Sept. 01, 2019 – Update #1 – NASA Satellites Monitor Progress as Hurricane Dorian Reaches Dangerous Category 5 Status
The National Hurricane Center’s (NHC) 8:00 am EDT advisory reports that Hurricane Dorian has reached Category 5 status on the Saffir-Simpson Hurricane Wind scale. Data from an Air Force Hurricane Hunter plane which just penetrated the eye of Dorian indicate that the maximum sustained winds have increased to near 160 mph (260 km/h) with higher gusts. Devastating hurricane conditions are expected in the Abacos Islands very soon and these conditions will spread across Grand Bahama Island later today.
As of Saturday, August 31, Hurricane Dorian’s rain field had changed. During its early days near Puerto Rico, Dorian’s inner-core rain rate had peaked once every 24 hours, but during the most recent two days, Dorian’s rain rate has been persistently heavy. Heavy precipitation under the eyewall suggests that a great deal of energy is being released in the atmosphere,
which is the fuel that allows a hurricane to sustain or increase its wind intensity.
These rain estimates come from the Global Precipitation Measurement mission (GPM)’s 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.
NASA’s Aqua satellite also was providing scientists with data about the storm when it passed overhead on Aug. 31, 2019.
This image, captured by NASA’s Aqua satellite at 2:17 am EDT the morning of the 31st, shows incredibly cold temperatures in the cloudtops of the storm. The area of purple, the coldest temperatures, extends out widely from the very distinct eye of the hurricane. The stronger the storms, the higher they extend into the troposphere, and the colder the cloud temperatures become so the AIRS instrument gives a good picture to scientists of the strength of the storm.
The NHC has reported that hurricane-force winds extend outward up to 30 miles (45 km) from the center, and tropical-storm-force winds extend outward up to 105 miles (165 km). Elbow Cay in the Abaco Islands just reported winds of 35 mph (56 km/h). The minimum central pressure just measured by an Air Force plane has dropped to 927 mb (27.37 inches).
The following information is directly from the National Hurricane Center’s 8:00 am EDT advisory:
“A Hurricane Warning is in effect for…* Northwestern Bahamas excluding Andros Island
A Hurricane Watch is in effect for…* Andros Island
A Tropical Storm Warning is in effect for…* North of Deerfield Beach to Sebastian Inlet
A Tropical Storm Watch is in effect for…* North of Golden Beach to Deerfield Beach
A Hurricane Warning means that hurricane conditions are expected
somewhere within the warning area. Preparations to protect life and
property should be rushed to completion.
A Hurricane Watch means that hurricane conditions are possible within the watch area.
A Tropical Storm Warning means that tropical storm conditions re expected within the warning area within 36 hours.
A Tropical Storm Watch means that tropical storm conditions are possible within the watch area, generally within 48 hours.
Interests elsewhere in southern and central Florida should continue to monitor the progress of Dorian. Additional watches or warnings may be required for portions of the east coast of Florida today.
For storm information specific to your area in the United States, including possible inland watches and warnings, please monitor products issued by your local National Weather Service forecast office. For storm information specific to your area outside of the United States, please monitor products issued by your national meteorological service.
Tropical storm conditions are expected within the tropical storm warning area on Monday.
Tropical storm conditions are possible within the tropical storm watch area by Monday night.
STORM SURGE: A life-threatening storm surge will raise water levels by as much as 15 to 20 feet above normal tide levels in areas of onshore winds on the Abaco Islands and Grand Bahama Island. Near the coast, the surge will be accompanied by large and destructive waves.
RAINFALL: Dorian is expected to produce the following rainfall totals through late this week:
Northwestern Bahamas…12 to 24 inches, isolated 30 inches.
Coastal Carolinas…5 to 10 inches, isolated 15 inches.
Central Bahamas and the Atlantic Coast from the Florida peninsula
through Georgia…2 to 4 inches, isolated 6 inches.
This rainfall may cause life-threatening flash floods.
SURF: Large swells will affect the east-facing shores of the Bahamas, the Florida east coast, and the southeastern United States coast during the next few days. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office.”
For further information on the storm visit: https://www.nhc.noaa.gov
By Lynn Jenner
NASA Goddard Space Flight Center