Early week pleasant before more rain, strong cold front
A front has moved through, winds have subsided and seasonable weather is on tap for the first two days of May. More rain, possibly heavy, is pegged for mid-week.
Today and Tonight: Your Monday will feature pleasant weather. With a front through to the east, cooler and drier air has taken hold with high temperatures stopping near 80 degrees. Abundant sunshine is expected through the day. The U.V. Index will be maxed out today, so be sure to wear sunscreen, a hat and sunglasses if spending time outside. Tonight will be clear and quiet with lows near 56 degrees.
Sunday, the entire area received rain, as expected. About 2-4 inches fell with maximum amounts in northern East Baton Rouge Parish and West Baton Rouge Parish. Parts of St. Mary Parish only picked up about an inch.
Up Next: Some humidity will creep back late Tuesday, but likely not to the levels reached over the weekend. By Wednesday evening, more rain and storms will arrive. Right now, the threat for severe weather doesn't look too great, but an additional 2-3 inches of rain may fall, which given Sunday’s precipitation, could create some flooding issues. The cold front responsible for this 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, the weather is looking outstanding for outdoor plans with sunny skies, cooler than average temperatures and low humidity.
Per the Climate Prediciton Center, the month of May will feature above average temperatures in the west with below avergae temperatures in the Ohio Valley. Southeast Louisiana and Southwest Mississippi will find thermometers averaging out near normal. For perspective, normal in early May means highs in the low 80s and lows in the low 60s and by late May highs should be in the upper 80s with lows in the upper 60s.
THE SCIENCE: The combination of largely zonal flow in the mid and upper levels along with a strong ridge of high pressure in the low levels will keep a relatively dry and stable airmass in place across the forecast area both today and tomorrow. As the high pushes to the east tomorrow the weak cold pool will also depart resulting in a return to more seasonable highs in the middle 80s. Conditions will begin to rapidly transition tomorrow night as a fast moving shortwave feature ejects out of the Four Corners region and slides 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 flow will also increase noticeably through the night, and expect to see a 30 to 35 knot low level jet develop by daybreak on Wednesday over the western Gulf and southwest Louisiana. Low level moisture convergence will take place along the warm front, and expect to see scattered showers and isolated thunderstorms begin forming after midnight just west of the forecast area. Our area will remain on the more stable side of the boundary tomorrow night and temperatures should cool into the upper 50s and lower 60s. Wednesday should be increasingly unsettled as more favorable jet dynamics form over the Gulf South and the warm front surges inland into the 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. It looks like the front should be draped in a northwest to southeast orientation extending from near Baton Rouge through the New Orleans area in the afternoon and evening hours. After reviewing model soundings for the area, there is a window for some possibly 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 MS Gulf coast where any convection should remain elevated due to a stable layer existing near the surface. Storm relative helicity values should exceed 300m2/s2 in the vicinity of the front, and overall bulk shear in the lowest 6km should be over 55 knots. Ample instability is also noted with MLCAPE 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 regime will set up on Thursday and remain in place through Sunday. Strong negative vorticity advection and subsidence throughout the atmospheric column will keep skies clear. The northwest flow pattern will also allow for a deep layer cold pool to advect 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.