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

HRD Monthly Science Meeting of April 2015

April’s science meeting consisted of 7 presentations:

  1. Vijay Tallapragada (EMC): Evaluation of Proposed FY15 Upgrades for NCEP Operational HWRF: NATL/EPAC Storms, 2011-2014
  2. Xuejin Zhang: Development of Atmosphere-Ocean-Land Fully Coupled Basin-scale HWRF System
  3. Christina Holt (DTC): Large Scale Verification of HWRF
  4. Hua Chen: Numerical Experiments with Hurricane Isaac (2012)
  5. Bachir Annane: Time-Resolved Observations of Precipitation and storm Intensity with a Constellation of Smallsats (TROPICS)
  6. Jeff Stewart (JPL/UCLA): Tropical and Mid-Latitude Covariance Comparison for AIRS brightness temperatures
  7. Jason Dunion: Global Hawk Dropsonde Observations of the TC Diurnal Cycle

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

HRD & AOML researchers at 95th American Meteorological Society Annual Meeting, Phoenix, AZ – 4-8 January 2015

Screen Shot 2015-04-04 at 5.42.29 PMAbstracts and recordings of  the 13 presentations and 4 posters AOML & HRD researchers presented (or were co-authors) at the 95th AMS Annual Meeting are available online from the AMS website:


  1. Improving the Performance of the Basin Scale HWRF SystemJavier Delgado, University of Miami/CIMAS and NOAA/AOML/HRD, Miami, FL; and T. Quirino, X. Zhang, and S. Gopalakrishnan
  2. Targeting on the Research to Operational Transition with the Basin-scale HWRF Modeling SystemXuejin Zhang, NOAA/AOML/HRD, Miami, FL; and T. Quirino, S. Trahan, Q. Liu, Z. Zhang, R. St. Fleur, S. Gopalakrishnan, V. Tallapragada, and F. D. Marks Jr.
  3. A Global to Local-Scale Hurricane Forecasting SystemXuejin Zhang (for Sundararaman Gopalakrishnan), University of Miami/CIMAS and NOAA/AOML/HRD, Miami, FL; and T. Black, T. Quirino, V. Tallapragada, Z. Janjic, and T. L. Schneider
  4. Real-time Airborne Radar Data Quality Control and transmission from NOAA Aircraft for assimilation into HWRFJohn F. Gamache, NOAA/AOML/HRD, Miami, FL; and S. Otero, J. W. Hill, and P. P. Dodge
  5. NOAA’s Hurricane Forecast Improvement Project – HFIPFrank D. Marks Jr., NOAA/AOML/HRD, Miami, FL; and F. Toepfer, R. L. Gall, E. Rappaport, and V. Tallapragada
  6. Tropical Cyclone Research Utilizing the Global Hawk Unmanned AircraftJason Dunion (for Michael Black), University of Miami/CIMAS and NOAA/AOML/HRD, Miami, FL; and R. E. Hood and G. A. Wick
  7. Observing System Simulation Experiments to Assess the Potential Impact of Proposed Observing Systems on Hurricane PredictionRobert Atlas, NOAA/AOML, Miami, FL; and L. Bucci, A. Aksoy, B. Annane, R. N. Hoffman, G. D. Emmitt, Y. Xie, S. J. Majumdar, J. Delgado, and L. Cucurull
  8. Fusion of Hurricane Models and Observations: Developing the Technology to Improve the ForecastsSvetla Hristova-Veleva, JPL, Pasadena, CA; and M. Boothe, S. G. Gopalakrishnan, Z. Haddad, B. Knosp, B. Lambrigtsen, P. P. Li, M. Montgomery, N. Niamsuwan, T. P. Shen, V. Tallapragada, S. Tanelli, and F. J. Turk
  9. North Atlantic OSSEs in support of improved hurricane forecasting: Nature Run evaluationVilly H. Kourafalou, Univ. of Miami/RSMAS, Miami, FL; and G. R. Halliwell Jr., R. Atlas, H. S. Kang, M. F. Mehari, M. Le Henaff, L. K. Shay, R. Lumpkin, and G. Goni

Student presentations (HRD Hollings Scholars):

  1. An Extreme Event in the Eyewall of Hurricane FelixKelly Marie Nunez Ocasio, University of Puerto Rico, Mayagüez,, PR; and S. D. Aberson and J. Zhang
  2. A Statistical Take on the Hurricane’s Structure and Its Spatial ExtentRobert G. Nystrom, University of Illinois at Urbana-Champaign, Urbana, IL; and A. Askoy


  1. Impact of CYGNSS Data on Hurricane Analyses and Forecasts in a Regional OSSE FrameworkBachir Annane, Univ. of Miami/CIMAS and NOAA/AOML/HRD, Miami, FL; and B. McNoldy, J. Delgado, L. Bucci, R. Atlas, and S. Majumdar
  2. OSSE Evaluation of a Hyperspectral Sounder and its Potential Impact on Hurricane PredictionLisa Bucci, Univ. of Miami/RSMAS and NOAA/AOML/HRD, Miami, FL; and B. Annane, J. Delgado, and R. Atlas
  3. Wave and Wind Direction Effects on SFMR Brightness Temperatures – Heather M. Holbach, Florida State University, Tallahassee, FL; and E. W. Uhlhorn and M. A. Bourassa
  4. Improving Physical Parameterizations of the Operational Hurricane Model Using Aircraft ObservationsJun Zhang, NOAA/AOML/HRD and Univ. of Miami/CIMAS, Miami, FL; and F. D. Marks Jr., S. Gopalakrishnan, R. Rogers, and V. Tallapragada