1. October 28, 2008 Created by: Mike July Presented by: Matthew Dux

2.  Review Kansas City Snow Climatology  Review Synoptic Patterns Conducive to Heavy Snow  Review Freezing Rain Climatology

3. 1835 Snow Events 15 /year 144 Events ~ >4”snow ~1 /season 57 Events ~ >6” snow ~1 /2 seasons 1835 Snow Events 15 /year 144 Events ~ >4”snow ~1 /season 57 Events ~ >6” snow ~1 /2 seasons 1634 Snow Events < 4”

5.  Northwest Flow System or “Clipper”  Southwest Low  Progressive Short Wave Trough  Deepening Low

6. Northwest Flow System or “Clipper” Four Primary Patterns Favorable for Heavy Snowfall in the EAX CWA

7. Southwest Low Four Primary Patterns Favorable for Heavy Snowfall in the EAX CWA

8. Progressive Short Wave Trough Four Primary Patterns Favorable for Heavy Snowfall in the EAX CWA

9. Deepening Low

10. Freezing Rain/Freezing Precipitation Climatology

11. 3.2 events/yr 30 yr average (1971-2000) – 3.2 events/yr 3.2 events/yr 30 yr average (1948-1977) – 3.2 events/yr 3.2 events/yr 53 yr average (1948-2000) – 3.2 events/yr

12. FZRA events peak in December/January Kansas City Kansas City December, January and February have an equal distribution of FZRA events

13. 92% chance FZRA will occur in during the cold season (Nov-Mar). 83% chance FZRA will occur on 1 to 5 days per cold season. 58% chance FZRA will occur on 2 to 4 days (annual avg 3.2/cold season)

14. (1971-2000) – 3.2 days/yr (1948-1977) – 3.2 days/yr ( not shown ) (1948-2000) – 3.2 days/yr

17. Studies by Bennett (1958), Changnon (2003) and Rauber, et al (2001) came to very similar conclusions……… 1)Arctic Fronts account for 42% 2)Warm Front / Occlusion – 19% 3)Cyclone/Anticyclone – 26% Pattern 3 most severe due to heavy icing plus high winds. Area of FZRA/FZDZ is typically narrow and just north of 0C surface isotherm. 1 2 3

18.  FZDZ occurs much more frequently than FZRA.  In KC freezing rain peaks in Dec/Jan.  Three primary weather patterns account for the vast majority of all freezing precipitation in Kansas City (possibly as high as 90%).  Between 1 and 5 freezing rain events per cold season with an annual average of 3.2/season.  Around 80% of all FZRA events occur with 2m temperatures within a tight range (28-32F) whereas the vast majority of FZDZ events occur within a much broader range (21-32F).  The Freezing Precipitation Frequency graphics from NCDC look suspect….especially for December.