1. 1 Of Capping Lids, Drylines, and Alberta Thunderstorms* * and Support to UNSTABLE G.S. Strong - Ardrossan, AB Susan Skone - UofC, Calgary, AB Craig Smith - EC, Saskatoon, SK geoff.strong@shaw.ca A developing storm over Rocky Mountain House, 16 July 2003 All things are connected like the blood which unites one family. Chief Seattle, 1854.

2. 2 To acknowledge all(?) our Sponsors & Contributors....

3. 3 The basic large-scale Conceptual Model What to Look for: 1) Synoptic conditions 6-18 hours preceding - subsidence preceding upper ridge - ascent preceding upper trough - orographic subsidence/ascent - location - location - location (where/when cyclogenesis?) 2)What’s going on between the synoptic and meso-γ scales?

4. 4 Storm formation ~ 18:30Z Pre-storm period) cm s -1

5. 5 Critical changes occur in the BL during late-morning (1400-1600 UTC)...HOW?

6. 6 Major Topographic Features to Consider

7. 7 Proposed Modification to the Multi-scale Conceptual Model of Alberta Thunderstorms to account for dryline initiation of storms.

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9. 9 Surface Transect across Dryline

10. 10 GPS Precipitable Water Trend on 20 July 2003 Storm peak moves by ~ 2200Z Earliest radar echoes 2030Z 1730Z

11. 11 How important is local evapotranspiration to storm formation? - Some background for this from a study of moisture contrast between prairie grass and a wheat field in St. Denis, SK, July-August, 1992 (previously unpublished data). St. Denis, SK Fieldsite, July-August, 1992

12. 12 St. Denis, SK Crop/Grass ET Field Tests, July-Aug., 1992 (18-day average for each half hour) - after Hrynkiw & Strong (1992) - grass - transition - wheat

13. 13 Conclusions/Recommendations for UNSTABLE: 1.Preceding (6-18 hours) synoptic conditions. 2.What’s going on between scales? 2a) Everyone: Documented cloud photography and manual observations!! 3) Document mesoscale conditions over foothills 2-6 hours preceding storm initiation. 4) Note foothills topography. 5) Need high temporal resolution soundings (2-hour intervals recommended during morning); tethered balloons and/or instrumented towers (100-m) would be great assets. 6) Document storm initiation & life cycle (radar/satellite). 7) Mobile surface transects deep into the foothills (late morning and mid-afternoon). 8) High spatial/temporal resolution GPS PW data, concentrate on -4 to +2 hours of storm initiation. 9) Need reliable soil moisture (and ET) data in major soil zones regions. Analyses: 1.Precedent synoptic conditions, 6-18 hours. 2.Precedent mesoscale conditions, 2-6 hours. 3.Everything for storm initiation period (-1 to + hours)! 4.Storm-scale (meso-gamma) for storm life cycle. 5.Diurnal trends in all variables.

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15. 15 UNSTABLE Proposal to CFCAS, Feb 2002 - To investigate synoptic to micro-scale interactions with thunderstorms at three interfaces as indicated, - Focus on the pre-storm to storm initiation periods.

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17. 17 Sundre (WAV) (Skew-T) Soundings 20 July 03 at 1530Z & 2352Z Precipitable Water 1530Z - 19.9 mm 2352Z - 20.9 mm EA3 18Z - 15.9 mm EA2 00Z - 15.7 mm EF4 12Z - 15.6 mm EF4 17Z - 16.2 mm

18. 18 Analyses of surface MIXING RATIO

19. 19 - after Strong (2005) Climatological Trend of Mixing Ratio (YXD, YXE, YWG)