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for South Central and Southeast Wisconsin
Waterspout Threat
Hazard Map Threat Levels Safety & Impact
Marine Weather Safety Rules
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Have an escape plan in mind. Thunderstorms and weather related hazards form quickly. Never let these storms cut off your route back to land.
Dark, threatening clouds usually foretell the approach of severe weather. Other things to watch for are a steady increase in wind or seas.
If a thunderstorm threatens while afloat, be sure everyone aboard is wearing a life jacket as a small boat can be overturned by gusty winds.
If lightning is threatening, keep below decks if possible; keep away from metal objects that are not grounded to the boat's protection system; don't touch more than one grounded object at the same time.
Listen to NOAA Weather Radio for the latest warnings, watches, advisories and forecasts from the local National Weather Service Office.
Check the weather before departure.
File a float plan at your marina.
Have a VHF marine band radio on board.
Know the limitations of your boat. Weather conditions can change quickly.
Gale Warning
A gale warning is issued when sustained winds of 34 to 47 knots (39 to 54 miles per hour) are expected over the nearshore and open waters of Lake Michigan and immediate adjacent land areas.
Storm Warning
A storm warning is issued when sustained winds of 48 knots or greater (55 miles per hour) are expected over the nearshore and open waters of Lake Michigan and immediate adjacent land areas.
Special Marine Warning
Special marine warnings are issued when short-lived frequent wind gusts of 34 knots (39 miles per hour) or greater are occurring or expected to occur over water. These winds are most often associated with thunderstorms. Special marine warnings are also issued when waterspouts are observed or expected to occur over water.
Small Craft Advisory
Small craft advisories are issued when sustained winds or frequent gusts of 22 to 33 knots (25 to 38 miles per hour) or waves generally equal to or greater than 4 feet are expected.
Marine Weather Statements
Marine weather statements are issued to advise boaters of significant weather phenomena that threaten small boats but do not reach the criteria of the other warnings or advisories.
SMALL BOAT SAFETY

Boating is a popular pastime in Wisconsin, but sudden changes in the weather can turn an otherwise sunny day into a dark and scary afternoon.

Typical weather across the nearshore and open waters of Lake Michigan can produce many hazards to small boats. All of the National Weather Service offices around the Great Lakes with Marine forecast responsibility, issue many types of warnings, watches and advisories to inform boaters Great Lakes waters of the potential weather-related dangers. Smart boating means planning for adverse weather and always wearing a personal flotation device.

Local weather service offices also issue a short term forecast that covers a period up to six hours so boaters can plan their days on the water.

The NOAA Weather Radio is the best way to receive immediate warnings and other weather forecast information from the local National Weather Service office. Information is broadcasted on different radio frequencies across the Great Lakes, 24 hours per day, each day of the year.  The weather radios are equipped with alarms that alert people of the warnings, watches and advisories issued by the local weather service office. The Coast Guard also rebroadcasts some of these warnings, advisories and statements across the marine radio emergency channel.

Person working on boatBoaters need to be warned of any changes to the current weather. Some examples of dangerous weather that can occur include strong winds, rough seas, lightning and waterspouts.  Generally, wind gusts of 34 knots (39 mph) or more are often strong enough to capsize small boats, especially when they catch the boater off-guard. Strong winds are usually generated by thunderstorms or fast moving rain showers over the Great Lakes waters.  

Another danger to boaters is a severe thunderstorm that can turn calm waters into dark and rough seas.  

Lightning is also a hazard for boaters. There are no warnings for lightning issued by the National Weather Service but the short term forecast and marine weather statements will most likely mention the possibility of cloud to water lightning strikes.

Small Boat SafetyWaterspouts are similar to tornadoes over water.  Waterspouts are simply tornadoes that form over water and they have the same characteristics as a land tornado.

  • National Weather Service
  • Milwaukee/Sullivan, WI Weather Forecast Office
  • N3533 Hardscrabble Road
  • Dousman, WI 53118
  • 262-965-2074
  • Page Author: MKX Webmaster
  • Web Master's E-mail: w-mkx.webmaster@noaa.gov
  • Page last modified: 2-Nov-2005 10:23 PM UTC
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