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Florence Still Producing Heavy Rain and Floods in Carolinas

Although former Hurricane Florence weakened to a tropical depression on Sunday, it was still producing heavy rain and causing floods in portions of the Carolinas.  At 5:00 p.m. EDT on Sunday the center of Tropical Depression Florence was located at latitude 34.6°N and longitude 82.2°W which put it about 25 miles (40 km) south-southeast of Greenville, South Carolina.  Florence was moving toward the north at 14 m.p.h. (22 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 1006 mb.

Slow movement of Tropical Depression Florence resulted in persistent heavy rain over portions of North Carolina and South Carolina.  The National Weather Service Office in Newport/Morehead City, North Carolina measured 25.20 inches (64.0 cm) of rain with Florence.  The airport in Wilmington, North Carolina measured 23.59 inches (59.9 cm) of rain.  A Remotely operated Automated Weather Station (RAWS) in Marion, South Carolina measured 18.13 inches (46.0 cm) of rain.  There were reports of up to ten inches (25.4 cm) at some locations around Charlotte, North Carolina.  Runoff of the persistent heavy rain has caused floods in many locations.  The Cape Fear River near Chinquapin, North Carolina has risen above the previous record flood level.  Parts of the Cape Fear River, Neuse River, Trent River and Lumber River are at major flood levels.  Minor and moderate flooding is occurring in numerous other places around North Carolina and South Carolina.

Tropical Depression Florence has started to move toward the north.  Florence will move into western Carolina on Sunday night.  It will move over eastern Tennessee, western Virginia, eastern Kentucky, and West Virginia on its way toward Ohio on Monday.  One primary rainband on the eastern side of the circulation will continue to drop heavy rain over parts of eastern South Carolina for a few more hours.  Convergence into the low will produce heavy rain that could move into western Virginia and West Virginia on Monday.  Flash Flood Watches have been issued for South Carolina, North Carolina, western Virginia and southern West Virginia.

Hurricane Florence Moves Closer to the Carolinas

Hurricane Florence moved closer to the Carolinas on Wednesday.  At 11:00 p.m. EDT on Wednesday the center of Hurricane Florence was located at latitude 32.0°N and longitude 73.7°W which put it about 280 miles (455 km) east-southeast of Wilmington, North Carolina.  Florence was moving toward the northwest at 17 m.p.h. (28 km/h).  The maximum sustained wind speed was 110 m.p.h. (175 km/h) and there were wind gusts to 130 m.p.h. (210 km/h).  The minimum surface pressure was 957 mb.

A Hurricane Warning was in effect for the portion of the coast from South Santee River, South Carolina to Duck, North Carolina including Pamlico and Albemarle Sounds.  A Hurricane Watch was in effect for the portion of the coast from Edisto Beach, South Carolina to South Santee River, South Carolina.  A Tropical Storm Warning is in effect for the portion of coast from Duck, North Carolina to the North Carolina-Virginia border.  A Tropical Storm Watch was in effect for the portion of the coast from the North Carolina-Virginia border to Cape Charles Light, Virginia and for Chesapeake Bay south of New Point Comfort.

The wind speed in Hurricane Florence decreased on Wednesday but the circulation increased in size.  It appeared that another eyewall replacement cycle could have started.  Satellite microwave images suggested that there could be two eyewalls and a reconnaissance plane reported a double wind maxima.  Both of those things could be evidence of concentric eyewalls.  In addition, counterclockwise flow around a small upper level low near Florida may have produced southerly winds that blew toward the south side of Hurricane Frances.  Those winds may have inhibited the upper level divergence to the south of Florence.  Since the hurricane was unable to pump out as much mass, the surface pressure increased and the wind speed decreased.

The circulation of Hurricane Florence increased in size on Wednesday.  Winds to hurricane force extended out about 80 miles (130 km) from the center of circulation.  Winds to tropical storm force extended out about 200 miles (320 km) from the center.  The Hurricane Intensity Index (HII) for Hurricane Florence was 19.2.  The Hurricane Size Index (HSI) was 25.5 and the Hurricane Wind Intensity Size Index (HWISI) was 44.7.  Those indices are very similar to the numbers for Hurricane Jeanne just before Jeanne made landfall in southeast Florida in 2004.

Hurricane Florence will move through an environment favorable for intensification on Thursday.  Florence will move over water where the Sea Surface Temperature is near 29°C.  Florence will move farther away from the upper low near Florida and the low should not inhibit divergence to the south of the hurricane as much.  In addition, Hurricane Florence will move over the warm water in the Gulf Stream about 6 to 12 hours before it reaches the coast.  It will be able to extract extra energy at that time.  If the inner core becomes more organized, then Hurricane Florence could intensify on Thursday.  If the inner core does not get better organized, then Florence will likely maintain its current intensity or weaken slowly.

Hurricane Florence will move near the western end of the subtropical high pressure system over the western Atlantic Ocean.  The high will steer Florence toward the northwest on Thursday.  On its anticipated track the center of Hurricane Florence will be near the coast of North Carolina on Thursday night.  A ridge over the eastern U.S. is likely to block the northward motion of Hurricane Florence when it reaches the coast.  The ridge will steer Florence slowly toward the west-southwest on Friday and Saturday.

Hurricane Florence will have the impact of a major hurricane regardless of the actual sustained wind speed.  The large circulation and slow rate of movement when Florence reaches the coast means that locations could experience strong winds for extended periods of time.  Wind damage and power outages could be extensive.  Some places in North Carolina had a rainy summer and strong winds could uproot trees.  Hurricane Florence will produce a dangerous storm surge along the coast.  The surge could exceed 10 feet (3 meters) in some locations east of where the center makes landfall.  The slow forward speed also means that Hurricane Florence could drop locally heavy rain and severe flooding could occur.

Elsewhere the rest of the Atlantic Ocean was also very active.  Tropical Storm Isaac was nearing the Lesser Antilles, Hurricane Helene was weakening south of the Azores and Subtropical Storm Joyce formed northwest of Helene.

At 11:00 p.m. EDT on Thursday the center of Tropical Storm Isaac was located at latitude 15.3°N and longitude 58.0°W which put it about 220 miles (355 km) east of Dominica.  Isaac was moving toward the west at 20 m.p.h. (32 km/h).  The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 65 m.p.h. (105 km/h).  The minimum surface pressure was 1006 mb.  Tropical Storm Warnings were in effect for Guadeloupe, Martinique and Dominica.  Tropical Storm Watches were in effect for Antigua, Montserrat, St, Kitts and Nevis, Saba and St. Eustatius, St. Martin and St. Maarten.

At 11:00 p.m. EDT on Thursday the center of Hurricane Helene was located at latitude 22.4°N and 36.9°W which put it about 1270 mile (2045 km) south-southwest of the Azores.  Helene was moving toward the north at 13 m.p.h. (20 km/h).  The maximum sustained wind speed was 80 m.p.h. (130 km/h) and there were wind gusts to 95 m.p.h. (155 km/h).  The minimum surface pressure was 983 mb.

At 11:00 p.m. EDT on Thursday the center of Subtropical Storm Joyce was located at latitude 15.3°N and longitude 46.6°W which put it about 910 miles (1465 km) west-southwest of the Azores.  Joyce was moving toward the southwest at 6 m.p.h. (10 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 1006 mb.

Unusual Tropical Depression Alberto Reaches Michigan

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 Drops Heavy Rain Over Southeast U.S.

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 Makes Landfall in Northwest Florida

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.

System Could Bring Heavy Rain to Southeast U.S.

A weather system over the southeastern Gulf of Mexico could bring heavy rain to the southeastern U.S. this week.  An upper level low over the eastern Gulf of Mexico could transfer enough kinetic energy down to the lower troposphere to spin up a low at the surface.  Air flowing around the eastern side of the low is contributing to upper level divergence over Florida.  The divergence enhanced rising motion over Florida and rain fell over parts of the southern and central portions of that state.

The weather system is forecast to move slowly northward during the next several days.  The Sea Surface Temperatures in the southeastern Gulf of Mexico are 24°C to 26°C.  There is enough energy in the upper levels of the water to support the formation of a tropical cyclone.  The upper level low will create southerly winds which will cause moderate vertical wind shear.  The shear will inhibit development, although those winds could contribute to upper level divergence to the east of the weather system.  Upper level divergence could allow the surface pressure to decrease and a low pressure system could form at the surface.  The National Hurricane Center (NHC) issued a special Tropical Weather Outlook on Sunday afternoon on the weather system.  NHC indicated the probability was 40% that a tropical or subtropical cyclone could form during the next five days.

Guidance from numerical models suggest that the weather system will move slowly northward over the eastern Gulf of Mexico during the next few days.  Counterclockwise rotation around the low will transport moist air northward on the eastern side of the low.  The moist air combined with upper level divergence will create the potential for locally heavy rainfall over the southeastern U.S.  Heavy rain could result in floods in some locations.

Hurricane Nate Brings Gusty Winds and Surge to Mississippi Coast

Hurricane Nate brought gusty winds, heavy rain and a storm surge to the coast of Mississippi on Saturday night.  At 11:00 p.m. EDT on Saturday the center of Hurricane Nate was located at latitude 29.9°N and longitude 89.1°W which put it about 35 miles (60 km) south-southwest of Biloxi, Mississippi.  Nate was moving toward the north at 20 m.p.h. (32 km/h).  The maximum sustained wind speed was 85 m.p.h. (140 km/h) and there were wind gusts to 100 m.p.h. (160 km/h).  The minimum surface pressure was 983 mb.

A Hurricane Warning was in effect for the portion of the coast from the mouth of the Pearl River to the Alabama/Florida border.  Tropical Storm Warnings were in effect for the portion of the coast from Grand Isle, Louisiana to the mouth of the Pearl River, for New Orleans and Lake Pontchartrain and for the coast from the Alabama/Florida border to Indian Pass, Florida.

Some drier air wrapped into the western side of Hurricane Nate on Saturday afternoon.  In addition an upper level trough approaching Nate from the west produced southwesterly winds which caused vertical wind shear.  The drier air and shear caused the circulation of Hurricane Nate to become asymmetrical.  The stronger winds are occurring in the eastern half of the circulation.  The winds are weaker in the western side of the hurricane.  The bands of showers and thunderstorms are also occurring in the eastern half of Hurricane Nate.  Very little rain was falling on the western side of the hurricane.

The partial eyewall north of the center of Hurricane Nate was moving over the coast of Mississippi from Pascagoula to Gulfport.  Strong gusty winds and heavy rain were falling on that section of the coast.  Winds blowing water toward the coast were pushing a storm surge onto the coast.  A water level gauge at a NOAA laboratory in Pascagoula, Mississippi was reporting a storm surge of 6.75 feet (2.06 meters).  The highest surges were occurring in Mississippi, but there were also storm surges on the coast of Alabama and Florida.  Bands of showers and thunderstorms were dropping heavy rain over southeastern Mississippi, southwestern and central Alabama and northwestern Florida.  Brief tornadoes spun up in some of the thunderstorms on Saturday.

Hurricane Nate will move inland over southeastern Mississippi during the overnight hours.  Nate will weaken after it moves inland, but it will continue to bring gusty winds as it spins down.  There is a strong flow of moist air from the south and heavy rain will continue to fall east of the track of Hurricane Nate.  Places west of the track will experience weaker winds and will receive little rain.  Locations west of a line from New Orleans to Hattiesburg to Meridian,  Mississippi could see little minimal impacts from Nate.  Nate will cross over west central Alabama on Sunday morning.  It will continue to move toward the north-northeast and the remnants of Nate could reach eastern Tennessee on Sunday night.  Areas of heavy rain will fall over northwestern Florida, Alabama, northern Georgia, eastern Tennessee and western North Carolina.  Fresh water flooding could occur in some of those areas.  Tornadoes could develop in the rainbands again on Sunday afternoon.

Tropical Storm Irma Still Bringing Gusty Winds and Storm Surges to Southeast U.S.

Tropical Storm Irma was still bringing gusty winds, locally heavy rain and storm surges to parts of the Southeastern U.S. on Monday afternoon.  Gusty winds were blowing down trees and bringing down power lines in parts of Florida, Georgia, South Carolina and North Carolina.  Locally heavy rainfall resulted in the issuance of Flood Watches and Warnings for portions of those states.  Strong winds were blowing water toward the coast in northeastern Florida, Georgia and South Carolina.  Storm surges caused flooding in Jacksonville, Florida and Savannah, Georgia.  The water level at Charleston, South Carolina was higher than it was during Hurricane Matthew in 2016.

At 5:00 p.m. EDT on Monday the center of Tropical Storm Irma was located at latitude 31.5°N and longitude 84.0°W which put it about 10 miles (15 km) east of Albany, Georgia.  Irma was moving toward the north-northwest at 17 m.p.h.  The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 65 m.p.h. (105 km/h).  The minimum surface pressure was 985 mb.

A Tropical Storm Warning remained in effect for the portion of the coast from Altamaha Sound to South Santee River.

The structure of Tropical Storm Irma evolved as it moved further inland.  Drier air wrapped around the  western side of the circulation.  Convergence between a large surface high north of Irma and the tropical storm produced heavy rain northeast of the center of circulation.  The heaviest rain fell over Georgia, South Carolina and the western half of North Carolina.  The northern edge of the rain shield was moving over Tennessee and southeast Kentucky.  The pressure difference between the high and Irma also generated strong winds in the eastern half of Irma’s circulation.  Those strong winds pushed water toward the coast in northern Florida, Georgia and South Carolina.  The wind caused storm surges of up to 10 feet (3 meters) in some locations.  Water was reported in parts of downtown Jacksonville, Florida and Charleston, South Carolina.

Tropical Storm Irma will continue to move toward the north-northwest and weaken.  The circulation of Irma is very large, and it will take a few more days to spin completely.  There could be stronger winds in the high elevations of Appalachian Mountains.  Locally heavy rain could also create the potential for floods in some valleys.  The storm surges along the coast should gradually subside as the wind speeds decrease.

Elsewhere, Hurricane Jose was moving northward east of the Bahamas.  At 5:00 p.m. EDT on Monday the center of Hurricane Jose was located at latitude 31.5°N and longitude 84.0°W which put it about 555 miles (895 km) east of Nassau, Bahamas.  Jose was moving toward the north at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 100 m.p.h. (160 km/h) and there were wind gusts to 120 m.p.h. (195 km/h).  The minimum surface pressure was 973 mb.  Hurricane Jose is forecast to make a slow clockwise loop this week.  On it anticipated track Hurricane Jose could still be east of the Bahamas at the end of the week.

Hurricane Irma Makes Landfall on Marco Island, Florida

The center of Hurricane Irma made landfall on the coast at Marco Island, Florida on Sunday afternoon.  The Marco Island Emergency Operations Center reported a wind gust to 135 m.p.h. (217 km/h) when the northern portion of the eyewall passed over.  The airport at Naples, Florida reported sustained winds to 88 m.p.h. (142 km/h) and wind gusts to 135 m.p.h. (217 km/h).

At 5:00 p.m. EDT on Sunday the center of Hurricane Irma was located at latitude 26.2°N and longitude 81.8°W which put it about 5 miles (10 km) north of Naples, Florida.  Irma was moving toward the north at 14 m.p.h. (22 km/h).  The maximum sustained wind speed was 110 m.p.h. (175 km/h) and there were wind gusts to 130 m.p.h. (210 km/h).  The minimum surface pressure was 938 mb.

A Hurricane Warning was in effect for the portion of the coast from Fernandina Beach to Indian Pass, Florida including the Florida Keys and Lake Okeechobee.  A Hurricane Watch was in effect from Fernandina Beach, Florida to Edisto Beach, South Carolina.  A Tropical Storm Warning was in effect for the portion of the coast from Fernandina Beach, Florida to the South Santee River, South Carolina and from Indian Pass, Florida to the Okaloosa/Walton County line.  A Tropical Storm Watch was in effect for Bimini and Grand Bahama Island.

The intensity of Hurricane Irma decreased gradually on Sunday.  The hurricane began to pull in some drier air over the southeastern U.S. into the west side of the circulation.  In addition an upper level trough over the eastern U.S. caused an increase in the vertical wind shear.  The drier air and increased shear also produced a more asymmetrical wind field around Hurricane Irma.  The area of stronger winds was much larger in the eastern half of the circulation than it was on the western half of the circulation.  Winds to hurricane force extended out 80 miles (130 km) from the center of circulation.  Winds to tropical storm force extended out about 220 miles (350 km) from the center.

Hurricane Irma will gradually weaken as it moves northward over Florida.  Irma is a large hurricane and it will spin down slowly.  Hurricane Irma will move steadily northward.  Irma is forecast to still be a hurricane when the center moves near Tampa and Central Florida.  Hurricane Irma is capable of causing widespread significant wind damage.  Isolated tornadoes could develop in thunderstorms in the outer rainbands.  Hurricane Irma will produce storm surges over a long section of the coast.  There was not much surge on the west coast of Florida on Sunday afternoon, because the winds were blowing the water away from the coast.  However, after the center moves north of an area, the wind will blow from the opposite direction and the water will rise quickly at the coast.  A station on the coast near Naples, Florida reported a water rise of six feet (two meters) in less than two hours after the center of Hurricane passed to the east.  Easterly winds on the eastern fringe of Hurricane Irma were blowing the water toward the coast and there were water rises from Miami, Florida to Charleston, South Carolina.  Strong southwesterly winds were still causing storm surges in the Florida Keys.  Hurricane Irma will also drop heavy rain over a prolonged period and it could cause freshwater flooding of rivers and streams.

Elsewhere over the tropical Atlantic Hurricane Jose moved away from the northern Leeward Islands on Sunday.  At 5:00 p.m. EDT om Sunday the center of Hurricane Jose was located at latitude 22.8°N and longitude 66.9°W which put it about 285 miles (455 km) east-northeast of Grand Turk Island.  Jose was moving toward northwest at 16 m.p.h. (26 km/h).  The maximum sustained wind speed was 120 m.p.h. (195 km/h) and there were wind gusts to 140 m.p.h. (225 km/h).  Hurricane Jose is forecast to stall over the tropical Atlantic east of the Bahamas and it could make a long slow loop during the next week.

Tropical Storm Harvey Moves Into Louisiana, Irma Strengthens Quickly

Tropical Storm Harvey finally moved into Louisiana on Wednesday after lingering for several days over the northwestern Gulf of Mexico.  Harvey weakened to a tropical depression after it moved inland.  At the same time a new tropical storm named Irma strengthened quickly over the eastern Atlantic Ocean.  At 11:00 p.m. EDT on Wednesday the center of Tropical Depression Harvey was located at latitude 31.7°N and longitude 92.3°W which put it about 30 miles (50 km) north-northeast of Alexandria, Louisiana.  Harvey was moving toward the north-northeast at 9 m.p.h. (15 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 998 mb.

After dropping record rainfall and causing destructive floods of parts of southeastern Texas and western Louisiana, Tropical Depression Harvey finally started to move steadily toward the north-northeast on Wednesday.  Harvey was still producing heavy rain over parts of western Louisiana, but the fact that it was moving should limit the total rainfall at any location.  Bands of showers and thunderstorms on the far eastern periphery of Harvey’s circulation were also dropping heavy rain.  Some of those thunderstorms were strong enough to approach severe criteria.  Tropical Depression Harvey is forecast to move toward the Ohio River Valley during the next several days and it will bring windy, wet weather to the Middle Mississippi and Ohio River Valleys.  Rain associated with the circulation of Tropical Depression Harvey could also reach the Mid-Atlantic States later this week.

At 11:00 p.m. EDT on Wednesday the center of Tropical Storm Irma was located at latitude 16.4°N and longitude 32.2°W which put it about 545 miles (875 km) west of the Cabo Verde Islands.  Irma was moving toward the west at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 65 m.p.h. (105 km/h) and there were wind gusts to 80 m.p.h. (130 km/h).  The minimum surface pressure was 999 mb.

The circulation of Tropical Storm Irma organized quickly on Wednesday.  Numerous bands of showers and thunderstorms formed and began to revolve around a well organized center of circulation.  Thunderstorms in the core of Irma generated well developed upper level divergence which pumped away mass in all direction.  There were occasional satellite images which hinted that an eye could be forming at the center of Tropical Storm Irma.

Tropical Storm Irma will be moving through an environment that will be favorable for intensification.  Irma will move over water where the Sea Surface Temperature is near 28°C.  The upper level winds are weak and there is little vertical wind shear.  Irma is likely to become a hurricane on Thursday and it could intensify rapidly if an eye forms.  Tropical Storm Irma is forecast to become a major hurricane and it could become one of the big classic Cape Verde hurricanes.

A strong subtropical high to the north of Irma is steering the tropical storm toward the west and a general westerly motion is forecast to continue for the next few days.  There is more divergence in the model guidance after a few days and the future track of Irma when it nears the Lesser Antilles is more uncertain.  Tropical Storm Irma has the potential to become a big dangerous hurricane and it will need to be watched carefully.