Go/No-Go Event Briefing

Seabreeze Harbor Half Marathon & 10K · waterfront park and coastal road course, Palm Beach County, Florida

Operating window: Sat 04:30 – 14:00 EDT
Race window: 06:30 – 10:30 EDT
Issued: Wed 18:00 EDT
Next update: Fri 18:00 EDT
Prepared by: Justice Falasco

GO High confidence

Run the race as scheduled. Plan teardown to finish by 13:00, and treat anything after that as borrowed time.

The race window is the easy part of this day. No front, no organized forcing, and the atmosphere does not get going until the sea breeze does. Your exposure is not the race. It is heat on the back half of the course and storms over the teardown crew.

Race 06:30–10:30 · Go Heat 09:00–10:30 · Caution Teardown after 13:00 · Likely hold

The setup

Why the morning is clean and the afternoon is not.

A weak surface ridge sits east of the peninsula with deep easterly flow around 8 to 12 knots. Precipitable water is near 1.70 inches, which is moist but unremarkable for the season. There is no front, no shortwave of consequence, and nothing upstream that arrives inside your window.

That means the day is driven by heating, not by a system. Convection waits for the east coast sea breeze to collide with the interior boundary, and on an easterly flow day that collision happens west of you and late, somewhere between 13:00 and 16:00. Storms then drift back toward the coast as they mature.

Practically: the atmosphere is still capped and stable when your runners are out. It is uncapped and unstable when your crew is pulling down the arch.

Event-window timeline

Your day, hour by hour.

Hour (EDT)	04	05	06	07	08	09	10	11	12	13	14
Phase	Load-in		Race				Recovery			Teardown
Lightning	—	—	—	—	—	—	—	10%	25%	55%	70%
Wind / gusts	8G14	8G14	9G15	10G16	11G17	12G18	12G19	13G21	14G22	G35+	G35+
Rain rate	—	—	—	—	—	—	—	—	lgt	hvy	hvy
WBGT flag	Grn	Grn	Grn	Grn	Yel	Yel	Red	Red	Red	Red	Red
Visibility	2 mi	2 mi	5 mi	10 mi	10 mi	10 mi	10 mi	10 mi	10 mi	3 mi	2 mi

Within limits Approaching a threshold At or past a threshold

Threshold sheet

The limits we agreed, before the week started.

These are yours. They were set against your course, your staging, and your medical capacity in a calm room on a Tuesday, which is the only reason they will hold up at 09:40 on Saturday.

Condition	Your limit	Action it triggers
Lightning	Any strike < 8 NM	Clear the course and staging. Thirty-minute restart clock, reset by every new strike inside the radius.
Sustained wind	25 kt	Strike the inflatable arch, banners, and unweighted signage.
Wind gust	35 kt	Full teardown hold. Nobody on a lift or a ladder.
Rain rate	0.50 in/hr	Cover timing mats and distribution electrical. Course stays open unless lightning joins it.
WBGT	Red at 73°F Black at 82°F	Red: extra aid-station ice and water, announce the advisory at the start. Black: shorten or stop the event.
Visibility	0.5 mi	Delay the start. Marshals cannot see runners at intersections.

Lightning and convection

The clock you are actually working against.

First strikes are expected inland, roughly 15 to 25 miles west of the venue, between 12:30 and 13:30. Cells then track west to east and reach the coastal strip between 13:30 and 15:00. Coverage is scattered rather than solid, so this is a timing problem, not a washout.

What matters operationally is the restart clock. Your thirty minutes resets on every new strike inside 8 nautical miles. On a scattered afternoon that regularly means a 30-minute hold becomes 75 minutes of standing around. Teardown crews get caught by this more often than race fields do, because the crew is still on site two hours after the last runner has gone home.

Front-load anything tall. Arch, tenting, and lighting down before 12:00.
Brief the crew on the radius and the reset rule at the morning safety meeting, not when the first strike lands.
Have an indoor or vehicle shelter plan sized for the full teardown crew, not a token few.

Heat and WBGT

The number your medical lead needs.

Air temperature is the wrong metric for this event. Wet bulb globe temperature accounts for humidity, radiant load, and wind together, and on an easterly flow day in Florida it rises faster than the thermometer does.

Expected progression: green through 07:30, yellow from about 08:00, and red by 09:45, holding red through the afternoon. Black is not expected, but the margin is roughly two degrees, so it is worth a look at the Friday update rather than an assumption.

The practical consequence: your slowest half-marathon finishers, the people least acclimated and least likely to have paced for heat, cross the line inside the red window. That is where your medical tent load comes from, not from the lead pack.

Ice and cold towels staged at the last two aid stations before 09:00, not restocked reactively after.
Announce the heat advisory at the start line. Runners adjust their pace when told; they rarely adjust it on their own.
Consider a hard course-closure time rather than letting the back of the field finish in full red conditions.

Decision timeline

Every call, and when it has to be made.

Fri 18:00

Final pre-event update

Confirms the WBGT curve and the convective timing. This is the last point at which a schedule change is cheap.

Sat 04:30

Load-in go/no-go

Visibility only. Coastal fog near 2 miles is likely and harmless for setup, but it decides whether your marshals can see the intersections at 06:00.

Sat 06:00

Start confirmation

Thirty minutes before the gun. Lightning, visibility, and the WBGT reading at the start line.

Sat 09:00

Heat checkpoint

Live WBGT against the red threshold. Decide here whether a course-closure time gets announced, rather than deciding it when somebody collapses.

Sat 11:30

Teardown window call

The one that matters most. Current radar trends against your remaining teardown list, and a realistic answer on how much time you have.

Sat 14:00+

Live monitoring

Direct phone and text while anyone is still on site. Updates when the picture changes, not on a schedule.

What would change this

Where I could be wrong.

Honest confidence, stated plainly, is worth more than a clean-looking forecast. Three things would move this call:

The sea breeze fires early. If the easterly flow backs off overnight, the collision happens closer to the coast and two hours sooner. That would put lightning risk into the late race window and change the start-time conversation. I am watching the 12Z guidance for this.
Dewpoints run higher than modeled. Two degrees of dewpoint moves WBGT into black territory by late morning, which is a shorten-or-stop decision rather than an advisory.
Morning fog is denser than expected. Low confidence item. If visibility drops below half a mile at 06:00, the start slips 30 minutes and everything downstream shifts into worse heat.

After the event I write up what actually happened against what I said here, including anything I got wrong, and we adjust the thresholds for next year. That debrief is the part that compounds.