National Weather Service United States Department of Commerce

Lala Impacting Hawaii; Severe Thunderstorm and Flash Flooding Risks; Excessive Heat

Areas of gusty winds, heavy rain leading to flash flooding, and high surf continue across portions of Hawaii as Tropical Storm Lala continues to move away from the islands. Severe thunderstorm, heavy rainfall, and flash flooding threats continue from the Midwest to the Mid-Atlantic and across the central High Plains. Record heat continues for areas of the central/southern Plain into the Southeast Read More >

Automatically generated image showing areas of storm relative helicity.

 

Thumbnail of an automatically generated image showing areas of storm relative helicity. Thumbnail of an automatically generated image showing areas of storm relative helicity. Thumbnail of an automatically generated image showing areas of storm relative helicity.
Hour - 1 Hour - 2 Hour -3

4 Panel Display | Animated Loop

Helicity (0-1 Km) 

This is the 0-1 km (approximately 0-3,000 Ft. AGL) storm relative helicity which is a measure of the amount of low level wind shear available for tornadogenesis. This is not a good indicator of supercell potential which is related more strongly to 0-6 KM vertical shear. Values greater than 100 m**2/s**2, do suggest an increased threat of tornadoes provided a supercell is present.  Larger values are generally better, but there are no clear "boundaries" between non-tornadic and significant tornadic supercells.

The arrows indicate the approximate right supercell storm motion using the Bunkers technique.

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