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 0-3 km storm relative helicity.

 

Thumbnail of an automatically generated image showing areas of 0-3 km storm relative helicity. Thumbnail of an automatically generated image showing areas of 0-3 km storm relative helicity. Thumbnail of an automatically generated image showing areas of 0-3 km storm relative helicity.
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Helicity (0-3 Km) 

This is the 0-3 km (0-10,000 Ft. AGL) storm relative helicity which is a measure of the amount of wind shear available from the ground to roughly 700 MB.   Values greater than 250 m**2/s**2 suggest an increased threat of tornadoes, but high values with this index do not necessarily suggest that the environment is supportive of supercell structures (look at 0-6 km shear).  Larger values are generally better, but there are no clear "boundaries" between non-tornadic and significant tornadic supercells.  Negative values suggest that anti-cylonic (left moving) supercells will dominate.

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