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Advanced Shallow Weather and Orographic

Advanced Shallow Weather and Orographic. Boundaries. Thunderstorm Outflows Lake Breezes. Gust Fronts. Very shallow feature, emanate from a thunderstorm. Recall the depth-detection discussion. Reflectivity “thin lines”. Arc of blowing dust. Example of Boundary in Reflectivity -10 to 20 dBZ.

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Advanced Shallow Weather and Orographic

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  1. Advanced Shallow Weather and Orographic

  2. Boundaries Thunderstorm Outflows Lake Breezes

  3. Gust Fronts Very shallow feature, emanate from a thunderstorm. Recall the depth-detection discussion. Reflectivity “thin lines” Arc of blowing dust

  4. Example of Boundary in Reflectivity-10 to 20 dBZ

  5. Rapid Storm Evolution (Time lapse < 5 hours) Animation 120 km

  6. Movie Loop Showing Cold Front, Gravity Wave and Dry Line Interactions International H20 Water Vapor Project (IHOP) May 11, 2002

  7. Gravity Waves International H20 Water Vapor Project (IHOP) May 11, 2002

  8. Drizzle

  9. A Typical Z – RBeijing Summer

  10. Reflectivity and DrizzleBeijing Summer

  11. How to remember beamheight numbers? Aside

  12. S = r θ s θ r • 1o = 180/pi = 0.0175 radians • At r=100 km then s = 100 * 0.0175 • S = 1.75km = beamwidth at 100km • For flat Earth, for beam at 1o elevation angle, height of beam centre ~= 1.75km H = sqrt ( r^2 + 2*Ke*ae*r + sin ( theta_e ) ) – ke * ae

  13. Beam Height Diagram

  14. What is the approximate Height / Width the Beam Arc distance = r theta 1 deg = 180 / pi = 0.01745329

  15. Forest Fires

  16. Kelowna Forest Fires

  17. Nocturnal bird migration looks like drizzle

  18. Insect migration and Cb

  19. Pat King and Dave Sills Lake Breezes and Tornados

  20. Lake Breeze Boundaries Lake Huron Lake Ontario Lake St Clair Lake Erie Mid Afternoon “Pure” LB example Enhance convergence Morning

  21. Lake Breezes + + = Pure lake breeze Moderate SW Flow

  22. Average of 6 VIS Images from 1500-1800 UTC

  23. Spring (15 Mar - 15 Jun) Tornado Touchdown Points Confirmed and probable only

  24. Spring (15 Mar - 15 Jun) Tornado Touchdown Points … overlaid with boundaries from 31 July 1994 ... Forecasters use knowledge of lake breeze positions in their severe weather forecast for weak tornadoes … tornadoes are suppressed in regions where Southwest winds are onshore ... … and enhanced in regions where lake breeze boundaries often form.

  25. Lee Side Troughing On a very small terrain feature

  26. Topography of Southern Ontario Georgian Bay Lake Huron Lake Ontario Southern Ontario is relatively flat. Elevations rise from about 200m on Lake Huron to about 400m just south of Georgian Bay. Lake Erie

  27. Dissipation of Clouds in a SW Flow Moderate WSW flow Dissipation of thin SC cloud in downslope flow SC cloud forming beneath an inversion at 1500 m above ground Topography of Southern Ontario Average of six GOES images over a 3-hour period

  28. Niagara Escarpment Topography of Southern Ontario Average of six GOES images over a 3-hour period

  29. 20 February, 2008 2008 NWA Conference - Louisville, KYSam Lashley – National Weather Service Northern IndianaJon Hitchcock – National Weather Service Buffalo, NY

  30. Mountain Top Radars Show Rodger Brown Paper graphs

  31. Negative Elevation Scans Show DEM and the one degree beam Show negative elevation angle Discuss caveats – need gc filtering Need 3dB filling Show

  32. Scanning in Complex TerrainValley Radars Show the v10 radar DEM and discuss with respect the weather NOT surveillance

  33. Radar Detection Issues CAPPI (too high) 0o PPI

  34. Lake Breezes and Convection Initiation/Suppression • Review the wilson boundary rules/Aurora did a poster on this • Show Pat King Lake Breeze and Prevailing Wind Analysis • Show Pat King Tornado climatology and Lake Breezes • Show AF358 or another case

  35. Lake Effect Snow Bands Show the EGPM lake effect snow bands Show single bands Show multiple bands Show the convergence in the middle of the band Talk about TREC tracking

  36. Sea Spray

  37. Orographic Effects Precipitation Enhancement upslope condensation and development Precipitation Suppression lee side troughing Blocked flow Radar Blockage – can not see Explanation Impact of Froude Number

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