Severe Weather Seminar Spring 2011 [email protected].
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Transcript of Severe Weather Seminar Spring 2011 [email protected].
![Page 1: Severe Weather Seminar Spring 2011 Pat.spoden@noaa.gov.](https://reader036.fdocuments.us/reader036/viewer/2022070412/56649e535503460f94b49f7d/html5/thumbnails/1.jpg)
Operational Use of Spectrum Width
Severe Weather Seminar
Spring 2011
![Page 2: Severe Weather Seminar Spring 2011 Pat.spoden@noaa.gov.](https://reader036.fdocuments.us/reader036/viewer/2022070412/56649e535503460f94b49f7d/html5/thumbnails/2.jpg)
What is Spectrum Width?
• One of the 3 base moments available with WSR-88D
• Measures the variability of movement within a bin
• With super-high resolution, there is much we can see
• Not available on the web – GR software only – Color scales important, as always
![Page 3: Severe Weather Seminar Spring 2011 Pat.spoden@noaa.gov.](https://reader036.fdocuments.us/reader036/viewer/2022070412/56649e535503460f94b49f7d/html5/thumbnails/3.jpg)
Spectrum Width
• Spectrum Width depicts a measure of velocity dispersion. It provides a measure of the variability of the mean radial velocity estimates due to wind shear, turbulence, and/or the quality of the velocity samples. It is used to estimate turbulence associated with boundaries, thunderstorms, mesocyclones.
![Page 4: Severe Weather Seminar Spring 2011 Pat.spoden@noaa.gov.](https://reader036.fdocuments.us/reader036/viewer/2022070412/56649e535503460f94b49f7d/html5/thumbnails/4.jpg)
Spectrum Width
Low Spectrum Width High Spectrum Width
Both situations can be helpful…
![Page 5: Severe Weather Seminar Spring 2011 Pat.spoden@noaa.gov.](https://reader036.fdocuments.us/reader036/viewer/2022070412/56649e535503460f94b49f7d/html5/thumbnails/5.jpg)
Low Spectrum Width
• Depicts a smooth flow• Supercell• May 2, 2010
![Page 6: Severe Weather Seminar Spring 2011 Pat.spoden@noaa.gov.](https://reader036.fdocuments.us/reader036/viewer/2022070412/56649e535503460f94b49f7d/html5/thumbnails/6.jpg)
Low Spectrum Width
Low, or smoothvalues
![Page 7: Severe Weather Seminar Spring 2011 Pat.spoden@noaa.gov.](https://reader036.fdocuments.us/reader036/viewer/2022070412/56649e535503460f94b49f7d/html5/thumbnails/7.jpg)
Low Spectrum Width
Rear FlankDowndraft
![Page 8: Severe Weather Seminar Spring 2011 Pat.spoden@noaa.gov.](https://reader036.fdocuments.us/reader036/viewer/2022070412/56649e535503460f94b49f7d/html5/thumbnails/8.jpg)
Low Spectrum Width
Tornado is now“cutoff” and soon dissipates
![Page 9: Severe Weather Seminar Spring 2011 Pat.spoden@noaa.gov.](https://reader036.fdocuments.us/reader036/viewer/2022070412/56649e535503460f94b49f7d/html5/thumbnails/9.jpg)
Damage Map
Tornado RFD wind damage
![Page 10: Severe Weather Seminar Spring 2011 Pat.spoden@noaa.gov.](https://reader036.fdocuments.us/reader036/viewer/2022070412/56649e535503460f94b49f7d/html5/thumbnails/10.jpg)
High Spectrum Width
Distant Supercell
May 2, 2010
EF0 Tornado in northern Butler
Image from 10-15mintues prior to touchdown
![Page 11: Severe Weather Seminar Spring 2011 Pat.spoden@noaa.gov.](https://reader036.fdocuments.us/reader036/viewer/2022070412/56649e535503460f94b49f7d/html5/thumbnails/11.jpg)
High Spectrum Width
![Page 12: Severe Weather Seminar Spring 2011 Pat.spoden@noaa.gov.](https://reader036.fdocuments.us/reader036/viewer/2022070412/56649e535503460f94b49f7d/html5/thumbnails/12.jpg)
Other Uses
• TBSS – Three Body Scatter Spike
![Page 13: Severe Weather Seminar Spring 2011 Pat.spoden@noaa.gov.](https://reader036.fdocuments.us/reader036/viewer/2022070412/56649e535503460f94b49f7d/html5/thumbnails/13.jpg)
1949 @ 9.9 (19,500 ft)
August 14, 2010
-Signature seen5-10 minutesprior to 65-70mph microburst.
![Page 14: Severe Weather Seminar Spring 2011 Pat.spoden@noaa.gov.](https://reader036.fdocuments.us/reader036/viewer/2022070412/56649e535503460f94b49f7d/html5/thumbnails/14.jpg)
1954 Cross Section
![Page 15: Severe Weather Seminar Spring 2011 Pat.spoden@noaa.gov.](https://reader036.fdocuments.us/reader036/viewer/2022070412/56649e535503460f94b49f7d/html5/thumbnails/15.jpg)
• It is not always clear nor easy to locate the true “leading edge.”
• Strong winds can push storms upshear which may complicate the matter
Next Question
Where is the “leading edge”
??
![Page 16: Severe Weather Seminar Spring 2011 Pat.spoden@noaa.gov.](https://reader036.fdocuments.us/reader036/viewer/2022070412/56649e535503460f94b49f7d/html5/thumbnails/16.jpg)
• Use Spectrum Width or Velocity productSolutions
![Page 17: Severe Weather Seminar Spring 2011 Pat.spoden@noaa.gov.](https://reader036.fdocuments.us/reader036/viewer/2022070412/56649e535503460f94b49f7d/html5/thumbnails/17.jpg)
Where is the “leading edge?”
Where you thought?
![Page 18: Severe Weather Seminar Spring 2011 Pat.spoden@noaa.gov.](https://reader036.fdocuments.us/reader036/viewer/2022070412/56649e535503460f94b49f7d/html5/thumbnails/18.jpg)
Another way to help spot interfaces and mesovortices – use SPECTRUM WIDTH!
![Page 19: Severe Weather Seminar Spring 2011 Pat.spoden@noaa.gov.](https://reader036.fdocuments.us/reader036/viewer/2022070412/56649e535503460f94b49f7d/html5/thumbnails/19.jpg)
Spectrum Width
• Depicts turbulence within the range bin.• Low values suggest “smooth flow”
– RFDs, inflow
• High values suggest turbulent flow– Boundaries– Potential of tornadic signatures with weak
rotation