An Examination of Model Track Forecast Errors for Hurricane Ike (2008) in the Gulf of Mexico

2011 ◽  
pp. 110324113650092 ◽  
Author(s):  
Michael J. Brennan ◽  
Sharanya J. Majumdar
Keyword(s):  
Gulf Of Mexico ◽  
Track Forecast ◽  
Forecast Errors ◽  
Hurricane Ike

An Examination of Model Track Forecast Errors for Hurricane Ike (2008) in the Gulf of Mexico

2011 ◽  
Vol 26 (6) ◽  
pp. 848-867 ◽  
Author(s):  
Michael J. Brennan ◽  
Sharanya J. Majumdar
Keyword(s):  
Gulf Of Mexico ◽  
Short Wave ◽  
Track Forecast ◽  
Forecast Errors ◽  
Multiple Sources ◽  
Hurricane Ike ◽  
Initial State ◽  
Ensemble Forecasts ◽  
Wave Trough ◽  
Subtropical Ridge

Abstract Sources of dynamical model track error for Hurricane Ike (2008) in the Gulf of Mexico are examined. Deterministic and ensemble model output are compared against National Centers for Environmental Prediction (NCEP) Global Forecast System (GFS) analyses to identify potential critical features associated with the motion of Ike and its eventual landfall along the upper Texas coast. Several potential critical features were identified, including the subtropical ridge north of Ike and several synoptic-scale short-wave troughs and ridges over central and western North America, and Tropical Storm Lowell in the eastern North Pacific. Using the NCEP Gridpoint Statistical Interpolation (GSI) data assimilation scheme, the operational GSI analysis from the 0000 UTC 9 September 2008 cycle was modified by perturbing each of these features individually, and then integrating the GFS model using the perturbed initial state. The track of Ike from each of the perturbed runs was compared to the operational GFS and it was found that the greatest improvements to the track forecast were associated with weakening the subtropical ridge north of Ike and strengthening a midlevel short-wave trough over California. A GFS run beginning with an analysis where both of these features were perturbed produced a greater track improvement than either did individually. The results suggest that multiple sources of error exist in the initial states of the operational models, and that the correction of these errors in conjunction with reliable ensemble forecasts would lead to improved forecasts of tropical cyclone tracks and their accompanying uncertainty.

scholarly journals Diagnosis of Track Forecast Errors for Tropical Cyclone Rita (2005) Using GEFS Reforecasts

2015 ◽  
Vol 30 (5) ◽  
pp. 1334-1354 ◽  
Author(s):  
Thomas J. Galarneau ◽  
Thomas M. Hamill
Keyword(s):  
Tropical Cyclone ◽  
Weather Prediction ◽  
Weather Research And Forecasting ◽  
Track Forecast ◽  
Forecast Errors ◽  
Subtropical Anticyclone ◽  
Cutoff Low ◽  
Layer Flow ◽  
Upper Level ◽  
Mass Evacuation

Abstract Analysis and diagnosis of the track forecasts for Tropical Cyclone (TC) Rita (2005) from the Global Ensemble Forecast System (GEFS) reforecast dataset is presented. The operational numerical weather prediction guidance and GEFS reforecasts initialized at 0000 UTC 20–22 September 2005, 2–4 days prior to landfall, were all characterized by a persistent left-of-track error. The numerical guidance indicated a significant threat of landfall for the Houston, Texas, region on 24 September. The largest mass evacuation in U.S. history was ordered, with the evacuation resulting in more fatalities than TC Rita itself. TC Rita made landfall along the Texas–Louisiana coastal zone on 24 September. This study utilizes forecasts from the GEFS reforecast and a high-resolution regional reforecast. The regional reforecast was generated using the Advanced Hurricane Weather Research and Forecasting Model (AHW) with the GEFS reforecasts providing the initial and boundary conditions. The results show that TC Rita’s track was sensitive to errors in both the synoptic-scale flow and TC intensity. Within the GEFS reforecast ensemble, the nonrecurving members were characterized by a midlevel subtropical anticyclone that extended too far south and west over the southern United States, and an upper-level cutoff low west and anticyclone east of TC Rita that were too weak. The AHW regional reforecast ensemble further highlighted the role of intensity and steering-layer depth in TC Rita’s track. While the AHW forecast was initialized with a TC that was too weak, the ensemble members that were able to intensify TC Rita more rapidly produced a better track forecast because the TCs followed a deeper steering-layer flow.

scholarly journals Ensemble Sensitivity Tools for Assessing Extratropical Cyclone Intensity and Track Predictability

2013 ◽  
Vol 28 (5) ◽  
pp. 1133-1156 ◽  
Author(s):  
Minghua Zheng ◽  
Edmund K. M. Chang ◽  
Brian A. Colle
Keyword(s):  
Wave Packet ◽  
Great Plains ◽  
Rossby Wave ◽  
Short Wave ◽  
Empirical Orthogonal Functions ◽  
Track Forecast ◽  
Forecast Errors ◽  
Southern Great Plains ◽  
Cyclone Intensity ◽  
Wave Trough

Abstract This paper applies ensemble sensitivity analysis to a U.S. East Coast snowstorm on 26–28 December 2010 in a way that may be beneficial for an operational forecaster to better understand the forecast uncertainties. Sensitivity using the principal components of the leading empirical orthogonal functions (EOFs) on the 50-member European Centre for Medium-Range Weather Forecasts (ECMWF) ensemble identifies the sensitive regions and weather systems at earlier times associated with the cyclone intensity and track uncertainty separately. The 5.5-day forecast cyclone intensity uncertainty in the ECMWF ensemble is associated with trough and ridge systems over the northeastern Pacific and central United States, respectively, while the track uncertainty is associated with a short-wave trough over the southern Great Plains. Sensitivity based on the ensemble mean sea level pressure difference between two run cycles also suggests that the track's shift between the two cycles is linked with the initial errors in the short-wave trough over the southern Great Plains. The sensitivity approach is run forward in time using forward ensemble regression based on short-range forecast errors, which further confirms that the short-term error over the southern plains trough was associated with the shift in cyclone position between the two forecast cycles. A coherent Rossby wave packet originated from the central North Pacific 6 days before this snowstorm event. The sensitivity signals behave like a wave packet and exhibit the same group velocity of ~29° longitude per day, indicating that Rossby wave packets may have also amplified uncertainty in both the cyclone amplitude and track forecast.

scholarly journals Gulf of Mexico hurricane wave simulations using SWAN: Bulk formula-based drag coefficient sensitivity for Hurricane Ike

2013 ◽  
Vol 118 (8) ◽  
pp. 3916-3938 ◽  
Author(s):  
Yong Huang ◽  
Robert H. Weisberg ◽  
Lianyuan Zheng ◽  
Marcel Zijlema
Keyword(s):  
Gulf Of Mexico ◽  
Drag Coefficient ◽  
Hurricane Ike ◽  
Bulk Formula

scholarly journals Atlantic Hurricane Season of 2011*

2013 ◽  
Vol 141 (8) ◽  
pp. 2577-2596 ◽  
Author(s):  
Lixion A. Avila ◽  
Stacy R. Stewart
Keyword(s):  
United States ◽  
The United States ◽  
Tropical Storms ◽  
Track Forecast ◽  
Forecast Errors ◽  
Eastern Canada ◽  
The Bahamas ◽  
Hurricane Wind ◽  
Level Of Activity ◽  
High Level

Abstract The 2011 Atlantic season was marked by above-average tropical cyclone activity with the formation of 19 tropical storms. Seven of the storms became hurricanes and four became major hurricanes (category 3 or higher on the Saffir–Simpson hurricane wind scale). The numbers of tropical storms and hurricanes were above the long-term averages of 12 named storms, 6 hurricanes, and 3 major hurricanes. Despite the high level of activity, Irene was the only hurricane to hit land in 2011, striking both the Bahamas and the United States. Other storms, however, affected the United States, eastern Canada, Central America, eastern Mexico, and the northeastern Caribbean Sea islands. The death toll from the 2011 Atlantic tropical cyclones is 80. National Hurricane Center mean official track forecast errors in 2011 were smaller than the previous 5-yr means at all forecast times except 120 h. In addition, the official track forecast errors set records for accuracy at the 24-, 36-, 48-, and 72-h forecast times. The mean intensity forecast errors in 2011 ranged from about 6 kt (~3 m s−1) at 12 h to about 17 kt (~9 m s−1) at 72 and 120 h. These errors were below the 5-yr means at all forecast times.

Diagnosing Initial Condition Sensitivity of Typhoon Sinlaku (2008) and Hurricane Ike (2008)

2011 ◽  
Vol 139 (10) ◽  
pp. 3224-3242 ◽  
Author(s):  
William A. Komaromi ◽  
Sharanya J. Majumdar ◽  
Eric D. Rappin
Keyword(s):  
Initial Conditions ◽  
Storm Track ◽  
Wrf Model ◽  
Short Wave ◽  
Track Forecast ◽  
Hurricane Ike ◽  
Control Simulation ◽  
Wave Trough ◽  
Local Perturbations ◽  
First Case

Abstract The response of Weather Research and Forecasting (WRF) model predictions of two tropical cyclones to perturbations in the initial conditions is investigated. Local perturbations to the vorticity field in the synoptic environment are created in features considered subjectively to be of importance to the track forecast. The rebalanced analysis is then integrated forward and compared with an unperturbed “control” simulation possessing similar errors to those in the corresponding operational model forecasts. In the first case, Typhoon Sinlaku (2008), the premature recurvature in the control simulation is found to be corrected by a variety of initial perturbations; in particular, the weakening of an upper-level low directly to its north, and the weakening of a remote short-wave trough in the midlatitude storm track. It is suggested that one or both of the short waves may have been initialized too strongly. In the second case, the forecasts for Hurricane Ike (2008) initialized 4 days prior to its landfall in Texas were not sensitive to most remote perturbations. The primary corrections to the track of Ike arose from a weakening of a midlevel ridge directly to its north, and the strengthening of a short-wave trough in the midlatitudes. For both storms, the targets selected by the ensemble transform Kalman filter (ETKF) were often, but not always, consistent with the most sensitive regions found in this study. Overall, the results can be used to retrospectively diagnose features in which the initial conditions require improvement, in order to improve forecasts of tropical cyclone track.

A Conceptual Model for the Influence of TUTT Cells on Tropical Cyclone Motion in the Northwest Pacific Ocean

2009 ◽  
Vol 24 (5) ◽  
pp. 1215-1235 ◽  
Author(s):  
Jason E. Patla ◽  
Duane Stevens ◽  
Gary M. Barnes
Keyword(s):  
Conceptual Model ◽  
Large Scale ◽  
Separation Distance ◽  
Northwest Pacific ◽  
Track Forecast ◽  
Forecast Errors ◽  
Northwest Pacific Ocean ◽  
Transient Feature ◽  
The Northwest Pacific Ocean ◽  
Joint Typhoon Warning Center

Abstract Eleven (10 Pacific, 1 Atlantic) tropical cyclones (TCs), which include typhoons/hurricanes and tropical storms, are examined using the latest 40-yr ECMWF Re-Analysis (ERA-40) dataset and Joint Typhoon Warning Center (JTWC) best-track data to determine if and how tropical upper-tropospheric trough (TUTT) cells influence TC tracks. This type of interaction has led to rather large TC track forecast errors at 72 h (2000+ km) in the northwest Pacific and is often ignored or poorly forecast due to inadequate numerical model TUTT cell predictions. Ten selected cases out of the initial 25 potential Pacific cases exhibited a “nonstandard” TC track; a TUTT cell was the sole large-scale transient feature within 2000 km of the TC’s center, and the TC intensity was >17 m s−1. The circulations’ separation distance, orientation, intensity, and TUTT cell’s closed circulation size are critical characteristics in determining the likelihood of a TUTT cell influencing a TC track. Interactions occur at distances greater than 1700 km, continue for periods from 24 to 48 h, and occur 2–3 times per year in the NW Pacific. Examination of the TC’s tropospheric winds’ deep layer mean (100–1000 hPa), and upper (100–500 hPa), middle (300–850 hPa), and lower (500–1000 hPa) layers, along with various quadrants of the upper layer, demonstrate a link between the TUTT cell’s wind field and the nonstandard TC tracks. A conceptual model of how a TUTT cell can influence TC track is presented. The model provides decision-grade operational guidance for TC forecasters using pattern recognition scenarios. Application of the conceptual model at the JTWC is currently under way.

scholarly journals Understanding the Unusual Looping Track of Hurricane Joaquin (2015) and Its Forecast Errors

2019 ◽  
Vol 147 (6) ◽  
pp. 2231-2259 ◽  
Author(s):  
William Miller ◽  
Da-Lin Zhang
Keyword(s):  
Inner Core ◽  
Track Forecast ◽  
Forecast Errors ◽  
Vortex Center ◽  
The Bahamas ◽  
Model Estimate ◽  
Motion Error ◽  
Hybrid Data Assimilation ◽  
Upper Level ◽  
Environmental Prediction

Abstract Hurricane Joaquin (2015) took a climatologically unusual track southwestward into the Bahamas before recurving sharply out to sea. Several operational forecast models, including the National Centers for Environmental Prediction (NCEP) Global Forecast System (GFS), struggled to maintain the southwest motion in their early cycles and instead forecast the storm to turn west and then northwest, striking the U.S. coast. Early cycle GFS track errors are diagnosed using a tropical cyclone (TC) motion error budget equation and found to result from the model 1) not maintaining a sufficiently strong mid- to upper-level ridge northwest of Joaquin, and 2) generating a shallow vortex that did not interact strongly with upper-level northeasterly steering winds. High-resolution model simulations are used to test the sensitivity of Joaquin’s track forecast to both error sources. A control (CTL) simulation, initialized with an analysis generated from cycled hybrid data assimilation, successfully reproduces Joaquin’s observed rapid intensification and southwestward-looping track. A comparison of CTL with sensitivity runs from perturbed analyses confirms that a sufficiently strong mid- to upper-level ridge northwest of Joaquin and a vortex deep enough to interact with northeasterly flows associated with this ridge are both necessary for steering Joaquin southwestward. Contraction and vertical alignment of the CTL vortex during the early forecast period may have also helped draw the low-level vortex center southward. The results indicate that for TCs developing in vertically sheared environments, improved inner-core sampling by means of cloudy radiances and aircraft reconnaissance missions may help reduce track forecast errors by improving the model estimate of vortex depth.

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