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J. P. Kossin, 62 nd IHC, Charleston, SC An Objective Tool for Identifying Hurricane Secondary Eyewall Formation Jim Kossin and Matt Sitkowski Cooperative.

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Presentation on theme: "J. P. Kossin, 62 nd IHC, Charleston, SC An Objective Tool for Identifying Hurricane Secondary Eyewall Formation Jim Kossin and Matt Sitkowski Cooperative."— Presentation transcript:

1 J. P. Kossin, 62 nd IHC, Charleston, SC An Objective Tool for Identifying Hurricane Secondary Eyewall Formation Jim Kossin and Matt Sitkowski Cooperative Institute for Meteorological Satellite Studies University of Wisconsin Madison, WI kossin@ssec.wisc.edu 62 nd Interdepartmental Hurricane Conference Charleston, SC, March 2008

2 J. P. Kossin, 62 nd IHC, Charleston, SC This work is supported by the National Oceanic and Atmospheric Administration under the GOES-R Risk Reduction program and the Office of Naval Research under Grant No. N00014-07-1-0163

3 J. P. Kossin, 62 nd IHC, Charleston, SC Goal: Create a tool that uses readily available data to estimate the probability of secondary eyewall formation events in tropical cyclones Motivation: These events are generally associated with marked changes in the intensity and structure of the inner core:  rapid intensity deviations  significant broadening of the surface wind field  changes in storm surge, sea-state, radius of 50 kt wind Despite the importance of secondary eyewall formation in tropical cyclone forecasting, there is presently no objective guidance to diagnose or forecast these events.

4 J. P. Kossin, 62 nd IHC, Charleston, SC Data and Method: Our first step was to utilize the SHIPS developmental data.  ambient environmental features  geostationary satellite-derived features The features were then separated into 2 classes (using microwave, radar, recon reports, anything available): Classes were limited to Category 1 hurricanes or greater, with centers over water. 10 years (1997–2006). 1) a secondary eyewall formed at some time in the following 12 h 2) a secondary eyewall did not form at any time in the following 12 h

5 J. P. Kossin, 62 nd IHC, Charleston, SC The algorithm is based on the Bayes probabilistic model  P (C yes | F) estimates the probability of imminent secondary eyewall formation, given the set F of observed features.  P (C yes ) is the climatological probability (~10% in the North Atlantic). Based on class separation

6 J. P. Kossin, 62 nd IHC, Charleston, SC “Leave-one-season-out” cross validated algorithm performance 970 (984)52 (45) 20 (25)22 (15)12 (7) skill Inclusion of IR increases the confidence of the model

7 J. P. Kossin, 62 nd IHC, Charleston, SC Cross validation hindcast example (hits, misses, false alarms)

8 J. P. Kossin, 62 nd IHC, Charleston, SC Ivan, 13 Sep 2004, 06Z ~12 h later  Misses and false alarms? 13 Sep 06Z (too early)

9 J. P. Kossin, 62 nd IHC, Charleston, SC The algorithm has been alerting us to secondary eyewall formation events that we had previously missed

10 J. P. Kossin, 62 nd IHC, Charleston, SC Mitch, 27 Oct 1998, 00Z ~12 h later  False alarm? 27 Oct 1998, 00Z URNT12 KNHC 260508 DETAILED VORTEX DATA MESSAGE A. 26/0508Z B. 16 DEG 20 MIN N 81 DEG 53 MIN W C. 700 MB 2391 M D. NA E. NA F. 064 DEG 124 KT G. 342 DEG 9 NM H. 922 MB I. 14 C/ 3047 M J. 19 C/ 3024 M K. 15 C/ NA L. CLOSED WALL M. CO8-15 N. 16 DEG 20 MIN N 81 DEG 53 MIN W 26/0508Z O. 12345/7 P..25/2 NM Q. AF966 1113A MITCH OB 09 KNHC DETAILED MAX FL WIND 124 KT NW QUAD 0500Z. GOOD RADAR PRESENTATION. DOUBLE EYEWALL, WIND CENTER 3 NM DIA.;

11 J. P. Kossin, 62 nd IHC, Charleston, SC A miss and a false alarm

12 J. P. Kossin, 62 nd IHC, Charleston, SC False Alarm

13 J. P. Kossin, 62 nd IHC, Charleston, SC Hurricane Isabel (2003) 12 Sep 00Z  hit 17 Sep 00Z  miss

14 J. P. Kossin, 62 nd IHC, Charleston, SC Hurricane Rita (2005) 22 Sep 00Z  hit 23 Sep 06Z  miss

15 J. P. Kossin, 62 nd IHC, Charleston, SC Work in progress:  Extension beyond SHIPS features  Application to EPAC & WPAC tropical cyclones  Apply results to numerical simulations of secondary eyewall formation to better understand the physical mechanisms at work We hope to piggyback a beta-version onto SHIPS as soon as possible

16 J. P. Kossin, 62 nd IHC, Charleston, SC End

17 J. P. Kossin, 62 nd IHC, Charleston, SC


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