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Tuesday Morning video forecast
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After a warm afternoon, more severe storms and heavy rain will give way to a significant early May cool down.
THE FORECAST:
Today and Tonight: Another pleasant, but milder afternoon is expected with sunshine stretching high temperatures into the mid 80s. The U.V. Index (11) will be extreme, so be sure to wear sunscreen, a hat and sunglasses if spending time outside. Tonight, some clouds will return as a southerly breeze keeps low temperatures in the low 60s.
The National Weather Service has confirmed that TWO tornadoes occurred in the WBRZ Weather forecast area on Sunday. An EF1 damaged a church and mobile in Livonia while an EF0 produced 70mph winds in Zachary.
Up Next: Wednesday afternoon and evening will bring more rain and storms to the area. During the first part of the event, likely midday through afternoon, there will a possibility of severe weather. At this time, tornadoes are the main concern. Into the evening, a squall line will approach the area which could bring damaging wind gusts and heavy rain—on the order of 2-3 inches. Given the 2-4 inches that fell last weekend, there could be some runoff issues—so we will be monitoring that. Rain will wrap up by dawn on Thursday. As a reminder, review your severe weather plan and monitor the forecast. Stick with the WBRZ Weather Team on Facebook and Twitter and catch forecast on WBRZ News 2 for updates through the day. Additionally, the *free* WBRZ WX App. sends push notifications to mobile devices if a watch or warning is issued for your location.
The cold front responsible for active weather will cool the area considerably. In fact, some places in the forecast area could reach the upper 40s by Friday night! Into the weekend, weather is looking just about perfect for outdoor plans with sunny skies, cooler than average temperatures and low humidity.
THE SCIENCE: As a surface high system pushes to the east today, a shallow cold pool will also depart resulting in a return to more seasonable highs in the middle 80s. Conditions will begin to rapidly transition tonight as a fast moving, upper level shortwave moves into Texas. Increasing positive vorticity advection and forcing over a broad baroclinic zone in the western Gulf will result in the formation of a warm front. Mid-level winds will also increase through the night with a 30 to 35 knot low level jet developing by daybreak Wednesday over the western Gulf and southwest Louisiana. Low level moisture convergence will take place along the warm front, causing scattered showers and isolated thunderstorms to begin forming after midnight just west of the forecast area. Wednesday should be increasingly unsettled as more favorable jet dynamics form over the Gulf South and the warm front surges inland into the WBRZ Weather forecast area. A 75 to 80 knot jet streak should develop over Mississippi and Alabama placing the forecast area in a favorable region of enhanced upper level forcing during the afternoon and evening hours. Additionally, a 40 to 50 knot low level jet should be over the area in the afternoon and early evening hours. The warm front should be draped in a northwest to southeast orientation extending from near Baton Rouge through New Orleans in the afternoon and evening hours. After reviewing model soundings for the area, there is a window for strong to severe thunderstorms to affect areas near the warm front during the afternoon and evening hours on Wednesday. Conditions turn less favorable north of the front across Southwest Mississippi and the Gulf Coast where any convection should remain elevated due to a stable layer existing near the surface. Storm relative helicity values should exceed 300-400m2/s2 in the vicinity of the front. Ample instability is also noted with CAPE values of 1000 to 1500 J/KG noted near the warm front. These parameters would support the development of some supercell thunderstorms capable of producing strong damaging winds, tornadoes, and hail. During the overnight hours of Wednesday night, the impacts associated with the warm front should dissipate as a deepening longwave trough digs into the Mississippi Valley driving a cold front toward the forecast area. The wind field should become less favorable for tornadic development as a line of thunderstorms in advance of the front rolls through the forecast area before daybreak on Thursday. However, decent speed shear and near unidirectional winds throughout the column could support a continued damaging wind threat through the overnight hours. The other concern will be locally heavy rainfall throughout the event Wednesday and Wednesday night. Storm total rainfall could exceed 3 inches in a few spots. Temperatures will begin to cool quickly after the front moves through, and expect to see lows dip into the lower to middle 50s over northwest portions of the forecast area by daybreak on Thursday. Once the system clears the coastal waters Thursday morning, conditions will become very benign for the upcoming weekend. A deep layer northwest flow will set up on Thursday and remain in place through Sunday. Strong negative vorticity advection and subsidence throughout the atmosphere will keep skies clear. The northwest flow pattern will also allow for a deep layer cold pool to move into the area on Thursday and Friday. Daytime highs should only rise into the lower 70s on Thursday and the middle 70s on Friday. Under clear skies, overnight lows will easily dip into the 40s and 50s each night. These readings are well below average. Some moderation in temperatures is expected for Saturday and Sunday as the cold pool shifts farther to the east and some weak southerly flow develops in the low levels. However, temperatures should remain cooler than normal with highs only rising to near 80 degrees. Lows will cool into the 50s and lower 60s Saturday and Sunday night.
--Josh
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