1. Thunderstorm Ceiling/Visibility Climatology
Mary-Beth Schreck, L. David Williams, and Kenneth R. Cook

2. Aviation Forecast Climatology Studies
BUFKIT: Forecasting Wind and Wind Gusts from Momentum Transport Winds
Observed Visibility and Ceiling During Snow
Thunderstorm Climatologies in Various Forms
Fog Climatologies
Observed Visibility and Ceiling During Thunderstorms
Verification Suffers in Summer

3. Give forecasters some probabilities of occurrence based on climatology
Goal
Since convective season is when verification suffers (cig/vsby):
Give forecasters some probabilities of occurrence based on climatology

4. Process and Results
For the 30 year period ending 2006, found all observations with TS for April – August for KRSL, KSLN, KICT, KCNU
From these, found # of occurrences (hours) for each station for the following visibility categories (SM):
<0.5
0.5 – <1.0
1.0 - <2.0
2.0 - <3.0
3.0 – 5.0
>5.0
Found % of each category (i.e. How many times does each occur) as % of total of all TSRA Fog obs
These were done for each station for each month
This is a real mind bender.

5. Process and Results

6. Process and Results

7. Process and Results

8. Process and Results

9. Process and Results

10. Process and Results

11. Process and Results
At this point, we have isolated TS obs that contain a MVFR or lower visibility. Using these data we then determined how many of these contained a MVFR or lower ceiling.
These were plotted as a percentage of the total number of TS obs w/ MVFR vsby (i.e. with a ceiling)
More drilling down.

12. Process and Results

13. Process and Results
Out of these (the ceilings that are below 3000 ft.):
Found maximum, minimum, 1st and 3rd quartiles for each visibility category by station by month.
Plotted results as “box and whiskers” plot
More drilling down.

14. Process and Results

15. Process and Results

16. Process and Results

17. Process and Results

18. Process and Results

19. Conclusions Visibilities gradually increased through the season
By July: 75-80% of TS obs had visibilities >5SM.
TS w/ MVFR or lower visibilities that contained a MVFR ceiling also decreased through the season.
By July, it was a statistically “rare” event to have MVFR ceiling and visibility with a thunderstorm.