The 2015 Invitational Mills Trophy Race
A Meteorological Summary
Introduction
The 2015 Invitational Mills Trophy Race, organized by the Toledo Yacht Club and the Storm Trysail Club, was held on Friday, June 5, 2015. The race includes three courses ranging from 37.7 to 70.9 nautical miles (Figure 1). All of the courses begin near Toledo, Ohio, and continue east through Lake Erie's South Passage, an area between the northern Ohio shoreline and the islands of South Bass and Kelleys. Turning north, the race finishes near South Bass Island, a popular destination in Lake Erie's western basin. The race begins at 5:00 pm with the participants expected to finish during the overnight or early morning hours. As an early season distance race, it is considered a warm-up to the longer, and more demanding, Lake Michigan and Lake Huron Macs held each July.
Strong northerly winds and steep waves battered the fleet as it sailed through the South Passage, and approximately 40 boats withdrew from the Race in response to the demanding conditions. Tragically, one participant was lost after falling overboard near Catawba Island (click here for a map of the area).
This article provides an analysis of the wind and wave conditions near the location of the accident near Catawba Island and the entrance to West Harbor.
The Forecast
The surface forecasts issued by the Weather Prediction Center (WPC) suggested the cold front and small area of low pressure that was located northwest of Lake Erie on Friday morning (click here) would continue moving southeast across the region. Based upon the Convective Outlook (click here) and Thunderstorm Outlooks (click here and here) issued by the Storm Prediction Center (SPC), the potential for thunderstorms during the race was very low.
The nearshore marine forecast issued by the Cleveland office of the National Weather Service (NWS) at 3:12 pm indicated:
.TONIGHT...NORTHEAST WINDS 5 TO 15 KNOTS BECOMING NORTH 10 TO 20 KNOTS. MOSTLY CLOUDY. A CHANCE OF RAIN SHOWERS WITH ISOLATED THUNDERSTORMS THIS EVENING. WAVES 2 FEET OR LESS BUILDING TO 1 TO 3 FEET.
.SATURDAY...NORTHEAST WINDS 10 TO 20 KNOTS. MOSTLY SUNNY. WAVES
1 TO 3 FEET BUILDING TO 3 TO 5 FEET.
The updated forecast issued at 9:50 pm on Friday night (click here) mentioned that a Small Craft Advisory was in effect. In addition, the speed of the northerly winds expected on Friday evening was increased from 5 to 15 knots to 15 to 25 knots and wave heights were raised from 2 to 4 feet to 3 to 5 feet.
Observations
As the race got underway, observations from the automated weather stations near the South Passage (Figure 4) indicated that winds were rather light. At 5:00 pm, the sustained winds at the South Bass Island lighthouse (NDBC SBIO1) were northerly at 3.4 knots with gusts to 11.4 knots, while winds at the Marblehead Light (NDBC MRHO1) were nearly easterly at 3.4 knots, gusting to 4.7 knots.
The only offshore weather buoy in Lake Erie -- NDBC 45005 -- is located approximately 17 nautical miles northeast of the Marblehead Light (Figure 4). At 5:00 pm on Friday, the sustained winds at the buoy were easterly at 2.2 knots with gusts to 4.5 knots. Wave heights at the time were 0.3 feet.
As Friday evening progressed, barometric pressure across Lake Erie's western basin steadily increased (Figure 6) as the cold front shifted to the southeast. The increase in barometric pressure produced a strengthening of the pressure gradient force (PGF) across the region and a corresponding jump in wind speeds. (Note: a primer on the atmospheric forces that control the direction and speed of the wind can be found here.) A similar trend in barometric pressure was observed at South Bass Island (click here) and the Marblehead Light (click here). A series of surface charts showing the transition in barometric pressure can be reviewed here.
At 8:00 pm, in response to the increasing PGF, the sustained winds at South Bass Island were north northeast (17°) at 8.1 knots with gusts approaching 20 knots. The winds at Marblehead were also north northeast (20°) at 13.9 knots with gusts to 17.2 knots. At NDBC buoy 45005, the winds were northerly (350°) at 20.1 knots with gusts to 24.6 knots. Wave heights at the buoy were 1.6 feet.
The winds near the South Passage remained northerly and steadily increased over the next several hours. The strongest winds of the race were observed between 8:00 pm and midnight on Friday night, with a gust of 26.4 knots occurring at both South Bass Island and the Marblehead Lighthouse at 9:07 pm and 9:06 pm, respectively. A 31.3 knot gust was observed at NDBC 45005 at 9:58 pm.
Near the time of the accident (12:15 am on Saturday, June 6), the sustained winds at South Bass Island were 13.9 knots with gusts to 23.0 knots. At Marblehead Lighthouse, the sustained winds were 16.1 knots with gusts to 19.7 knots. At NDBC buoy 45005, the sustained winds were 20.1 knots with gusts to 29.1 knots. Observed wave heights were 3.3 feet. Race participants reported wave heights of 4 to 6 feet in the South Passage. While these observations can't be documented, they are entirely reasonable considering the additional fetch and close proximity of the fleet to Lake Erie's southern shore. The water temperature at the intake near the Marblehead Lighthouse was approximately 60° F (click here). A review of the radar data from the NWS station in Cleveland indicates that no precipitation was occuring at the time of accident (click here for radar loop). A more complete set of observational data is presented in Figures 7 through 15 (below).
Observations From South Bass Island (SBIO1)
Observations From Marblehead (MRHO1)
Observations From NDBC Buoy 45005
