Southern hemisphere tropical cyclone intensity forecast methods used at the Joint Typhoon Warning Center, Part III: forecasts based on a multi-model consensus approach

Abstract The value of assimilating targeted dropwindsonde observations meant to improve tropical cyclone intensity forecasts is evaluated using data collected during the Pre-Depression Investigation of Cloud-Systems in the Tropics (PREDICT) field project and a cycling ensemble Kalman filter. For each of the four initialization times studied, four different sets of Weather Research and Forecasting Model (WRF) ensemble forecasts are produced: one without any dropwindsonde data, one with all dropwindsonde data assimilated, one where a small subset of “targeted” dropwindsondes are identified using the ensemble-based sensitivity method, and a set of randomly selected dropwindsondes. For all four cases, the assimilation of dropwindsondes leads to an improved intensity forecast, with the targeted dropwindsonde experiment recovering at least 80% of the difference between the experiment where all dropwindsondes and no dropwindsondes are assimilated. By contrast, assimilating randomly selected dropwindsondes leads to a smaller impact in three of the four cases. In general, zonal and meridional wind observations at or below 700 hPa have the largest impact on the forecast due to the large sensitivity of the intensity forecast to the horizontal wind components at these levels and relatively large ensemble standard deviation relative to the assumed observation errors.

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A Consensus Approach for Estimating Tropical Cyclone Intensity from Meteorological Satellites: SATCON

Weather and Forecasting ◽

10.1175/waf-d-20-0015.1 ◽

2020 ◽

Vol 35 (4) ◽

pp. 1645-1662 ◽

Cited By ~ 2

Author(s):

Christopher S. Velden ◽

Derrick Herndon

Keyword(s):

Tropical Cyclone ◽

Real Time ◽

Tropical Cyclones ◽

Intensity Analysis ◽

Tropical Cyclone Intensity ◽

Consensus Approach ◽

Cyclone Intensity ◽

Weighting Strategy ◽

The Individual ◽

Intensity Estimate

ABSTRACTA consensus-based algorithm for estimating the current intensity of global tropical cyclones (TCs) from meteorological satellites is described. The method objectively combines intensity estimates from infrared and microwave-based techniques to produce a consensus TC intensity estimate, which is more skillful than the individual members. The method, called Satellite Consensus (SATCON), can be run in near–real time and employs information sharing between member algorithms and a weighting strategy that relies on the situational precision of each member. An evaluation of the consensus algorithm’s performance in comparison with its individual members and other available operational estimates of TC intensity is presented. It is shown that SATCON can provide valuable objective intensity estimates for poststorm assessments, especially in the absence of other data such as provided by reconnaissance aircraft. It can also serve as a near-real-time estimator of TC intensity for forecasters, with the ability to quickly reconcile differences in objective intensity methods and thus decrease the uncertainty and amount of time spent on the intensity analysis. Near-real-time SATCON estimates are being provided to global operational TC forecast centers.

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Accuracy of Atlantic and Eastern North Pacific Tropical Cyclone Intensity Forecast Guidance

Weather and Forecasting ◽

10.1175/waf1015.1 ◽

2007 ◽

Vol 22 (4) ◽

pp. 747-762 ◽

Cited By ~ 86

Author(s):

Russell L. Elsberry ◽

Tara D. B. Lambert ◽

Mark A. Boothe

Keyword(s):

Fluid Dynamics ◽

Tropical Cyclone ◽

North Pacific ◽

Phase Iii ◽

False Alarms ◽

Rapid Intensification ◽

Tropical Cyclone Intensity ◽

Geophysical Fluid Dynamics ◽

Cyclone Intensity ◽

Intensity Forecast

Abstract Five statistical and dynamical tropical cyclone intensity guidance techniques available at the National Hurricane Center (NHC) during the 2003 and 2004 Atlantic and eastern North Pacific seasons were evaluated within three intensity phases: (I) formation; (II) early intensification, with a subcategory (IIa) of a decay and reintensification cycle; and (III) decay. In phase I in the Atlantic, the various techniques tended to predict that a tropical storm would form from six tropical depressions that did not develop further, and thus the tendency was for false alarms in these cases. For the other 24 depressions that did become tropical storms, the statistical–dynamical techniques, statistical hurricane prediction scheme (SHIPS) and decay SHIPS (DSHIPS), have some skill relative to the 5-day statistical hurricane intensity forecast climatology and persistence technique, but they also tend to intensify all depressions and thus are prone to false alarms. In phase II, the statistical–dynamical models SHIPS and DSHIPS do not predict the rapid intensification cases (≥30 kt in 24 h) 48 h in advance. Although the dynamical Geophysical Fluid Dynamics Interpolated model does predict rapid intensification, many of these cases are at the incorrect times with many false alarms. The best performances in forecasting at least 24 h in advance the 21 decay and reintensification cycles in the Atlantic were the three forecasts by the dynamical Geophysical Fluid Dynamics Model-Navy (interpolated) model. Whereas DSHIPS was the best technique in the Atlantic during the decay phase III, none of the techniques excelled in the eastern North Pacific. All techniques tend to decay the tropical cyclones in both basins too slowly, except that DSHIPS performed well (12 of 18) during rapid decay events in the Atlantic. This evaluation indicates where NHC forecasters have deficient guidance and thus where research is necessary for improving intensity forecasts.

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Tropical Cyclone Forecasters Reference Guide 6. Tropical Cyclone Intensity.

10.21236/ada302328 ◽

1995 ◽

Cited By ~ 2

Author(s):

C. R. Sampson ◽

R. A. Jeffries ◽

C. J. Neumann ◽

J-H. Chu

Keyword(s):

Tropical Cyclone ◽

Tropical Cyclone Intensity ◽

Cyclone Intensity ◽

Reference Guide

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