Thursday, March 25, 2010

Thunderstorms in Lower MS,TS valley.

Akshay Deoras
Extreme Weather Forecaster

Concerning- Slight risk of thunderstorms
The present RUC models are indicating a cut off trough spining with the root over EAST TX,AK,LA. This cut off trough with the upper level jets of 100kt is likely to shift E-NE WRDS later this afternoon and will reside over MS and TS valley. 30-40kt jets at the low level just below this low will transfer moisture but as the Gulf of Mexico seems to be cooler, it will not be able to bring sufficient moisture. Instability too will move E-NE wds with the Lows and at the 1hr+ low level shears will develop to the very east of the trough and the cold front mainly over MS valley and to the north of it. Some areas will get 500m2 s2 shears. Its for sure a cold core setup as the dewpoints are fair 50F throughout the action. Within the next 2-3 hours, the lows will sweep towards low LA coast and some lows will develop over MS and TS valley. By 7-9hrs, the low level jets will get converted to strong one of 40kt jets.
By that time, the low level shear will be modified to 200m2 s2 but it will be over Albama and other regions but the low level jets shall just reach upper MS and lower TS valley reducing the rotations of thunderstorms. With just 60F temp over land during day, the atmosphere shall not destablise that much required for severe thunderstorms.By the 9th hr, the instability shall just be 750J/kg in MS and TS valley which for surely are alerted for 2% risk of tornadoes. The risk of Hails is 15% due to cold aloft at 700mb. The risk for hails will be Upper MS,ALbama and lower central TS during this time. High winds too are possible in this region but I shall say overall a dud system as the threat is too low leading to lower probabilities.
Hails and winds will be prominent with absolute limited threat for tornadoes from the scattered T.storm
Another low will sweep through weekend
Stay tuned for that one!!

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