Unusual Tropical Depression Alberto reached southern Michigan on Wednesday as it continued its northward journey from the Gulf of Mexico. At 11:00 p.m. EDT on Wednesday the center of Tropical Depression Alberto was located at latitude 42.4°N and longitude 85.3°W which put it about 45 miles southwest of Lansing, Michigan. Alberto was moving toward the north-northeast at 26 m.p.h. (43 km/h). The maximum sustained wind speed was 30 m.p.h. (50 km/h) and there were wind gusts to 40 m.p.h. (65 km/h). The minimum surface pressure was 996 mb.
The circulation of Tropical Depression Alberto remained intact even though it had been over land for more than two days. There was a distinct low level center of circulation. Several bands of showers and thunderstorms were revolving around the center of circulation. Storms in the core of the circulation were generating upper level divergence. Tropical Depression Alberto looked like a tropical cyclone on both satellite and radar imagery.
Gusty winds in some of the bands of showers and thunderstorms caused damage to trees and power lines in Indiana and Ohio. Most of the damage was minor. The peripheral parts of the circulation of Tropical Depression Alberto interacted with other weather system to produce bands of heavier rain over parts of the southeastern U.S. The heavy rain contributed to flooding in several states.
Tropical Depression Alberto will move northeast across the Great Lakes and into Canada on Thursday. The broader circulation around Alberto will again interact with other weather systems to produce bands of heavier rain. The potential flooding will exist in several states in the southeastern U.S. and Great Lakes region.
Tropical Depression Alberto dropped heavy rain over portions of the southeastern U.S. on Tuesday. At 11:00 p.m. EDT on Monday the center of Tropical Depression Alberto was located at latitude 36.3°N and longitude 87.5°W which put it about 45 miles (75 km) west-northwest of Nashville, Tennessee. Alberto was moving toward the north at 16 m.p.h. (26 km/h). The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (75 km/h). The minimum surface pressure was 999 mb.
The core of Tropical Depression Alberto moved northward across Alabama and into Tennessee on Tuesday. The circulation remained well developed and there was a band of showers and thunderstorms that surrounded most of the center. Upper air data from Nashville, Tennessee indicated that the system might have a warm core and the Weather Prediction Center called it a Tropical Depression in the 11:00 p.m. EDT advisory. A large counterclockwise circulation extended all the way to eastern North Carolina. Bands of showers and thunderstorms were rotating northward in the eastern half of the circulation.
Those bands of showers and thunderstorms were dropping heavy rain as they passed over some locations. A weather station in Asheville , North Carolina received nearly two inches of rain on Tuesday. Heavier rain likely fell over parts of the Appalachians where the wind forced the air to rise up the mountains. There were reports of flooding in several locations and Flash Flood Warnings were in effect for a number of counties in western North Carolina. The National Weather Service Forecast Office in Greenville-Spartanburg, South Carolina issued a Flash Flood Emergency for areas downstream of the Lake Tahoma Dam in central McDowell County, North Carolina due to imminent failure of the dam. Flash Flood Watches remained in effect from Georgia to Virginia and westward to the Lower Ohio River Valley.
The core of Tropical Depression Alberto will move northward across Indiana on Wednesday. Bands of showers and thunderstorms will continue to drop heavy rain in the eastern half of the circulation. The greatest risk for flooding will be in locations where bands of heavier rain remain over those areas for several hours. The ground is already very wet in parts of the eastern U.S. Water levels in streams and rivers could rise quickly. Saturated ground could also contribute to potential mudslides in steeper terrain.
Subtropical Storm Alberto made landfall in northwest Florida late on Monday afternoon. According to the National Hurricane Center the center of Subtropical Storm Alberto officially made landfall near Laguna Beach, Florida. At 5:00 p.m. the center of Subtropical Storm Alberto was located at latitude 30.3°N and longitude 85.9°W which put it about 15 miles (25 km) west-northwest of Panama City, Florida. Alberto was moving toward the north at 9 m.p.h. (15 km/h). The maximum sustained wind speed was 45 m.p.h. (75 km/h) and there were wind gusts to 60 m.p.h. (95 km/h). The minimum surface pressure was 994 mb. A Tropical Storm Warning was in effect for the portion of the coast from Aucilla, River, Florida to the border between Florida and Alabama.
Subtropical Storm Alberto weakened slowly as it approached the coast of northwest Florida. Several factors contributed to the weakening of Alberto. Drier air spiraled into the core of the circulation. The drier air inhibited the development of taller thunderstorms in the eastern and southern quadrants of the circulation. Most of the stronger storms developed north and west of the center of circulation. Daytime heating of the land made the atmosphere more unstable and the instability contributed to the development of thunderstorms in rainbands in those parts of Alberto. Subtropical Storm Alberto also mixed cooler water to the surface as it moved slowly toward the coast of Florida. The Sea Surface Temperature near the coast was about 26°C before Subtropical Storm Alberto arrived. However, the layer of warmer water was very thin. The winds caused by Alberto mixed the water in the upper levels of the Gulf of Mexico. The mixing brought cooler water to the surface and the Sea Surface Temperature cooled to near 24°C. The cooler water meant there was less energy to support the circulation around Subtropical Storm Alberto.
The circulation of Subtropical Storm Alberto will weaken slowly as it moves inland. Winds blowing water toward the coast will continue to produce a storm surge of 3 to 4 feet (1 to 1.3 meters) east of the center of circulation for another 12 to 24 hours. A large surface high pressure system over the Atlantic Ocean will steer Subtropical Storm Alberto slowly toward the north during the next several days. Locally heavy rain could produce flooding as Alberto moves northward. Flood Watches have been issued for areas between the Gulf Coast and the Lower Ohio River Valley. Flood Watches have also been issued for places as far east as the Carolinas and Virginia. The risk of flooding is even greater for locations that already received heavy rain from previous weather systems.
The circulation around Tropical Depression Bill brought strong storms to the Lower Ohio River Valley on Friday. At 5:00 p.m. EDT on Friday the center of Tropical Depression Bill was located at latitude 37.1°N and longitude 90.1°W which put it about 30 miles (50 km) west of Cape Girardeau, Missouri. Bill was moving toward the east-northeast at 15 m.p.h. (24 km/h). The maximum sustained wind speed was 25 m.p.h., but there were higher gusts in thunderstorms. The minimum surface pressure was 1004 mb.
The circulation around Tropical Depression Bill retained enough tropical characteristics on Friday to be considered a tropical cyclone. There was still evidence of a warm core in the middle troposphere with a strong center of circulation at the surface and divergent outflow in the upper levels. Spiral bands of showers and thunderstorms continued to rotate cyclonically around the center, and some thunderstorms approached severe criteria. A stationary frontal boundary ran from New Jersey across Ohio to central Missouri. However, the circulation around the tropical depression was south of the boundary and it was clearly a distinct area of low pressure.
Tropical Depression Bill is expected to continue its east-northeasterly motion during the weekend. It will pass south of Ohio on Saturday and cross New Jersey on Sunday. The tropical depression will continue to produce locally heavy rainfall and the potential for isolated severe thunderstorms.
Tropical Depression Bill continued its slow movement over the South Central U.S. on Thursday and it brought rain to Arkansas and southern Missouri. At 11:00 p.m. EDT on Thursday the center of Tropical Depression Bill was located at latitude 35.9°N and longitude 93.8°W which put it about 20 miles (30 km) east of Fayetteville, Arkansas. Bill was moving toward the east-northeast at 10 m.p.h. (16 km/h). The maximum sustained wind speed was 20 m.p.h. (30 km/h) and the minimum surface pressure was 1005 mb.
Even thought the center of Bill has been over land for more than 48 hours, it retains many of the characteristics of a tropical cyclone. It has a well defined cyclonic circulation with a warm core in the middle troposphere and there is upper level divergence. As a result, Bill is still officially classified as a tropical depression.
Bill is moving around the western end of a high pressure system centered over the Atlantic Ocean. It should continue to move toward the east-northeast during the next several days. On its anticipated track Bill will bring rain to northern Arkansas and southern Missouri on Friday. It will move up the Ohio River Valley on Saturday and enhance the rainfall in those areas. The circulation of the tropical depression could merge with a nearly stationary frontal boundary north of the Ohio River during the weekend. Heavy rain falling on saturated ground could create the potential for flooding in some areas.
Tropical Depression Bill moved northward across north Texas on Wednesday and brought heavy rain to parts of Texas and Oklahoma. At 11:00 p.m. EDT on Wednesday the center of Tropical Depression Bill was located at latitude 33.7°N and longitude 97.3°W which put it about 65 miles (105 km) north-northwest of Dallas, Texas. Bill was moving toward the north at 10 m.p.h. (16 km/h). The maximum sustained wind speed was 30 m.p.h. (50 km/h). There were wind gusts to 50 m.p.h. (80 km/h) in some thunderstorms. The minimum surface pressure was 999 mb.
Bill still has a well organized circulation at the surface and throughout the troposphere. There is still a warm core in the middle troposphere and divergence in the upper levels. The upper level divergence pumped out the same amount of mass as converged in the lower levels and the surface pressure remained constant on Wednesday. Some drier air is wrapping around the southern part of the circulation and most of the rain is falling north and east of the center. The slow movement of Bill has generated significant amounts of rain and flooding is occurring in some parts of Texas and Oklahoma. A few thunderstorms have also produced damaging wind gusts.
Bill is expected to turn toward the northeast as is moves around the western end of a high pressure system centered off the southeast coast of the U.S. It will move slowly across Oklahoma on Thursday and across Arkansas on Friday before moving up the Ohio River Valley during the weekend.