National Weather Service United States Department of Commerce

Snow in the Rockies; Showers and Thunderstorms Along the Gulf Coast; Potential Winter Storm for Northern Mid-Atlantic and Interior New England

A winter-like pattern will continue over much of the Lower 48 over the next few days, with snow stretching from the Rockies today into the Middle Mississippi Valley on Monday. Showers and thunderstorms will develop along the Gulf Coast and Southeast on Monday. As the storm moves northward late Monday into Tuesday, winter weather is possible from the Central Appalachians to Interior New England. 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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