HRD/NHC CHART Seminar – Jason Dunion, CIMAS and AOML/HRD – 18 May 2015

Jason Dunion presented a seminar on “NOAA Shout-Sensing Hazards with Operational Unmanned Technology- Plans for the Global Hawk UAS – Unmanned Aircraft Systems – during the 2015 Atlantic Hurricane Season” which is available on the NHC science presentation web site or at:


A three-year joint experiment between NOAA and NASA, called Sensing Hazards with Operational Unmanned Technology, or SHOUT, will study whether the Global Hawk observations help improve weather forecasting of storms at sea as well as what the cost of Global Hawk operations would be for NOAA. Scientists started the experiment by using computer simulations of Global Hawk data for testing. Next, they will collect actual Global Hawk observations by flying over oceanic storms.  

The first flight by the NASA Global Hawk in the experiment will take off during hurricane season 2015 over the Atlantic Ocean.  In flights of up to 26 hours, the Global Hawk can gather continuous weather data on wind, temperature, and humidity from an altitude of approximately 60,000 feet above the Earth’s surface, more than 15,000 feet higher than most manned airplanes operate. This data and simulated data will be assimilated into forecast models to evaluate whether it substantially improves the accuracy of severe weather forecasts.

The team working on the experiment includes scientists from across NOAA, including its Unmanned Aircraft System Program, Atlantic Oceanographic and Meteorological Lab/Hurricane Research Division, Earth Systems Research Lab, and NOAA Cooperative Institute (CI) for Marine and Atmospheric StudiesNOAA Corps officers with the Office of Marine and Aviation Operations will remotely operate the NASA Global Hawk. NOAA’s Weather Service and Satellite Service are part of the team evaluating the feasibility and cost of using unmanned systems in NOAA National Weather Service operations. NASA scientists and personnel will also participate and contribute their Global Hawks.

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30th anniversary of Bangladesh cyclone

Damage from 1985 cyclone (BBC)

Damage from 1985 cyclone (BBC)

Very early on May 25, 1985, a severe cyclone came ashore near Chittagong, Bangladesh.  It inundated many islands with a storm surge near 10 feet (3 m) in depth and whipped the mainland with winds of 96 mph (154 km/hr).  Despite plenty of warning time, people had few shelters and little transportation to reach them.  Over 11,000 people perished in the storm.

Paper on the resistance of hurricanes to wind shear released online in the Journal of the Atmospheric Sciences

Vertical wind shear, the difference of wind velocity between the ground and the top of the tropical cyclone, generally restricts tropical cyclone intensification. A tropical cyclone can become tilted by the wind shear so that that the circulation at the top is displaced from that near the ground. Sometimes the tropical cyclone is able to again become upright and intensify, but often such tilting is the beginning of the storm’s demise. A simple mathematical model predicts how much tilt the tropical cyclone will have based on how much cloudiness is within the eyewall as well as the structure of the wind outside the eyewall. This paper clarifies basic ways that a tropical cyclone can resist wind shear.

Important Conclusions:

Tropical cyclones are better able to stay upright in vertical wind shear when there are lots of clouds in the eyewall.

Tropical cyclones are better able to stay upright in vertical wind shear when the wind’s spin quickly decays away from the eyewall.

A simple mathematical model confirms these findings.

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There paper can be accessed at

Paper on the relative roles of the ocean and atmosphere in maintaining hurricanes published in Monthly Weather Review

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Until now, it was believed that hurricanes are maintained by the ocean alone.  Observations from 62 hurricanes during 32 years support a different, nuanced conclusion.  Besides the ocean, near-surface air temperature and moisture play a large, often dominant, role in maintaining a hurricane.

Important conclusions:

1.  The long-held belief that an ocean surface temperature of at least 26 degrees C (80 degrees F) is required to maintain a hurricane was not supported in 6% of the cases studied.  Atmospheric moisture conditions in areas of high wind speeds are what cause the “80-degree F threshold” for hurricanes.

2.  For hurricanes within 29 degrees of the equator, the atmosphere, not the ocean, was found to be the most important factor in maintaining the hurricane.

The full paper can be accessed at

2015 Hurricane Field Program/Intensity Forecast EXperiment (HFP/IFEX) Planning Meeting

On Tuesday, May 19, 2015, Dr. Robert Rogers led a kick off meeting to discuss our flight experiments and modules that will be part of the 2015 hurricane field campaign. Click here to review the proposed experiments.

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HRD seminar – Dave Jones (Storm Center Communications) and Svetla Hristova-Veleva (NASA/JPL) – 13 May 2015

Dave Jones and Svetla Hristova-Veleva provided an overview of the Tropical Cyclone Information System (TCIS) developed at NASA Jet Propulsion Laboratory (JPL) to facilitate the inter-comparison of hurricane model simulations and passive microwave satellite observations within a common geo-referenced and web-based application. The purpose of their visit was to engage operational hurricane forecasters and researchers in providing:

  • Useful input & feedback into the capabilities of TCIS;
  • Identify strengths and weaknesses; and
  • Identify modifications that will better serve NHC & HRD

The intent of the feedback session is to enable JPL and StormCenter Communications to modify TCIS to better serve the needs of the hurricane research and operational communities. Dave provided an overview of StormCenter Communications role in improving access to TCIS and Svetla summarized TCIS and gave numerous examples of TCIS products and analysis tools. Copies of their presentations are available in a zip archive on the ftp site at: