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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:
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
Foreca
st - h
igh w
ater m
ark
Surge i
s water
from
sea
Surge a
nd tsunam
is are
the s
ame
Surge c
aused b
y rain
Surge o
nly w
ithin
mile
of c
oast
Surge f
oreca
sts a
ccount f
or tid
es .
Category
inclu
des ra
in a
nd inla
nd flood
Surge p
rimary
reaso
n to ev
acuate
Category
refer
s to w
ind a
nd surg
e
Close
ly re
lated
to w
ind 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.
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 WARNING
VERY OR EXTREMELY
A 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• ?
Please send comments & suggestions to:
[email protected]@bmorrow.com