HFIP Workshop on Rapid Intensification of Tropical ...Intensification of Tropical Cyclones: A Brief...
Transcript of HFIP Workshop on Rapid Intensification of Tropical ...Intensification of Tropical Cyclones: A Brief...
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HFIP Workshop on Rapid Intensification of Tropical Cyclones:
A Brief Summary
Chris Davis
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Topics and People
• Observations and Mechanisms• Current Prediction Capabilities• Future Directions
Speakers:Ed ZipserHaiyan JiangJon ZawislakRob RogerFalko JudtMark DeMaria
John KaplanVijay TallapragadaFuqing ZhangChris RozoffGopal
Panelists:Greg TripoliShuyi ChenJun ZhangJim DoyleJason SippelDave Nolan
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The non-existence of RIas a distinct phenomenon?
Still, RI dominates the largest intensity forecast errors
Kaplan, DeMaria and Knaff, 2010
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The nature of convection prior to RI• No evidence that intense “deep” convection precedes RI• Convection migrating to upshear side of vortex is observed
prior to RI
Haiyan Jiang
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Where Convection Occurs
Schubert and Hack 1982
Rob Rogers
Inertial stability and the radial location of convection relative to the RMW
Knowledge of the spatial relation between convection and RMW is important => reconn data
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Questions
• What is “deep” convection? Can microwave and aircraft data be consistent?
• Is the increase of area coverage a cause or a signal (vortex alignment)?
• Do we need to resolve enhanced inertial stability inside the RMW? requires 1-km resolution Rob Rogers
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Current RI prediction• Dynamical models (HWRF) show some skill in W. Pac• Statistical models work well in E. Pac• Nothing works well in Atlantic• Are statistical methods and models better equipped
to handle favorable environments?• Are the sources of non-favorability so diverse that it
is tough to model them (or represent them statistically)?
• Why do models fail in the E. Pac? Resolution?
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Perspective from Shuyi Chen, RSMAS/University of Miami
1. Modeling Issues: resolution and physics (biases)2. Deterministic vs. probabilistic forecasts3. Initial Condition Issues
Need accurate observation (not bogus) of vortex (outer and inner core winds)!
Judt et al. (2014)
168 h
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Vortex Initialization
• Vortex/environment initialization:– Adjust the model initial state to a structure consistent with
model dynamics and environmental effects (shear)
• Poor RI prediction may result from spinup in the short range, and limited predictability beyond the first day or two.
• Vortex initialization perhaps most important for stronger storms that can still undergo RI
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Predictability• Strong shear: high predictability, no RI• Moderate shear: low predictability, especially about timing• Weak shear: better predictability, perhaps still some
uncertainty to the extent that convective features are important
Fuqing Zhang
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Moving Forward1 year; 3 years
1. RI is a probabilistic forecast, but NHC requires deterministic forecasts: how can ensembles inform these products?
– Develop products that define the most likely scenario (cluster) from the ensemble (if possible): reduce adverse effect of outliers
– Reduce model bias (see #3)2. Model initialization hampers RI prediction: What can be done?3. Can idealized simulations with HWRF be useful?
– reproduce PDF of RI– assess physics shortcomings: energy fluxes and dissipation
4. SHIPS-products using input from HWRF: Could this indicate an environmental or model error?5. Further test/implement updated statistical prediction methods (using microwave data); can reconn data be incorporated?