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 →
Seasoned boaters know first-hand that weather conditions on the Great Lakes can change from pleasant to terrifying very quickly. From dangerous lightning to high winds, thunderstorms can ruin an outing in many ways. However, reading the marine forecast before leaving the dock and regularly checking weather radar along the way will dramatically increase your chances of avoiding uncomfortable or dangerous conditions. Continue reading →
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 →
Introduction Even when the atmosphere is supportive of thunderstorms, a source of lift is necessary to provide the upward motion required by a fledgling storm’s updraft. A reliable source of lift is often found near a cold, warm, or stationary front accompanying an approaching low pressure system (figure 1). Terrain or the leading edge of a downdraft from an existing thunderstorm (outflow boundary) can also provide a storm with this all-important ingredient. Continue reading →
Sailors have been watching clouds since the first boat was launched. As aficionados know, clouds come in an infinite variety of shapes and sizes. The overall shape of a cloud and the altitude where it forms help tell the story of current and short-term weather patterns.
Introduction On the afternoon on December 10, 2018, an area of what initially appeared to be precipitation (Figure 1) was detected northwest of Evansville, Indiana by the National Weather Service (NWS) Doppler Weather Radar station at Paducah, Kentucky (KPAH). When first detected, the blob was 100 nm northeast of KPAH at an elevation of approximately 12,000 feet. A check of surface weather stations near the blob and visible satellite imagery (Figure 2) indicated that no precipitation was occurring and that skies were clear in the area.
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.)
Introduction Lake Michigan sailors have had a challenging summer. In mid-July, competitors in the Chicago-Mac were treated to a rare type of downburst known as heat burst (or dry downburst) near Milwaukee late on Saturday night (click here for the summary). Three weeks later, sailors at the T-10 North American Championship near Chicago had an encounter with a different kind of downburst, one that blasted the fleet with hurricane-force winds. These downbursts, while similar in some ways, are very different in others. The downburst at the T-10 Nationals offers an opportunity to introduce a pair of relatively unknown Doppler weather radar products – storm heights (echo tops) and vertically integrated liquid (VIL) – that can help shed light on the evolution of an approaching thunderstorm.
Introduction After a challenging 2016 Chicago Mac (click here for a summary), this year’s competitors were likely hoping for an easier trip to the island. But as is often the case, Mother Nature wasn’t inclined to cooperate. Although the race started in pleasant sailing conditions, a rare weather phenomenon known as a heat burst, or dry microburst, caused two separate and frightening incidents late on Saturday night. The one-two punch of Saturday’s heat burst, combined with brisk northerly winds following the passage of a cold front on Sunday, caused nearly 30% of the fleet to retire from the race. Continue reading →
Introduction Weather-savvy mariners know the best resource for monitoring the location, size, intensity, and movement of thunderstorms is Doppler Weather Radar from the National Weather Service (NWS). In the first of a two-part series, I’ll explain the basics of radar and introduce the most common types of imagery. Continue reading →