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Large hail is not a killer, but does considerable damage

Hail. Large hail is not a killer, but does considerable damage. Falling from 20,000 feet or higher, large hailstones pack quite a punch!. Large hail does significant damage to cars . Terminal Fall Velocity. Average annual number of days with hail.

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Large hail is not a killer, but does considerable damage

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  1. Hail Large hail is not a killer, but does considerable damage

  2. Falling from 20,000 feet or higher, large hailstones pack quite a punch!

  3. Large hail does significant damage to cars.

  4. Terminal Fall Velocity

  5. Average annual number of days with hail

  6. This is the biggest hailstone known. It fell at a town called Aurora, NE on June 22, 2003.

  7. The Aurora hailstone was 7 inches in diameter. Imagine that falling on your head from 20,000 feet up!

  8. This is the previous record-holder, the Coffeyville hailstone with some props (egg, hand) for comparison.

  9. The Coffeyville hailstone cut into sections. Notice the layers This stone fell on Coffeyville, KS on Sept 3, 1970.

  10. The rings are caused by different growth regimes. Clear ice is deposited slowly and contains few air bubbles. Cloudy ice occurswhen water freezes quickly, trapping the air bubbles.

  11. Hail is often categorized by its size in relation to everyday objects

  12. Marble Sizes of hail and the everyday objects used as adjectives (e.g., baseball-sized hail is 2.75” in diameter)

  13. Oneonta hail, June 15, 2009. This is marble-sized

  14. Those are small pine cones for comparison.

  15. A schematic supercell radar echo with a hook echo. Tornadic thunderstorms often also have large hail. The hailfall area is close to the tornado.

  16. Ingredients for Hail Growth • In a basic sense, 3 Main “ingredients” are required: • 1. Adequate updraft to keep hailstone aloft for an appropriate amount of time, -10 to -30C • 2. Sufficient supercooled water near the hailstone to enable growth during transit through an updraft • 3. A piece of ice or snow (embryo) for it to grow upon

  17. Vertical cross section of a supercell hailstorm.

  18. Forecasting Hail • Deep, Moist Convection (DMC) has 3 Ingredients: • Sufficiently deep low level moisture • Steep lapse rates (related to instability) • Sufficient lifting from LCL to LFC  Once DMC identified as possibility, look for hail signal

  19. Hail Ingredients Provided DMC Possible • Strong updrafts necessary but not sufficient •  High CAPE in hail growth zones

  20. Hail Ingredients Provided DMC Possible 2.Storm scale winds: Speed/Direct-ional shear important

  21. Wet-bulb Zero (WBZ): This is the level where evaporative cooling reduces a parcel temperature to 0C. It correlates well with large hail when the altitude of the WBZ is between 2200 meters and 2800 meters. • If the WBZ is higher than 2800 meters, hailstones must fall through a large layer which is above 0C and usually do not reach the ground in frozen form. • If the WBZ is lower than 2200 meters, the lower atmosphere is relatively cold and stable so the large updrafts needed for hail formation don’t exist. • The exception to the above guidelines is when the ground level is significantly above sea level. That usually reduces the thickness of the low-level warm layer and hail becomes more common. This is the reason for the hail maximum in the High Plains and especially east of the Colorado Rockies. • Source: A World of Weather by Lee Grenci and Jon Nese (2001)

  22. Example of Skew-T Log P determination of WBZ

  23. WBZ 729 mb 2788m

  24. 184 hail reports, mostly in Missouri, 6 reports ≥ 2”,

  25. The general severe outlook certainly included Missouri The hail outlook was not maximized in the right region but it did include most of it.

  26. SHIP - Sig. Hail Parm. SHIP = MUCAPE * MUMR * 7-5LR * 500T* 0-6 SHR / Constant MUMR = Mixing Ratio of Most Unstable Parcel

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