Reviews of high shear-low CAPE severe weather events

At the recent CSTAR meeting, there was some discussion of what general format an event review should follow and what should be included.  We have completed several informal reviews and posted them to our ‘Local Research” section of our web page, which can be found at…

I have included links to recent reviews of high shear-low CAPE events near the top.  While the reviews attempt to follow the AMS author’s guide in a conference paper format, the intended audience is the interested public, so some technical aspects are left out. 

Reviews do not necessarily have to follow the format that we use, which might be considered as having too much detail.  Other offices may choose to follow a different format, such as the excellent one used by NWS Raleigh.  However, in my opinion, at a minimum each review should contain some discussion of the pre-storm or near-storm environment (CAPE, CIN, shear, SRH), some examples of radar imagery, any notable or unusual radar signatures, and some reference to verification (local storm reports, Storm Data, or public information statements) so we know what happened (unless it was a null event).  Of course, this may change if Dr. Parker has specific needs.  I can help with data sources and I know that Jonathan Blaes also has a list of data sources.
Until Dr. Parker begins to mine the SPC datasets, a good starting point for identifying events would be to go through local Storm Data to pick out tornado or wind damage reports in the cool season.

I look forward to more discussion on this topic.  -Pat Moore

A classic "Broken-S" signature was observed at 0052 UTC on 17 February 2001 associated with a tornado over Elbert County, Georgia. The damage from the tornado was rated at EF0 along an intermittent three mile path near the town of Bowman. The tornado occurred near the southern appendage of the trailing line segment.

KGSP base velocity 0.5 degree scan at 0052 UTC on 17 February 2001.

About nws-pat moore

B.S. Meteorology, State Univ. of New York - College at Oneonta (1987) M.S. Meteorology, The Florida State University (1996) National Weather Service (12/3/90 to present), stationed at GSP since 8/16/98.
This entry was posted in CSTAR, High Shear Low Cape Severe Wx. Bookmark the permalink.

7 Responses to Reviews of high shear-low CAPE severe weather events

  1. Michael Cammarata says:

    Those look good Pat…I think including all of the parameters on the RAOB sounding is good. After a number of cases have been compiled we may find something interesting that the the tornadic vs null cases share in common. It might be interesting to include VWP’s as well.

    • Pat Moore says:


      This is hopefully the beginning of a discussion on what we can agree to include in a review (formal or informal). As for a RAOB sounding, that would be a good idea. Do you mean an observed sounding, or the parameters from a model sounding viewed with the RAOB software? If the latter, then we should agree on what the source of the sounding should be. We could include the parameters either in a table, or as an image or screencapture that shows the parameters. I look forward to compiling some statistics on these parameters. I’m already working on such a “climatology” from our events, but it will hardly be statistically significant. As for VWPs, it shouldn’t be that difficult to dig them up, too.

      -pat moore

      • Michael Cammarata says:

        I was referring to the RAOB software. As for the data we have a multitude of options including observed and forecast. I am interested to hear what others have to say on this. It would be interesting to include HME data for future cases now that we have that going.

  2. Matt Parker says:

    I think your resources are going to be extremely useful, Pat. Thanks for making them known to us all!

    With regard to what case studies ought to include, my thoughts are:

    1. Full synoptic work-up
    a) depiction of large scale features using NARR or RUC analyses
    b) careful hand surface analysis depicting all relevant boundaries

    2. All basic environmental parameters related to instability and shear
    a) local sounding(s) (observed if available, plus RUC analysis soundings)
    b) plan view maps (SPC mesoanalyses)

    3. Full volume radar analyses of both reflectivity and radial velocity
    a) early/developing stages
    b) mature stage, with careful correlation of radar to warnings and reports
    c) any other times at which “high impact” signatures appear (hook echo, broken S, MDA or TVS detection, etc.)
    d) documentation of depth and longevity of these kinds of radar signatures

    Probably it will not be too hard to identify the cases/events/”hits”. The hard part will be identifying some good null cases we can sink our teeth into. It seems clear that a lot of HSLC tornadoes occur with broken-S signatures. What is unclear (at least to me) is how often the broken-S produces a false alarm. A nice sample of nulls might help us get some traction on that question.

    All the best,

    • Pat Moore says:


      Thanks for the guidance on what you would like to see in case studies. This should give everyone a good idea for what to include. Here are a few comments/questions that I have…

      1. Do you have a reference for where to obtain NARR/RUC analyses for the synoptic overview? I usually go with the SPC/HPC objective analysis graphics, but I can re-tool. It would be desirable for case studies to use the same basis for the large scale stuff.

      2. We might also need a source for the RUC analysis soundings.

      3. The radar stuff should be fairly easy to obtain as for the most part 88D data is available at NCDC. It is interesting to note that in many of the HSLC cases the convection is relatively shallow. Unless the convective line is close to the radar, usually most of what is interesting can be found on the lowest four elevation scans.

      By the way, I already have some null events in mind and will share at a later date.


  3. Jonathan Blaes says:


    We archived the SPC mesoanlysis images for our region and have been doing it for many years. Initially we only archived a small subset of the hourly images (keyed in on the bigger most important ones), now we archive every single image for sector 17 which covers our region. There are periods where we missed data because of a disk problem or other issues, but we have most of it and can share the imagery. I may grab a student and see if they can put together some sort of list of the available data.


    • nws-pat moore says:


      I really appreciate that you are archiving the SPC mesoanalysis graphics for our sector. Is ‘sector 17’ the same as the EC sector on the SPC page? We used to be able to pull the images from the archive running at NWS Omaha, but that has been unreliable since the SPC went to static mesoanalysis sectors earlier in the year. At any rate, your archive will be a valuable reference for us moving forward. Thanks!


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