Extra-Tropical Storm Surge (ETSS 2.0) Pre-Implementation Briefing College Park, MD May 14, 2015 Arthur Taylor, Huiqing Liu and Ryan Schuster MDL/NWS/NOAA

2 Extra Tropical Storm Surge (ETSS)  Predicts storm surge to the coastline but not overland  Uses 0.5 degree Global Forecast System (GFS) winds and pressure as input 4 times a day  Does so in the following areas Arctic AK (updated Jan 1996), Bering Sea (updated Oct 1998), Gulf of AK (updated Apr 2008), East Coast (updated Feb 2009), Gulf of MX (updated Jan 2011), West Coast (updated Feb 2011)  Based on the SLOSH model  Intended for extra-tropical storms (versus hurricanes)  Does not model Tides, Waves, River Flow

3 Motivation  Future coastal flood and storm surge warnings will likely require overland guidance  ETSS and ESTOFS predict storm surge to the coastline but not overland May 2015 (ETSS 2.0)  Overland storm surge guidance  for East Coast and Gulf of MX  Operationalize total water level guidance Aug 2015 (ETSS 2.1)  Overland “surge and tide” guidance  for East Coast and Gulf of MX  Merge Bering Sea and Arctic basins creating coarse overland “surge and tide” guidance ETSS (1995 – 2014) ESTOFS (2012 – ) ETSS 1.5 (2014 – 2015) Extra-TropicalTropical Overland Storm Surge Storm Surge to Coastline SPLASH (1972 – 1984) ETSS 2.0 (May 2015) No Real-Time Ensemble No Climate Ensemble SLOSH (1984 – ) P-Surge 1.0 (2008 – 2013) MEOW/MOM (1986 – ) Overland Storm Surge + Gridded Tide ETSS 2.1 (Aug 2015) P-ETSS ( ) No Climate Ensemble SLOSH + Tide (2012 – ) P-Surge 2.0 (2014 – 2015) P-Surge 2.5 (May 2015) No Climate Ensemble

4 ETSS 2.0 Objectives 1.For East Coast and Gulf of Mexico …  Nest coarse extra-tropical with fine scale tropical basins  Overland calculations based on surge only 2.Operationalize ETSS post processing at stations  Provide AWIPS/AHPS with SHEF encode total water level guidance Benefits  For East Coast and Gulf of Mexico …  Provide overland extra-tropical storm surge guidance to WFOs  Combine the extended areal coverage of the extra-tropical grids with the finer overland details of the tropical grids  Provide bias corrected surge + tide (a.k.a. total water level) guidance at coastal stations to WFOs and RFCs via AWIPS/AHIPs  Make the ETSS post-processing more resilient

5 Objective 1: Nesting Grids East Coast and Gulf of Mexico A sample of finer overland tropical grids nested within the coarser extra-tropical grids Extra-tropical grids provide a boundary condition for tropical grids

6 ETSS 2.0 Accuracy RMSE2011 Irene2012 Sandy2013 Extra Tropical 2014 Extra Tropical ETSS feet1.23 feet0.82 feet0.78 feet ETSS feet0.99 feet0.78 feet0.73 feet Mean Peak Error 2011 Irene2012 Sandy2013 Extra Tropical 2014 Extra Tropical ETSS feet1.52 feet0.96 feet1.04 feet ETSS feet1.13 feet0.76 feet0.99 feet Mean Error2011 Irene2012 Sandy2013 Extra Tropical 2014 Extra Tropical ETSS feet-0.89 feet-0.42 feet-0.67 feet ETSS feet-0.63 feet-0.26 feet-0.62 feet

7 Irene-2011 Forecasting (Aug 26 00Z to Aug 30 00Z)

8 Sandy-2012 Forecasting (Oct 28 00Z to Nov 1 00Z)

9 ET-March 2013 Forecasting (Mar 5 00Z to Mar 9 00Z)

10 ETSS 2.0 Timeliness? StepJobVersion 1.5Version – CONUS – ModelJETSS1 CPU, 4m 20s5 CPU, 3m 1 – AK – ModelJETSS1 CPU, 4m 20s1 CPU, 3m 2 – CONUS – ModelJETSS6 CPU, 30m Historic Product Timeline4m 20s33m and 3m 2 – AK Post ProcessJETSS_GEMPAK_AK1 CPU, 18s1 CPU, 45s 3 – CONUS Post ProcessJETSS_GEMPAK_CONUS(done in step 2)1 CPU, 50s 3 – Begin SHEF encodeJETSURGE_PARSEDATNA6 CPU, 1m 10s 4 – SHEF Encode JETSURGE_GRIDDAT, JETSURGE_COMBDAT NA 1 CPU, 1m 10s 1 CPU, 1m 50s Finish4m 38s37m 10s ProductVersion 1.5Version 2.0 Station Text – EC, GM ; Grid – CONUS4m 20s after model start33m after model start Station Text – WC, AK ; Grid – AK4m 20s after model start3m after model start (*) Times can vary some from test to test due to weather

11 Reasons for Slower Run Time  Model is serial (per basin)  Tropical basins take longer to compute –23-m (*) for Chesapeake (slowest Tropical basin on East coast) –20-m (*) for Pensacola (slowest Tropical basin in Gulf of Mexico)  Tropical basins have to wait for Extra-Tropical basins –23-m 30-s (*) combined for Chesapeake (East Coast takes 30-s) –25-m (*) combined for Pensacola (Gulf of Mexico takes 5-m)  Investigating ways to increase run-times (*) These times are on Phase 2

12 Objective 2: ETSS Post Processing – Total Water Level at Stations  Use observations to account for model bias, sea level rise, rainfall, wave action, etc. t = hourly 5-day hindcast t = hourly 96-hour forecast Anomaly(t) = Obs(t) – (Tide(t) + Surge(t))Total Water Level(t) = F(t) + (Tide(t) + Surge(t)) F(t), for the first 12 hours, is a linear interpolation between Anomaly(t=0) and the 5-day Avg. Anomaly. After that, F(t) is the 5-day Avg. Anomaly. Goal: Provide WFOs, and RFCs with total water level guidance at stations via SHEF messages to AWIPS

13 ETSS Post Processing (ET-Surge)

14 ETSS Post Processing (ET-Surge)

15 ETSS Post Processing (ET-Surge) Goal 1: Use Google maps to allow for addition of more stations Goal 2: Provide information as to when the maximum surge will occur Goal 3: Provide more interactive hydrographs Goal 1: Use Google maps to allow for addition of more stations Goal 2: Provide information as to when the maximum surge will occur Goal 3: Provide more interactive hydrographs  Goal 4: Incorporate gridded information  Goal 5: Incorporate other model’s guidance (e.g. ESTOFS)  Goal 6: Incorporate user requests  Goal 4: Incorporate gridded information  Goal 5: Incorporate other model’s guidance (e.g. ESTOFS)  Goal 6: Incorporate user requests

16 ETSS 2.0 Should we Implement? Objectives 1.For East Coast and Gulf of Mexico … Nest coarse extra-tropical with fine scale tropical basins Overland calculations based on surge only 2.Operationalize ETSS post processing at stations Provide AWIPS/AHPS with SHEF encode total water level guidance Recommend Implementation MDL NHC/TAFB Eastern Region NCO  Others?

17 Backup

18 Aug 2015 – ETSS 2.1  Goal 1: Create a replacement basin (ENO3) for the Arctic (Jan 1996) and Bering Sea (Oct 1998) basins, which is capable of overland calculations  Goal 2: Enable the model to compute overland (versus to the coast) storm surge  Goal 1: Create a replacement basin (ENO3) for the Arctic (Jan 1996) and Bering Sea (Oct 1998) basins, which is capable of overland calculations  Goal 2: Enable the model to compute overland (versus to the coast) storm surge  Goal 3: Compute gridded surge + gridded tide

19 Aug 2015 – ETSS 2.1 Goals 1 & 2: Created a replacement basin with six km resolution overland, which can compute overland (versus to the coast) storm surge Goal 3: Computing gridded tide based on 13 constituents from OSU – TPXO global tidal model  Develop and nest higher resolution overland basin(s)  Switch to 37 constituents  Use tidal constituents from local ADCIRC model  Switch to 37 constituents  Use tidal constituents from local ADCIRC model

20 Aug 2015 – ETSS 2.1 Norton Sound, YK Delta

21 Future Efforts  Create a West Pacific basin to replace Gulf of Alaska (Apr 2008) and West Coast (Feb 2011)  Provides overland information  Models surge flowing along the Canadian coast  Create Probabilistic Extra-Tropical Storm Surge (PETSS) using 21 GFS ensemble members as input  Provides probabilistic overland inundation guidance to assist with future storm surge warnings  Scalable to include other ensemble models  Ensemble member results can be provided to RFCs