Assessing Storm Surge Information

Jeff Lazo, NCARBetty Morrow, NCAR and ERG

2011 NOAA Hurricane ConferenceNovember 29, 2011National Hurricane Center

Special thanks to Hugh Gladwin (FIU) and Crystal Burghardt (NCAR) for their assistance with some of the projects reported here.

MAJOR QUESTIONS TO ADDRESS

• Do coastal residents understand storm surge?• Do they understand the level of surge risk where

their home is located?• Where do they get their coastal storm

information?• What forecast products do they currently rely

on?• What, if any, new storm surge products are

indicated?

DATA COLLECTION

• Review of Surge Questions on Past Surveys– VA, AL, GA, MS

• HFIP Coastal Residents Internet Survey– Panel Survey– NC – TX– N = 1238

Coastal Emergency Managers Survey

– Internet Survey– NC – TX– N = 53

• Extratropical – Tropical Cyclone Survey– Telephone Survey– Atlantic, Gulf, Pacific– N = 900

Of those in Cat 1 zone, about one third are each of these:

• Very concerned

• Somewhat concerned

• Not very concerned

Hampton Road VA Evacuation Study. 2010. Morrow & Gladwin through Dewberry for FEMA and USACE

n = 1599

SURGE RELATED FINDINGS FROM PAST SURVEYS

Evacuation Survey Results

Hampton Road VA Evacuation Study. Betty Morrow and Hugh Gladwin through Dewberry. 2009.Hampton Road VA Evacuation Study. 2010. Morrow & Gladwin through Dewberry for FEMA

and USACE

Coastal Georgia Evacuation Study. 2010. Morrow & Gladwin through Dewberry. 2009 for FEMA and USACE.

Each dot = one interview

Not Very Likely

Somewhat Likely

Very Likely

Likelihood Would Be Flooded in Major Hurricane:

Coastal Mississippi Behavioral Study. 2011. Morrow & Gladwin through Dewberry for FEMA and UCACE

Coastal Alabama Behavioral Survey. 2011. Morrow & Gladwin through Dewberry for FEMA and USACE

Coastal Alabama Behavioral Survey. 2011. Morrow & Gladwin through Dewberry for FEMA and USACE

Not at all likely Not very likely Somewhat likely Very likely Extremely likely0%

10%

20%

30%

40%

50%

Not surge exposed Surge exposed

Likelihood of Surge Damage by Surge Exposure

HFIP Coastal Residents Survey. 2010. Lazo and Morrow

Forecast

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ater m

ark

Surge i

s water

from se

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Surge a

nd tsunamis a

re the s

ame

Surge c

aused by ra

in

Surge o

nly with

in mile

of coast

Surge f

orecasts

acco

unt for t

ides .

Category

inclu

des ra

in and inland flo

od

Surge p

rimary

reason to

evacu

ate

Category

refer

s to w

ind and surg

e

Closely re

lated to

wind st

rength

1

2

3

4

5

Understanding Of Storm Surge

Disagree

Completely

Agree

Completely

Disagree

Somewhat

Agree

Somewhat

Neutral

EMERGENCY MANAGERS SURVEY

Note: These results are similar to those reported in our November 2010 public survey where 55% said yes for a separate watch and 66% for a separate warning.

EMERGENCY MANAGERS SURVEY

Preference For Delivery Of Surge Information

• Most thought maps would be most useful, followed by graphics and pictures

• 90% thought it extremely or very useful to express in feet above ground level

• 83% thought showing probability of different depths would be extremely or very useful

EMERGENCY MANAGERS SURVEY

EXTRATROPICAL – TROPICAL CYCLONE COASTAL RESIDENTS SURVEY

• Atlantic, Gulf and Pacific States (22)• Sample proportional to population at risk• Alaska did not have any respondents due to low

population• Sample skewed toward older adults, retirees, white,

middle-class*• 60% live within one mile of coast• Questions on ET-TC experience, knowledge, attitudes,

behavioral intentions

* Will be compared to 2010 Census demographics for the same areas.

EXTRATROPICAL – TROPICAL CYCLONE COASTAL RESIDENTS SURVEY

TC ONLY

AL, FL, GA, HI, LA, MS, TX

n = 271

30% of sample

ET ONLY

CA, OR, WA

n = 342

38% of sample

ET & TC

CT, DE, MA, MD, ME, NC, NH, NJ, NY, RI, SC, VA

n = 287

32% of sample

EXTRATROPICAL SAMPLEQUESTION: Severe coastal storms aren’t limited to tropical cyclones, and can occur year-round in all ocean areas. In the North Atlantic region these coastal storms are referred to as nor’easters. On example occurred in November 2009 when the mid-Atlantic states experienced high prolonged onshore winds causing near-record flooding in VA and severe beach erosion along the NJ and DE coasts. Another example occurred in late July 2008 when a severe coastal storm in Alaska’s Bering Sea caused a combination of high surf and storm surge which destroyed seawalls, damaged structures and homes, and severely damaged a critical airstrip in northwest AK. Do you live in an area that can be impacted by severe coastal storms like these?

57% in ET ONLY states, 26% in ET-TC states, and 58% in TC ONLY states said they were not in an area that could be affected by severe coastal storms like these.

Hurricane Irene*• 84% were very or somewhat concerned• 58% were very or somewhat concerned about potential

damage from storm surge• 44% were very or somewhat concerned about potential

injury or loss of life from surge• 90% rated the quality of the forecasts as excellent or good• Information sources (in order) were local TV, Weather

Channel, national TV, local radio and the Internet• 24% said they used the Internet a great deal for hurricane

information*Asked of North Carolina to Maine Only

TOTAL SAMPLE• 60% had been affected by a severe coastal storm (less for ET region)• 39% said a severe storm had turned out to be worse than they

expected• 48% had evacuated before (less for ET region)• 47% live in an official surge or evacuation zone• 29% said they didn’t know their elevation• 60% said they had never heard how high surge could be where their

home is located• 68% said it was not very likely their home would ever be flooded by

surge (no important regional differences)• 78% said it was very or somewhat likely they would evacuate for a

major storm; 38% for Cat 1 or 2

TOTAL SAMPLE• 48% had never seen a flood map for their home’s

location• 84% were familiar with forecasts and warnings from

their local WFO• 50% were familiar with WFO website• 79% said the NWS issues Coastal Flood Watches or

Warnings in their area• 85% think existing flooding forecasts sufficient• 72% favor a separate storm surge warning for severe

coastal events

USE OF WEBSITES

PRODUCTEXTENSIVELY

1 2 3 4NEVER

5

Local NWS Site*

12% 9%

17%

12%

50%

NHC Website

TC Only States

21%

10%

16%

9%

44%

ET-TC States

14%

8%

14%

10%

54%

* Includes Total Sample

EXTENT RELY ON EACH PRODUCT A GREAT DEAL

PRODUCTTC ONLY STATES

ET ONLY STATES

ET-TC STATES ALL STATES

DON’T KNOW

Coastal Flood Watch

30%

18%

28%

25%

3%

Coastal Flood Warning

42%

24%

35%

33%

3%

Hurricane Watch

65%

20%

51%

43%

2%

Hurricane Warning

71%

23%

60%

49%

2%Hazardous Weather Outlook

37%

28%

35%

33%

6%

IMPORTANCE OF INCLUDING IN A COASTAL SURGE WARNINGVERY OR

EXTREMELYA LITTLE OR SOMEWHAT

NOT AT ALL OR DON’T KNOW

Timing 74% 17% 8%

Location 77% 15% 8%

Depth 71% 19% 11%

How Far Inland 74% 15% 11%

Impacts 60% 28% 12%

Protective Action 57% 29% 14%

SUMMARY• High risk coastal residents often not aware of:

– Flood and surge potential

– Possible effects of surge

– Evacuation or surge zone status

– Elevation

– Flood map status

• Insufficient concern about coastal storms, particularly in ET states

• Rely mostly on local TV, cable & national TV, and local radio for forecasts, but growing use of Internet

SUMMARY• Support for separate surge information

– Among coastal residents– Among emergency managers

• Should include (in order of preference):– Location, timing, how far inland– Depth, impacts, protective actions

• Preferences for receiving surge information:– Stated as feet above ground level– Maps, graphics and pictures

Future Tasks

• Further analysis of ET-TC Survey data• Testing of possible surge forecast products

with various users• Survey of Coastal ET-TC Broadcast

Meteorologists and EMs• ?

QUESTIONS?

DISCUSSION

Please send comments & suggestions to:

lazo@ucar.edubetty@bmorrow.com