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Building a Weather-Ready Nation
Interagency Collaboration & Decision Support Services in
the 2015 Meramec River Record Flood
Jonathon Thornburg
Hydrologist
NOAA/NWS North Central River Forecast Center
North Central River Forecast Center
Chanhassen, MNBuilding a Weather-Ready Nation
NWS River Forecast Centers
13 Offices (12 CONUS + 1 Alaska/Pacific)
Hydro-geologic boundaries
Some modeling of headwaters in Canada/Mexico (no
forecast services)
Daily Operations
Data collection and
quality control
Precipitation and
Hydrologic Forecasts
North Central River Forecast Center
Chanhassen, MNBuilding a Weather-Ready Nation
Interagency Collaboration
North Central River Forecast Center
Chanhassen, MNBuilding a Weather-Ready Nation
December 26-28, 2015
3,900 sqmi drainage
area
Event Summary
Record event for 5 of
8 NWS forecast
points in Meramec
watershed
2 Day total rainfall in
excess of 9 inches
over saturated soils
7.30 inch watershed
average
North Central River Forecast Center
Chanhassen, MNBuilding a Weather-Ready Nation
December 26-28, 2015
3,900 sqmi drainage
area
Event Summary
Record event for 5 of
8 NWS forecast
points in Meramec
watershed
2 Day total rainfall in
excess of 9 inches
over saturated soils
7.30 inch watershed
average
North Central River Forecast Center
Chanhassen, MNBuilding a Weather-Ready Nation
Fenton, MO
Event Summary
Photos by David Carson Post-Dispatch via AP (Top Left) and Michael B. Thomas/Getty Images (bottom left)
Arnold, MOFloodwater covers I-55
Valley Park, MOFloodwater surrounds the bridge
deck of I-44 and Highway 141
Photo by Jeff Roberson via AP (Right)
North Central River Forecast Center
Chanhassen, MNBuilding a Weather-Ready Nation
Event Summary
Neighborhood homes flooded by
Meramec River on December 29th
Photos by Reuters (Left) and Jeff Roberson via AP (Right)
Pacific, MO
Submerged roads and houses
flooded by Bourbeuse River on
December 29th
Union, MO
North Central River Forecast Center
Chanhassen, MNBuilding a Weather-Ready Nation
Evolution of Hydrologic Forecasts
North Central River Forecast Center
Chanhassen, MNBuilding a Weather-Ready Nation
Reality vs. modeling
Valley Park, MO
3800 square miles of uncertainty upstream
North Central River Forecast Center
Chanhassen, MNBuilding a Weather-Ready Nation
General
Forcings (forecast and observed)
Soil conditions
Record/Major events do not have
history
Model calibration quickly acquire bias
River Forecast Uncertainties
Photo by The State Journal-Register Chris Young
Meramec 2015 Forecast rainfall
Ongoing rainfall
Unknown runoff efficiency
Ratings (or lack of)
Unknown storage
Levees overtopping
Back water affects
Gaging equipment failure
Seasonality (vegetation shifts)
Ungaged basins
North Central River Forecast Center
Chanhassen, MNBuilding a Weather-Ready Nation
River Forecast Timeline
Major Flood Stage = 26 feet Moderate Flood Stage = 22 Feet Minor Flood Stage = 22 Feet
Union, MO30
20
10
North Central River Forecast Center
Chanhassen, MNBuilding a Weather-Ready Nation
River Forecast Timeline
48 hr QPF not
capturing whole
event (25th)
QPF forecast tapering
runoff (26th)
Ongoing rainfall
with more QPF
and cut some
runoff
Rainfall came
earlier than
forecast (~3-6 hrs)
and runoff
Rainfall obs higher
than QPF and max
runoff (27th)
1st forecast with
little QPF. Rainfall
and runoff
increased on all
headwater basins
(28th)
Major Flood Stage = 26 feet Moderate Flood Stage = 22 Feet Minor Flood Stage = 22 Feet
Union, MO
--NWS Major FS
30
20
10
30
20
10
North Central River Forecast Center
Chanhassen, MNBuilding a Weather-Ready Nation
Uncertainty in River
Forecasting starts
with forcings
Increases with
atmospheric
instability
QPF uncertainties
Quantity
Placement
Timing
Type
Dangers of Forecast Rainfall
North Central River Forecast Center
Chanhassen, MNBuilding a Weather-Ready Nation
River Forecast Timeline
Major Flood Stage = 25 feet Moderate Flood Stage = 19 Feet Minor Flood Stage = 16 Feet
Valley Park, MO
40
30
20
North Central River Forecast Center
Chanhassen, MNBuilding a Weather-Ready Nation
River Forecast Timeline
Major Flood Stage = 25 feet Moderate Flood Stage = 19 Feet Minor Flood Stage = 16 Feet
Model adjustments
to headwater
basins still rising
(28th)
Valley Park, MO
Backwater model
adjustments
First USGS
measurement at
SEEM7 (-7.3%)
Manual
Observation at
Spring Bluff
Adjusted model to
Spring Bluff
observation and
continued
adjusting
backwater impact
(29th)
USGS measurement at
Union near crest
(29th – PM)
Coordinated with USACE
on hydraulic crest 43-44
feet. Questionable levee
overtopping height
40
30
20
North Central River Forecast Center
Chanhassen, MNBuilding a Weather-Ready Nation
River Forecast Timeline
Major Flood Stage = 25 feet Moderate Flood Stage = 19 Feet Minor Flood Stage = 16 Feet
Model adjustments
to headwater
basins still rising
(28th)
Valley Park, MO
Backwater model
adjustments
First USGS
measurement at
SEEM7 (-7.3%)
Manual
Observation at
Spring Bluff
Adjusted model to
Spring Bluff
observation and
continued
adjusting
backwater impact
(29th)
USGS measurement at
Union near crest
(29th – PM)
Coordinated with USACE
on hydraulic crest 43-44
feet. Questionable levee
overtopping height
40
30
20
North Central River Forecast Center
Chanhassen, MNBuilding a Weather-Ready Nation
Lost Communication
Major Flood Stage = 26 feet Moderate Flood Stage = 22 Feet Minor Flood Stage = 22 Feet
Union, MO30
20
10
North Central River Forecast Center
Chanhassen, MNBuilding a Weather-Ready Nation
Miscommunication
AdjustedRaw
~50 kcfs
~70 kcfs
Spring Bluff observation assistance and impacts
“Based on only one Spring Bluff observation it’s hard to tell rate of rise or fall, but
since Union was rising faster tried to adjust Spring Bluff simulation accordingly” -
PM forecaster December 28th
Wire weight
ObservationWire weight
Observation
North Central River Forecast Center
Chanhassen, MNBuilding a Weather-Ready Nation
I. How do we communicate risk with maximum lead time
without degrading forecast credibility
II. How do we communicate effectively and convey why forecast
change during an event
III. How can communication help improve River Forecast
Center’s forecast and reduce uncertainty before an event
Three tough questions
Communication and Collaboration
North Central River Forecast Center
Chanhassen, MNBuilding a Weather-Ready Nation
Communication and Collaboration
Risk communication products
North Central River Forecast Center
Chanhassen, MNBuilding a Weather-Ready Nation
Communication and Collaboration
North Central River Forecast Center
Chanhassen, MNBuilding a Weather-Ready Nation
Know Your NWS POC
https://www.weather.gov/contact
North Central River Forecast Center
Chanhassen, MNBuilding a Weather-Ready Nation
Closing the loop
Observation
Keep your RFC informed!
Need data
Need feedback
Need to be informed
North Central River Forecast Center
Chanhassen, MNBuilding a Weather-Ready Nation
Resources
Probabilistic Forecast Precipitation
• http://www.wpc.ncep.noaa.gov/pqpf/conus_hpc_pqpf.php
NCRFC products
• http://www.weather.gov/ncrfc/LMI_ncrfc_forecast_products
RFC Contingency Forecast
• http://www.weather.gov/crh/rfc_ensemble *Read site disclaimer before using
NWS Service Hydrologist and Hydro Focal Point contact
• https://www.weather.gov/contact *Search page for Hydrologic Contacts
Questions