Posted: Mar 28, 2014 1:15 PM by Meteorologist Josh Eachus
A second round of showers and thunderstorms is expected to roll across Louisiana on Friday Night. The National Weather Service Storm Prediction Center continues to highlight the area for an increased risk of severe weather. The primary threats from the strongest storms will be large hail, damaging winds and heavy rains. At this time, though isolated thunderstorms may develop later in the afternoon, the greatest risk for organized and widespread showers and storms will occur between 9pm and 4am with drying and clearing through Saturday Morning.
METEOROLOGICAL DISCUSSION: A low pressure system along with an associated cold front and dry-line will approach Louisiana on Friday Evening. Ahead of the complex, some areas from Northeast Texas eastward to Western Mississippi have seen clearing skies. Added heating for those locations is helping to destabilize an atmosphere already well-primed for severe storms. Ample surface moisture continues to advance northward into the Gulf South as indicated by dew points ranging from 72° at Grand Isle to 67° in Shreveport as of 1pm-readings more akin to a mid-summer moisture field. Aloft, the mid-levels continue to be relatively dry. Saturated surface air underlying a dry layer aloft sets an atmospheric profile very favorable for large hail and damaging winds. Hail develops as falling ice and rain droplets aloft are continuously cycled through vertically deep, below freezing clouds allowing the ice and rain droplets to continue accumulating layers and thickening. Damaging winds occur as the quickly rising warm, moist air rapidly cools and saturates the dry air aloft. This air becomes denser and heavier and then races to the surface all at once in the form of strong winds. Furthermore, a number of indicies calculated from the data returned by morning weather balloons are very favorable for severe storms, particularly strong winds. However, current radar simulations are indicating the most intense line of showers and thunderstorms developing in the northern half of the state which is in-line with areas that will receive more afternoon sunshine and destabilize further. While the threat is greater to the north, the Baton Rouge area should be prepared in the event that stronger thunderstorms do develop overnight as a number of ingredients remain in place.