Severe Weather Risk 1/2/2017

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As we start the new year, the severe weather risk will be increasing. New Year’s Day will feature a risk back in Texas. For this particular post, we will be focusing on the risk for Monday across much of Louisiana, Mississippi, and the adjacent states.

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One of the first things we look at for a severe risk is the quality of moisture available. Dewpoints shown here Monday evening are forecast to rise well into the 60s. This will be especially true down in southeast Texas, along with southern portions of Louisiana, Mississippi, and Alabama.

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When one normally looks at the Surface Based Convective Available Potential Energy (SBCAPE), they may think it does not look overly impressive. However, since we are in the Winter season, it does not take much to do so. The higher SBCAPE values (greens and yellows) are located in the areas included in the slight risk for Monday.

The crossover map indicates in general the wind direction at the surface, 850 mb (5,000 feet above ground level), and 500 mb (18,000 feet above ground level). Surface winds are generally south to southeast. The winds at 850 mb  and 500 mb are more to the southwest. That indicates potential for rotation in any severe thunderstorm that does develop.

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While not overly impressive, the amount of wind shown here (surface, 850 mb, 500 mb) will be more than sufficient for any severe thunderstorm to tap into.

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The amounts of 1km helicity (100 units or more) and 3km helicity (250 units or more) for Monday evening are forecast to be more than sufficient for updrafts to become sustained in any severe thunderstorm that does develop. Areas at higher risk look to be down along the Gulf Coast in Louisiana, Mississippi, and Alabama.

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While the amounts of shear in the lower 1km to 6km for Monday evening, the amounts look to be more than sufficient for any severe thunderstorm to develop supercell characteristics.

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The Vorticity Generation Parameter indicates where the best tornado potential will be for a certain location. Areas in the yellows, oranges, and reds along the Gulf Coast in Louisiana, Mississippi, and Alabama indicate that the highest tornado potential looks to be located along that region.

However, all of the areas in the slight risk will be running the risk for possible tornado activity. Also, damaging straight-line winds will be a risk. While the hail risk will not be particularly high, some reports of large hail are a distinct possibility. We will continue to monitor the situation for you in the next couple of days. Stay tuned.

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