Introduction
Several weeks ago, I published a summary of storm-force sustained winds, hurricane-force gusts, and a drop in water level approaching six feet across Lake Erie’s western basin, all courtesy of the passage of a deep low pressure system on November 27, 2019 (click here to read the summary). This article examines how the weather forecast models performed during the event. Continue reading
Category Archives: Wind Forecasting
Hurricane Force Winds on Lake Erie
Introduction
Wednesday, November 27, 2019 was a wild day on Lake Erie thanks to the passage of a deep low pressure system and its accompanying cold front. The surface forecasts issued by the Weather Prediction Center (WPC) suggested the powerful and fast-moving low and its cold front would reach Lake Erie’s western basin around sunrise on the 27th (Figure 1) and the eastern end of Lake Ontario by early evening (click here for forecast graphic). Continue reading
A One-Two Weather Punch: The Sunday Morning Cold Front
Introduction
By any measure, the 2017 Chicago Yacht Club Race to Mackinac was no picnic. The Race started on Saturday under very pleasant southwesterly breezes and the fleet made good progress toward Mackinac Island. However, as the fleet worked north, two weather features delivered a one-two punch that prompted nearly a third of the competitors to withdraw from the Race. (Click here for Matt Gallagher’s thorough analysis of the reasons competitors gave for retiring.)
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.
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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