Author Archives: LakeErieWX

Doppler Weather Radar: It Isn’t Live But It’s Getting Better

Introduction
Doppler Weather Radar is your best defense against a hair-raising and wind-blown encounter with thunderstorms. The 155 stations in the National Weather Service’s (NWS) network provide overlapping, ground-based coverage of the nation’s inland and coastal boating areas. With an effective range of approximately 120 nautical miles, data from the NWS radar network is not accessible if you are well offshore. (Regardless of how you obtain your radar imagery, you are viewing NWS data as theirs is the only national radar network.)

Scanning The Atmosphere
Strong thunderstorms may be several miles high, and so the radar station must collect data from the Earth’s surface up into the upper reaches of the atmosphere in order to completely analyze the storm. Stations use a variety of scanning strategies, called Volume Coverage Patterns (VCP) to accomplish this goal. The antenna makes an initial, or base, scan by making one complete revolution at an elevation of 0.5° above the Earth’s surface, alternating between emitting and collecting backscattered energy pulses. When this base scan is complete, the antenna completes additional scans, repeatedly increasing the elevation by about one degree, until the highest elevation of the VCP is reached. The highest elevation scanned by NWS radar is 19.5°.
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Understanding Meteorological Time

Introduction
Weather recognizes no geographic or political borders. In order to coordinate their observations and forecasts, meteorologists around the world use a standard timekeeping system. The original standard timekeeping system was Greenwich Mean Time (GMT) a 24-hour clock system based on the local time in Greenwich, England. For example, 1:00 am in Greenwich is 0100 GMT, noon is 1200 GMT, and 6:00 pm is 18 GMT.

Since GMT is technically a time zone, it was replaced with Coordinated Universal Time (UTC) in the early 1970s. Similar to GMT, UTC is a 24-clock system that doesn’t recognize local adjustments such as Daylight Saving Time. The National Weather Service’s version of UTC is called Zulu, which is typically abbreviated as “Z” on their forecast maps and text products.
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Sloshing and Surfing on Lake Erie

Introduction
The marine forecast for Lake Erie on Saturday, June 27, 2015 suggested conditions were going to be unusually nautical for late June. Sustained northeasterly winds were likely to reach 35 knots, while gusts approaching 45 knots were possible. Significant wave heights were expected to reach 11 feet (click here for the wave forecast valid at 2 pm).

Figure 1: NWS wind speed and direction forecast for 2:00 pm on June 27, 2015. Click here for a larger version.
Figure 2: NWS wind gust forecast for 2:00 pm on June 27, 2015. Click here for a larger version.



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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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