ATL: LEE - Remnants - Discussion

[Wthrman13]

Regarding the forecast central pressures from these various models, please keep in mind that most of these models, particularly the global ones such as the CMS, ECMWF, and GFS lack the resolution to capture the inner cores of tropical cyclones, and as such will often underestimate the central pressure of a mature hurricane.

On the other hand, the high-res limited area models that are specialized for hurricanes (i.e. the GFDL and HWRF) often are way off on intensity (either too high or too low, depending on the circumstances). In this case, it's not a lack of resolution that is the problem, but problems with the model physical parameterizations and initial and boundary conditions.

The bottom line is, take the forecast central pressures with a huge grain of salt, and don't focus on the exact numbers (i.e. the "quantitative" approach). Rather, pay closer attention to the general intensity that the models are forecasting (i.e. a few closed isobars vs. many closed isobars). This is the "qualitative" approach, which is about as good as we can get with the current generation of numerical models. If most of the models are forecasting a system with many closed isobars, it's a good bet that they are picking up on robust development, but beyond that, whether we are talking about a Cat 1 or Cat 5 is a completely different question and is simply beyond the ability of our forecast models at this point in time. Check back in 10 years; it may be a different story.

[Jagno]

Thank you for helping us to understand this better.

[South Texas Storms]

0z Euro looks like it initializes 93L well.

[BigB0882]

Euro is running? Thank goodness. It shouldn't take long since we aren't looking at something very far off then I can go to bed! Someone please post images if at all possible.

[maxintensity]

Regarding the forecast central pressures from these various models, please keep in mind that most of these models, particularly the global ones such as the CMS, ECMWF, and GFS lack the resolution to capture the inner cores of tropical cyclones, and as such will often underestimate the central pressure of a mature hurricane.

On the other hand, the high-res limited area models that are specialized for hurricanes (i.e. the GFDL and HWRF) often are way off on intensity (either too high or too low, depending on the circumstances). In this case, it's not a lack of resolution that is the problem, but problems with the model physical parameterizations and initial and boundary conditions.

The bottom line is, take the forecast central pressures with a huge grain of salt, and don't focus on the exact numbers (i.e. the "quantitative" approach). Rather, pay closer attention to the general intensity that the models are forecasting (i.e. a few closed isobars vs. many closed isobars). This is the "qualitative" approach, which is about as good as we can get with the current generation of numerical models. If most of the models are forecasting a system with many closed isobars, it's a good bet that they are picking up on robust development, but beyond that, whether we are talking about a Cat 1 or Cat 5 is a completely different question and is simply beyond the ability of our forecast models at this point in time. Check back in 10 years; it may be a different story.

I believe this statement should be front and center on the website. It seems like people always insist on taking the pressure from a global model and extrapolating that into a saffir simpson category. Unfortunately, they will continue to do it in the future despite this post and many others before it telling them otherwise. One thing I have noticed though is that Euro is the only global that seems to generate actual pressures (see irene or katrina for example). Although certainly even then you cant morph that into a saffir simpson category. Globals are good for cyclone gensis, steering, and the environment.

[pwrdog]

The Euro seem to think florida now... If I have the right time stamp..

[South Texas Storms]

The Euro seem to think florida now... If I have the right time stamp..

Nope I think you have the wrong model or run. It isn't out to 24 hours yet.

[maxintensity]

The Euro seem to think florida now... If I have the right time stamp..

Euro is not out for me but it has never showed florida so timestamp would not be a problem. You sure your looking at euro?

[Jagno]

No one is insisting anything. Some of us are trying to learn and all too often it's only by the understanding and patience of our great mets on board that we learn the correct way to assess these systems.

[Nikki]

No one is insisting anything. Some of us are trying to learn and all too often it's only by the understanding and patience of our great mets on board that we learn the correct way to assess these systems.

Couldn't have said it better myself Jagno!

[South Texas Storms]

0z GFDL looks reasonable.
http://coaps.fsu.edu/~maue/extreme/gfdl ... _nest3.png

[HouTXmetro]

GFDL would make much of Texas Happy

[Wthrman13]

Regarding the forecast central pressures from these various models, please keep in mind that most of these models, particularly the global ones such as the CMS, ECMWF, and GFS lack the resolution to capture the inner cores of tropical cyclones, and as such will often underestimate the central pressure of a mature hurricane.

On the other hand, the high-res limited area models that are specialized for hurricanes (i.e. the GFDL and HWRF) often are way off on intensity (either too high or too low, depending on the circumstances). In this case, it's not a lack of resolution that is the problem, but problems with the model physical parameterizations and initial and boundary conditions.

The bottom line is, take the forecast central pressures with a huge grain of salt, and don't focus on the exact numbers (i.e. the "quantitative" approach). Rather, pay closer attention to the general intensity that the models are forecasting (i.e. a few closed isobars vs. many closed isobars). This is the "qualitative" approach, which is about as good as we can get with the current generation of numerical models. If most of the models are forecasting a system with many closed isobars, it's a good bet that they are picking up on robust development, but beyond that, whether we are talking about a Cat 1 or Cat 5 is a completely different question and is simply beyond the ability of our forecast models at this point in time. Check back in 10 years; it may be a different story.

I believe this statement should be front and center on the website. It seems like people always insist on taking the pressure from a global model and extrapolating that into a saffir simpson category. Unfortunately, they will continue to do it in the future despite this post and many others before it telling them otherwise. One thing I have noticed though is that Euro is the only global that seems to generate actual pressures (see irene or katrina for example). Although certainly even then you cant morph that into a saffir simpson category. Globals are good for cyclone gensis, steering, and the environment.

Thanks for the comment!

The Euro has the highest resolution of any of the global models (though I'll have to double-check that), so it's not surprising that it tends to produce lower central pressures in tropical cyclones.

Also, I don't think anyone was trying to pin down Saffir-Simpson categories from the model pressures in this particular thread, but my comment was aimed more generally as a word of caution, and an appeal to not read too much into the exact numbers.

[South Texas Storms]

GFDL would make much of Texas Happy

Yep yep!

[paintplaye]

Euro is similar to 12z through 48h but a little farther south:

http://raleighwx.americanwx.com/models/ ... _loop.html

[Jagno]

Euro is similar to 12z through 48h but a little farther south:

http://raleighwx.americanwx.com/models/ ... _loop.html

Please post it here. Every time I click on this link my internet explorer stops working.

[paintplaye]

Euro is similar to 12z through 48h but a little farther south:

http://raleighwx.americanwx.com/models/ ... _loop.html

Please post it here. Every time I click on this link my internet explorer stops working.

Sorry about that. Here you go:

[paintplaye]

96: Also ridging looks to be building up north really fast so i don't expect much more of a north movement.

[pwrdog]

0z GFDL looks reasonable.
http://coaps.fsu.edu/~maue/extreme/gfdl ... _nest3.png

That's a lot like the Canadian model was showing.. That would be a glimer of hope..

[stormhunter7]

with that ridge building to north.. expect a left or west turn after 96+