Tag: Isaias 2020

Aug. 05, 2020 – NASA Satellites Capture Isaias’ Nighttime Track Into Canada

Tropical Storm Isaias has transitioned into a post-tropical storm as it moved out of the U.S. and into eastern Canada on Aug. 5 and 6. NASA created an animation of nighttime satellite imagery that shows Isaias’ track up the U.S. East Coast. In addition, NASA’s Aqua satellite provided a view of Isaias’ powerful storms over New York and New England.

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 lows, make up 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.

NASA Tracks Isaias at Night

Infrared instruments enable satellites to gather imagery on storms at night because they read temperature. At NASA’s Goddard Space Flight Center in Greenbelt, Md. an animation of imagery from the VIIRS instrument aboard NASA-NOAA’s Suomi NPP satellite imagery showed the positions of Tropical Storm Isaias from Aug. 2 to Aug. 5 at night as it moved north along the U.S. East Coast.

NASA’s Earth Observing System Data and Information System (EOSDIS) Worldview application provides the capability to interactively browse over 700 global, full-resolution satellite imagery layers and then download the underlying data. Many of the available imagery layers are updated within three hours of observation, essentially showing the entire Earth as it looks “right now.”

Isaias’ Rain Potential Over New York and New England

On Aug. 4 at 1:53 p.m. EDT (1753 UTC) NASA’s Aqua satellite analyzed cloud top temperatures in Tropical Storm Isaias using the Atmospheric Infrared Sounder or AIRS instrument. Isaias was centered near Albany, New York at the time of the over pass.

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 the colder the cloud temperatures. AIRS found coldest cloud top temperatures as cold as or colder than minus 63 degrees Fahrenheit (minus 53 degrees Celsius). NASA research has shown that cloud top temperatures that cold indicate strong storms that have the capability to create heavy rain.

That heavy rain potential was included in the National Hurricane Center (NHC) forecast at 5 p.m. EDT, “Heavy rainfall near the path of Isaias, through the Hudson River Valley, is likely to result in flash flooding, particularly through urban areas and the surrounding terrain of the Catskills, Adirondack and Green Mountain Ranges through Tuesday night. Scattered minor to moderate river flooding is likely across portions of the Mid-Atlantic.”

Status of Isaias on Aug. 6

At 5 a.m. EDT (0900 UTC) on Aug. 6, the center of Post-Tropical Cyclone Isaias was located near latitude 47.5 degrees north and longitude 71.8 degrees west. That is about 55 miles (90 km) north-northwest of Quebec City, Quebec, Canada. The post-tropical cyclone is moving toward the north-northeast near 28 mph (44 kph), and this general motion is expected with a decrease in forward speed through tonight.

Maximum sustained winds are near 40 mph (65 kph) with higher gusts. Weakening is expected, and the winds are expected to drop below tropical-storm force this morning. Tropical-storm-force winds extend outward up to 140 miles (220 km) to the northeast and east of the center primarily over and near the St. Lawrence River. The estimated minimum central pressure is 1000 millibars.

NHC Forecast for Isaias

The NHC said, “Gale-force winds will continue over and near the St. Lawrence River this morning. Gale-force wind gusts are possible elsewhere over southeastern Quebec today. Rainfall accumulations of 1 to 3 inches are expected along and near the track of Isaias across southern Quebec. The post-tropical cyclone is expected to dissipate over southeastern Canada on Thursday, Aug. 7.”

NASA Researches Tropical Cyclones

Hurricanes/tropical cyclones are the most powerful weather events on Earth. NASA’s expertise in space and scientific exploration contributes to essential services provided to the American people by other federal agencies, such as hurricane weather forecasting.

For more than five decades, NASA has used the vantage point of space to understand and explore our home planet, improve lives and safeguard our future. NASA brings together technology, science, and unique global Earth observations to provide societal benefits and strengthen our nation. Advancing knowledge of our home planet contributes directly to America’s leadership in space and scientific exploration.

For updated forecasts, visit: www.nhc.noaa.gov

By Rob Gutro
NASA’s Goddard Space Flight Center

Aug. 04, 2020 (update #1) – NASA Providing Data on Tropical Storm Isaias as it Blankets Eastern Seaboard

Tropical Storm Isaias made landfall late on Aug. 3 and by today, Aug. 4, the huge storm stretched from Virginia to Maine. NASA satellites have been providing forecasters with rainfall rates, cloud top temperatures, storm extent and strength as Isaias batters the U.S. East Coast.

Warnings and Watches for Tuesday, August 4, 2020

NOAA’s National Hurricane Center (NHC) posted many warnings and watches on Aug. 4. Storm Surge Warning is in effect for the Pamlico and Albemarle Sounds, Ocracoke Inlet, North Carolina to the North Carolina/Virginia border.

A Tropical Storm Warning is in effect from north of Surf City, North Carolina to Eastport, Maine, for the Pamlico and Albemarle Sounds, the Chesapeake Bay, the Tidal Potomac River, Delaware Bay, Long Island and Long Island Sound, NY, Martha’s Vineyard, Nantucket, and Block Island.

Infrared Imagery Reveals Isaias’ Rain Potential

One of the ways NASA researches tropical cyclones is using infrared data that provides temperature information. 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 the colder the cloud temperatures.

On Aug. 3 at 2:47 p.m. EDT (1847 UTC) NASA’s Aqua satellite analyzed Isaias using the Atmospheric Infrared Sounder or AIRS instrument. The infrared data showed the bulk of the storms wrapped from west to north to east of the center of circulation. AIRS found coldest cloud top temperatures as cold as or colder than minus 63 degrees Fahrenheit (minus 53 degrees Celsius). NASA research has shown that cloud top temperatures that cold indicate strong storms that have the capability to create heavy rain. That heavy rain brought flooding to areas of South and North Carolina as the storm approached for landfall.

Isaias Landfall  

Doppler radar imagery and surface observations indicate that eye of Hurricane Isaias made landfall in southern North Carolina around 11:10 p.m. EDT (0310 UTC) on Monday, Aug. 3 near Ocean Isle Beach, with maximum sustained winds of 85 mph (140 kph).

Isaias’ Water Vapor Content

The Moderate Resolution Imaging Spectroradiometer or MODIS instrument that flies aboard NASA’s Aqua satellite provided forecasters at the National Hurricane Center with water vapor imagery in Tropical Storm Isaias. NASA’s Aqua satellite passed over Isaias on Aug. 4 at 2:50 a.m. EDT (0650 UTC).

Coldest cloud top temperatures were as cold as or colder than minus 70 degrees Fahrenheit (minus 56.6 degrees Celsius) in some of the bands of thunderstorms north of Isaias’s center and were over parts of Virginia, Pennsylvania, Maryland, Delaware, and over the Atlantic Ocean. Storms with cloud top temperatures that cold have the capability to produce heavy rainfall.

Water vapor analysis of tropical cyclones tells forecasters how much potential a storm has to develop. Water vapor releases latent heat as it condenses into liquid. That liquid becomes clouds and thunderstorms that make up a tropical cyclone. Temperature is important when trying to understand how strong storms can be. The higher the cloud tops, the colder and the stronger they are.

That rainfall potential is evident in the NHC forecast for Aug. 4. The following rainfall accumulations are expected along and near the track of Isaias: central and eastern North Carolina into the Mid-Atlantic: 3 to 6 inches, isolated totals a maximum of 8 inches; eastern New York into Vermont: 2 to 4 inches, isolated maximum totals 6 inches; and western Connecticut, western Massachusetts, New Hampshire and western Maine: 1 to 3 inches.

Status of Isaias on Aug. 4

At 8 a.m. EDT (1200 UTC), the center of Tropical Storm Isaias was located over southeastern Virginia near latitude 37.7 degrees north and longitude 76.8 degrees west. That is about 15 miles (20 km) south-southeast of Tappahannock, Virginia.

Isaias is moving toward the north-northeast near 33 mph (54 kph), and this general motion accompanied by some additional increase in forward speed is expected through today. Maximum sustained winds are near 70 mph (110 kph) with higher gusts. The estimated minimum central pressure based on surface observations is 993 millibars.

In the 7 a.m. EDT hour, the National Weather Service reported sustained winds of 63 mph (101 kph) and a gust to 77 mph (124 kph) at Third Island, Virginia, at the mouth of the Chesapeake Bay.

NHC noted, “In addition to the storm surge and wind threats, Isaias is expected to produce heavy rainfall along and just west of the I-95 corridor today, and the Weather Prediction Center has placed a portion of this area in a high risk for life-threatening flash flooding. There is also a risk of tornadoes from southeast Virginia to New Jersey through midday. The risk of tornadoes will spread northward into southeastern New York this afternoon and across New England by tonight.”

NHC Forecast for Isaias

Only gradual weakening is anticipated while Isaias moves north northeastward near the mid-Atlantic coast today.  A faster rate of weakening is expected to begin tonight, and the system is forecast to become post-tropical tonight or early Wednesday. On the NHC forecast track, the center of Isaias will continue to move near or along the coast of the mid-Atlantic states today, and move across the northeastern United States into southern Canada tonight.

NASA Researches Tropical Cyclones

Hurricanes/tropical cyclones are the most powerful weather events on Earth. NASA’s expertise in space and scientific exploration contributes to essential services provided to the American people by other federal agencies, such as hurricane weather forecasting.

For more than five decades, NASA has used the vantage point of space to understand and explore our home planet, improve lives and safeguard our future. NASA brings together technology, science, and unique global Earth observations to provide societal benefits and strengthen our nation. Advancing knowledge of our home planet contributes directly to America’s leadership in space and scientific exploration.

For updated forecasts, visit: www.nhc.noaa.gov

By Rob Gutro
NASA’s Goddard Space Flight Center

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Aug. 04, 2020 (update #2) – NASA’s CloudSat Takes a Slice from Tropical Storm Isaias 

NASA’s CloudSat passed over Tropical Storm Isaias as it was strengthening back into a hurricane on Aug. 3, and before it made landfall in North Carolina. CloudSat revealed areas of heavy rain and ice particles in high, powerful clouds.

Tropical Storm Isaias was going through a period of intensification from a tropical storm into a minimal hurricane as vertical wind shear weakened around the system. Wind shear is outside winds that can affect a tropical cyclone and weaken its structure or even blow it apart, if strong enough. The wind shear that had been affecting Isaias was weakening allowing the storm to intensify back into a hurricane as it did y 8 p.m. EDT on Aug. 3.

CloudSat passed east of the storm center revealing the large area of deep convection (rising air that condenses and forms the thunderstorms that make up a tropical cyclone). “The anvil of the system extended northwestward across North and South Carolina with maximum cloud heights estimated at 16-17 km (~10 to ~11 miles),” said Natalie Tourville of the Cooperative Institute for Research in the Atmosphere, Colorado State University, Fort Collins.

CloudSat also found areas of rain bands associated with Isaias in southeastern portion of the system. Those were smaller areas of convection over the Atlantic Ocean.

CloudSat is the first satellite to use an advanced cloud-profiling radar to “slice” through clouds to see their vertical structure, providing a completely new observational capability from space. The mission furnishes data that evaluate and improve the way clouds and precipitation are represented in global models, contributing to better predictions of clouds and their role in climate change.

For more information about NASA’s CloudSat satellite, visit: http://www.nasa.gov/CloudSat or http://CloudSat.atmos.colostate.edu

By Rob Gutro
NASA’s Goddard Space Flight Center

Aug. 03, 2020 – NASA Puts Visible and Water Vapor Eyes on Tropical Storm Isaias

NASA’s Aqua satellite obtained visible and water vapor imagery as Tropical Storm Isaias continued moving along the east coast of Florida. On Aug. 3, Warnings and Watches stretched from Florida to Maine.

NASA Satellite View: Isaiah’s Organization

The Moderate Resolution Imaging Spectroradiometer or MODIS instrument that flies aboard NASA’s Aqua satellite captured a visible image of Tropical Storm Isaias on Aug. 2 at 1:30 p.m. EDT. There was no visible eye in the storm at the time of the imagery. The satellite image was created using NASA’s Worldview product at NASA’s Goddard Space Flight Center in Greenbelt, Md.

Water Vapor Imagery Shows Location of Heaviest Rain

NASA’s Aqua satellite passed over Isaias on Aug. 3 at 3:45 a.m. EDT (0745 UTC) when it was off the coast of northeastern Florida and found highest concentrations of water vapor and coldest cloud top temperatures were offshore and mostly north and northeast of the center.

NHC noted, “Isaias continues to produce an area of vigorous convection near and to the northeast of its low-level center.  Overnight radar data from Melbourne and Jacksonville have shown a transient mid-level eye feature that is located northeast of the low-level center.”

Coldest cloud top temperatures were as cold as or colder than minus 70 degrees Fahrenheit (minus 56.6 degrees Celsius) in those storms. Storms with cloud top temperatures that cold have the capability to produce heavy rainfall.

Water vapor analysis of tropical cyclones tells forecasters how much potential a storm has to develop. Water vapor releases latent heat as it condenses into liquid. That liquid becomes clouds and thunderstorms that make up a tropical cyclone. Temperature is important when trying to understand how strong storms can be. The higher the cloud tops, the colder and stronger they are.

The heavy rain potential in the storm is in the forecast as Isaias makes landfall and moves northeast along the U.S. East Coast. The National Hurricane Center (NHC) noted, “Heavy rainfall will result in flash and urban flooding, some of which may be significant in the eastern Carolinas and the mid-Atlantic, through midweek along and near the path of Isaias across the East Coast of the United States. Widespread minor to moderate river flooding is possible across portions of the Carolinas and the mid-Atlantic. Additionally, quick-responding rivers in the southern Appalachians and Northeast will be susceptible to minor river flooding.”

Warnings and Watches Posted All Along U.S. East Coast

On Aug. 3, 2020, the National Hurricane Center posted watches and warnings along the U.S. East coast from Florida to Maine.

A Storm Surge Warning is in effect for Edisto Beach, South Carolina to Cape Fear, North Carolina. A Storm Surge Watch is in effect for Cape Fear to Duck, North Carolina and the Pamlico and Albemarle Sounds. A Hurricane Warning is in effect for South Santee River, South Carolina to Surf City, North Carolina. A Tropical Storm Warning is in effect for Flagler/Volusia County Line, Florida to South Santee River, South Carolina; north of Surf City, North Carolina to west of Watch Hill, Rhode Island; Chesapeake Bay south of North Beach; Tidal Potomac River south of Cobb Island; Delaware Bay; Long Island and Long Island Sound; Pamlico and Albemarle Sounds. A Tropical Storm Watch is in effect for Watch Hill, Rhode Island to Stonington, Maine and for Martha’s Vineyard, Nantucket, and Block Island.

Tropical Storm Isaias on Aug. 3

At 8 a.m. EDT (1200 UTC) on Aug. 3, the center of Tropical Storm Isaias was located by an Air Force Reserve reconnaissance aircraft and NOAA Doppler weather radars near latitude 30.2 degrees north and longitude 80.1 degrees west. That is about 100 miles (155 km) east-southeast of Jacksonville, Fla. and about 250 miles (400 km) south-southwest of Myrtle Beach, So. Carolina. The estimated minimum central pressure is 994 millibars.

Isaias is moving toward the north near 13 mph (20 kph).  A turn toward the north and north-northeast along with an increase in forward speed is expected later today and Tuesday, Aug. 4. Maximum sustained winds are near 70 mph (110 kph) with higher gusts. Some strengthening is anticipated today, and Isaias is forecast to regain hurricane strength before it reaches the coast of northeastern South Carolina or southern North Carolina tonight. Slow weakening is forecast after Isaias makes landfall in the Carolinas and moves across the U.S. mid-Atlantic region tonight and Tuesday.

 An 8 a.m. EDT Florida Observation on Aug. 3

During the 7 a.m. hour a wind gust to 40 mph (65 kph) was observed at the St, Augustine Pier, Florida, and a sustained wind of 34 mph (55 kph) and a gust to 40 mph (65 kph) were measured by a Weatherflow station at the Jacksonville Beach Pier, Florida.

Isaias’ Forecast and Track  

The NHC Discussion at 8 a.m. EDT on Aug. 3 noted that the vertical wind shear that has been plaguing Isaias is forecast to abate slightly today as the storm turns north-northeastward. All of the intensity models shows some slight strengthening during the next 12 hours, and the global models also indicate some deepening. As a result, the updated NHC intensity forecast calls for Isaias to regain hurricane status before the system moves over the coast of  the Carolinas.

 The NHC noted, “On the forecast track, the center of Isaias will pass well east of the Georgia coast through this morning.  The center of Isaias will then approach the coast of northeastern South Carolina and southern North Carolina within the hurricane warning area later today.  The center will then move inland over eastern North Carolina tonight, and move along the coast of the mid-Atlantic states on Tuesday and into the northeastern United States by Tuesday night.”

About NASA’s Worldview and Aqua Satellite

NASA’s Earth Observing System Data and Information System (EOSDIS) Worldview application provides the capability to interactively browse over 700 global, full-resolution satellite imagery layers and then download the underlying data. Many of the available imagery layers are updated within three hours of observation, essentially showing the entire Earth as it looks “right now.”

NASA’s Aqua satellite is one in a fleet of NASA satellites that provide data for hurricane research.

Tropical cyclones/hurricanes are the most powerful weather events on Earth. NASA’s expertise in space and scientific exploration contributes to essential services provided to the American people by other federal agencies, such as hurricane weather forecasting.

For updated forecasts, visit: www.nhc.noaa.gov

By Rob Gutro
NASA’s Goddard Space Flight Center

Aug. 01, 2020 – NASA Examines Hurricane Isaias’ Soaking Potential

NASA analyzed the cloud top temperatures in Hurricane Isaias using infrared light to determine the strength of the storms that make up the tropical cyclone. NASA’s Aqua satellite found very cold cloud temperatures indicative of storms with heavy rainmaking capabilities.

Isaias is expected to approach the southeast coast of Florida later today, Aug. 1 and into Sunday, Aug. 2.

An Infrared Analysis of Isaias

One of the ways NASA researches tropical cyclones is using infrared data that provides temperature information. Cloud top temperatures identify where the strongest storms are located. The stronger the storms, the higher they extend into the troposphere, and the colder the cloud temperatures.

On July 31 at 2:11 p.m. EDT (1811 UTC) NASA’s Aqua satellite analyzed the storm using the Atmospheric Infrared Sounder or AIRS instrument. Isaias was over the southern and central Bahamas at the time, and generating soaking rains.

The AIRS imagery showed the strongest storms circling the center of circulation. In those areas, AIRS found coldest cloud top temperatures as cold as or colder than minus 63 degrees Fahrenheit (minus 52.7 degrees Celsius). NASA research has shown that cloud top temperatures that cold indicate strong storms that have the capability to create heavy rain.

Tropical cyclones do not always have uniform strength, and some sides have stronger sides than others, so knowing where the strongest sides of the storms are located helps forecasters. NASA then provides data to tropical cyclone meteorologists so they can incorporate it in their forecasts.
Isaias Forecast Rainfall

The NHC rainfall forecast for Isaias calls for 4 to 8 inches in the Bahamas, 1 to 2 inches in Cuba with a maximum of 4 inches there. Rainfall forecasts from July 31 to Aug. 4 in South Florida into east-Central Florida call for between 2 to 4 inches, with isolated maximum totals of 6 inches. From northeast Florida into coastal Georgia, 1 to 2 inches are currently forecast. These totals are also subject to change based on any deviation of the track of the storm.

In addition to the heavy rainfall, hurricane-force winds, dangerous storm surge and ocean swells are expected. For an updated list of hazards, visit the NHC website.

A View from the International Space Station

The International Space Station provides a window onto the world and shortly after NASA’s Aqua satellite passed over Isaias, the ISS was close enough to get a view of the storm. Around 5:30 p.m. EDT on July 31, Astronaut Col. Doug Hurley photographed Isaias when it was located between Cuba and the Bahamas.

Hurricane Isaias on Saturday, August 1, 2020

At 8 a.m. EDT on Saturday, August 1, 2020, the National Hurricane Center (NHC) reported that Isaias ragged eye was near eastern Andros Island. The center was near near latitude 24.3 degrees north and longitude 77.5 degrees west. Isaias is moving toward the northwest near 12 mph (19 kph). A general northwestward motion with some decrease in forward speed is expected for the next day or so, followed by a turn toward the north-northwest by late Sunday.

NHC noted that reports from the reconnaissance aircraft indicate that maximum sustained winds remain near 85 mph (140 kph) with higher gusts.  Little change in strength is expected through Sunday, and Isaias is forecast to remain a hurricane during this time. The minimum central pressure recently measured by the aircraft was 987 millibars.

Watches and Warnings in Effect

NHC has posted many warnings and watches for Isaias. A Hurricane Warning is in effect from Boca Raton to the Volusia/Flagler County Line, Florida and for the Northwestern Bahamas. A Hurricane Watch is in effect for Hallandale Beach to south of Boca Raton, Florida.

In addition, a Storm Surge Watch is in effect for Jupiter Inlet to Ponte Vedra Beach, Florida. Dangerous storm surge is possible along the Florida east coast from Jupiter Inlet to Ponte Vedra Beach where water rises of 2 to 4 feet above ground level are possible along the immediate coastline and adjacent waterways.

A Tropical Storm Warning is in effect from north of Ocean Reef to south of Boca Raton, Florida and for Lake Okeechobee. A Tropical Storm Watch is in effect for Volusia/Flagler County Line to Ponte Vedra Beach, Florida.

Isaias’ Forecast Path

NHC forecasters noted, “On the forecast track, the center of Isaias will move near or over Andros Island in the Northwestern Bahamas this morning and continue to move near or over the rest of Northwestern Bahamas later today, and move near the east coast of the Florida peninsula tonight through Sunday (Aug. 1).”

NASA Researches Tropical Cyclones

Hurricanes/tropical cyclones are the most powerful weather events on Earth. NASA’s expertise in space and scientific exploration contributes to essential services provided to the American people by other federal agencies, such as hurricane weather forecasting.

For more than five decades, NASA has used the vantage point of space to understand and explore our home planet, improve lives and safeguard our future. NASA brings together technology, science, and unique global Earth observations to provide societal benefits and strengthen our nation. Advancing knowledge of our home planet contributes directly to America’s leadership in space and scientific exploration.

For updated forecasts, visit: www.nhc.noaa.gov

By Rob Gutro
NASA’s Goddard Space Flight Center  

July 31, 2020 – NASA Examines Water Vapor and Structure in Hurricane Isaias      

When NASA’s Aqua satellite passed over the North Atlantic Ocean, it gathered water vapor data on Isaias, while NASA-NOAA’s Suomi NPP satellite provided forecasters with a visible image that showed a more organized tropical cyclone.

A Visible View of Isaias

NASA-NOAA’s Suomi NPP satellite passed over the Atlantic Ocean during the afternoon on July 30, the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument provided forecasters with a visible image of Isaias as it was intensifying. VIIRS revealed strong thunderstorms had circled the center of circulation. The image showed the center near the northeastern coast of the Dominican Republic and bands of thunderstorms from the eastern quadrant stretching over Puerto Rico. At the time of the image, Isaias had not yet reached Turks and Caicos. A thick band of thunderstorms from the center of circulation also stretched out in a southwesterly direction and over the Caribbean Sea.

Water Vapor Imagery Reveals Heavy Rainfall Potential

Water vapor analysis of tropical cyclones tells forecasters how much potential a storm has to develop. Water vapor releases latent heat as it condenses into liquid. That liquid becomes clouds and thunderstorms that make up a tropical cyclone. Temperature is important when trying to understand how strong storms can be. The higher the cloud tops, the colder and stronger the storms.

NASA’s Aqua satellite passed over Hurricane Isaias on July 31 at 3:20 a.m. EDT (0720 UTC), and the Moderate Resolution Imaging Spectroradiometer or MODIS instrument gathered water vapor content and temperature information. The MODIS image showed highest concentrations of water vapor and coldest cloud top temperatures were around the center of circulation and in a thick band of thunderstorms that extends southwest over western Hispaniola and into the Caribbean Sea. Those cloud top temperatures were as cold as or colder than minus 70 degrees Fahrenheit (minus 56.6 degrees Celsius) in those storms. Storms with cloud top temperatures that cold have the capability to produce heavy rainfall.

That rainfall potential is apparent in today’s forecast from the National Hurricane Center. NHC said the Dominican Republic and northern Haiti: 4 to 8 inches, with isolated maximum totals of 12 inches through Saturday. For the Bahamas, Turks and Caicos: 4 to 8 inches, and for Cuba: 1 to 2 inches, with isolated maximum totals of 4 inches.

Warnings and Watches on July 31, 2020

On July 31, NOAA’s National Hurricane Center (NHC) issued a Hurricane Warning for the northwestern Bahamas including Andros Island, New Providence, Eleuthera, Abacos Islands, Berry Islands, Grand Bahamas Island, and Bimini. It is also in effect for the southeastern Bahamas including the Acklins, Crooked Island, Long Cay, the Inaguas, Mayaguana, and the Ragged Islands; and for the central Bahamas, including Cat Island, the Exumas, Long Island, Rum Cay, and San Salvador.

A Tropical Storm Warning is in effect for the Dominican Republic entire southern and northern coastlines, and the Turks and Caicos Islands. In addition, a Tropical Storm Watch is in effect for the east coast of Florida from Ocean Reef to Sebastian Inlet and for Lake Okeechobee.

Isaias’ Status on July 31, 2020

At 8 a.m. EDT (1200 UTC) on July 31, NHC reported the center of Hurricane Isaias was located by NOAA and Air Force Reserve Hurricane Hunter aircraft near latitude 21.3 north, longitude 73.9 west. That puts the center about 30 miles (50 km) northwest of Great Inagua Island, and 340 miles (545 km) southeast of Nassau. Reports from the reconnaissance aircraft indicate that the minimum central pressure is 990 millibars.

Isaias was moving toward the northwest near 17 mph (28 kph), and a generally northwestward motion with some decrease in forward speed is expected for the next couple of days followed by a turn toward the north-northwest. Maximum sustained winds are near 80 mph (130 kph) with higher gusts.  Some strengthening is possible today, and Isaias is expected to remain a hurricane for the next few days.

NOAA’s NHC Forecast for Isaias

On the forecast track, the center of Isaias will move near or over the southeastern Bahamas today. Isaias is forecast to be near the central Bahamas tonight, and move near or over the northwestern Bahamas and be near or east of the Florida peninsula on Saturday and Sunday.

Interests elsewhere along the southeast coast of the United States should monitor the progress of this system. Additional watches or warnings may be required for a portion of the Florida peninsula later today.

NASA Researches Tropical Cyclones

Hurricanes/tropical cyclones are the most powerful weather events on Earth. NASA’s expertise in space and scientific exploration contributes to essential services provided to the American people by other federal agencies, such as hurricane weather forecasting. NASA’s Aqua satellite is one in a fleet of NASA satellites that provide data for hurricane research.

For more than five decades, NASA has used the vantage point of space to understand and explore our home planet, improve lives and safeguard our future. NASA brings together technology, science, and unique global Earth observations to provide societal benefits and strengthen our nation. Advancing knowledge of our home planet contributes directly to America’s leadership in space and scientific exploration.

For updated forecasts, visit: www.nhc.noaa.gov

By Rob Gutro
NASA’s Goddard Space Flight Center

July 30, 2020 – NASA-NOAA Satellite Tracks Isaias’ Development, Movement, Soaking Potential

NASA-NOAA’s Suomi NPP satellite provided visible imagery of the development and movement of Tropical Storm Isaias is it moved into the eastern Caribbean Sea. NASA’s Aqua satellite provided temperature information that gave insight into Isaias’ rainmaking potential.

The Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard Suomi NPP provided a visible image of Potential Tropical Cyclone 9 on July 28.  The storm developed into Tropical Storm Isaias on July 29. The imagery showed the broader circulation of the disturbance had become slightly better defined but at the time of the July 29 image, Air Force Reserve reconnaissance aircraft was still unable to find a well-defined circulation.

Later in the day, by 5 p.m. EDT, deep convection continued to increase and a band of thunderstorms developed over the southwestern portion of the broad circulation. By 11 p.m., the storm had developed into a tropical storm. The National Hurricane center noted, “Observations from recent scatterometer passes over the system show that it now has a sufficiently well-defined center to be designated as a tropical cyclone.”

Many Warnings and Watches in Effect

The National Hurricane Center (NHC) posted many watches and warnings as Isaias moved through the Caribbean Sea on July 30.

A Tropical Storm Warning is in effect for Puerto Rico, Vieques, Culebra; the U.S. Virgin Islands;  the Dominican Republic entire southern and northern coastlines; the north coast of Haiti from Le Mole St. Nicholas eastward to the northern border with the Dominican Republic; Turks and Caicos Islands; the southeastern Bahamas including the Acklins, Crooked Island, Long Cay, the Inaguas, Mayaguana, the Ragged Islands; the Central Bahamas, including Cat Island, the Exumas, Long Island, Rum Cay, and San Salvador.

A Tropical Storm Watch is in effect for the northwestern Bahamas including Andros Island, New Providence, Eleuthera, Abacos Islands, Berry Islands, Grand Bahamas Island, and Bimini.

NASA Infrared Data Reveals a Heavy Rainmaker

The AIRS instrument aboard NASA’s Aqua satellite captured a look at cloud top temperatures in Isaias and gave insight into the size of the large storm and its rainfall potential.

Cloud top temperatures provide information to forecasters about where the strongest storms are located within a tropical cyclone. Tropical cyclones do not always have uniform strength, and some sides have stronger sides than others. The stronger the storms, the higher they extend into the troposphere, and the colder the cloud temperatures. NASA provides that data to forecasters at NOAA’s National Hurricane Center or NHC so they can incorporate in their forecasting.

On July 30 at 2:35 a.m. EDT (0635 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 63 degrees Fahrenheit (minus 53 degrees Celsius). NASA research has shown that cloud top temperatures that cold indicate strong storms that have the capability to create heavy rain.

Rainfall Forecast from NHC

NASA’s AIRS data, combined with other data is used by NHC in their forecasts. NHC said Isaias is expected to produce the following rain accumulations:

• In Puerto Rico, the Dominican Republic and northern Haiti: 4 to 8 inches, with isolated maximum totals of 10 inches.
• In the Bahamas, Turks and Caicos: 4 to 8 inches.
• In Cuba: 1 to 2 inches, with isolated maximum totals of 4 inches.

These rainfall amounts will lead to life-threatening flash flooding and mudslides, as well as river flooding.  Urban and small stream flooding is expected for the U.S. Virgin  Islands, eastern and southwestern Puerto Rico, and Hispaniola. Heavy rains associated with Isaias may begin to affect South Florida Saturday morning. This rain could result in isolated flash and urban flooding, especially in low-lying and poorly drained areas.

Isaias’ Status on July 30

By 11 a.m. EDT on July 30, Isaias had moved northwest and was bringing heavy rain and gusty winds to Puerto Rico. The rainfall was producing life-threatening flash flooding. Heavy rains and gusty winds were also spreading over the Dominican Republic.

The center of Tropical Storm Isaias was located near latitude 18.1 degrees north and longitude 68.9 degrees west. That is 50 miles (75 km) southwest of Punta Cana, Dominican Republic. Isaias was moving toward the northwest near 20 mph (31 kph), and a west-northwestward to northwestward motion with some decrease in forward speed is expected over the next couple of days.

Maximum sustained winds are near 60 mph (95 kph) with higher gusts. Some slight weakening is possible as Isaias moves over Hispaniola today. Re-strengthening is forecast on Friday into Friday night. Tropical-storm-force winds extend outward up to 310 miles (500 km) primarily to the north of the center. Tropical-storm-force winds are occurring along the southern coast of Puerto Rico. The estimated minimum central pressure is 1003 millibars.

Forecast for Isaias

On the forecast track, the center of Isaias will move over Hispaniola today, July 30, and move near the Southeastern Bahamas by tonight or early Friday. Isaias is forecast to be near the Central Bahamas Friday night and approach the Northwest Bahamas or southern Florida Friday night and Saturday, August 1.

NHC Key messages for Isaias can be found in the Tropical Cyclone Discussion  on the web at www.hurricanes.gov/text/MIATCDAT4.shtml.

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For updated forecasts, visit: www.nhc.noaa.gov

By Rob Gutro 
NASA’s Goddard Space Flight Center