Downpours, severe weather possible Thursday
One more sunny afternoon is ahead. The dry spell will end Thursday, as a strong storm system comes into the area.
Today and Tonight: Winds will shift southeasterly on Wednesday allowing some moisture and warmer temperatures to sneak back into the atmosphere. All the while, cirrus clouds will overtake mostly sunny skies as highs sneak into the 70s. Overnight, clouds will thicken and thermometers will stop in the low 60s. Showers and thunderstorms may develop as early as daybreak.
Up Next: On Thursday, rain is likely and some ingredients will be present to support downpours and strong thunderstorms as well. Conditions looks supportive for all types of severe weather should any storms reach those levels. While the window for severe weather appears small and confined to midday, a longer duration of rain could spell 1-3” across the area. While it has been dry lately, runoff may not be an issue, but as you know, a lot at once could lead to street and poor drainage flooding.
Stay tuned as our team tracks the storms. After arrival, this system will stall, keeping showers in the forecast through Saturday until the next front comes into play later in the weekend. Highs in the 80s look likely Saturday, and for most of next week.
With spring beginning, we get the unfriendly, sneezing reminder that pollen season is upon us. You can get an updated allergy report each weekday morning on 2une In and every day from the WBRZ Weather Facebook and Twitter pages.
The Mississippi River: At Baton Rouge, major flood stage continues with a level of 42.8’ as of Wednesday morning. Peaking at 44.1’ on March 19, the river set its 7th highest recorded crest at Baton Rouge. In addition, at 88 days this is now the 4th longest period above flood stage. Due to river flooding and drainage north of the area, runoff will keep the river high for many days to come. The high water is primarily an issue for river traffic and river islands, although some inundation will continue unprotected low-lying areas. The grounds of the older part of Louisiana State University's campus become soggy. This includes the area around the Veterinary Medicine building, the Veterinary Medicine Annex, the stadium and ball fields. The city of Baton Rouge and the main LSU campus are protected by levees up to 47 feet. Some seepage may be noted due to the long duration of high water placing pressure on the levees. Water from the extensive Missouri River flooding across the Upper Midwest will not reach Baton Rouge until April and the Mississippi River is expected to have fallen some by that time. As some of the Mississippi River diverts into the Atchafalaya River, gauges at Krotz Springs and Morgan City will stay high as well. Like Big Muddy, this is expected to be a prolonged event but is not uncommon for the time of year. Read more HERE.
By Wednesday afternoon, a surface high will shift east and onshore flow will commence. Moisture will build ahead of a storm system set to enter the region on Thursday. At the surface, a warm front will lift through the area on Thursday morning. An upper level region of positive vorticity advection will accompany this boundary leading to widespread development of rain and thunderstorms. Overall, it looks like a rather messy presentation on radar per high-resolution forecast models. First, just enough instability and spin will be available to support severe thunderstorms, especially north of I-10. At this time, unidirectional low to mid-level winds would be supportive of a cluster of storms. The Storm Prediction Center has outlined areas northwest of Baton Rouge in a 2 out of 5 “slight risk” for severe weather. The atmosphere will be capable of supporting storms with gusty wind, hail and a tornado. The overlap of favorable instability and shear appears to be for a short time. Once daytime warming begins to aid instability, wind shear and the upper level vorticity will be departing to the northeast. Therefore, late Thursday morning into early afternoon, will be the most likely time for strong storms. By the time the cold front arrives late Thursday, much of the atmosphere will have been worked over enough to limit the threat for severe storms. Second, above average moisture content in steady onshore flow will lead to a longer duration of high rain chances.1-3 inches of precipitation is likely across the area on Thursday. The front will stall along the coast, leaving the possibility of showers around on Friday and Saturday. The decaying boundary will need assistance from weak, upper level disturbances to set off rounds of showers, so washouts are not in the cards those days, but shower dodging will be. Another upper trough and cold front will follow over the weekend brining rain chances back up by Sunday into Monday. Even after the next cold front passes Monday, temperatures will simply ease back to seasonal averages in the upper 70s and mid 50s. Plenty of 80s appear to be in store for the latter half of the 7-Day forecast and beyond.
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