Bufkit Questions

[chrispt]

So I've started digging into Bufkit and had a few questions:

 

1. When looking at the P-Type tab, specifically under thickness, can one deduce what kind of precipitation is occurring at ground level?
   1. So, if say my largest dot is under R, then can I assume that it is probably raining at the ground?
2. I know that the Skew-T will show what I assume it interpolates as the precipitation on the left-hand side (Green R, Blue S, etc.) with the varying intensities. Should this be taken over what is seen on the P-Type chart?

[isohume]

So I've started digging into Bufkit and had a few questions:

 

1. When looking at the P-Type tab, specifically under thickness, can one deduce what kind of precipitation is occurring at ground level?
   1. So, if say my largest dot is under R, then can I assume that it is probably raining at the ground?
2. I know that the Skew-T will show what I assume it interpolates as the precipitation on the left-hand side (Green R, Blue S, etc.) with the varying intensities. Should this be taken over what is seen on the P-Type chart?

 

The p-type shown next to the sounding depends on which p-type algorithm is chosen. The default is the thickness technique for all the models, except the GFS, which uses the Ramer technique as it's default. Therefore, using the GFS output, you could see differences btw the profile p-type and the thickness chart. If you toggle on the Bourgoin Precip Type, it's output will be seen next to profile and this p-type will correspond to the energy chart no matter which model you select. 

 

You should have a reason for wanting to select one algorithm over another for any specific thermal setup and there are strengths and weaknesses to all p-type techniques. For example...the thickness scheme does not account for micro physics and ignores a large part of the atmosphere...sometimes fooled by shallow thermal layers, but it's useful to visualize key processes and to quickly view the orientations of p-type boundaries. The Bourgoin (Energy) method assumes ice nucleation and does not account for terminal velocities, thus it cannot account for residence time of a parcel in warm/cold layers...yet it does have a fairly high POD for fzra.     

[chrispt]

So, I am looking at the Energy option under the P-type section in Bufkit. I am assuming that is what I am under because the button now says "Thickness" which I assume means to change to the thickness model. It is a little difficult to understand, but do you basically see which section the dot falls under? I see the profile changes as I move and sometimes the dot is green and in the upper right-hand corner. For example, I am looking at the GFS for KROA for 2/9/13 at 0600Z and it shows Sleet, 3 diagonal green lines and then below that Freezing Rain. The dot is yellow and falls just within the sleet area at 100 J/kg Negative Energy and about midway between 0 and 50 on the X-axis.

[isohume]

So, I am looking at the Energy option under the P-type section in Bufkit. I am assuming that is what I am under because the button now says "Thickness" which I assume means to change to the thickness model. It is a little difficult to understand, but do you basically see which section the dot falls under? I see the profile changes as I move and sometimes the dot is green and in the upper right-hand corner. For example, I am looking at the GFS for KROA for 2/9/13 at 0600Z and it shows Sleet, 3 diagonal green lines and then below that Freezing Rain. The dot is yellow and falls just within the sleet area at 100 J/kg Negative Energy and about midway between 0 and 50 on the X-axis.

 

I'm not sure what your question is, but if you are wondering why the sounding does not indicate IP while the energy diagram does, it's because the Bufkit sounding and the cross section will only output a p-type icon if there is enough available moisture. The Bourgoin and the thickness methods do not account for dry layers.     

[chrispt]

Ah, so when in doubt, trust the p-type icon because it does take into effect this dry layer. The P Type section on the left (whether it be the energy or the thickness) just indicates that somewhere in the atmosphere there may be IP, but it may not make it through the dry layer?

[isohume]

Ah, so when in doubt, trust the p-type icon because it does take into effect this dry layer. The P Type section on the left (whether it be the energy or the thickness) just indicates that somewhere in the atmosphere there may be IP, but it may not make it through the dry layer?

 

No, the different algorithms only describe the thermal structure and the most likely p-type based on that alone. The Bourgoin method assumes ice nucleation as an input, but besides that, these methods don't take into account the actual moisture seen on the soundings. The profile and the x-section do piece all of this data together tho.   

[chrispt]

Thanks for the explanation. So Bufkit interprets the data in the sounding to determine whether to add the P R or other icons directly on the sounding?

I appreciate the assistance. I am just a weenie and am trying to learn to interpret Bufkit.

Sent from my SGS3

[isohume]

Thanks for the explanation. So Bufkit interprets the data in the sounding to determine whether to add the P R or other icons directly on the sounding? I appreciate the assistance. I am just a weenie and am trying to learn to interpret Bufkit. Sent from my SGS3

 

Yeah, the sounding looks at the modeled rh and combines that with the selected thermal algorithm to assign a p-type. The thermal charts are always good to look at for trends, layered advections, and assessing the p-type potential when the model rh fields are suspect or disparate, which is usually the case btw the models and through time.