Severe storms likely along Central Gulf Coast Tuesday
A strong storm system advancing into Southeastern Louisiana and Southern Mississippi will generate showers and thunderstorms through Tuesday Afternoon.
Today and Tonight: Unseasonably warm and muggy air will be in place with high temperatures reaching for the low 70s by early afternoon. Skies will be mostly cloudy. Breaks of sunshine are possible but that will further destabilize an atmosphere already set up for severe weather. Southwesterly winds will continue to stiffen through the day—ramping up into the 15-25mph range. Showers and thunderstorms will increase in coverage during the late morning hours and any of the storms could quickly become severe. Isolated storms will be the issue at first, with storm cells organizing into a squall line during the mid-afternoon hours. Rain will end prior to dawn Wednesday with cooler air filtering into the region as winds turn northwesterly. Lows will end up in the upper 40s.
Bulletins: The National Weather Service Storm Prediction Center has much of the forecast area a “moderate risk” for severe weather meaning that there is a 45% chance of a severe weather hazard within 25 miles of any point in this risk area.
Threats: 1. Damaging Wind | 2. A Few Tornadoes | 3. Large Hail | 4. Downpours | 5. Frequent Lightning
Timing: Isolated storm cells may develop as early as 10am Tuesday Morning bringing the greatest threat for tornadoes. As the mode transitions into a squall line, damaging wind gusts will become the concern into Tuesday Afternoon. Therefore 10am - 6pm will be the MOST LIKELY period for severe weather. Rain will end from west to east prior to dawn Wednesday.
Actions: Be alert to rapid changes in weather, have access to bulletins through the WBRZ WX app., the WBRZ Cable Weather Channel, WBRZ Weather on Facebook and @WBRZweather on Twitter. With both the weather app. and Twitter, you can change your cellular phone settings to allow push notifications and alerts for updates from the WBRZ Weather team. PLEASE share information with those that do not have access to digital media sources. Share Facebook posts and retweet alerts from our weather team. Make a phone call to those without TV or internet. Any such step could be life saving. Secure loose outdoor objects. Move cars under covered areas where possible. Review storm safety plans with friends and family. Understand the difference between a watch and a warning. A watch means conditions could lead to the development of severe weather. A warning means severe weather is happening and you need to take action.
Additional Notes: A *WIND ADVISORY* is in effect until 6am Wednesday. Winds will be sustained at 15-25mph with gusts over 30mph.
Up Next: Clouds and possibly an isolated shower will linger on Wednesday. Temperatures will be noticeably cooler with high struggling to reach 60 degrees. Some sun may return late. Skies will continue clearing into Thursday with lows dipping into the upper 30s. Sunshine and highs in the low 60s are expected for afternoon. Friday will be a repeat.
Forecast Discussion: An upper trough will move a diverging 100+ knot jet streak over the region from Late Tuesday through Wednesday. A deepening shortwave trough at 500mb is cutting across the southern tier of the nation. The surface response is evident in a deep surface low developing along a stalled boundary through Central Texas. This surface low and the consequent cold front will whip through the region Tuesday Afternoon and Evening with the surface low near Nashville and the cold front east of Mobile by Wednesday Morning. Ahead of this front, the atmosphere is destabilizing with mild and moist air in place at the surface. Dew points are in the low 60s with ambient temperatures forecast to be in the low 70s. Any sunshine will provide additional warmth and instability. Forecast CAPE values are in the 1,000 range. These readings anticipated by the models could be passive given the sharply colder air pushing in aloft. These colder temperatures aloft will again bring the threat for hail to the area. Strong southwesterly surface winds will veer to even stronger westerly winds in the upper levels. Speed and directional shear will be robust with helicity values projected well over 400. Thus, any isolated storm cells will rotate with relative ease during the afternoon. With this noted, the tornado threat will be greatest during the late morning and early afternoon hours when wind shear is maximized. With the surface front approaching from the west, storm mode will transition to linear during the afternoon hours and then threats would focus around damaging wind gusts mixing down to the surface. Rain will end from west to east on Tuesday Night as the cold front translates east. Cooler air will spill in as winds turn northwesterly. Clouds will slowly break on Wednesday as a lagging trough axis may trap some moisture at the surface. By Wednesday Night, high pressure in the Midwest will take hold of the area, moving to the Central Gulf Coats by Friday and staying in place through Saturday. With cold air advection ongoing from Wednesday Morning to Friday Night, temperatures will be below average with morning lows in the upper 30s and highs in the low 60s.