National Weather Service United States Department of Commerce

East Coast Storm; Heavy Rain and Flooding in the Southwest U.S.; Typhoon Remnants Impacting Alaska

A coastal storm continues to bring heavy rain, coastal flooding, high surf, dangerous rip currents, and gusty winds to the East Coast into early Tuesday. A heavy rain and flash flood risk continues for the Southwest/Four Corners region with lingering tropical moisture through Monday. Typhoon remnants are causing strong winds, heavy rain, and coastal flooding across western Alaska through Monday. 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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