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Super Cells

Super Cells. The Granddaddy of them all. Textbook Definition Of A Supercell. A thunderstorm with a deep persistent mesocyclone (rotating updraft). Creating a Rotating Updraft. Directional Shear. Speed Shear. Updraft. What Makes Supercells So Unique?.

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Super Cells

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  1. Super Cells The Granddaddy of them all

  2. Textbook Definition Of A Supercell A thunderstorm with a deep persistent mesocyclone (rotating updraft)

  3. Creating a Rotating Updraft Directional Shear Speed Shear Updraft

  4. What Makes Supercells So Unique? • Rotation significantly enhances the vertical velocity of the updraft. • Updrafts become stronger (show more intense upward motion) and are more persistent after they begin to rotate. • Stronger updrafts transport more water and ice mass upward, potentially leading to larger hailstones, strong, damaging downdrafts and tornadoes. • About 90% of supercells produce severe weather • About 15% of supercells produce a tornado

  5. Thunderstorm Structure

  6. Updrafts And Downdrafts • Supercell strength depends on the intensity of the updrafts and downdrafts motion Strong Updrafts And Strong Downdrafts Lead to active weather Rain Free Base Primary “Action Area”

  7. Supercell Updrafts • “back side” of storm • Towering clouds • Rain free base • Upward cloud motion

  8. Supercell Downdrafts • “Front side” of storm • Dark area of storm • Rainfall region • Downward motion • Rain/Hail threat

  9. Real World Example Looking NW ANVIL MAMMATUS UPDRAFT TOWER DOWNDRAFT Hail & Rain FLANKING LINE “ACTION AREA”

  10. Rear Flank Down Draft Strong Downward Winds – sometimes cause dust whirls Form “clear slot” often in the shape of a horseshoe

  11. From A Spotters Perspective Heavy Rain and Hail Mesocyclone Wall Cloud Wrapped in Rain RFD

  12. Pop Quiz! ? ? ? Rain Free Base Wall Cloud / Updraft Area ? Downdraft Area Hail & Rain Tornado

  13. Supercell Types

  14. The Ideal Spotter Position View from the north obscured by rain and hail. Radar image of a tornadic storm. Bird’s-Eye View Where should a spotter be positioned? Possible tornado at tip of “hook echo”.

  15. The Ideal Spotter Position If you’re lucky, you might see this – but you need to be very close View from southwest obscured by hook and strong RFD winds.

  16. The Ideal Spotter Position View from southeast offers unobstructed and safe look at the storm as it moves left to right.

  17. In General, For Proper Positioning • You need to be able to see the updraft area of the storm • This is the action area • Severe weather most likely here • Find the updraft region • SQUALL LINE – leading edge (worst first) • SUPERCELL – back edge (worst last)

  18. What You Might See:Wall Cloud • Isolated lowering of the cloud base • Attached to the cloud base • May or may not rotate • May see upward cloud motions • May slope down toward the rain area • Always Follows the Rain

  19. More On Wall Clouds • Many storms produce wall clouds • Most do NOT produce tornados • Key: Identify dangerous wall clouds • Watch all clouds for danger signs • Report and monitor DOWNDRAFT Rain Rain INFLOW

  20. Dangerous Wall Clouds • Look for… • …organized, sustained and persistent rotation • …clouds moving inward and upward • …strong surface inflow

  21. Wall Clouds Shelf Clouds • Abrupt or “blocky” lowering • Linear feature • Associated with storm’s inflow • Associated with storm’s outflow • Sometimes has a tail that points to the precipitation • Slope away from precipitation • Move along with the rain area • Separate from the rain area • Never produce tornadoes • Sometimes produce tornadoes

  22. Rain “Foot” Gives appearance of a foot Indicates strong winds • Results from strong downward winds • Rain slams into ground and spreads outwards

  23. Funnel Clouds A rotating, funnel-shaped cloud extending downward from a thunderstorm base.

  24. Funnel Clouds • Usually located near the updraft & within or along the edge of the wall cloud • Attached to cloud base • Exhibit rapid rotation • Often laminar or smooth in appearance • Circulation does not reach ground

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