Probabilistic Hurricane Storm Surge A Local Perspective

Transcription

1 Probabilistic Hurricane Storm Surge A Local Perspective Florida Governor Hurricane Conference May FLGHC TS 22 Pablo Santos Meteorologist In Charge NWS Miami/South Florida Forecast Office

2 Motivation What is there in it for me in this presentation? A better understanding of the surge/inundation probabilities available to you nationally and at the local level and: What they mean What questions you might have that THEY CAN answer Potential Applications Complements: TS 23 presentation on Local Storm Surge Forecast Tue Morning TS 23 presentation on Local Surge Impact Recognition/Messaging - Tue Morning Workshop 139 on Local Storm Surge Considerations Friday Morning

3 Probabilistic Surge Guidance (tide included) % Exceedance of SurgePlusTide heights above NAVD88 for 10% to 50% at 10% intervals. No time sequence with it. Both probabilities above are cumulative for the duration of the event. Probability of SurgePlusTide heights above NAVD88 exceeding 2 to 25 feet at 1 foot increment. No time sequence with it. Both probabilities above are cumulative for the duration of the event. % Exceedance inundation heights for 10% to 50% at 10% intervals. Available in both incremental and cumulative form in 6 hours time steps Probability of inundation heights exceeding 2 to 25 feet at 1 foot increment. Available in both incremental and cumulative forms in 6 hours time increments. Notice 6 different data types. Available at NWS local office at 625m resolution. Some of this data will be available to you through the Hurricane Center Website that was shown earlier to you. The goal is to give you a picture of what is available to your local NWS offices, what questions each of these data types can answer, and therefore how the local NWS office can help you with this.

4 Illustration Case

5 AWIPS Surge Guidance P-Surge 2.0/PHISH SurgePlusTide (NAVD88) Cumulative 10% Exceedance Example

6 AWIPS Surge Guidance P-Surge 2.0/PHISH SurgePlusTide (NAVD88) Cumulative 5 ft Probability Example

7 AWIPS Surge Guidance P-Surge 2.0/PHISH Inundation Cumulative 10% Exceedance Example

8 AWIPS Surge Guidance P-Surge 2.0/PHISH Inundation Cumulative 5 ft Probability Example

9 AWIPS Surge Guidance P-Surge 2.0/PHISH Inundation Incremental 10% Exceedance Example

10 AWIPS Surge Guidance P-Surge 2.0/PHISH Inundation Incremental 5 ft Probability Example

11 Inundation Threat Assessment Based on Different Exceedance Levels Based ON PHISH!! Choice of Forecast Confidence Level in Coordination with SSU

12 Threat Based on Potential Impact

13 Storm Tide MHHW Storm Tide MLLW Storm Tide NAVD Storm Tide MSL

14 Customer Questions What questions can we answer for you? Cumulative (SurgePlusTide and Inundation) What are the chances inundation thresholds of interest to you will occur from 0-6, 0-12,,0 to 78 hours with this event at your location? Incremental (Inundation) What are the chances that values of interest to you will occur during a particular period at your location? How likely is the event to happen during that period? How likely is it to last? Given the your risk tolerance, what are the potential inundation values and periods of greatest concern? Onset* (Inundation) What are the chances your critical threshold values will begin during a particular period at your location? And given that, what is the most likely period of onset of these conditions? Given customer risk tolerance, what is the period with the most abrupt increase in surge forecast? * Not explicitly available.

15 Applications Threat/Potential Impact Graphics Briefings Can be used as decision making aid by planners (example follows). Communicate to the public graphically degree of preparation needed. Can be used by EM and Media along with NWS to help communicate the bottom line message to the public. Inundation Graphic Threat based Most applicable to help you iron out evacuations. Decision making guides by planners Storm Surge Watch/Warning (*2015 Experimentally)

16 Surge Threat/Potential Impacts Graphic Perfect Forecast Actual Threat/Potential Impacts Example: Approaching major hurricane at the onset of the watch period (~ 48 hours). QUESTION: When advocating the measure of protective actions according to surge impacts, which is better? FLGHC

17 Potential Inundation Graphic (2014) Not a deterministic inundation graphic! Based on exceedance graphics (10%, 20%, 30%?) Values above ground level are potential values given exceedance chosen. EM sensitivity regarding confusing evacuation messages / conflicting information Develop talking points and use them

18 Qualities of Desired Decision Tool Science based Consistency Flexible Visual Neal Batista

19 Storm Intensity Neal Batista Cat 3 ( Kt) Threat? OR FORECAST VALID XX/XX00Z 31.4N 77.5W MAX WIND XXX KT...GUSTS XXX KT.

20 Clearance Times Neal Batista Forecast impact 33hrs? Available 2012 season FORECAST VALID XX/XX00Z 31.4N 77.5W MAX WIND XXX KT...GUSTS XXX KT.

21 Neal Batista Wind Probabilities 64Kt Incremental wind prob 25%?

22 Coastal Flooding (i.e., Inundation) Impact Neal Batista PSurge2.0 in 10% Exceedance Cumulative Form Inundation impact in zone A, B, or C low? Low an elevated threat to life and property; reasonable chance of combined storm surge and tide resulting in sea water inundation of 1 3 ft.

23 Other Decision Making Tools Some EMs (Example from Lee County) have developed tools to incorporate probabilistic data into decision making process. Each county is different some sophisticated, some not. Example Provided by Mike Gittinger from TBW

24 Take Away We can provide hi res surge estimates of surge relative to NAVD 88 and AGL: Inundation (AGL) component suited to convey uncertainty based timing information. Suited to answer wide spectrum of customer questions Tide already factored. Long term goal: include waves and fresh water forecasts. Grid scale estimates of surge relative to MHHW, MLLW, MSL, NAVD, and AGL. For high res INUNDATION MAPPING application you must refer to the NHC new experimental inundation graphic. More appropriate to fine tune evacuation decisions. Local NWS office can convey grid scale threat assessment/potential impact information which is still based on the same data. Suitable to communicate to the public area wide threat level and potential impact information. Watch/Warning application. SLOSH will assume the application it was intended for during planning, response and recovery (MEOWs, MOMs, and landfall simulations of surge). Local NWS and NHC expertise with this data can help you target specific and applications.