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Of Capping Lids , Drylines , and Alberta Thunderstorms* * and Support to UNSTABLE

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.

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Of Capping Lids , Drylines , and Alberta Thunderstorms* * and Support to UNSTABLE

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  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 All things are connected like the blood which unites one family. Chief Seattle, 1854. A developing storm over Rocky Mountain House, 16 July 2003

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

  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?) • What’s going on between the synoptic • and meso-γ scales?

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

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

  6. Major Topographic Features to Consider

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

  8. Surface Transect across Dryline

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

  10. 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study of moisture contrast between • prairie grass and a wheat field in St. Denis, SK, July-August, 1992 • (previously unpublished data).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

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

  12. Conclusions/Recommendations for UNSTABLE: • Preceding (6-18 hours) synoptic conditions. • 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: • Precedent synoptic conditions, 6-18 hours. • Precedent mesoscale conditions, 2-6 hours. • Everything for storm initiation period (-1 to + hours)! • Storm-scale (meso-gamma) for storm life cycle. • Diurnal trends in all variables.

  13. 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.

  14. Sundre (WAV) (Skew-T) Soundings 20 July 03 at1530Z &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

  15. Analyses of surface MIXING RATIO

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

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