Posted: May 2, 2014 11:17 AM by Meteorologist Josh Eachus
Updated: May 2, 2014 11:17 AM
"The forecast area is on the optimistic side of a very wet and highly efficient boundary that has been pummeling Southern Alabama and the Florida Panhandle overnight. This event is remarkably similar to May 9, 1995, just displaced about 70 miles east." Those remarks topped the area forecast discussion issued by the National Weather Service in New Orleans on Wednesday Morning.
As reports have shown, a two-part, three day rainfall event from April 28-30 produced amounts exceeding 15 inches in many locations from Mobile, Alabama to Destin, Florida. The surge marked an unceremonious bulls-eye on Pensacola, Florida. There, storm-total rainfall estimates are above 20 inches making it a 100-200 year event. Gushing waters produced sinkholes, cut and caved-in roads and necessitated a temporary closure of Interstate-10 on Wednesday Morning. Residents likened the impact to that of Hurricane Danny in 1997. Photos and video coming from the scene make The National Weather Service statement (above) hard to believe. However, the following retrospective may verify their comparison.
Over a 40 hour stretch of time from May 8-10 of 1995, Southeastern Louisiana and Southern Mississippi experienced what was described as a "paralyzing" bout of historic flooding and severe weather. More than 44,000 homes were flooded, countless roads were washed out and more than a million residents were impacted by damages that exceeded $3 billion. At times, Interstate-12 near Slidell was flooded over. An F1 and an F2 tornado each touched down in Louisiana. There were six deaths in New Orleans and one in Southern Mississippi. Deemed a federal disaster area by President Clinton the National Guard was called in to assist in evacuation and rescue efforts.
Between the two rounds of precipitation May 8-10 average rain amounts across the area were between 10-20 inches. The highest recorded rainfall total from the event checked in at 27.5" coming from a bucket near Necaise Crossing in Hancock County Mississippi.
The storm produced two distinctly separate bouts of rain. From the evening of May 8 to the morning of May 9 10-13" fell across Southeast Louisiana and Coastal Mississippi over a 3-6 hour period. Audubon Park in New Orleans measured 12.2" of rain between 6:30 p.m. and 11:30 p.m. Incredibly, this event would be outdone between the evening of May 9 and the morning of May 10. Over the course of the second and record-breaking monthly and century rainfall, 10-15" of rain fell on the towns of Abita Springs, Covington, Mandeville and Slidell in Louisiana. Most came between 11 p.m. and 7 a.m. Locally, the event was considered a 100-500 year occurrence.
Meteorological synopsis of 1995 event: A squall line and trailing cold front entered a saturated, tropical air mass in Southern Louisiana on May 8. At the same time, a fast moving mid-level trough dipped through the region and rapidly exited northeast. However, upper level winds remained strong along for the continuing rising and dispersion of ongoing warm, moist air pumping in from the Gulf. But with no more mid-level steering support, the remnant squall line and dissipating front stalled and served as a forcing mechanism for the development of continued heavy rain. On an even smaller scale, a slight low pressure trough existed from Lake Pontchartrain to New Orleans to Thibodeaux. Most of the heaviest rains occurred around this trough on May 9. After a brief break in precipitation, the atmosphere rapidly destabilized once again as a pool of cold air aloft slid over the region. A jet streak whipped through the trough and served as another forcing mechanism over the weakening surface front perpendicular to the upper wind flow. The alignment of surface boundary to upper winds is significant because it ensured little geographical displacement of the weak front resulting in even heavier rains than the previous round.
As indicated by the National Weather Service in New Orleans, a review of the meteorological setup for the recent flood event in Florida and Alabama would draw an immensely similar picture.
You can get forecasts from Meteorologist Josh Eachus weekdays on 2une-In from 5-7am and News 2 at Noon from 12-1pm. Additionally, you can get the fastest and latest forecasts and weather news by checking in with wbrz.com/weather, liking Josh on Facebook and following him on Twitter.