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Hurricane-Like Derecho Spreads Destruction Across the Upper Midwest

Written by Team Morecast

 

A swath of destructive winds up to 110 mph (175 kph) accompanied a long-lived squall line known as a derecho through the Midwest. The 700+ mile (1,125+ km) path included the Chicago metro area on Monday afternoon. An embedded tornado within the squall caused enhanced damage on the city’s north side. More than a million residents in the region remained without power as late as Tuesday morning.

 

 

The derecho began as a cluster of severe storms along the South Dakota-Nebraska border early Monday morning. In the first few hours, giant hail was the main hazard with some stones up to softball-sized. By late morning the cluster had organized into a fast-moving bow echo raking central Iowa. This was probably where the highest winds and worst damage occurred. Midway, Iowa recorded a gust to 112 mph (180 kph), as strong as a Category Two hurricane. Residents reported these intense winds lasted up to 15-20 minutes. They compared the destruction to tornadoes that typically cover a smaller area and last a shorter amount of time. Officials estimate up to one-third of the state’s staple corn crop was destroyed, only weeks after the region had celebrated recovery from a drought. The damage was so widespread that it was visible on satellite imagery the next day (see bottom tweet).

 

 

 

 

The squall line crossed into northern Illinois early in the afternoon, slamming Chicago in the mid- to late afternoon. Gusts were measured up to 80 mph (130 kph) in the city, felling many trees and powerlines. The derecho slowly weakened in the evening, but continued to cause significant damage across northern Indiana and even northwest Ohio. By the end of its 14-hour lifespan, the derecho had produced more than 500 high wind reports across eight states and covered 770 miles (1,240 km). That’s an average speed of 55 mph (90 kph), but at its peak the squall moved as fast as 70 mph (110 kph)!

TUESDAY NIGHT UPDATE: Isaias Rakes the Eastern Seaboard with High Winds, Tornadoes!

Written by Team Morecast

 

Hurricane Isaias made landfall in southern North Carolina late on Monday evening. Less than 24 hours later, the storm is leaving the New England states. In between lies a path of damaging winds, flooding rains, and tornadoes. The densest population centers in the U.S. saw widespread winds of 60-80 mph (100-130 kph), felling countless trees and powerlines and leaving millions without power.

 

 

 

 

Isaias has left a unique mark on the history of tropical cyclones. The storm experienced a surge of intensification before landfall near Ocean Isle Beach, NC. That intensification helped produce a dangerous surge up to six feet (1.8 m) high for coastal NC, flooding homes and cars and leaving a thick layer of beach sand burying whole communities. Isaias interacted with a large trough in the Midwest that injected extra energy into the storm. The storm was thus able to retain strength over inland areas where most cyclones die. Destructive winds swept up the entire East coast with gusts of 70-80 mph (115-130 kph) reported as far north as the Big Apple. The highest winds lasted only a few hours with the storm sprinting north, but it was plenty enough to cause widespread damage. At least 25 tornadoes were also reported during the morning hours in the Mid-Atlantic, producing smaller pockets of extreme damage. Inland areas saw heavy rain up to ten inches (250 mm) leading to localized flooding. Lead photo courtesy flickr user woodleywonderworks.

TUESDAY MORNING UPDATE: Upgraded Hurricane Isaias Makes Landfall in North Carolina!

Written by Team Morecast

 

As feared, Isaias gained strength on Monday feeding on warm Gulf Stream waters off the southeast US coast. The storm was upgraded back to hurricane status before making landfall late on Monday evening near Ocean Isle Beach, NC. Very strong winds have occurred near the landfall point with one gust measured to 87 mph (140 kph). A major storm surge is also being reported (see tweet video below) up to six feet (1.8 m) in places, some of the highest water levels ever recorded. A devastating fire sparked by the high winds has consumed multiple homes in Ocean Isle Beach with fatalities reported. Dangerous winds and tides will continue to affect portions of the North Carolina coast through the early morning hours.

 

 

 

 

 

Isaias will continue to accelerate north-northeastward through the Mid-Atlantic and Northeast in the next 24-36 hours. The storm is merging with a strong trough over the Midwest which will lend it energy. As a result, Isaias will not weaken as fast as tropical cyclones usually do. Destructive winds and flooding rainfall will continue to accompany the storm as it moves northeastward. The coastal Mid-Atlantic will see the brunt of the storm during the day on Tuesday. New England residents should expect tropical storm-force conditions late Tuesday afternoon into Tuesday night. Winds commonly reaching 60-75 mph (100-120 kph) will lead to numerous downed trees and branches and widespread power outages through the major cities of the urban corridor. Isolated tornadoes will also be a danger, resulting in localized extreme damage. Interior areas will see the heaviest rains, up to 5-6 inches (125-150 mm) in spots, leading to serious flash flooding. By early Wednesday, the storm’s remnants will be affecting Maritime Canada.

MONDAY MORNING UPDATE: Isaias Raking the Southeast Coast, Could Still Intensify!

Written by Team Morecast

 

Tropical Storm Isaias has remained somewhat disorganized through Sunday. The eastern (offshore) half of the storm has remained dominant, sparing the Atlantic coast of Florida the heaviest winds and rains. However, there are signs that Isaias could regain its hurricane status as it turns toward the Carolinas on Monday. Destructive winds and flooding are still major threats along the Carolina coast.

 

 

Radar and satellite imagery continues to show a lopsided tropical storm with the heaviest activity well to the east of Florida. Wind gusts over Florida have remained less than 50 mph (80 kph). Rainfall totals have generally been less than two inches (50 mm). Upper level shear is relaxing over the storm, however, and the latest satellite scans indicate that Isaias may be becoming more symmetrical. Isaias is expected to continue on a north-northwesterly path into Monday before it turns north and north-northeast. This path would keep it far enough east to minimize the disruptive influence that land usually has on a tropical cyclone. The storm will also be moving over very warm Gulf Stream waters. Model guidance is coming around to the idea that Isaias may gain strength before landfall in the Carolinas Monday night.

 

 

Regardless of whether Isaias is a strong tropical storm or a weak hurricane, dangerous weather will threaten the coastal Carolinas within the next 24-36 hours. Landfall is likely to occur near the Carolina border. Near and east of the landfall point, watch for a destructive storm surge of up to 3-4 feet (1-1.2 m). Damaging winds locally gusting 70-90 mph (110-145 kph) will also occur. Tropical storm-force winds could impact areas as far north as southern New England by midweek as the storm accelerates. Flooding rainfall will encompass a much larger region as the storm merges with a large trough now over the Midwest. Very heavy rains will fall from the Appalachians through the Mid-Atlantic and Northeast (see tweet above).