Tuesday, May 10, 2011

May 10 Risk of Severe Weather

Today's overall risk
There is expected to be a slight risk for storms today and tonight in portions of the country. In the Appalachians, warming temperatures and a weather disturbance should ignite the original storms around noon with very scattered coverage but begin to increase around 3 pm in coverage and intensity. The moderate/strong instability in the atmosphere, as proven by a 0z sounding indicating 3000 j/kg of CAPE forecast, will provide breeding grounds for storms. The environment, while it may be supportive of supercells with a primary hail threat, locally enhanced instability may boost the tornado threat and hail size potential. A wind threat is also possible should line segment storms develop. At this point, models aren't handling this solution with a grip, but the GFS has been noted as aggressive.

In the Plains and Upper MS Valley, strong mid level jet stream of up to 70 knots will pump warm air into the region, setting the stage for instability. Storm initiation is expected late this afternoon, around 4 pm CDT, with the storms actually firing up into 5 pm. With potential CAPE values into the 4500 j/kg marks, a large hail threat is expected with supercellular storms that may initiate. This threat is more likely should a storm cluster continue through the evening, when the low level flow is expected to strengthen.

Finally, in Texas, strong low level flow and instability will collide with a high amplitude, upper level trough in the region. Storm initiation can be expected on the eastern portion of the mid level jet stream. This jet stream will create moderate shear, which, combined with the factors above, will become favorable for supercells. A large hail threat is possible. The models indicate convection should be somewhat isolated, and the SPC has decided to delineate only a narrow portion of Texas.

Threat of Hail

Threat of Tornado

Threat of damaging winds

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