Tragedy Strikes The Dauphin Island Race
Mobile Bay In The Crosshairs
NWS Mobile issued its first severe thunderstorm warning --#28 (click here) -- associated with the approaching complex at 1:28 pm (1828Z). The particular thunderstorm drawing their attention was located approximately 40 miles northwest of Mobile Bay and was moving east at nearly 30 knots. The storm was not expected to threaten Mobile Bay.
At 1:35 pm (1835Z), the Storm Prediction Center issued Severe Thunderstorm Watch #113 (click here for the text of watch) to alert the public that the long-lived cluster of thunderstorms (figures 8 and 9) spreading damaging wind gusts east across Louisiana was likely to reach Alabama and the Florida panhandle. The text of the Watch mentioned that the “primary threats include isolated very large hail to 2 inches in diameter possible and isolated damaging wind gusts to 70 mph possible.” Mobile Bay was directly in the path of the approaching complex.
Shortly after publication of Watch #113 by the SPC, NWS Mobile issued an updated Marine forecast at 1:42 pm (1842Z), alerting mariners on both northern and southern Mobile Bay that “severe thunderstorm watch 113 is in effect until 9 pm CDT this evening”.
In order to focus additional attention on the continuing risk of severe thunderstorms across the Gulf Coast and to support the issuance of Severe Thunderstorm Watch #113, the SPC issued Mesoscale Discussion #455 at 1:50 pm (1850Z). The text of Discussion #455 (click here) reinforced the likelihood that the thunderstorm complex would continue moving eastward across Alabama and persist in producing damaging wind gusts along its path.
NWS New Orleans’ County Warning Area (CWA) ends at the Mississippi and Alabama border. At 2:09 pm (1909Z), the office issued Severe Thunderstorm #27 for an isolated thunderstorm (figure 10) approaching the Alabama border. The storm, located in front of the approaching complex, was capable of “producing damaging wind gusts of 60 mph” and was moving northeast at nearly 50 knots.
At 2:17 pm (1917Z), NWS New Orleans issued Marine Warning #131 covering the eastern portion of the coastal waters (figure 11) within their CWA. The thunderstorms covered by the Warning were moving east-northeast at approximately 60 knots and were “capable of producing dangerous winds in excess of 50 knots.”
The thunderstorm which was the subject of NWS New Orleans Warning #27 continued its journey east and was poised to cross into Alabama at approximately 2:21 pm (1721Z). In response to the approaching threat, NWS Mobile issued Severe Thunderstorm Warning #29. Warning #29 covered the southwestern corner of Alabama (figure 12) but did not include Mobile Bay or the coastal waters of Alabama.
The warning indicated the storm was “capable of producing … damaging winds over 60 mph … and was moving east at 70 mph.” At the time of the warning, the thunderstorm was less than 20 miles west of Mobile Bay. Based upon its appearance on radar, the storm weakened considerably as it travelled northeasterly towards upper Mobile Bay. The storm produced only modest gusts in the range of 15 to 18 knots as it passed by the Mobile Coast Guard station (NDBC MCGA1) at about 2:40 pm (1940Z).
As the main body of the trailing complex continued east, it prompted the issuance of Severe Thunderstorm Warning #29 by NWS New Orleans at 2:29 pm (1929Z). When combined with Marine Warning #131 issued at 2:17 pm (1917Z), nearly 75% of the thunderstorms approaching Alabama were included in warnings issued by NWS New Orleans (figure 13).
These two severe thunderstorms warnings were well founded, as the storms produced a 36 knot gust at Gulfport, MS; a 29 knot gust at Biloxi, MS; a 50 knot gust near Latimore, MS; and a 46 knot gust at Pascagoula, MS before continuing on their way towards the Alabama state line.
As the cluster approached the Alabama border, NWS Mobile issued Severe Thunderstorm Warning #30 at 2:47 pm (1947Z). Similar to Warning #29 issued nearly 30 minutes earlier, the warning included the southwestern corner of Alabama but not Mobile Bay or the coastal waters located in the office’s CWA (figure 14).
Approximately 10 minutes after the issuance of Warning #30 (2:57 pm (1957Z)), the Grand Bay weather station maintained by the South Alabama Mesonet recorded a gust of 41.7 knots. A mere 2 minutes later at 2:59 pm (1959Z), a gust of 40 knots was recorded at the NWS Mobile office.
The storms raced east across southwestern Alabama at nearly 60 knots, reaching the western shore of Mobile Bay at approximately 3:08 pm (2008Z). At 3:09 pm (2009Z), NWS Mobile issued Special Marine Warning #34 (figure 15) covering all of Mobile Bay and the coastal waters from Pascagoula, MS to Pensacola, FL. The Warning mentioned that “a line of thunderstorms producing strong winds of 34 knots or greater was located along a line extending from north of Battleship Park to near central Dauphin Island moving east at 50 knots”. Mariners were advised to “seek safe harbor immediately.” NWS Mobile updated the Marine Forecast at 3:10 pm (2010Z) and included a reminder that “Severe Thunderstorm Watch 113 is in effect until 9 pm CDT this evening.”
