Transcript Duluth La Nina Winter Statistics

Multi-Partner Decision Support
Lessons Learned
Experiences from the 2010 Spring Flood
Diane Cooper
Service Hydrologist
NWS Weather Forecast Office Twin Cities, MN
2010 National Flood Workshop
October 26, 2010
Discussion Points
 Setting the Stage
 Pre-Flood Decision
Support
 Decision Support during
the Flood
 Evaluation of Partner
Survey Results
 Lessons Learned
Setting the Stage
Key Factors
• Very wet soils & high river
levels prior to freeze up Oct was 200% to 300% + of
normal .
• High Snow Water
Equivalents (SWE) of 3 to 5
in – rivaling 1997 and 2001
levels (Flood of Records in
Upper Minnesota Valley).
• Snow Depths were
deceiving at near to
slightly below normal in
East Central MN.
Bulk of precipitation fell between early Dec
through Mid Jan.
Pre-Flood Decision Support
With the moist frozen soils, thick river ice and an
above normal water in the snowpack….by mid
January ingredients were coming together for a
widespread Spring Flood!
Minor Flood
Outlook as
of 2/19
Actions taken:
• Coordinated with Local, State and Federal partners a month before the official
Feb 19th “Spring Flood Outlook” was released.
• Hosted briefings at regional-quarterly county emergency manager (EM) meetings
(Mid to Late Jan).
• Contacted communities of “higher concern” via EM (7 total).
• Local city meetings
• Toured flood problem areas and reviewed impacts
• Explained river probabilistic outlooks – highlighted the probability to see “known”
impacts and top 5 historic floods
• Discussed local actions, preparations, and sensitive concerns
• Coordinated with Minnesota State Homeland Security (HSEM) for “Flood Fight
workshops” in Feb.
Unlike the Red River Valley, it had been approx 9 years since a significant
widespread flood impacted the Minnesota and upper Mississippi Rivers.
Pre-Flood Decision Support
Actions taken (cont):
• Briefed navigation industry at USCG
Workshop
• Retooled MN Flood Briefing Webpage
• Created an “Enhanced Spring Flood
Outlook Webpage”
Toped Rating Curve
 Indicated probability to see “key”
impacts and top 5 historical floods; color
coded by flood category.
“Perspective for “how bad it could be.”
•
Extensive coordination with Key
State and Federal partners.
 Extra Snow cores and ice reports
 Extension of rating curves at “sensitive
locations”
 Reservoir Spring Drawdown schedules
Mississippi River at St Paul, MN
Likelihood of Flood Categories
90% - Minor Flood Stage (above norm)
86% – Moderate Flood Stage (above norm )
65% – Major Flood Stage (above norm)
Likelihood of Impacts
•60% - 18 ft -Warner Road impassable .
•61% - 17.5 ft -Harriet Island submerges
•83% - 14.0 ft- Lilydale residential area begins to flood
The Flood Begins!!!
 Second week in March
(10th– 12th)- Strong Low
ushered very warm air in
from the Southeast .
 Snowpack eroded from east
to west.
 Rain on snow situation with
widespread 0.5 to 1.0 in and
pockets of up to 2.5 in.
 Triggered an atypical rapid
melt….2 weeks ahead of
normal.
Significant flood with 16
locations seeing a top ten or
higher event and 5 experiencing
a top 5 historical crest.
Decision Support During the Event
•
•
•
•
•
MN Tile Network
3/11/10
Issued “typical NWS” hydrology
products (issued flood warnings
early…up to 7 days in advance).
Began Email briefings on 3/9 and
Webinars on 3/11. Long duration
event - provide a blend of both
through March.
Henderson 3/5/10
Recruited MN DNR Area Hydrologists
and EM’s to be “eyes in the field“ for
flowing of tiles, standing water and
remaining snow piles, ice jams and
flood impacts.
Webpage headlines asking for public
ice jam reports and pictures.
Areal photos from National
Operational Hydrologic Remote
Sensing Center(NOHRSC) and Civil
Air Patrol (CAP) flights.
S Fork Crow River 3/20/10
Decision Support During the Event
Granite Falls, MN
(3/23/10)
•NWS ”NCRFCAgencies” and “MPX”
Chat used extensively with “key”
partners and media.
Break out
flow
•Espotter for general reports.
•NOHRSC provided processed
satellite images for overland
flooding and breakout detection.
•Long duration “polygon” areal flood
warnings for “streams” and main
stem rivers.
 depicted “true” extent of flooding
 highlighted non-forecast point
impacts and road closures (7 of
11 bridges closed on the
Minnesota river for 50 mi)
Break outs in Granite Falls – road eroded.
Decision Support During the Event
HPC 6hr QPF
Confidence
Intervals
•Updated/added new impacts as
reported.
•In weeks following, used HPC
QPF Confidence Intervals and
NCRFC contingency river
forecasts.
 Provide insight for impacts
of additional rain.
 Key concern was when to
dismantle temporary levees,
reopen roads, etc.
 Ex – Easter weekend:
Henderson wanted to
remove the flood walls…
was that a good choice
given tight budgets and an
approaching storm?
River
Contingencies
4/1/10
Forecast Not for
Public Release.
What Did the Partners Think?
Formal OMB survey (#0648-0342) conducted in June to obtain feedback on partner satisfaction.
Strategy with this flood was an early preemptive approach. We used a variety of strategies to display
information and provide decision support.
What worked and what did not?
Survey was sent to 180 partners.
Responses from 42 individuals/user
groups. This was at least a 23%
response rate, as several state
partners provided a single response.
Most used meteorology and
hydrology in their daily duties and
84% attended a flood outlook briefing
or used the probabilistic forecast to
make pre-flood decisions.
Responding Entities
2
11
Federal Govt
2
6
State Govt
21
County Govt
City Govt
Other
Decisions made prior to the flood:
• We pre-staged flood supplies and had plans in place; we were much better prepared thanks to you!
(County Partner)
• The Flood Outlooks allowed us to prepare road closures more efficiently so we could keep them
open as long as safely possible. (State Partner)
What Did the Partners Think – Webinars and Email Briefings?
Preferred Methods to obtain Information
Frequency of Use
The NWS Website/AHPS
pages, the Flood Briefing
page, as well as the email
and webinar briefings
were the most common
methods to obtain
information.
All the responders
attended either a webinar
or used the email
briefing, 81% preferred a
blend of both.
35
30
25
20
15
10
5
0
Prior to
Flood
During
Flood
Comments on the webinars and email briefings:
• They were specific and gave me enough information for maintaining a plan of action if necessary
(State partner)
• Some days I just didn't have time to attend the webinar ;so having the email options was helpful. I
prefer the webinar as hearing a description helped me understand what graphs or other data meant.
(County Partner)
• Both are important. Once in the field, the e-mails were more valuable simply from an access point of
view (no time for the webinars then). (Federal Partner)
What Did the Partners Think – Areal Flood Warning?
A new strategy was used with the
issuance of the Areal Flood Warning
to show the broader impact of river
flooding along the main stem rivers
vs. simply the River Point Flood
Warnings.
Seventy-nine percent indicated that
this product was of value.
Of the 79%, over half said that
including road closure information
was helpful. (MN DOT 511 website
does not include county and township
roads)
Road Information in the Broad
Flood Warning??
5
16
yes
no
Lessons Learned for Future Events
• Decision support is becoming increasingly important on all levels.
• Partners need new ways to access information from both an office and
field environment. Mobile friendly options was a common request.
• Pre-Flood briefings and Workshops were of great benefit. It provided
them a head start to ensure all parties understood their roles and
strategic actions and tactical resources that would likely be needed.
• Be more proactive to identify and work with key city and county leaders
for each forecast location to ensure they understood the potential flood.
• Look for strategies to make the probabilistic graphics more intuitive
including plotting the impacts and historical floods on the graph and
provide the actual probabilities (i.e. numbers).
“I continue to be very impressed with the level of service
provided by the Chanhassen office.” (State Partner)
Acknowledgements
 Rich Hebert, WFO Twin Cities and Tim Szeliga, NOHRSC –
Assistance with the Processing of the TM MODIS Images.
 Ryan Alueck, student volunteer - Compilation of Survey
responses.
 Sarah Brabson, NOAA HQ - Assistance with the Survey.
Special Thanks to the WFO Twin Cities and NCRFC staffs as
well as our federal and state partners for the team effort in
the success of the forecasts and warnings to this event!!!
Contact Information
Diane Cooper
Service Hydrologist
NWS WFO - Twin Cities, MN
952-368-2542
[email protected]