Tragedy Strikes The Dauphin Island Race

The Forecasts

The potential for severe thunderstorms across the Gulf Coast, including Mobile Bay, was recognized several hours before the Race began. At 8:00 am (1300Z) on April 25, 2015, the Storm Prediction Center issued a Day One Convective Outlook (figure 2) (click here for text of the Outlook), placing a broad stretch of the Gulf Coast extending from central Texas to the Florida panhandle under a Slight risk of severe weather. (If you are unfamiliar with the National Weather Service (NWS) definition of a severe thunderstorm, or the risk categories used by the Storm Prediction Center to predict them, please click here.) The narrative of the updated Outlook mentioned that “several rounds of scattered strong to severe thunderstorms are expected today” for the lower Mississippi Valley and Gulf Coast. The storms were expected to “yield damaging gusts, severe hail, and perhaps a couple of tornadoes”. The Severe Thunderstorm Wind Outlook (figure 3) accompanying the Convective Outlook indicated a 15% probability of winds gusts of 50 knots or greater along most of the Gulf Coast.

Figure 2: SPC Convective Outlook issued at 7:00 am / 1300Z on April 25, 2015. Click here for larger version.
Figure 3: SPC Severe Wind Outlook issued at 7:00 am / 1300Z on April 25, 2015.Click here for larger version.

The SPC Thunderstorm Outlooks (figures 4, 5, and 6) accompanying the Convective Outlooks also focused on the potential for thunderstorms along the Gulf Coast. While the risk was expected to persist for most of the day, the greatest potential (70%) was to occur between 11:00 am and 3:00 pm (1600Z to 2000Z).

Figure 4: SPC Thunderstorm Outlook for 7:00 am to 11:00 am (12Z to 16Z). Click here for a larger version.
Figure 5: SPC Thunderstorm Outlook for 11:00 am to 3:00 pm (16Z to 20Z). Click here for a larger version.
Figure 6: SPC Thunderstorm Outlook for 3:00 pm to 7:00 pm (20Z to 00Z). Click here for a larger version.

As part of their daily forecast responsibility, NWS Mobile issues a Hazardous Weather Outlook (HWO), designed to alert the public to the potential for severe weather, along with details regarding the timing, geographic area, and nature of the severe weather threat. While Mobile Bay was not mentioned in the early morning HWO’s published by NWS Mobile, the version published at 10:45 am (1545Z) (click here for text) included the following:

Day One Today and Tonight
Thunderstorms will move in from the west this afternoon and across the marine area. Some of the thunderstorms may be strong or severe with gusty winds and large hail the primary threat.

The Race promised to be an upwind affair, with the Marine Forecast issued by the Mobile National Weather Service (MOBILE NWS) at 8:08 am (1318Z) (click here for marine forecast) predicted “southwest winds 3 to 8 knots increasing to 10 to 15 knots.” The portion of the marine forecast for southern Mobile Bay and the Mississippi Sound included a reference to “a chance of thunderstorms in the afternoon”. The updated marine forecast issued at 10:30 am (1530Z) (click here for marine forecast) included the following for all of Mobile Bay “chance of showers and thunderstorms late in the morning then showers and thunderstorms likely in the afternoon.”