somebody give their interpretation. I'd like to learn something here.

I am not sure why you expect someone to educate you on how to extrapolate the NAM, which is a pointless exercise.

[usedtobe]

Speaking of the nam, how would that play out? Isn't that look getting close to the look of two weeks ago? It almost looks like it would send a storm way west at least initially. Somebody give their interpretation. I'd like to learn something here.

The huge vortex over eastern canada probably won't be moving fast enough to allow the southern stream to cut to the lakes based on the NAM. It is a really strong vortex.

[usedtobe]

Extropolating the nam is really pointless. But it would suggest a further north track.. but the kicker will eventually send it ene..... I don't expect a low to go to far north givent he 50/50 low. I expect it would still go ene because of the set up in the Atlantic. Things of note... unless it takes longer to eject out allowing the 50/50 low to escape and relax the flow out east. That would mess up a lot of things really. But that really stretching things. x.x;

I actually disagree some about the nam. The upper low over eastern canada is huge and would really have to get out of the way to allow the low to track northeast very quickly. Big vortex usually are slower to move but as you say, at 84 hrs trying to extrapolate a model is pretty hard unless your only going to try to predict the next 12 hrs or so and then you have to hope the NAM has a decent forecast.