New national SPC analysis

Wow, they must have just changed the format lately. I like that view much better, because you can get an idea of where the sectors are compared to looking in those smaller boxes on the side like before. Oh and I love the clicking on the national sector and they show everything for the entire US!! That is a great new feature.. Now if only they could update it more than once an hr and this would be one of the best features to use!
 
Originally posted by Jayson Prentice
Now if only they could update it more than once an hr and this would be one of the best features to use!

I'm not sure it'd be of any practical use to to update it more than once per hour. Most surface observations are only reporting once an hour, so you really wouldn't have any additional observations from which to run the RUC model with... Now, if every ASOS/AWOS reported every 5 minutes (a la OK Mesonet stations) it may be of use, but this isn't the case, so I don't think it'd be of much utility to run the analysis more than once an hour...
 
Originally posted by Jeff Snyder+--><div class='quotetop'>QUOTE(Jeff Snyder)</div>
<!--QuoteBegin-Jayson Prentice
Now if only they could update it more than once an hr and this would be one of the best features to use!

I'm not sure it'd be of any practical use to to update it more than once per hour. Most surface observations are only reporting once an hour, so you really wouldn't have any additional observations from which to run the RUC model with... Now, if every ASOS/AWOS reported every 5 minutes (a la OK Mesonet stations) it may be of use, but this isn't the case, so I don't think it'd be of much utility to run the analysis more than once an hour...[/b]

I could see them doing it for locations with mesonet data, like OK, IA, and even MN, where I notice many SFC stations report every 20 minutes or so. But, they would still be merging this data with the "older" RUC data, so it would be somewhat misrepresentative, but not so much as to create an erroneous analysis. But, that would only be worthwhile for those few states that operate mesonets...
 
That is a good point, I wasn't thinking completely at the moment. ;) But, back to the main point at hand. The national picture is a great way to look at the large surface features over the entire US. I really do like it, a great job by the SPC.
 
Jeff is right about the once-an-hour observational input data. Also, the RUC itself only runs once an hour. The national sector is supposed to provide a broader overview, and to give some attention to areas not covered in more detail by the regional sectors, at least until SPC eventually is able to set aside enough computing resources to run a truly national mosaic of mesoanalysis sectors. When? Don't know.

Another important improvement, physically and conceptually, is the idea of effective parcel use in deriving CAPE, bulk shear, SRH and the parameters like SCP and STP that are derived from them. Right now just the SRH is "turned on," but we want to get the other effective parcel based parameters up ASAP. Be patient; development activities always slow down during spring and summer for what I hope are obvious reasons. :wink:

For a basic description of the idea of effective parcels (i.e., as applied to SRH), see

http:/www.spc.noaa.gov/exper/mesoanalysis/help/help_esrh.html

For a detailed look at the effective-parcel methods and thinking, read these papers...

Effective Bulk Shear in Supercell Thunderstorm Environments:
http://www.spc.noaa.gov/publications/thomp...on/effshear.pdf

Effective Storm-Relative Helicity in Supercell Thunderstorm Environments:
http://www.spc.noaa.gov/publications/thomp...son/eff-srh.pdf

An Update to the Supercell Composite and Significant Tornado Parameters:
http://www.spc.noaa.gov/publications/thomp...son/stp_scp.pdf

Assessment of Anticyclonic Supercell Environments Using Close Proximity Soundings from the RUC Model:
http://www.spc.noaa.gov/publications/edwar...ds/leftmove.pdf

Any questions/suggestions about the mesoanalysis page parameters (not answered by those papers) or layout, just fire off an e-mail to Rich ([email protected]).
 
JAn Update to the Supercell Composite and Significant Tornado Parameters:
http://www.spc.noaa.gov/publications/thomp...son/stp_scp.pdf

This contains some fascinating stuff! As does this: http://www.spc.noaa.gov/sfctest/help/sfcoa.html. An STP value of 1.2 or higher would seem to be one HECK of a differentiator between tornadic and non-tornadic supercells.

I see that Earl Barker's experimental products page contains STP Model charts. Has anyone used these on chase day? Do the models give you values or contours that allow one to differentiate 1.2 or higher values?

Does anyone provide historical data pages so that one can go back and look at model predictions of STP and see how well they correlate to actual tornadic supercells?

Darren Addy
Kearney, NE
 
Earl Barker's site has several recent historical tornado days with the STP and other severe parameters mapped:

http://www.wxcaster.com/historical.htm

As with many of the contour maps on this site, it looks like local maximum (minimum) values are marked by an "X" with the value listed. It appears from the historical example the STP value is carried to the 1st decimal point.
 
JAn Update to the Supercell Composite and Significant Tornado Parameters:
http://www.spc.noaa.gov/publications/thomp...son/stp_scp.pdf

This contains some fascinating stuff! As does this: http://www.spc.noaa.gov/sfctest/help/sfcoa.html. An STP value of 1.2 or higher would seem to be one HECK of a differentiator between tornadic and non-tornadic supercells.

I see that Earl Barker's experimental products page contains STP Model charts. Has anyone used these on chase day? Do the models give you values or contours that allow one to differentiate 1.2 or higher values?

Does anyone provide historical data pages so that one can go back and look at model predictions of STP and see how well they correlate to actual tornadic supercells?

Darren Addy
Kearney, NE

Darren,

The statistical plots shown on the mesoanalysis help page are derived from RUC model analysis soundings, so the numbers are quite similar to what we display on the mesoanalysis sectors. Earl Barker has just updated his STP calculations to include all of the effective bulk shear/SRH terms, and now we normalize the mlCAPE to 1500 J/kg (instead of 1000 J/kg). The net result is STP values that are ~50% smaller than the original version, and a little lower false alarm. Earl plots STP every 0.1, and the more significant values don't show up until the start of yellow (STP=1).

Model forecasts of STP can be reasonably good, but there are are few things to consider. First, the Eta shallow convective scheme tends to produce unrealistic moist layers near the ground and reduce CIN in some situations, and those changes impact the STP. Probably the best way to handle the model forecasts is to look at Earl's maps and then check out a few forecast soundings to make sure they look realistic. I've been using STP as part of the forecast routine at SPC for about 3 years, and it works pretty well in identifying the more serious tornado days, assuming the basic pattern is reasonably well handled.

Rich T.
 
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