March Rolling Obs/Banter

[Deck Pic]

Sorry, I've looked at that one countless times. 

 

nice diversion. 

 

again...nice straw man....saying one model is better than another, is not saying that the better model is a "correct" model...but I am sure you realize that...or maybe you don't, which would be really sad...The premise is that the NAM is a poor model...saying that no model is correct does not counter that argument...Is this line of thinking over your head?

[isohume]

again...nice straw man....saying one model is better than another, is not saying that the better model is a "correct" model...but I am sure you realize that...or maybe you don't, which would be really sad...The premise is that the NAM is a poor model...saying that no model is correct does not counter that argument...Is this line of thinking over your head?

 

Sorry again, operationally each model has it's own ups and downs as far as providing good guidance. The idea is to not modelcast for a specific verification. The idea is to forecast with a degree of confidence based on the known biases and strengths/limitations of each model. The idea is to know your forecast area and how specific weather variables interact with each other to produce the most likely sensible wx. Is this line of thinking over your head?   

[Deck Pic]

Sorry again, operationally each model has it's own ups and downs as far as providing good guidance. The idea is to not modelcast for a specific verification. The idea is to forecast with a degree of confidence based on the known biases and strengths/limitations of each model. The idea is to know your forecast area and how specific weather variables interact with each other to produce the most likely sensible wx. Is this line of thinking over your head?   

 

Agreed...so what strengths does the NAM bring to the table in winter storms for washington DC...

[ACFD FIREMAN]

Sorry again, operationally each model has it's own ups and downs as far as providing good guidance. The idea is to not modelcast for a specific verification. The idea is to forecast with a degree of confidence based on the known biases and strengths/limitations of each model. The idea is to know your forecast area and how specific weather variables interact with each other to produce the most likely sensible wx. Is this line of thinking over your head?   

And the NAM still sucks according to your line of thinking.....

[isohume]

Agreed...so what strengths does the NAM bring to the table in winter storms for washington DC...

 

I don't forecast for that area. I'd imagine you should know. You live there. 

 

[ravensrule]

 

I don't forecast for that area. I'd imagine you should know. You live there. 

 

Lolz you are a terrible troll.

[Deck Pic]

 

I don't forecast for that area. I'd imagine you should know. You live there. 

 

 

I do know....none...As a forecaster you are going to do better in the means verifying for DC metro in the winter by pretending the NAM doesn't exist than by trying to use it for some limited purpose...at least in my experience...perhaps there are others who feel their forecasting has benefited by blending it

[wxmeddler]

Surprise snow shower made it over the mountians. Nothing sticking but its great to see dendrites again.

[Ellinwood]

I do know....none...As a forecaster you are going to do better in the means verifying for DC metro in the winter by pretending the NAM doesn't exist than by trying to use it for some limited purpose...at least in my experience...perhaps there are others who feel their forecasting has benefited by blending it

While not good during the "real" events in winter, the NAM can help pick out if lake-effect or lake-enhanced showers will make it over the mountains into the DC/MD/NoVA region. It's higher resolution and mesoscale strengths help it in that regard vs. the GFS, Euro, etc. It can also add value in some all-snow events where there are no temperature issues so long as you account for the QPF bias (by cutting it in half usually).

EDIT: And this is all usually within 48 hours of an event. I almost never rely on the NAM beyond 48 hours in winter.

[mattie g]

Lolz you are a terrible troll.

 

Why are you getting involved in a discussion that has nothing to do with you?

[isohume]

I do know....none...As a forecaster you are going to do better in the means verifying for DC metro in the winter by pretending the NAM doesn't exist than by trying to use it for some limited purpose...at least in my experience...perhaps there are others who feel their forecasting has benefited by blending it

 

Odd the NAM provides no useful guidance up there. It does here. It generally outperforms the other guidance across the mtns with gap and drainage flow leading to better temp fcsts. It usually is given more weight to lee side bndrys and weakening CAD TMBs, which enables a more focused depiction of cool season convection. The NAM has also way outperformed the GFS on numerous occasions wrt to the placement and degree mlvl frontogenesis along with the attendant isen lift leading to better mixed p/type fcsts. Mech lift and coupled omega is also sometimes better handled by the NAM depending on the depicted upper layered vort energy by the other models. There are other situations, but suffice to say the NAM provides value in the fcst process in my area.      

[Ian]

Strange how we are still having this oversimplified argument about the nam

[Deck Pic]

While not good during the "real" events in winter, the NAM can help pick out if lake-effect or lake-enhanced showers will make it over the mountains into the DC/MD/NoVA region. It's higher resolution and mesoscale strengths help it in that regard vs. the GFS, Euro, etc. It can also add value in some all-snow events where there are no temperature issues so long as you account for the QPF bias (by cutting it in half usually).

EDIT: And this is all usually within 48 hours of an event. I almost never rely on the NAM beyond 48 hours in winter.

 

why not just use Euro QPF which is much better and needs less adjustment?

[Ellinwood]

Also, forecasts aren't just snow and QPF during threats. Gotta think about all the other days in between where the NAM can also add value to a forecast (like when we get smacked by CAD/the marine layer and what-not).

[Deck Pic]

Strange how we are still having this oversimplified argument about the nam

 

As long as people use it here, this argument will surface a lot...I think a lot of the problem is it comes out at good times, so a lot of people are awake or chilling, and there is no other guidance conflicting

[Deck Pic]

Also, forecasts aren't just snow and QPF during threats. Gotta think about all the other days in between where the NAM can also add value to a forecast (like when we get smacked by CAD/the marine layer and what-not).

 

yeah...but the discussion is about snow and we know it overdoes CAD

[Ellinwood]

why not just use Euro QPF which is much better and needs less adjustment?

You can use the Euro QPF instead, but it's not just about the QPF. NAM can help pick out favorable banding areas that, while overdone on QPF, could indicate where the highest totals and sharp cut-offs will occur.

[ravensrule]

Why are you getting involved in a discussion that has nothing to do with you?

The same reason your annoying self does all the time.

[Ellinwood]

yeah...but the discussion is about snow and we know it overdoes CAD

My bad... I was trying to speed-read through the whole convo and missed that detail in your earlier post.

[Deck Pic]

You can use the Euro QPF instead, but it's not just about the QPF. NAM can help pick out favorable banding areas that, while overdone on QPF, could indicate where the highest totals and sharp cut-offs will occur.

 

it is pretty much awful with those too...primarily because it doesnt get the track correct and will swing wildly from run to run even inside its range...It isn't just weenies who use it...The NAM/SREFS has had a significant role in LWX and other media busts ....12/26/10, 10/29/11, 3/6/13 are just a few examples...12/26 in particular as a good example of the cutoff...the NAM and pretty much every SREF member was giving us ~0.75 QPF on the precipice of the storm causing LWX to issue WSW's...it completely folded at the end but it was too late...It isn't just us..professional forecasters are getting suckered by it regularly...if mets don't know how to use it in the winter, perhaps it shouldnt be blended at all

[isohume]

Also, forecasts aren't just snow and QPF during threats. Gotta think about all the other days in between where the NAM can also add value to a forecast (like when we get smacked by CAD/the marine layer and what-not).

 

True. I see a lot of focus on the QPF output of the models, which is the most complicated thing for a model to generate. It is no wonder the QPF changes from run to run and model to model. It's a measure of how all the variables and parameterizations interact and influence each other. If one variable changes, which is simplistic, the whole chain down the line modifies the QPF output. It's better to focus on what the models can handle a little better, like heights, kinematics, dynamics, and energy transfers. QPF is normally one of the last outputs I look at and it's never taken at face value.        

[Ellinwood]

it is pretty much awful with those too...primarily because it doesnt get the track correct and will swing wildly from run to run even inside its range...It isn't just weenies who use it...The NAM/SREFS has had a significant role in LWX and other media busts ....12/26/10, 10/29/11, 3/6/13 are just a few examples...12/26 in particular as a good example of the cutoff...the NAM and pretty much every SREF member was giving us ~0.75 QPF on the precipice of the storm causing LWX to issue WSW's...it completely folded at the end but it was too late...It isn't just us..professional forecasters are getting suckered by it regularly...if mets don't know how to use it in the winter, perhaps it shouldnt be blended at all

Whenever I see sharp cut-offs on the NAM, I take into account the fact that there probably will be a sharp cut-off somewhere, and not on exactly where the NAM has placed it. Sometimes with the marginal temp issues the GFS and Euro may not pick up such a defined gradient. It's up to interpreting that data along with where you think the actual track will end up that can help add some detail to the overall outlook.

[mattie g]

The same reason your annoying self does all the time.

 

Do I?  I think you have me confused with someone else.

[Deck Pic]

Whenever I see sharp cut-offs on the NAM, I take into account the fact that there probably will be a sharp cut-off somewhere, and not on exactly where the NAM has placed it. Sometimes with the marginal temp issues the GFS and Euro may not pick up such a defined gradient. It's up to interpreting that data along with where you think the actual track will end up that can help add some detail to the overall outlook.

 

You are a better forecaster than most people...your maps are usually very good

[H2O]

You are a better forecaster than most people...your maps are usually very good

 

agreed

[mappy]

The same reason your annoying self does all the time.

Do I? I think you have me confused with someone else.

Stop being so damn annoying, gesh

[mattie g]

Stop being so damn annoying, gesh

 

I know.  I need to stop introducing myself into other peoples' conversations.  Shame on me.

[Ian]

As long as people use it here, this argument will surface a lot...I think a lot of the problem is it comes out at good times, so a lot of people are awake or chilling, and there is no other guidance conflicting

 

Well, I think a big part of it is people are misusing the model. It would be great if it was better at range or more consistent at any point. It certainly has a number of issues with big synoptic storms. I don't personally factor it into my thinking all that much until about a day out.. even then you never know sometimes.  With t-storms it and the SREF are both pretty valuable tools from 24-48 out or so. 

[WxUSAF]

It is the banter thread, but let's keep the petty arguments in PM or in OT.  

[WxUSAF]

No problem - but please have Ravensrule please stop referring to other people as my lover, or me as their girlfriend. Those types of posts are really unncessary and uncalled for.

Agreed.  

 

RR be aware.