2016 Hurricane Season ends

Brad Klotz celebrates the end of missions into Hurricane Matthew

Brad Klotz celebrates the end of missions into Hurricane Matthew

Today marks the last day of the 2016 Atlantic hurricane season, and it was a busy one for us.  AOML’s Hurricane Research Division (HRD) participated in 57 missions into six different tropical cyclones: Colin, Earl, Javier (East Pacific), Hermine, Karl, and Matthew.  From early June to the start of October, HRD personnel either flew on-board research flights or processed data on the ground in real time from these missions.  Here is a break down of the sorties by aircraft platform:

  • P-3                  32 missions
  • G-IV                17 missions
  • Global Hawk   8 missions

NOAA launched over 1000 dropsondes in and around storms this season, a massive deployment executed through the Intensity Forecasting EXperiment (IFEX), conducted in collaboration with NOAA’s Environmental Modeling Center and National Hurricane Center, and the Sensing Hazards with Operational Unmanned Technology (SHOUT) campaign in cooperation with NASA and NOAA’s Earth System Research Laboratory.

Some highlights from this season’s efforts:

  • Testing and development of new observing technologies including Doppler Wind Lidar data gathered in Earl and Javier.
  • Prolonged genesis and intensification of Hermine was observed.  Hermine was the first land-falling hurricane in Florida since Wilma (2005).
  • A  unique data set was collected during the extratropical transition of Karl.  This was the first storm flown from cyclogenesis to extratropical transition.
  • Hurricane Matthew was the first category-5 hurricane in Atlantic basin since Felix (2007).

The various data sets gathered this year will be studied extensively to look for possible relationships between rainfall patterns and storm intensity changes.  The dropsondes and Doppler radar data collected in conjunction will help improve the new generation of computer simulations that model the inner workings of the hurricane vortex.  This will help improve the forecasting of intensity change, a central goal of HRD.


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Through the Eyewall – My Experience with the NOAA Hurricane Hunters, Nicholas Komisarjevsky, Science Communications Intern, NOAA AOML


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HRD Seminar – Kelly Ryan, CIMAS and AOML/HRD, Tucson, AZ – 28 October 2016

Kelly Ryan presented a seminar titled  “OSSE Evaluation of the Impact of Aircraft Observations on Hurricane Analyses and Forecasts” at the University of Arizona.

A copy of the presentation is available on the anonymous ftp site: ftp://ftp.aoml.noaa.gov/pub/hrd/blog/seminars/2017/Ryan_UA_seminar_Oct2016.pdf


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HRD observation team monthly meeting – 17 November 2016

The purpose of the observation team meetings is to bring together the people who use observations in their research on a regular basis to discuss issues they’re having, provide updates on observations they’re analyzing or collecting, and any other information that may be of interest to the broader group.  These meetings are also an excellent opportunity to integrate all of the many uses of observations in HRD’s capacity to improve the understanding and prediction of tropical cyclones.

Agenda for November 2016:

Updates & Outlook
1) SFMR reprocessing (Brad Klotz)
2) Coyote outlook (Joe Cione)
3) DWL update (Lisa Bucci/Jun Zhang)

Research & Development
4) Dropsonde analysis tool development (Jon Zawislak)
5) Dropsonde impact study (Hui Christophersen)

The presentation from the meeting is available on the anonymous ftp site: ftp://ftp.aoml.noaa.gov/pub/hrd/blog/meetings/2017/Observations/HRD_ObsMeet_20161117.zip

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Paper on a simple way to simulate winds closest to the surface in tropical cyclones released online in Boundary-Layer Meteorology

Screen Shot 2016-11-16 at 12.51.04 PM.png

You can read the article here

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HRD Monthly Science Meeting of November 2016

November’s science meeting consisted of 7 presentations:

  1. Shun-Nan Wu (RSMAS), “The signal of future TC intensification in the CloudSat measurements”
  2. Jon Zawislak (FIU/CIMAS/HRD), “The Relationship Between Precipitation and Environmental Forcing during Tropical Cyclone Formation”
  3. Leon Nguyen (HRD), “Thermodynamic and kinematic influences on precipitation symmetry in sheared tropical cyclones: Bertha and Cristobal (2014)”
  4. Brad Klotz (CIMAS/HRD): “SFMR reprocessing update”
  5. Sim Aberson (HRD), “On HWRF Spindown”
  6. Jun Zhang (CIMAS/HRD): “Impact of parameterized boundary layer structure on tropical cyclone rapid intensification forecast in HWRF”
  7. Ghassa Alaka (CIMAS/HRD): “2016 Basin-Scale HWRF, Part I: Matthew Track Forecasts”

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


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Paper on a new way to run forecast models with multiple hurricanes at the same time released online in Weather and Forecasting

  • Summary:

HWRF is NOAA’s primary model for tropical cyclone (tropical depressions, tropical storms, and hurricanes) forecast. The distance between places where forecasts are made in the model (the grid resolution) must be small to make accurate forecasts. However, the amount of computer power needed increases as these points get closer together. To save computer power, HWRF runs with a higher resolution only around the tropical cyclone than outside using so-called nesting. The current HWRF can only forecast one tropical cyclone at a time. This paper presents a way to forecast up to four tropical cyclones at a time using movable multi-level nesting (MMLN). The nests

can follow each tropical cyclone. This paper documents the design of the MMLN for the first time. The model is run for four seasons.

  • Important Conclusions:

The version of HWRF wth MMLN improved forecasts of where the storm was going.

The version of HWRF with MMLN can better forecast places outside the tropical cyclone (the environment) that controls where the storm will go and how strong it will be than the regular version.

The version of HWRF with MMLN may be used during upcoming hurricane seasons to improve forecasts.Screen Shot 2016-11-10 at 4.08.06 PM.png

You can find the paper online at http://journals.ametsoc.org/doi/abs/10.1175/WAF-D-16-0087.1.

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Paper on new observations of rapid intensification during Hurricane Karl published in The Journal of the Atmospheric Sciences

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Read the paper at http://journals.ametsoc.org/doi/abs/10.1175/JAS-D-16-0026.1.

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Two-part paper on the intensification of Hurricane Edouard published in Monthly Weather Review

Summary: Hurricane Edouard (2014) is examined using radar onboard NOAA P-3 aircraft that flew the storm. Two periods are shown, one when the storm was intensifying to a major hurricane and the other when the storm was weakening. The location of strong thunderstorms, and how they changed over time, is examined to see if there is a difference over time and to determine what caused those differences.

Important Conclusions: (two – three)

  1. Strong thunderstorms that extend above 50,000 ft altitude are seen when Edouard was intensifying; when Edouard was weakening, no such thunderstorms are seen.
  2. When Edouard is intensifying, thunderstorms cover a large area and are located close to and inside where the strongest winds exist.
  3. More thunderstorms occur when the wind in the lowest few thousand feet flowing toward the central low pressure reaches past the eyewall where the strongest winds exist. Because this air flows inward from all directions, it must rise in the eyewall, and thunderstorms develop. These strength and longevity of these thunderstorms depends on the warmth of the ocean below the storm and the moisture in the air around it.

Screen Shot 2016-11-04 at 6.23.40 PM.png

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You can access Part I at http://journals.ametsoc.org/doi/abs/10.1175/MWR-D-16-0018.1 and Part II at http://journals.ametsoc.org/doi/full/10.1175/MWR-D-16-0017.1.

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HRD Seminar – Dr. Andy Hazelton, Princeton University and NOAA/GFDL – 28 October 2016

Dr. Hazelton presented a seminar on “Convective Burst Development and Evolution in Two Simulated Atlantic TCs”.


Understanding the structure and evolution of the tropical cyclone (TC) inner core remains an elusive challenge in tropical meteorology, especially transient asymmetric features such as localized strong updrafts known as convective bursts (CBs).  This study investigates the formation of CBs and their role in TC structure and evolution using high-resolution simulations of two hurricanes (Dean 2007 and Bill 2009) with the Weather Research and Forecasting (WRF) model. 

Several different aspects of the dynamics and thermodynamics of the TC inner-core region are investigated with respect to their influence on TC convective burst development.   Radius-height composites with CBs show stronger radial inflow in the lowest 2 km, and stronger radial outflow from the eye to the eyewall around z = 2-4 km, than composites without CBs.  Asymmetric vorticity associated with eyewall mesovortices appears to be a major factor in leading to some of the radial flow anomalies that lead to CB development.  Analysis of individual CBs and parcel trajectories show that many parcels are pulled into the eye, move outward into the eyewall, and rapidly ascend in CBs.  The positive buoyancy observed along the parcel paths support the importance of eye-eyewall exchange in CB development.

            Analysis of intensity change in the simulations shows that there are more inner-core CBs during times when the TCs are intensifying, while weakening/steady times appear to be associated with more CBs outside the radius of maximum wind (RMW), consistent with observational studies and theoretical work.  However, times when the TC has already been intensifying and continues to do so have more CBs than times when the TC has been weakening but then intensifies.  This result suggests that CB development may not always be predictive of intensification, but rather may occur as a result of ongoing intensification.  Rapid intensification (RI) in the simulations is found to be associated with an even higher density of CBs inside the RMW than slower intensification.  Lag correlations between CBs and intensity reveal a broad peak in correlation, with the CBs leading pressure falls by 0-3 hours.  These results confirm the notion that convective heating inside the RMW (where inertial stability is higher) is favorable for intensification.  However, it is shown that the relationship can vary in different cases depending on environmental conditions and the previous evolution of the TC.

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



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