On Monday morning, September 9, Hurricane Dorian was a post-tropical storm after a mid-latitude weather front and cold seas had altered its tropical characteristics over the weekend. NASA compiled data on Hurricane Dorian and created a map that showed the heavy rainfall totals it left in its wake from the Bahamas to Canada.
On Saturday and Sunday, Sept. 7 and 8, Hurricane Dorian struck eastern Canada, causing wind damage and bringing heavy rainfall. According to the Associated Press, a peak of 400,000 people were without power in Nova Scotia, Canada, because of Dorian.
At NASA’s Goddard Space Flight Center in Greenbelt, Maryland, a graphic was produced that shows precipitation that fell during the almost two-week period from August 27 to the early hours of Sept. 9. The near-real-time rain estimates come from the NASA’s IMERG algorithm, which combines observations from a fleet of satellites, in near real time, to provide near-global estimates of precipitation every 30 minutes.
This year, NASA began running an improved version of the IMERG algorithm that does a better job estimating precipitation at high latitudes, specifically north of 60 degrees North latitude. The post-tropical remnants of Hurricane Dorian were approaching this cold region at the end of the analysis period. While the IMERG algorithm is still unable to estimate precipitation falling over ice-covered surfaces (such as Greenland), IMERG can now give a more complete picture of the water cycle in places such as Canada, which is, for the most part, free of snow cover at this time of year.
In addition to rainfall totals, the map includes preliminary reports of tornadoes from 4:50 AM to 5:00 PM EDT on September 5 in North Carolina as provided by NOAA’s Storm Prediction Center.
IMERG showed largest rainfall amounts of more than 36 inches over the Bahamas and in an area off the coast of northeastern Florida. A large area of rainfall between 16 and 24 inches fell in many areas off the U.S. East Coast. Areas include those from South Carolina to the Bahamas, another off the North Carolina coast, a third area off the coasts of southern New Jersey, Delaware and Maryland, and the New England states.
By combining NASA precipitation estimates with other data sources, we can gain a greater understanding of major storms that affect our planet.
On Monday, Sept. 9 at 0300 UTC (Sept. 8 a t 11 p.m. EDT), NOAA’s National Hurricane Center (NHC) issued the final advisory on Dorian. At that time, Dorian had moved into the Labrador Sea and its impacts on Newfoundland were beginning to subside. Post-tropical cyclone Dorian had maximum sustained winds near 50 knots (57 mph/93 kph). It was centered near 52.1 degrees north latitude and 53.4 degrees west longitude. That puts the center about 375 miles north of Cape Race, Newfoundland, Canada. Dorian was speeding to the east-northeast at 21 knots. Minimum central pressure was 980 millibars.
On Sept. 9, additional rainfall totals expected from Dorian in far eastern Quebec, Newfoundland and Labrador are expected to be less than 1 inch. Meanwhile, life-threatening rip tide and surf conditions are expected to affect mid-Atlantic and New England coasts of the U.S., as well as the coast of Atlantic Canada.
The NHC said the cyclone will continue into the open Atlantic, where it will dissipate south of Greenland.
Sep. 08, 2019 – NASA Sees Post-Tropical Cyclone Dorian Over Eastern Canada
NASA’s Aqua satellite provided an infrared look at Post-Tropical Cyclone Dorian lashing parts of eastern Canada.
A tropical cyclone is the general name for a hurricane, tropical storm, depression or typhoon. NASA provides data and research on tropical cyclones to analyze intensification, weakening, structure, and behavior. NOAA’s National Hurricane Center uses that data in their forecasts.
NASA’s Views of Dorian Before and After Landfall
Instruments aboard NASA’s Aqua satellite use visible, microwave and infrared light to analyze various aspects of a tropical cyclone.
On Sept. 7 at 1:30 p.m. EDT (1730 UTC), the MODIS instrument that flies aboard NASA’s Aqua satellite provided a visible image that clearly showed Dorian’s center just south of Nova Scotia, Canada.
Dorian moved north and five hours later, Post-Tropical Dorian made landfall at 6:15 p.m. EDT near Sambro Creek in Nova Scotia, Canada, or about 15 miles (25 km) south of Halifax. The estimated maximum sustained winds at landfall were 100 mph (155 kph) and the estimated central pressure was 958 millibars.
After Dorian had crossed over Nova Scotia, at 2 a.m. EDT on Sept. 8, it was centered about 5 miles (10 km) north of the Magdalen Islands, near latitude 47.5 degrees north and longitude 61.8 degrees west in the Gulf of St. Lawrence.
NASA’s Aqua satellite passed over Dorian again and looked at the storm in infrared light. NASA uses infrared light to analyze the strength of storms by providing temperature information about the system’s clouds. The strongest thunderstorms that reach high into the atmosphere have the coldest cloud top temperatures.
On Sept. 8 at 3:05 a.m. EDT (0705 UTC), the Moderate Imaging Spectroradiometer or MODIS instrument that flies aboard NASA’s Aqua satellite gathered infrared data on Dorian and showed the storm bringing rains and gusty winds to areas of Newfoundland, Labrador, Quebec south, Prince Edward Island and Nova Scotia. MODIS showed thunderstorms had cloud top temperatures as cold as minus 50 degrees Fahrenheit (minus 45.5 Celsius).
What is a Post-Tropical Storm?
A Post-Tropical Storm is a generic term for a former tropical cyclone that no longer possesses sufficient tropical characteristics to be considered a tropical cyclone. Former tropical cyclones that have become fully extratropical, subtropical, or remnant low pressure areas, are three classes of post-tropical cyclones. In any case, they no longer possesses sufficient tropical characteristics to be considered a tropical cyclone. However, post-tropical cyclones can continue carrying heavy rains and high winds.
Warnings and Watches on Sept. 8, 2019
NOAA’s National Hurricane Center (NHC) noted on Sept. 8 that a Hurricane Warning is in effect for eastern Nova Scotia from Ecum Secum to Brule, and western Newfoundland from Indian Harbour to Hawke’s Bay. A Hurricane Watch is in effect for the Magdalen Islands. A Tropical Storm Warning is in effect for Prince Edward Island, Magdalen Islands, from Stone’s Cove to Indian Harbour, from Hawke’s Bay to Fogo Island and from Mutton Bay to Mary’s Harbour.
The Canadian Meteorological Service issued many warnings and watches on Sunday, September 8, 2019 for Newfoundland, Labrador, Quebec south, Prince Edward Island and Nova Scotia.
NHC noted that at 8 a.m. EDT (1200 UTC), the center of Post-Tropical Cyclone Dorian was located near latitude 49.4 degrees north and longitude 60.6 degrees west. Dorian’s center was about 55 miles (90 km) east-northeast of Heath Point, Anticosti Island, Canada, and about 90 miles (145 km) northwest of Cape St. George, Newfoundland, Canada. A sustained wind of 55 mph (89 km/h) with a gust to 73 mph (117 kph) was reported at Heath Point on Anticosti Island.
The post-tropical cyclone is moving toward the north-northeast near 26 mph (43 kph), and this general motion with a turn to the northeast is expected during the next couple of days. Maximum sustained winds are near 80 mph (130 kph) with higher gusts. These winds are occurring mainly over water. The post-tropical cyclone is forecast to drop below hurricane strength after passing Newfoundland later today.
The estimated minimum central pressure is 961 millibars.
What’s Next for Dorian?
Dorian is expected to remain a powerful storm through this afternoon, but the global models show steady weakening after the center moves northeast of Newfoundland tonight. Forecasters at NHC said “Dorian should continue north-northeastward today, then turn east-northeastward over the North Atlantic as it remains embedded within the mid-latitude westerlies.”
The forecast track takes Dorian south of Greenland on its trek across the Northern Atlantic. The post-tropical cyclone should should be absorbed by another extratropical low over the North Atlantic in 2 to 3 days.
Sept. 7, 2019 – Update #3 – NASA Finds Dorian Transitioning to an Extra-Tropical Cyclone
NASA satellites provided forecasters at the National Hurricane Center with infrared data and cloud top temperature information for Hurricane Dorian. Infrared data revealed that Dorian was becoming an extra-tropical cyclone as it moved northeast along the U.S. east coast and the area of strong storms had diminished around the storm.
NASA researches tropical cyclones and infrared data is one of the ways NASA uses. Cloud top temperatures provide information to forecasters about where the strongest storms are located within a tropical cyclone. The stronger the storms, the higher they extend into the troposphere, and they have the colder cloud temperatures.
On Sept. 6, at 2:23 p.m. EDT (1823 UTC), NASA’s Aqua satellite analyzed the storm using the Atmospheric Infrared Sounder or AIRS instrument. AIRS found coldest cloud top temperatures as cold as or colder than minus 80 degrees Fahrenheit (minus 62.2 degrees Celsius) circling around the center (eye) and in a thick band of thunderstorms northeast of the center. NASA research has shown that cloud top temperatures that cold indicate strong storms that have the capability to create heavy rain.
On Sept. 7 at 3 a.m. EDT (0700 UTC), it was NASA-NOAA’s Suomi NPP satellite that provided an infrared view of Hurricane Dorian as it was transitioning into an extra-tropical storm. Strongest storms had cloud top temperatures as cold as or colder than minus 80 degrees Fahrenheit (minus 62.2 degrees Celsius) where the heaviest rain was falling over the open waters of the Atlantic Ocean. Those storms were now limited to the southern side of the storm, unlike the previous day, when they circled the eye.
NOAA’s National Hurricane Center’s (NHC) discussion said “Satellite imagery this morning [Sept. 7] indicates that Dorian is starting extratropical transition, with cold air clouds entraining [moving] into the southwestern side of the cyclone and a developing warm front to the north and east.”
What is an Extra-Tropical Cyclone?
When a storm transitions into an extra-tropical cyclone, it means that a tropical cyclone has lost its tropical characteristics. The National Hurricane Center defines “extra-tropical” as a transition that implies both poleward displacement (meaning it moves toward the north or south pole) and the conversion of the cyclone’s primary energy source from the release of latent heat of condensation to baroclinic (the temperature contrast between warm and cold air masses) processes. It is important to note that cyclones can become extratropical and still retain winds of hurricane or tropical storm force.
Warnings and Watches in Effect on Sept. 7
NOAA’s National Hurricane Center’s (NHC) continued to issue warnings and watches as Dorian makes its way toward Canada today. A Hurricane Warning is in effect for eastern Nova Scotia from lower east Pubnico to Brule, and for western Newfoundland from Indian Harbour to Hawke’s Bay, Canada. A Hurricane Watch is in effect for Prince Edward Island and the Magdalen Islands.
A Tropical Storm Warning is in effect from east of Bar Harbor to Eastport, ME, and for Prince Edward Island, Canada. It is also in effect for southwestern Nova Scotia from Avonport to north of Lower East Pubnico, Fundy National Park to Shediac, Stone’s Cove to Indian Harbour, Hawke’s Bay to Fogo Island and from Mutton Bay to Mary’s Harbour, Canada.
Status of Hurricane Dorian on Saturday, September 7, 2019
On Saturday, September 7, 2019 at 11 a.m. EDT (1500 UTC), the center of Hurricane Dorian was located near latitude 42.0 degrees north and longitude 66.0 degrees west.
Dorian’s center is about 205 miles (330 km) south-southeast of Eastport, Maine and about 215 miles (350 km) southwest of Halifax, Nova Scotia, Canada.
The NHC said Dorian is moving toward the northeast near 29 mph (46 kph), and a general motion toward the northeast is expected to continue through Sunday night. Maximum sustained winds are near 85 mph (140 kph) with higher gusts. Dorian is expected to become a hurricane-force post-tropical cyclone as it moves across eastern Canada tonight or on Sunday, Sept. 8. The estimated minimum central pressure is 953 millibars.
What’s Next for Dorian?
Dorian is expected to finish transition into an extratropical cyclone over the next day as it merges with a strong mid- to upper-level trough (elongated area of low pressure) and its associated surface front.
On the NHC forecast track, the center of Dorian is expected to move across central or eastern Nova Scotia this afternoon or this evening, pass near or over Prince Edward Island tonight, and then move near or over portions of Newfoundland and Labrador on Sunday.
Sep. 07, 2019 – Update #2 – In the Wake of Hurricane Dorian
In the first week of September 2019, Hurricane Dorian left a path of destruction from the Caribbean to the Canadian Maritimes. Reaching category 5 strength for nearly two days and sustaining major hurricane status from August 30 to September 3, the storm devastated the northern Bahama Islands, strafed the southeast U.S. coast, and arrived in Nova Scotia as one of the five strongest hurricanes on record for that region.
The images above provide a broad view of the devastation in the northern Bahamas, which were lashed for nearly 40 hours by the second strongest Atlantic hurricane in modern meteorological records. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite acquired these natural-color images of Great Abaco Island and Grand Bahama on August 17 and September 7, 2019. Note the change in the color of the island landscape from green to brown, as well as the brightening of the reefs and shoals around the island due to sediments stirred up by the storm.
The widespread browning of Great Abaco and Grand Bahama could have several causes. Many trees were uprooted and destroyed by the storm, and some species of vegetation in the tropics have evolved to lose leaves and small branches in strong winds. The loss of leafy vegetation would give the satellite a view of more bare ground. Another possibility is that salt spray whipped up by the hurricane coated and desiccated some leaves while they were still on the trees.
Government officials from the Bahamas have reported at least 40 deaths, according to news accounts, though the number is expected to rise after search and rescue operations are complete. Hundreds of people are missing and an estimated 70,000 are homeless. Few areas have electric power or running water. National and international relief supplies are just beginning to arrive in the area, though transportation is difficult.
At the other end of the storm track, Dorian brought destructive winds and waves 1500 miles (2400 kilometers) to the north. After transitioning to an extra-tropical cyclone, the storm made landfall in Nova Scotia on the evening of September 7 at category 2 strength. Maximum wind speeds approached 100 miles (160 kilometers) per hour at the coast. According to Weather Underground, hurricane-force winds extended 115 miles (185 kilometers) from the center of the storm, and tropical storm-force winds extended 300 miles (500 kilometers).
According to news reports, Dorian knocked out power to more than 500,000 customers in the Canadian Maritime Provinces, including Nova Scotia. A near-record storm surge was observed in the harbor at Halifax and along the coast of New Brunswick. And according to preliminary weather data, an offshore weather buoy measured a peak wave height of 30.7 meters (100.7 feet) in the open ocean.
Sep. 07, 2019 – Update #1 – NASA Images Temperature of Hurricane Dorian from Space Station
NASA’s ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS) has imaged the temperature of Hurricane Dorian from the International Space Station. ECOSTRESS provides NASA’s highest resolution temperature measurement from space, and is able to map fine detail in temperature patterns from the hurricane. The patterns reveal the small cloud structures that contribute to the formation of the larger hurricane.
The image shows Hurricane Dorian on September 6, 2019 at 5:43 a.m. EDT, as it made landfall in North Carolina. Red colors are hotter temperatures, and purple/blue colors are cooler temperatures. The width of the color image is based on what ECOSTRESS sees as the Space Station flies over any given spot on Earth.
Launched to the International Space Station in June 2018, ECOSTRESS measures the surface temperature of the planet with high detail. ECOSTRESS measures variations in temperatures to within a few tenths of a degree and is able to detect temperature changes at various times of day over areas as small as a single farm. These measurements are used for a wide variety of applications, including plant stress and water use, urban heat, fires, water quality, volcanic activity, and hurricanes.
JPL built and manages the ECOSTRESS mission for NASA’s Earth Science Division in the Science Mission Directorate at NASA Headquarters in Washington. ECOSTRESS is an Earth Venture Instrument mission; the program is managed by NASA’s Earth System Science Pathfinder program at NASA’s Langley Research Center in Hampton, Virginia.
Sep. 06, 2019 – NASA Examines Dorian’s Rainfall, Temperatures Along Carolina Coast
As Hurricane Dorian continued to lash the coast of the Carolinas NASA’s IMERG assessed the rainfall the storm generated and NASA’s Aqua satellite provided a look at the temperatures of the cloud tops to assess strength.
NASA’s IMERG Analyzes Rainfall
By Friday morning, September 6, Hurricane Dorian was located off the coast of North Carolina, having generated tornadoes the previous day as the northern rainband came ashore in North Carolina. NASA’s satellite-based real time precipitation estimates suggest that, during the past day, most of the areas experiencing over 10 inches of rain accumulation remained offshore, while Dorian did drop heavy rain on South Carolina and North Carolina.
IMERG showed largest rainfall amounts of more than 36 inches over the Bahamas and in an area off the coast of northeastern Florida. A large area of rainfall between 16 and 24 inches fell off the coast from South Carolina to the Bahamas and in a small area far off the North Carolina coast.
The National Weather Service in Charleston, South Carolina noted that 3.06” fell yesterday, Sept. 5. In Wilmington, North Carolina, a rainfall record was set when Dorian dropped 8.58 inches. New Bern, North Carolina also set a rainfall record, when Dorian dropped 2.95 inches there.
The near-realtime rain estimates come from the NASA’s IMERG algorithm, which combines observations from a fleet of satellites, in near-realtime, to provide global estimates of precipitation every 30 minutes. The storm-total rainfall at a particular location varies with the forward speed of the hurricane, with the size of the hurricane’s wind field, and with how vigorous the updrafts are inside the hurricane. This graphic only shows precipitation that fell starting at 0000 UTC on September 1, and therefore does not show the precipitation that fell in late August, prior to Hurricane Dorian’s approach to the Bahamas.
More Rainfall Forecast from NHC
Using data from the GPM and other satellites, forecasters can estimate rainfall that Dorian will generate along its path.
The NHC said Dorian is expected to produce the following rainfall totals through Saturday: In northeastern North Carolina and additional 3 to 8 inches is forecast with isolated storm totals to 15 inches. Far southeast Virginia can expect 3 to 8 inches, extreme southeastern New England…2 to 4 inches, Nova Scotia and Prince Edward Island…3 to 5 inches and Newfoundland…1 to 2 inches.
Tornado Possibilities
NHC said a few tornadoes were possible during the morning of Sept. 6 across eastern North Carolina into southeastern Virginia.
As Hurricane Dorian interacted with the U.S. East Coast, the only tornado reports occurred from 4:50 a.m. to 5 p.m. EDT on September 5 in North and South Carolina. Scientists think of a hurricane as a heat engine that converts the warmth of the sun-warmed ocean into the kinetic energy of the hurricane’s strong, horizontal wind. When these strong winds reach land, the increased friction of the land surface vs. the ocean surface can convert some of this kinetic energy into tornadoes within the hurricane.
For information about Dorian’s winds, dangerous surf and storm surge, visit www.nhc.noaa.gov.
NASA’s Aqua Satellite Double View
Two instruments aboard NASA’s Aqua satellite used infrared light to analyze the strength of storms Dorian. Infrared data provides temperature information, and the strongest thunderstorms that reach high into the atmosphere have the coldest cloud top temperatures.
On Sept. 6 at 3:20 a.m. EDT (0720 UTC), NASA’s Aqua satellite provided temperature data on Hurricane Dorian to show where strongest storms were located with cloud top temperatures as cold as minus 70 degrees Fahrenheit (minus 56.6 Celsius).
On Sept. 5 at 8:15 a.m. EDT (1215 UTC), the Moderate Imaging Spectroradiometer or MODIS instrument that flies aboard NASA’s Aqua satellite found strongest thunderstorms had cloud top temperatures as cold as or colder than minus 70 degrees Fahrenheit (minus 56.6 Celsius). Those temperatures were in cloud tops of storms around the low-level center of circulation and in a thick band of thunderstorms that wrapped around the storm from west to north to east. Cloud top temperatures that cold indicate strong storms with the potential to generate heavy rainfall.
A second instrument aboard NASA’s Aqua satellite called the Atmospheric Infrared Sounder or AIRS instrument also provided infrared data. That data was false-colored in an infrared image created at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. AIRS gathered that data on Sept. 6 at 3:17 a.m. EDT (0717 UTC). The strongest storms were mostly over the Atlantic Ocean and east of the center.
Warnings and Watches on Sept. 6
The NHC posted many warnings and watches on Sept. 6. A Storm Surge Warning is in effect for Salter Path, NC to Poquoson, VA, for the Pamlico and Albemarle Sounds, the Neuse and Pamlico Rivers and the Hampton Roads area of Virginia. A Hurricane Warning is in effect from Surf City to the North Carolina/Virginia border and for the Pamlico and Albemarle Sounds. A Hurricane Watch is in effect for Nova Scotia, Canada.
A Tropical Storm Warning is in effect for the North Carolina/Virginia border to Fenwick Island, DE, for the Chesapeake Bay from Drum Point southward, for the Tidal Potomac south of Cobb Island, for Woods Hole to Sagamore Beach, MA, and for Nantucket and Martha’s Vineyard, MA. A Tropical Storm Watch is in effect for Prince Edward Island, Canada, the Magdalen Island, Fundy National Park to Shediac, and Francois to Boat Harbour.
The Hurricane Warning and the Tropical Storm Warning have been discontinued west of Surf City, North Carolina. The Storm Surge Warning south of Salter Path, North Carolina has been discontinued.
Hurricane Dorian’s Eye Near Cape Hatteras on Sept. 6
At 8 a.m. EDT on Sept. 6, the National Hurricane Center said the eye of Dorian was near Cape Hatteras, North Carolina. It was located near latitude 35.2 degrees north and longitude 75.7 degrees west. Dorian is moving toward the northeast near 14 mph (22 km/h) and this general motion with an increase in forward speed is expected through Saturday, Sept. 7.
Maximum sustained winds are near 90 mph (150 kph) with higher gusts. Dorian is forecast to become a post-tropical cyclone with hurricane-force winds by Saturday night as it approaches Nova Scotia, Canada.
The estimated minimum central pressure based on data from the Air Force Hurricane Hunters and surface observations is 956 millibars.
On the NHC forecast track, the center of Dorian should move to the southeast of extreme southeastern New England tonight and Saturday morning, and then across Nova Scotia late Saturday or Saturday night.
Sep. 05, 2019 – Update #2 – NASA Measures Dorian’s Heavy Rainfall from Bahamas to Carolinas
Hurricane Dorian continues to generate tremendous amounts of rainfall, and has left over three feet of rain in some areas of the Bahamas and is now lashing the Carolinas. NASA’s IMERG product provided a look at those rainfall totals.
By Thursday morning, September 5, Hurricane Dorian had dumped heavy rain on coastal South Carolina. An even greater accumulation of over 10 inches was occurring off shore along the path of Dorian’s inner core. In part because of Hurricane Dorian’s forward motion during the past two days, the recent rainfall totals have remained below the 36-inch accumulation observed when Dorian was stalled over the Bahamas.
NASA has the ability to estimate the rainfall rates occurring in a storm or how much rain has fallen. Rainfall imagery was generated using the Integrated Multi-satEllite Retrievals for GPM or IMERG product at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. These near-realtime rain estimates come from the NASA IMERG algorithm, which combines observations from a fleet of satellites in the GPM or Global Precipitation Measurement mission constellation of satellites, and is calibrated with measurements from the GPM Core Observatory as well as rain gauge networks around the world. The measurements are done in near-real time, to provide global estimates of precipitation every 30 minutes.
The storm-total rainfall at a particular location varies with the forward speed of the hurricane, with the size of the hurricane’s wind field, and with how vigorous the updrafts are inside the hurricane.
Warnings and Watches on Sept. 5
NOAA’s National Hurricane Center noted the following warnings and watches on Sept. 5. A Storm Surge Warning is in effect from the Savannah River to Poquoson, VA, Pamlico and Albemarle Sounds, Neuse and Pamlico Rivers and Hampton Roads, VA. A Hurricane Warning is in effect from the Savannah River to the North Carolina/Virginia border and for the Pamlico and Albemarle Sounds. A Tropical Storm Warning is in effect from the North Carolina/Virginia border to Chincoteague, VA, and for the Chesapeake Bay from Smith Point southward. A Tropical Storm Watch is in effect for north of Chincoteague VA to Fenwick Island, DE and the Chesapeake Bay from Smith Point to Drum Point, the Tidal Potomac south of Cobb Island, Woods Hole to Sagamore Beach, MA, Nantucket and Martha’s Vineyard, MA.
NHC: Dorian’s Status on Sept. 5
NHC’s latest bulletin at 8 a.m. EDT (1200 UTC) noted the eye of Hurricane Dorian was located near latitude 32.1 degrees North, longitude 79.3 degrees West. That puts the eye of Dorian about 70 miles (115 km) south-southeast of Charleston, South Carolina. Dorian is now moving toward the north-northeast near 8 mph (13 kph). Maximum sustained winds are near 115 mph (185 km/h) with higher gusts. Dorian is a category 3 hurricane on the Saffir-Simpson Hurricane Wind Scale. Some fluctuations in intensity are expected this morning, followed by slow weakening through Saturday. However, Dorian is expected to remain a hurricane for the next few days. Hurricane-force winds extend outward up to 60 miles (95 km) from the center, and tropical-storm-force winds extend outward up to 195 miles (315 km). Charleston International Airport recently reported a wind gust of 61 mph (98 kph). The estimated minimum central pressure based on Air Force Reserve Hurricane Hunter data is 959 millibars.
Dorian’s Forecast Path
The National Hurricane Center forecast calls for Dorian to turn toward the northeast by tonight, and a northeastward motion at a faster forward speed is forecast on Friday. On the forecast track, the center of Dorian will continue to move close to the coast of South Carolina today, and then move near or over the coast of North Carolina tonight and Friday. The center should move to the southeast of extreme southeastern New England Friday night and Saturday morning, and approach Nova Scotia later on Saturday.
After devastating the Bahamas and grazing Florida and Georgia, Hurricane Dorian rebounded and raked the coast of South Carolina with strong winds, heavy rains, and a storm surge. Wind, falling trees, and flooding damaged power infrastructure in coastal areas of the southeast U.S.
The Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi NPP satellite captured this nighttime composite image as the storm approached the coast at 3:42 a.m. Eastern Time (07:42 UTC) on September 5, 2019. At the time, Dorian packed maximum sustained winds of 115 miles (185 kilometers) per hour and was moving north at 8 miles per hour.
The VIIRS sensor observed thick cloud bands circulating around Dorian’s large eye, the part of the storm with mostly calm weather and the lowest atmospheric pressure. Hurricane eyes average about 20 miles (32 kilometers); the National Hurricane Center reported Dorian’s eye had a diameter of 50 miles (80 kilometers) around the time this image was acquired. Thinner clouds—part of the storm’s higher-level outflow—extended well inland across Georgia, South Carolina, and North Carolina.
The VIIRS image was captured by the sensor’s day-night band, which detects light in a range of wavelengths from green to near-infrared and uses filtering techniques to observe signals such as gas flares, city lights, and reflected moonlight. Infrared observations from VIIRS were used to enhance the visibility of clouds. Optical MODIS satellite data was layered into the image to make it easier to distinguish between ocean and land surfaces.
It is not possible to identify the locations of power outages based on the VIIRS night light image alone. However, as of 2 p.m. on September 5, several utility companies and Poweroutages.us were reporting more than 240,000 outages in South Carolina. The hardest hit area was Charleston County, where companies were reporting more than 130,000 outages.
In the coming days, forecasters expect Dorian to move near or over the coast of North Carolina and then toward New England and Nova Scotia.
Hurricane Dorian dropped excessive rainfall on the Bahamas and NASA calculated the rainfall the storm generated.
“By Wednesday morning, September 4, the rain accumulation from Hurricane Dorian exceeded 36 inches in an area that included parts of Grand Bahama Island and Abaco Island,” said Owen Kelley, researcher at NASA Goddard. “By that time, the Dorian’s center was north of the Bahamas and was moving further north, approximately parallel to Florida’s east coast.”
NASA Estimating Rainfall
NASA has the ability to peer under the clouds of a tropical cyclone and estimate the rainfall rates occurring in a storm or how much rain has fallen. Rainfall imagery was generated using the Integrated Multi-satEllite Retrievals for GPM or IMERG product at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. These near-realtime rain estimates come from the NASA IMERG algorithm, which combines observations from a fleet of satellites in the GPM or Global Precipitation Measurement mission constellation of satellites, and is calibrated with measurements from the GPM Core Observatory as well as rain gauge networks around the world. The measurements are done in near-real time, to provide global estimates of precipitation every 30 minutes.
The storm-total rainfall at a particular location varies with the forward speed of the hurricane, with the size of the hurricane’s wind field, and with how vigorous the updrafts are inside the hurricane.
During the past day, the maximum sustained surface winds speed (Dorian’s intensity) decreased from category 5 to category 2 on the Saffir-Simpson scale. At the same time, the geographic extent of tropical-storm strength winds increased significantly.
Warnings and Watches on Sept. 4
NOAA’s National Hurricane Center (NHC) posted many warnings and watches as Dorian continues to move north along the U.S. East Coast.
A Storm Surge Warning is in effect for Sebastian Inlet, FL to Surf City, NC. A Storm Surge Watch is in effect from north of Surf City, NC to Poquoson, VA, including Hampton Roads, Pamlico and Albemarle Sounds and the Neuse and Pamlico Rivers.
A Hurricane Warning is in effect for Volusia/Brevard County, FL line to Ponte Vedra Beach, FL and from north of the Savannah River to Surf City, NC. A Hurricane Watch is in effect from north of Ponte Vedra Beach, FL to the Savannah River, from north of Surf City, NC to the North Carolina/Virginia border and for the Albemarle and Pamlico Sounds.
A Tropical Storm Warning is in effect from the Sebastian Inlet, FL to the Volusia/Brevard County, FL line and from north of Ponte Vedra Beach, FL to Savannah River. A Tropical Storm Watch is in effect from the North Carolina/Virginia border to Chincoteague, VA and for Chesapeake Bay from Smith Point southward.
NHC: Dorian’s Status on Sept. 4
At 8 EDT (1200 UTC) on Sept. 4, NHC said the center of Hurricane Dorian was located near latitude 29.5 degrees north and longitude 79.6 degrees west. Dorian is about 95 miles (155 km) east-northeast of Daytona Beach, Florida.
Because hurricane-force winds extend outward up to 60 miles (95 km) from the center, and tropical-storm-force winds extend outward up to 175 miles (280 km), Daytona was experiencing those tropical-storm-force winds at 8 a.m. EDT.
Dorian is moving toward the north-northwest near 8 mph (13 kph), and a northwest or north-northwest motion is expected through this morning. Maximum sustained winds are near 105 mph (165 kph) with higher gusts. Some weakening is expected during the next couple of days. However, Dorian is expected to remain a powerful hurricane during the next few days. The minimum central pressure reported by an Air Force Reserve Unit Hurricane Hunter aircraft is 964 millibars.
NOAA’s Forecasts
NHC said, “A turn toward the north is forecast by this evening, followed by a turn toward the north-northeast on Thursday morning. On this track, the core of Hurricane Dorian will move dangerously close to the Florida east coast and the Georgia coast through tonight. The center of Dorian is forecast to move near or over the coast of South Carolina and North Carolina Thursday through Friday morning.”
In the early hours of Tuesday, September 3, Hurricane Dorian had been stationary over the island of Grand Bahama for 18 hours, most of the time as a category 5 hurricane. Storm-total rain accumulation over parts of Grand Bahama and Abaco Islands have exceeded 24 inches according to NASA satellite-based estimates.
On early Tuesday morning, Dorian’s central pressure had risen and its wind intensity had dropped to category 4 on the Saffir-Simpson scale. In addition, Dorian had experienced an eyewall replacement cycle on September 2, so by Tuesday morning Sept. 3, the geographic extent of its tropical-storm-force winds had expanded.
These rain estimates come from the NASA IMERG algorithm, which combines observations from a fleet of satellites, in near-realtime, to provide global estimates of precipitation every 30 minutes. The storm-total rainfall at a particular location varies with the forward speed of the hurricane, with the size of the hurricane’s wind field, and with how vigorous the updrafts are inside of the hurricane’s eyewall.
IMERG, or the Integrated Multi-satellitE Retrievals for GPM (IMERG) data product is generated by NASA’s Precipitation Processing System every half hour with a 6 hour latency from the time of data acquisition. It is produced using data from the satellites in the GPM or Global Precipitation Measurement mission constellation of satellites, and is calibrated with measurements from the GPM Core Observatory as well as rain gauge networks around the world.
IMERG is an example of the research role that NASA has in hurricanes – developing observational tools and building computer models to better understand the behavior of tropical cyclones. NASA’s research data is utilized by NOAA’s National Hurricane Center (NHC) to enhance their forecasts.
On Tuesday, September 3, 2019, at 8 a.m. EDT (1200 UTC), NHC reported at the eye of Hurricane Dorian was located by reconnaissance aircraft and NOAA Doppler radar near latitude 27.1 degrees North and longitude 78.4 degrees West. NHC said Dorian is beginning to move northwestward at about 1 mph (2 kph), and a slightly faster motion toward the northwest or north-northwest is expected later today and tonight.
At present maximum sustained winds are near 120 mph (195 kph) with higher gusts. Dorian is a category 3 hurricane on the Saffir-Simpson Hurricane Wind Scale. Dorian is expected to remain a powerful hurricane during the next couple of days. Hurricane-force winds extend outward up to 45 miles (75 km) from the center, and tropical-storm-force winds extend outward up to 160 miles (260 km). The latest minimum central pressure reported by reconnaissance aircraft is 952 mb (28.11 inches).
NHC forecasts a turn toward the north by Wednesday evening, followed by a turn to the north-northeast Thursday morning. On this track, the core of extremely dangerous Hurricane Dorian will gradually move north of Grand Bahama Island through this evening. The hurricane will then move dangerously close to the Florida east coast late today through Wednesday evening, very near the Georgia and South Carolina coasts Wednesday night and Thursday, and near or over the North Carolina coast late Thursday.
Sep. 02, 2019 – Update #2 4:00 pm EDT – NASA Overhead as Dangerous Hurricane Dorian Takes Aim at Grand Bahamas
Dangerous Hurricane Dorian has weakened slightly and is now a Category 4 storm as it continues to spin over the Bahamas. Dorian has slowed to a crawl in terms of speed of movement only moving at west-northwest at about 1 mph (2 km/h). This means that the Bahamas will continue to get lashed by this monstrous storm and the amount of rainfall totals for the area continue to grow. The National Hurricane Center (NHC) has reported that the eye of the hurricane has begun to wobble a bit over Grand Bahama Island. It is expected to stay over the island for much of the day causing extreme destruction.
Astronaut Christina Koch captured this image from the International Space Station earlier this morning.
NOAA-20 observed Hurricane Dorian at 2:13 am EDT (0613 UTC) on the extreme western edge of the scan (image below). It provided an image of the classic presentation of a strong hurricane, with a nearly symmetrical circulation. Tropospheric gravity waves coming off the convection surrounding the central circulation could be seen in the infrared imagery. The Day Night Band imagery (second image below) showed the general structure of the storm with some lightning streaks. In addition, some possible mesospheric gravity waves seemed to be near the circulation center.
NOAA/NASA’s Suomi NPP satellite flew over Dorian about 50 minutes later at 3:03 am EDT (0703 UTC) and it had the most ideal position for observing the eye of Dorian (image below) . Suomi NPP’s infrared imagery showed the classic presentation of a strong hurricane, though slightly rotated. The lights from the capital city of Nassau could also be seen through the clouds.
The MiRS rain rate product (image below) on NASA NOAA’s Suomi NPP satellite also showed the rain wrapping into the circulation center.
As of the NHC’s update at Dorian is producing maximum sustained winds of 145 mph (230 km/h) with wind gusts of 190 mph (305 km/h). The storm is located latitude 26.8N and longitude 78.4W which is about 25 miles (40 km) northeast of Freeport, Grand Bahama Island and about 105 miles (170 km) east of West Palm Beach, FL. The minimum central pressure is 940 Mb.
Sep. 02, 2019- Update #1 – 9:00am EDT – Destructive Dorian Lashing Grand Bahama Island
Hurricane Dorian is breaking records over the Bahamas as the most destructive hurricane to ever hit the Bahama Islands. Catastrophic winds with gusts over 200 mph are smashing through the islands leaving devastation in their wake. Storm surge of 18 to 23 feet above normal tide levels with higher destructive waves are expected throughout the storm’s passing.
On Dorian’s current track and speed of movement, the core of extremely dangerous Hurricane Dorian will continue to pound Grand Bahama Island through much of today and tonight. The hurricane will move dangerously close to the Florida east coast tonight through Wednesday evening.
NASA’s Global Precipitation Measurement mission (GPM) was on hand to measure the amount of rainfall that the Bahama Islands are experiencing now.
On Monday morning, September 2, Hurricane Dorian was over the island of Grand Bahama as a category 5 storm. As has been the case for the past several days, Dorian’s inner core continues to produce 6 to 14 inches of rain accumulation. Hurricane Dorian’s forward motion has slowed to walking pace, so future updates to this rain-accumulation map may show greater accumulation over Grand Bahama than elsewhere along the storm’s path.
NASA’s Aqua satellite captured this image of Dorian at 2:05 am EDT (0705 UTC) using its AIRS (Atmospheric Infrared Sounder) instrument analyzed temperatures within Hurricane Dorian. Cloud top temperatures within Dorian were as cold as or colder than minus 50 degrees Fahrenheit (minus 45.5 degrees Celsius). Infrared data provides temperature information, and the strongest thunderstorms that reach high into the atmosphere have the coldest cloud top temperatures. In this image, the amount of purple (coldest temperatures) surrounding the eye shows the huge and massive number of thunderstorms that continue to circle around the still very well-defined eye.
At present Dorian is located at latitude 26.7N and longitude 78.3W which is about 30 miles (50 km) east-northeast of Freeport, Grand Bahama Island and about 115 miles (185 km) east of West Palm Beach, FL. Maximum sustained winds are now 165 mph (270 km/h) down from a high of 185 mph (298 km/h). The present movement of storm is west at 1 mph (2 km/h) leaving the storm basically parked in location for hours. The minimum central pressure inside the storm is 916 mb.
Sep. 01, 2019 – Update #3 – 3:00 pm – Devastating Category 5 Hurricane Dorian Makes a Direct Hit on Abaco Islands
The eye of Category 5 Hurricane Dorian was directly over the Abaco Islands as of the National Hurricane Center’s (NHC) 2:00 pm EDT advisory and is now heading towards Grand Bahama Island. The hurricane is located about 185 miles (295 km) east of West Palm Beach, FL. Maximum sustained winds are 185 mph (295 km/h) with gusts over 200 mph. Dorian is moving west at 7 mph. The central pressure is 911 Mb which continues to lower meaning the storm continues to intensify. This is the fifth Category 5 hurricane sustained in the last five years.
NASA and NOAA satellites flew over the storm after the NHC’s 2:00 am EDT (0600Z) advisory each highlighting unique features within the storm. At 3:20 am EDT (0720 UTC) NASA’s Suomi NPP satellite caught Dorian (above) on the east side of the scan in the Day Night band but due to the angle did not yield as many features due to noise at the edge of the scan, however, the well-defined eye can still be seen along with the tropospheric convective gravity waves flowing away from the storm.
A slower westward motion should continue for the next day or two, followed by a gradual turn toward the northwest. On this track, the core of
extremely dangerous Hurricane Dorian will continue to pound Great Abaco today and the move near or over Grand Bahama Island tonight and Monday. The hurricane should move closer to the Florida east coast late Monday through Tuesday night.
Hurricane-force winds extend outward up to 45 miles (75 km) from the center and tropical-storm-force winds extend outward up to 140 miles (220 km). The eye of the hurricane is now 25 nautical miles across.