A New Spin on Waterspout Forecasting

Introduction
Several waterspouts, the intense columnar vortices considered “tornadoes over water”, have been reported across the Great Lakes over the past two weeks. Waterspouts come in two varieties – tornadic and fair weather—with the fundamental difference between them being the type of storm they are associated with, and the manner in which they form.
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Feeling The Pressure: The Value of A Barometer

Introduction
Every cruising boat should have a reliable barometer on board. Invented by Italian physicist and mathematician Evangelisata Rorricelli in 1643, a barometer helps a weather-wise boater stay abreast of developing weather patterns. The approach of a strong low pressure system with high winds, a squall line, or a hurricane is typically signaled by falling barometric pressure.  The steepness of the decline in pressure provides valuable insight into the strength of the approaching system. In contrast, rising barometric pressure usually heralds the arrival of fair weather and light winds. The ability to measure the rise and fall of barometric pressure only scratches the surface, however. What is barometric pressure, and what does it represent?
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Dramatic Differences: The Effects of Lake Temperature on Gusty Winds

Introduction
The Great Lakes — individually and collectively — play a significant role in the region’s weather. This is especially evident in the spring and early summer when cold lake waters promote the development of fog, suppress temperatures along the shore, and diminish the potential for strong thunderstorms offshore. One phenomenon of particular interest to sailors is the significant impact a relatively cold lake has on the wind well into the summer months.
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Marine Model Output Statistics: A Unique Wind Forecasting Resource

Introduction
Sailors spend a lot of time analyzing wind forecasts, whether they’re planning a short afternoon sail, preparing for a regatta, or developing a strategy for a long-distance race. Most of this analysis relies on graphical forecast products, such as the wind speed and direction forecast for Lake Huron published by the National Weather Service shown below.

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Doppler Radar: When Is A Storm Not A Storm

Doppler Weather Radar

Doppler weather radar has a lot to offer a weather-savvy boater. Before leaving the security of your dock, a quick look at the wide array of radar products offered by the National Weather Service (NWS) can help you determine if thunderstorms are occurring nearby. With a little knowledge and practice, you can use radar to identify where the strongest storms are located, the speed and the direction in which they are moving, and if they possess rotation which raises the possibility of a tornado or waterspout. But a quick look doesn’t always tell the full story.
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Bell’s Beer Bayview Mackinac Race Climatology

Introduction
Although the 2014 Bell’s Beer Bayview Mackinac Race is a less than two weeks away, it’s still too early for competitors to start working on their weather forecast. However, reviewing the long-term average conditions on Lake Huron during July is great way to set the stage for a weather forecast, particularly for those who are participating in the Race for the first time.

Wind and Wave Observations
The National Data Buoy Center (NDBC) maintains two floating discus bouys in Lake Huron. Buoy 45003 is located in the northern basin, while buoy 45008 is located in southern Lake Huron near the entrance to Saginaw Bay (click here for a map of Lake Huron).
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Chicago Yacht Club’s Race To Mackinac Climatology

Introduction
The Chicago Yacht Club’s Race to Mackinac is a little over two weeks away. It’s too early to begin working on your weather forecast. However, reviewing the long-term average conditions on Lake Michigan during July is great way to set the stage for a weather forecast, particularly for if you are participating in the Race for the first time.

Wind and Wave Observations
The National Data Buoy Center (NDBC) maintains two floating discus bouys in Lake Michigan. Buoy 45002 is located in the northern basin north of the Manitou islands, while buoy 45007 is located in southern Lake Michigan approximately 43 nautical miles southeast of Milwaukee, Wisconsion (click here for a map of Lake Michigan).
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Superstorm Sandy Produces Havoc On Lake Erie

A Superstorm Is Born

The remnants of Hurricane Sandy roared ashore near Atlantic City, New Jersey at approximately 7:30 pm on October 29, 2012 with sustained winds of 70 knots and storm surge exceeding 10 feet. Dubbed Superstorm Sandy, it ravaged the coast of New Jersey and New York and produced storm force winds as far west as the Great Lakes.

The weak atmospheric disturbance that would later become Sandy developed over western Africa on October 11. Over the next three weeks, the disturbance slowly strengthened as it travelled west towards the Caribbean. At 8:00 am on October 22, 2012, the National Hurricane Center (NHC) categorized the disturbance as a tropical depression (sustained winds were greater than 34 knots). Remarkably, the storm strengthened from a tropical depression to a tropical storm (sustained winds of 35 – 63 knots) in only six hours. Sandy was declared a hurricane (sustained winds => 64 knots) by the NHC at 8:00 am on October 24, as the storm was approximately 80 nautical miles south of Kingston, Jamaica.
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Forces Governing The Wind

Pressure Gradient Force

The speed and direction of the wind is governed by three forces; the pressure gradient force (PGF), the Coriolis Force and friction. PGF is the force produced by differences in barometric pressure between two locations and is responsible for the flow of air from an area of high pressure to an area of low pressure.

Flow of air produced by the pressure gradient force.

 

The diagram above shows an idealized surface weather map containing a 1030+ mb high pressure system and a 1002+ mb low pressure system. In the absence of the Coriolis Force and friction, the wind flows directly from the center of the high to the center of the low. The speed of this flow is dictated by the magnitude of the change in barometric pressure and the distance between the centers of the high and the low.
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