1. National Weather Service Des Moines IA The views expressed are those of the author and do not necessarily represent those of the National Weather Service. Using Bufkit to Diagnose Winter Weather Central Iowa NWA 12-5-07

2. Outline Cross-section mode Shear profile Instability Precipitation Type Other uses?

3. Temperature Time-Height Click on Overview button in the upper right hand corner of Bufkit GUI to display time-section -18 -12

4. Identify Dendritic Growth Zone

5. Scan Zone for Moisture and Identify Favored Growth Zone Favored Growth Zone

6. Display Model Omega

7. Overlay All Variables 3”- 4”/hr “Cross-hair” signature

8. Moderate Lift May Fall Outside Dendritic Growth Zone -14ub -1

9. 4” actual snow X Omega bullseye outside Dendritic Growth Zone DGZ Waldstreicher study correlates cross-hair signature with Advisory and Warning Criteria snowfall Snowfall output based on different SLR methods

10. Bufkit Time-Section 3-8 Km Shear Vector oriented same direction as heavy snow band X (Banacos, 2003) actual snow 10.5 “ Shear vector in main forcing layer will approximate the orientation of the heavy snow band Deep layer unidirectional shear favorable for maintaining frontogenetical circulation with heavy snow band Other operational uses of Bukfit data

11. Note elevated instability layer Near neutral or unstable lapse rates (with respect to a moist adiabat) implies multiple narrow and intense (maybe 5-10 km or so in width) bands.

12. Bourgouin Technique Review Divide the Temperature Profile into 1 to 4 layers Compute the + and - energy (J/kg) in each layer Divide the Temperature Profile into 1 to 4 layers Compute the + and - energy (J/kg) in each layer

13. The Freezing Rain Profile 3 layers Thickness method toggle

14. Bourgouin’s Strengths and Limitations For Snow Events, Bourgouin Always Assumes Ice Crystals are Present Top Down Approach (Microphysics) NOT Addressed For Snow Events, Bourgouin Always Assumes Ice Crystals are Present Top Down Approach (Microphysics) NOT Addressed

15. Summary A detailed Bufkit analysis should be part of every winter weather decision making process Waldstreicher study showed potential in differentiating Warning vs Advisory criteria using cross-hair technique Utilize full functionality, including overview mode, precipitation type, shear profiles, instability, SLR’s A detailed Bufkit analysis should be part of every winter weather decision making process Waldstreicher study showed potential in differentiating Warning vs Advisory criteria using cross-hair technique Utilize full functionality, including overview mode, precipitation type, shear profiles, instability, SLR’s

16. Any questions? …ask Chris Karstens Rich.Kinney@noaa.gov http://www.wdtb.noaa.gov/tools/BUFKIT/index.html Bufkit Resources: http://www.meteor.iastate.edu/~ckarsten/bufkit/bufkit.html