A large and vigorous storm system will bring rain and potentially severe thunderstorms to the Baton Rouge area on Thursday Afternoon and Evening before strengthening into a powerful Nor’Easter in the Mid-Atlantic on Friday and Saturday.

Today and Tonight: Thursday will be mostly cloudy and mild with high temperature approaching 70 degrees. Rain and thunderstorms are expected to develop by the afternoon hours, with the possibility of a few storms becoming severe. All severe weather hazards are on the table with conditions favorable for gusty wind, large hail and isolated tornadoes. Storms will quickly taper beyond a squall line which will cross the area this evening. Have a way to access alerts through the day, should they be issued. Overnight, temperatures will turn sharply colder as winds turn northwesterly. Lows will end up in the mid 40s.

Up Next: Friday will be wintry by local standards. Overcast skies may persist throughout the day as cold air continues to seep into the Gulf South. Temperatures will struggle to leave the 40s. Winds will be stiff out of the north at 15-25mph. The cloud cover, wind combination will keep “feels-like” temperatures or wind chills in the 30s through the day. There may even be some lingering drizzle. By the weekend, skies will go all clear, with freezing morning thermometers returning to the 50s during the afternoon.

THE SCIENCE: 

Forecast Discussion: An impressive upper wave and associated surface storm have organized over Texas. This energy will translate eastward through the sub-tropical jet stream today placing much of the Central Gulf Coast in the warm sector. Showers and thunderstorms will become more widespread as the day progresses, with much of the action occurring in the afternoon and evening hours. A strong upper jet stream, a dry pocket in the mid-levels and high helicity values due to veering low level winds will be supportive of rotating thunderstorms and gusty wind mixing down to the surface. However, the same elephant remains in the room for our “wintertime” severe weather setup—instability. The northward extent of a moisture plume from the Gulf of Mexico and any early day insolation will have a significant impact on the ability of storms to strengthen. A deep trough crossing the Southern U.S. will be pushing eastward, cooling temperatures aloft and steepening lapse rates. The sooner this occurs, the more readily storms will strengthen. The Storm Prediction Center has placed our region under an “enhanced risk” for severe weather given that forecast models ARE projecting instability to increase this afternoon with CAPE values in the 1,000-1,500 j/kg range and helicity values around 350. The environment will be supportive of cellular and clustered thunderstorms, the former of which should have the ability to rotate. Alas, as the front nears, a squall line will push through during the evening. For this reason, all types of severe weather are possible including damaging wind gusts, hail and tornadoes. Conditions will become clearer as the day evolves, so have forecast information and alerts available should they become necessary. Rain will wrap up from west to east over night with cold air advection quickly underway. By Friday Morning, a deepening surface low to the east and strong surface high to the north will increase chilly north winds into the 20mph range. Daytime temperatures will struggle to reach the upper 40s with wind chills in the 30s. It would not be surprising if wind advisories are needed. Beneath overcast skies created by the lagging upper trough, a few sprinkles may fall as well. By Saturday Morning, surface high pressure moving into the Upper Mississippi River Valley will help to clear the region out, but maintain the chill. Freezes appear likely north of I-10 on Saturday and Sunday Morning. As the high shifts east, southerly flow will allow Sunday Afternoon temperatures to return to average. A weaker storm system will return showers on Monday Evening.

Meteorologist Josh Eachus provides an in-depth analysis of the severe weather threat along the Gulf Coast on Thursday, plus the signficant snow event pegged for the Mid-Atlantic this weekend, CLICK HERE or see below to watch.

 --Josh

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