30th Anniversary of Hurricane Elena

Hurricane Elena near its peak as seen from the Space Shuttle Discovery (NASA)

Hurricane Elena near its peak as seen from the Space Shuttle Discovery (NASA)

Midday on September 2, 1985, Hurricane Elena came ashore near Biloxi, MS.  But it had been anything of a direct path.  Elena’s track had many twists that had vexed forecasters and emergency managers all along the northern Gulf coast.

Elena began as a disturbance in the deep tropical Atlantic, but hostile conditions prevented it from organizing until it had reached the Windward Passage between Hispanola and Cuba.  As it traveled northwestward along Cuba’s northern shore, a NOAA aircraft monitored its slow organization.  Once it reached the Gulf of Mexico, it began strengthening in earnest becoming a hurricane by mid-morning of the 29th.  By the next day, Elena’s forward speed had slowed considerably even as its maximum winds increased.  The hurricane then began an unexpected jog to the northeast, heading toward Florida’s Big Bend area.  Frantically, watches and warnings were shifted to the eastern Gulf shore.  Slowly throughout the 31st, Elena crawled closer to Florida.

Hurricane Elena rainfall amounts and track.

Hurricane Elena rainfall amounts and track.

Then its progress stopped as it made a clockwise loop just 50 miles from Cedar Key, FL.  It then resumed a west-northwesterly course and accelerated toward the Mississippi shore.  Although it weakened from its peak twelve hours before, Elena came ashore as a Category Three hurricane, bringing winds of 115 mph (177 km/hr) to Biloxi.  Because of its track moving parallel to the coast before landfall, high storm surges (up to 9 feet [2.7 m]) were recorded from Florida to Louisiana.  Elena cost 9 lives and US$1.3 billion in damage.  But Elena was even more disruptive in its changeable course.  The shifting warning zones caused what was to that time the largest peacetime evacuation in U.S. history.

Hurricane Research Division missions into Elena measured the storm at every phase of its history, and also detailed the erratic movements of its eye.  And research papers that came from examining the data written by HRD scientists are:

Corbosiero, K. L., J. Molinari, and M. L. Black, 2005: The Structure and Evolution of Hurricane Elena (1985). Part I: Symmetric Intensification. Mon. Wea. Rev., 133, 2905–2921.

Corbosiero, K. L., J. Molinari, A. R. Aiyyer, and M. L. Black, 2006: The Structure and Evolution of Hurricane Elena (1985). Part II: Convective Asymmetries and Evidence for Vortex Rossby Waves. Mon. Wea. Rev., 134, 3073–3091.

Black, M. L., R. W. Burpee, and F. D. Marks Jr., 1996: Vertical Motion Characteristics of Tropical Cyclones Determined with Airborne Doppler Radial Velocities. J. Atmos. Sci., 53, 1887–1909.

Samsury, C. E., and E. J. Zipser, 1995: Secondary Wind Maxima in Hurricanes: Airflow and Relationship to Rainbands. Mon. Wea. Rev., 123, 3502–3517.

Willoughby, H. E., 1990: Gradient Balance in Tropical Cyclones. J. Atmos. Sci., 47, 265–274.

Willoughby, H. E., 1990: Temporal Changes of the Primary Circulation in Tropical Cyclones. J. Atmos. Sci., 47, 242–264.

Burpee, R. W., and M. L. Black, 1989: Temporal and Spatial Variations of Rainfall Near the Centers of Two Tropical Cyclones. Mon. Wea. Rev., 117, 2204–2218.

80th Anniversary of the Labor Day Hurricane and first hurricane reconnaissance

Labor Day hurricane memorial

Labor Day hurricane memorial in Islamorada

On the evening of September 2, 1935, the most intense hurricane to strike the United States on record roared through the Florida Keys, taking hundreds of lives.  It would’ve come ashore virtually unannounced except for the unprecedented flight of an American barnstormer in the Cuba Army Air Corps (CAEC).  The storm was a record breaker and remained the yardstick by which other hurricanes were measured for decades to come.

1935 was the year the United States Weather Bureau (USWB) decided to reorganize its hurricane warning network. Responsibility for monitoring tropical oceanic weather for hurricanes and issuing warnings of their approach was decentralized from Washington DC to three other centers.  San Juan, PR, Jacksonville, FL, and New Orleans, LA, now shared the burden with USWB headquarters, and a new dedicated telegraph line was put at their disposal to facilitate immediate communication.

Gordon Dunn

Gordon Dunn

The Jacksonville Hurricane Warning Center was manned by Grady Norton and Gordon Dunn.  Late in August of 1935, they became aware of an area of disturbed weather to the east of the Bahamas. Forecasting responsibility for this storm fell to Dunn. As it approached Long Island in the Bahamas he was able to discern a closed circulation from wind direction reports received.  By the time it passed over Andros Island on the afternoon of Sept. 1st, he estimated it was of hurricane strength.  Because they were alerted by the Warning Center, ships began avoiding the Florida Straits and the storm.  However, this deprived Dunn of much needed observations of the storm’s position and strength.  He was forced to use persistence to forecast the hurricane, assuming it maintained the same direction and forward speed.  This track ought to have taken it over the north coast of Cuba, near Cardenas, by the morning of September 2nd.

Capt. Povey's Curtis Hawk II

Capt. Povey’s Curtis Hawk II

However, the Cuban weather service saw no evidence of the approaching storm by early on the 2nd, and no one was sure of where it was. Then a Pan Am flying boat pilot, on his daily Key West to Havana run, noticed a cloud mass to his east but much further north than where the hurricane should’ve been.  He alerted the Cuban National Observatory (their version of NHC and NWS combined) upon landing.  The Observatory requested CAEC send up a plane to confirm this.  Capt. Leonard Povey, the Corps’ chief training pilot and an American barnstormer, volunteered.  He soon found the hurricane, which he later described as an “inverted funnel of cloud”, much further north than expected and moving northwestward.  Since his Curtis Hawk II aircraft was open cockpit, he did not attempt to penetrate the clouds, but he did circle the hurricane to ascertain its motion.

1935Train

The National Observatory relayed the information to Jacksonville and by 4:30 pm they issued a special bulletin raising hurricane warnings for the Florida Keys.  The Florida Emergency Relief Administration (FERA) alerted the Florida East Coast (FEC) Railway to send a relief train to evacuate its work camps in the Keys.  Hundreds of World War I veterans were hired by FERA to build an overseas highway from Miami to Key West, and many had remained at the camps during the Labor Day holiday.  Unfortunately, since it was a holiday it took the FEC precious hours to assemble a train and crew.  By the time the train reached the Upper Keys, wind-blown debris was blocking the tracks, further delaying the train’s progress.  The train reached Islamorada’s station just as the hurricane’s storm surge did.  The in-rushing sea pushed all the cars off the track.  Fortunately, everyone on the train survived, although it was a harrowing night struggling to keep their heads above water.

The veterans in the FERA camps and the local Key residents in the area did not fare as well.  The surge wiped the vegetation and man-made structures off the tiny islands in its path.  Over 400 people drowned and many of their bodies were swept out into Florida Bay.  The telegraph lines were down and the railroad tracks washed out it parts.  For the few survivors there was no way to alert the outside world what a great tragedy had happened.

Local weather observer Ivar Olsen managed to rescue his barometer as the house in which he was riding out the storm fell apart around him.  He climbed into a tree with the instrument and managed to take a reading of 892 mb during the eye passage.  This became the record low pressure measured at a land station up to that point.  From this reading it’s been estimated that the maximum sustained winds in the Labor Day hurricane were 185 mph (295 km/hr).  The hurricane continued to sweep up near the west coast of Florida, but its power was greatly diminished by its second landfall in the panhandle region of the state.  It moved across Georgia and the Carolinas as a tropical storm, then restrengthened to hurricane status over the Atlantic.  It moved far out to sea and eventually was absorbed into a frontal zone.  During its rampage, the Labor Day hurricane cause some US$6 million in damage and killed an estimated 600 people.

Ernest Hemingway at the helm of his boat Pilar

Ernest Hemingway at the helm of his boat Pilar

The fallout from the storm was considerable.  Ernest Hemingway, who brought supplies to the disaster area on his boat Pilar and saw the devastation first-hand, lay the blame for the veteran’s fate on the Roosevelt Administration.  The Administration quickly produced a finding exonerating FERA officials.  Unsatisfied, Congress held hearings and compelled  Administration officials to testify about the role of the USWB and other federal agencies.  Capt. Povey came to Miami to persuade the US Government to fund CAEC to carry out further aerial reconnaissance of hurricanes near Cuba.  The Weather Bureau later expanded this into a proposal to hire commercial aircraft to track hurricanes threatening the United States.  However, the Roosevelt Administration, under pressure from the Texas Congressional delegation, instead decided to use Coast Guard cutters to reconnoiter storms in the Gulf of Mexico.  It was a plan that was never fully implemented.  The next time an aircraft deliberately flew into a hurricane, this time penetrating the eye of the storm, was Major Joe Duckworth’s flight in 1943.

The Global Hawk’s flight over Tropical Storm Fred is postponed

The unmanned aircraft, the Global Hawk will not fly today. The flight is postponed. It could possibly fly tomorrow depending on Fred’s status. Stay tuned.

In the meantime, have you seen what the Global Hawk looks like? Here’s a picture of it in its hangar.

Preflight AV-6

Photo courtesy of the NOAA/Sensing Hazards with Operational Unmanned Technology (SHOUT) field campaign.

The Global Hawk is set to fly a 24 hour mission over Tropical Storm Fred

The unmanned aircraft, the Global Hawk is taking off at 7AM Eastern this morning from Wallops Island, VA and will fly over Fred. It will collect data over the storm for 24 hours. The Global Hawk is part of NOAA’s Sensing Hazards with Operational Unmanned Technology (SHOUT) field campaign. It will launch dropwindsondes as well as gather data with other meteorological instruments on board. Below is the flight track. The Global Hawk will fly across the Atlantic Ocean to reach Fred. The dots on the flight track (shown in green) represent the aircraft turn points. The red dots in the figure show the locations that launch weather balloons twice a day while the purple dots are the locations that launch balloons once a day.

ftk

50th Anniversary of Hurricane Betsy

Eye of Betsy seen from research aircraft

Eye of Betsy seen from research aircraft (National Hurricane Research Laboratory [NHRL])

Early on Sept. 10, 1965, Hurricane Betsy came ashore in Louisiana, bringing devastating flooding to New Orleans.  Betsy became one of the most expensive storms up to that date, and it’s erratic path leading up to that landfall caused considerable consternation for the public, forecasters and research scientists alike.

Betsy formed from an Africa easterly wave that came off the African coast on August 23rd.  It was tracked by satellite and came within distance of Navy Hurricane Hunters by August 27th when it was discovered to have a closed circulation.  The tropical depression was prematurely named ‘Betsy’ shortly after this flight, but later analysis showed it did not reach tropical storm strength until the 29th.  By that time it was moving northwestward, toward the Project STORMFURY seeding area.

Betsy's track and STORMFURY seeding area

Betsy’s track and STORMFURY seeding area

Dr. Joanne Simpson, Project Director, had ordered the fleet of Navy and Weather Bureau research aircraft to deploy to Puerto Rico on August 28th.  Over the next two days, the planes monitored the storm’s slow progress toward the designated part of the ocean where they could carry out their weather modification experiments.  By August 31st, Betsy had just managed to crawl into the area as a hurricane, so a seeding experiment was scheduled for the next day.  The first aircraft had already taken off from Roosevelt Roads Naval Air Station, PR the morning of September 1st when word came from the National Hurricane Center that overnight Betsy had completed a loop in its track and was now headed southward and out of the allowed seeding area.  The seeding experiments were called off and the mission changed to a ‘dry run’, where the same patterns were flown but no silver iodide was released into the storm.  Unfortunately, no one informed the press which had been alerted to STORMFURY’s seeding intentions the previous day.

By the following day, Betsy had complete the loop and was headed westward, well outside of the seeding area.  The Weather Bureau aircraft continued to monitor the hurricane as it rapidly intensified.  By September 3rd it was moving northwestward east of the Bahamas, so a multi-level examination of the hurricane was carried out including two high-level jets, the Weather Bureau B-57 and an Air Force U-2.  As Betsy reached a strength of 138 mph (222 km/hr), it slowed again then completed another loop just east of Cape Canaveral.  Another multi-plane Air Force experiment was carried out as the storm idled at sea.  After a day, Betsy moved southwestward over the northern Bahamas then west through the Florida Keys as a major hurricane doing considerable damage to south Florida.

Houseboat damaged by Betsy in the Florida Keys (NHRL/Charlie True)

Houseboat damaged by Betsy in the Florida Keys (NHRL/Charlie True)

Once in the Gulf of Mexico, the hurricane turned northwestward, sped up, and headed directly toward Louisiana.  Betsy began strengthening again, this time achieving its peak winds of 155 mph (250 km/hr) just prior to slamming in to the Louisiana shore south of New Orleans.  Despite its winds diminishing just offshore, several levees protecting the city failed and New Orleans suffered catastrophic flooding.  Betsy continued its rapid weakening, but dumped heavy rain amounts along the Mississippi and Ohio River basins.  Along its track the hurricane was responsible for over 80 deaths and US$1.4 billion in damage.  As a consequence of the damage to New Orleans, the Federal Government ordered the U.S. Army Corps of Engineers to assume responsibility of rebuilding and maintaining the levee system around the ‘Crescent City’.

Flooding due to Betsy i New Orlean's 9th Ward. (NOAA)

Flooding due to Betsy in New Orleans’ 9th Ward. (NOAA)

As the storm was making landfall, south Florida newspapers ran articles blaming Betsy’s eccentric track on the supposed seeding done to it back on Sept. 1st.    Since no one at Project STORMFURY nor in the Weather Bureau had advised the public or the press that the actual seeding of the storm had been scrubbed, many people believed it had been carried out and the link to its odd path seemed plausible.  Although attempts to clarify the facts about STORMFURY and Betsy were made after the fact, the notion of a link persists to the present.

Betsy's rainfall (NOAA/WPC)

Betsy’s rainfall (NOAA/WPC)

Some research papers by HRD (NHRL)  scientists written concerning Betsy:

Westerink, J. J., R. A. Luettich, J. C. Feyen, J. H. Atkinson, C. Dawson, H. J. Roberts, Ma. D. Powell, J. P. Dunion, E. J. Kubatko, and H. Pourtaheri, 2008: A Basin- to Channel-Scale Unstructured Grid Hurricane Storm Surge Model Applied to Southern Louisiana. Mon. Wea. Rev., 136, 833–864.

Willoughby, H. E. , D. P. Jorgensen, R. A. Black, and S. L. Rosenthal, 1985: Project STORMFURY: A Scientific Chronicle 1962–1983. Bull. Amer. Meteor. Soc., 66, 505–514.

Black, P. G., and G. J. Holland, 1995: The Boundary Layer of Tropical Cyclone Kerry (1979). Mon. Wea. Rev., 123, 2007–2028.

Lewis. B. M., and H. F. Hawkins, 1982: Polygonal Eye Walls and Rainbands in Hurricanes. Bull. Amer. Meteor. Soc., 63, 1294–1301.

Miller, B.I., E.C. Hill, and P.P. Chase, 1968: A REVISED TECHNIQUE FOR FORECASTING HURRICANE MOVEMENT BY STATISTICAL METHODS. Mon. Wea. Rev., 96, 540–548.

Doppler radar quick-looks from 2:00 AM P-3 flight into Tropical Storm Erika, 28 August 2015

As Tropical Storm Erika passed south of Puerto Rico and Hispaniola (see the black lines outlining the two islands near the top of of analyses) a NOAA P-3 mission collected airborne Doppler radar data to use in initializing and evaluating model guidance.

The figure below depicts the aircraft flight track (P-3: yellow line) superposed on a visible satellite imagery.

Screen Shot 2015-08-28I1

Included below you see images of the horizontal winds within 180 km of Erika sampled from the tail Doppler radar on the P-3 aircraft during the early morning of 27 August 2015. These images are at three altitudes (1 km, 3 km, and 6 km) and are a composite of winds from the P-3 Doppler pattern around Erika. Also plotted on each analysis are the locations of dropsondes deployed by the P-3 (plotted using standard station symbols). These analyses show that Erika maintained a very asymmetric distribution of precipitation at all altitudes, with the bulk of the precipitation primarily in the eastern semicircle of the storm at all altitudes. There is slight indication of a very broad circulation center at 1- and 3-km altitudes, with the strongest winds 100 km east of the circulation center, and extending to 180 km to the east and northeast of the center onto the south coast of Puerto Rico. At 3-km altitude the strongest winds 150 -180 km east of the circulation center. At 6-km altitude there was still an indication of a circulation center in the heavy precipitation 100-125 km east-southeast of the 1-km altitude circulation center, indicative of very strong west-northwesterly shear of the horizontal wind over the low-level center.

All the Tropical Storm Erika radar composites at 0.5-km height resolution are available at: http://www.aoml.noaa.gov/hrd/Storm_pages/erika2015/radar.html.

Doppler radar quick-looks from 2:00 AM P-3 flight into Tropical Storm Erika, 27 August 2015

As Tropical Storm Erika approached Guadalupe (see the black lines outlining the island in the center left of analyses) a NOAA P-3 mission collected airborne Doppler radar data to use in initializing and evaluating model guidance. This P-3 mission coincided with the end of the first SHOUT Global Hawk mission into Erika.

The figure below depicts the aircraft flight track (P-3: red line, Global Hawk: blue line) superposed on the real-time lower fuselage radar and infrared satellite imagery.

Screen Shot 2015-08-27I1Included below you see images of the horizontal winds within 180 km of Erika sampled from the tail Doppler radar on the P-3 aircraft during the early morning of 27 August 2015. These images are at three altitudes (1 km, 3 km, and 6 km) and are a composite of winds from the P-3 Doppler pattern around Erika. Also plotted on each analysis are the locations of dropsondes deployed by the P-3 (plotted using standard station symbols). These analyses show that Erika maintained a very asymmetric distribution of precipitation at all altitudes, with the bulk of the precipitation primarily in the eastern semicircle of the storm at all altitudes. There is slight indication of a circulation center at 1-km altitude just southeast of Guadalupe, with the strongest winds 70 km northeast of the circulation center, and with strong winds extending to 180 km to the north and east of the center. At 3-km altitude there is slight indication of a circulation center 40-50 km south-southeast of the 1-km altitude circulation center with strong winds over the low-altitude center. At 6-km altitude there was an indication of a circulation center in the heavy precipitation 100-125 km east-southeast of the 1-km altitude circulation center, indicative of very strong west-northwesterly shear of the horizontal wind over the low-level center.

All the Tropical Storm Erika radar composites at 0.5-km height resolution are available at: http://www.aoml.noaa.gov/hrd/Storm_pages/erika2015/radar.html.

Doppler radar quick-looks from 2:00 PM P-3 flight into Tropical Storm Erika, 26 August 2015

As Tropical Storm Erika was 350 km east of the Leeward Islands (see the black lines outlining one of the island in bottom left of analyses) a NOAA P-3 mission collected airborne Doppler radar data to use in initializing and evaluating model guidance.

The figure below depicts the aircraft flight track (P-3: yellow line) superposed on the real-time lower fuselage radar and visible satellite imagery.

Screen Shot 2015-08-26I2_1Included here you see images of the horizontal winds within 180 km of Erika sampled from the tail Doppler radar on the P-3 aircraft during the evening of 26 August 2015. These images are at three altitudes (1 km, 3 km, and 6 km) and are a composite of winds from the P-3 Doppler pattern around Erika. Also plotted on each analysis are the locations of dropsondes deployed by the P-3 (plotted using standard station symbols). These analyses show that Erika maintained a very asymmetric distribution of precipitation at all altitudes, with the bulk of the precipitation primarily in the southeastern quadrant of the storm, particularly at 3- and 6- km altitude. There is indication of a circulation center at 1-and 3-km altitudes, with the strongest winds 50-60 km northeast of the circulation center, but with strong winds extending to 180 km to the north and east of the center. At 6-km altitude there was an indication of a circulation center in the heavy precipitation 125-150 km southeast of the 1-km altitude circulation center, indicative of very strong west-northwesterly shear of the horizontal wind over the low-level center.

All the Tropical Storm Erika radar composites at 0.5-km height resolution are available at: http://www.aoml.noaa.gov/hrd/Storm_pages/erika2015/radar.html.

Doppler radar quick-looks from 2:00 AM P-3 flight into Tropical Storm Erika, 26 August 2015

As Tropical Storm Erika was 600 km east of the Leeward Islands a NOAA P-3 mission collected airborne Doppler radar data to use in initializing and evaluating model guidance and a Saharan Air Layer Experiment (SALEX) mission.

The figure below depicts the aircraft flight track (P-3: yellow line) superposed on the real-time lower fuselage radar and infrared satellite imagery.

Screen Shot 2015-08-26I1Included here you see images of the horizontal winds within 180 km of Erika sampled from the tail Doppler radar on the P-3 aircraft during the early morning of 26 August 2015. These images are at three altitudes (1 km, 3 km, and 6 km) and are a composite of winds from the P-3 Doppler patterns around Erika. Also plotted on each analysis are the locations of dropsondes deployed by the P-3 (plotted using standard station symbols). These analyses show that Erika maintained a very asymmetric distribution of precipitation at all altitudes, with the bulk of the precipitation primarily in the southeastern quadrant of the storm, particularly at 3- and 6- km altitude. There is indication of a circulation center at 1-km altitudes, with the strongest winds 40-50 km northeast of the circulation center, but with strong winds extending to 180 km to the north and east of the center. At 3-km altitude the wind field appeared like a sharp trough oriented southwest-northeast with the strongest winds extending to the north or the 1-km altitude circulation center. At 6-km altitude there was an indication of a circulation center in the heavy precipitation 125-150 km southeast of the 1-km altitude circulation center, indicative of very strong west-northwesterly shear of the horizontal wind over the low-level center.

All the Tropical Storm Erika radar composites at 0.5-km height resolution are available at: http://www.aoml.noaa.gov/hrd/Storm_pages/erika2015/radar.html.