HRD seminar – Prof. U.C. Mohanty, India Institute of Technology (IIT), Bhubaneswar, Odisha, India – 16 June 2015

Prof. Mohanty presented a seminar on “Prediction of tropical cyclones over Bay of Bengal using 2013 version of HWRF system”.


More than 80-90% of the deaths due to Tropical Cyclones (TCs) are caused by fresh water flooding and storm surge; and hence realistic TC intensity, size and structure predictions are important at landfall for disaster management. The 2013 version of HWRF system is used with multiple moving nests spanning at (cloud resolving) resolution down to 3 km to predict tropical cyclones of 2013-14 over the Bay of Bengal (BoB).

Application of two versions of the HWRF system for the Bay of Bengal cyclones demonstrated that cloud resolving version of HWRF (27/9/3 km, 3 domains) is superior than HWRF run at reduced resolution around the vortex (27/9 km, 2 domains) for TC prediction (track, intensity and rainfall) that was used until recently over the Indian seas. Structure prediction is also improved with 27/9/3 km HWRF.  Real time application of 27/9/3 HWRF system showed potential to provide better intensity and structure forecast guidance for TCs over NIO. Further experiments suggest that vortex initialization and relocation in cyclic mode has a positive impact on track and intensity over cold start, though not significant (based on 4 cyclones, need for a number of cases).

HWRF provided realistic TC predictions consistently for track, intensity, rainfall and structure. The rainfall amount and structure is improved significantly, particularly, in case of Phailin, the model showed peak rainfalls over Northern parts of Odisha, as observed. HWRF is able to predict the rapid intensification of Phailin a day before to its actual occurrence. In case of Lehar, the model predicted rapid weakening and indicated the depletion of moisture associated with the weakening over the Bay of Bengal. When compared to ARW model predictions, HWRF is superior in predicting intensity and structure, even in 4 days or longer forecast length, while, track prediction is comparable. 

The improved longer range forecast of TC track, intensity and structure helped to increase the lead time of storm surge prediction over the Bay of Bengal basin. A 3-4 day forecast of maximum surge is reasonably good in terms of location and quantity. In case of Hud-Hud, a 4-day forecast of peak surge is about 1.4 m and a day forecast is about 1.7 m which provides better guidance when compared to the observed surge of 1.4 m at Vishakhapatnam.

A video recording of the presentation is available on the anonymous ftp site:

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HRD seminar – S. J. Lin and Lucas Harris (NOAA/Geophysical Fluid Dynamics Laboratory (GFDL)) – 10 June 2015

Drs. Lin and Harris provided an overview of GFDL’s unified weather-climate modeling system with two-way regional-global nesting capability.


We are taking a “seamless” approach in the development of the next generation weather-climate model at GFDL. All the requirements for short-term numerical weather predictions and century long climate change projections are taken into consideration. In particular, predictions of severe weather events such as hurricanes and tornado-producing supercell thunder storms are one of the primary focus. The outcome of this effort is an extremely flexible modeling/prediction system that can be shared between OAR and NWS as a common resource.

A video of their presentations is available on the ftp site at:

HRD Monthly Science Meeting of June 2015

June’s science meeting consisted of 3 presentations:

  1. Joshua Wadler (Hollings scholar from U. Oklahoma) – Convective Bursts: How their structure and environments vary in shear relative quadrants
  2. Kurt Hansen (Hollings scholar from SUNY Albany) – Downdrafts in Tropical Cyclones
  3. Jun Zhang – Effects of Vertical Diffusion on Forecasts of Rapid Intensifying Storms in HWRF – preliminary results

All the presentations and posters are available on the anonymous ftp site at:

70th Anniversary of Typhoon Connie

The foredeck of the USS Bennington, collapsed in the high seas of Typhoon Connie.

The foredeck of the USS Bennington, collapsed in the high seas of Typhoon Connie.

On June 5 1945, Typhoon Connie swept over the U.S. Navy’s Fifth Fleet southeast of Okinawa.  The fleet had been supporting the invasion of Okinawa when the Fleet Weather Center on Guam notified them of the existence of the storm to their south.  Admiral William “Bull” Halsey, who ran afoul of another typhoon just six months before, attempted to maneuver his ships to avoid the cyclone but managed to sail them into its path.  Although less severe than Typhoon “Cobra,” the 50- to 60-foot waves damaged 33 ships and cost the lives of six sailors.  125 airplanes aboard the carriers were also damaged when some broke loose from their moorings and the rolling seas smashed them into other planes still lashed down.

75th Anniversary of Gordon Dunn’s “isallobaric waves” paper

Gordon Dunn

Gordon Dunn

In June of 1940, Gordon Dunn published a paper in the Bulletin of the American Meteorological Society about the nature of disturbances in the Atlantic and their relationship to tropical cyclone formation.  While working as a junior hurricane forecaster at the Weather Bureau’s Jacksonville Hurricane Warning Center, Dunn analyzed daily weather maps for the Atlantic Ocean, and noticed displacements in the pressure field which were associated with disturbed weather.  He called them “isallobaric waves” since they appeared as horizontal waves on the isobar maps.  They seemed to be stable in structure as they moved from east to west from the coast of Africa to the Caribbean Sea, and were associated with a breakdown in the inversion layer common in the region.  They also provided the origins for many tropical cyclones, and he traced all of the hurricanes that formed in 1935, 1937, and 1938 to such waves.   This paper provided a new paradigm for tropical cyclogenesis.  Today isallobaric waves are called African Easterly Waves.

horizontal waves in the tropical Atlantic pressure field

Horizontal waves in the tropical Atlantic pressure field

Dunn, G.E., “Cyclogenesis in the Tropical Atlantic,” Bulletin of the American Meteorological Society, Vol. 21, No. 6, June 1940, p.215-229

HRD scientists “Feel the Force” at the Miami Museum of Science

Eric Uhlhorn discusses hurricane science for the TV camera.

Eric Uhlhorn discusses hurricane science for the TV camera.

On Saturday, May 30th, AOML personnel participated in the Patricia and Philip Frost Miami Science Museum’s annual “Feel the Force” outreach program.  The one-day event drew over 1000 people who learned about preparing their homes and families to deal with disasters, especially hurricanes.  HRD scientists staffed the exhibit dedicated to explaining how scientists fly into storms to gather scientific data.  In addition to speaking to people about the experience of flying into tropical cyclones, they also took the opportunity to explain the latest innovations in technology being tested this season and how our work will benefit hurricane intensity forecasts.  In addition, the scientists granted media interviews and even led a team of children in the Museum’s “Wild and Crazy Weather Challenge”.

Gus Alaka points out the illustration of a NOAA P3 making a hurricane eye penetration

Gus Alaka and friend point out the illustration of a NOAA P3 making a hurricane eye penetration

Dr. Frank Marks checks the schedule of events.

Dr. Frank Marks checks the schedule of events.

Gus Alaka leads a winning team inte Wild and Crazy Weather Challange.

Gus Alaka leads a winning team in the Wild and Crazy Weather Challenge.

Frank Marks discusses what it is like to fly into the eye of a hurricane at the Patricia and Phillip Frost Museum of Science – 28 May 2015

HRD Director Frank Marks gave a presentation “Inside the Eye of the Storm” as part of the Science Up Close Series at the Patricia and Phillip Frost Museum of Science on Thursday, May 28th.


Advances in the study and forecasting of hurricanes came about through scientific and technological improvements in our ability to observe different aspects of the storms using aircraft. Aircraft missions into hurricanes provide the basis for understanding hurricane structure and evolution. Technological advances in aircraft, instrumentation, and telecommunications over the last 20 years enables real-time transmission of all of these observations directly to the operational forecasters and into numerical models greatly increasing our ability to forecast hurricanes. Each of these technologies started as tools used by researchers flying into these storms in order to better determine a hurricane’s location, intensity, and structure. In order to increase the pace of forecast improvement NOAA developed the Hurricane Forecast Improvement Project (HFIP) in 2008 whose goal is to decrease the error in forecast guidance for track and intensity by 20% in 5 years and 50% in 10 years. In order to achieve such and ambitious goal HFIP is pursuing a strategy to make better use of the aircraft observations to provide better initial analyses of the storm’s structure for the models to start from. 


The presentation (161 Mb) is available on the anonymous ftp site at: