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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



Interagency Collaboration



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



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)



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



Evolution of Hydrologic Forecasts



Reality vs. modeling

Valley Park, MO

3800 square miles of uncertainty upstream



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



River Forecast Timeline

Major Flood Stage = 26 feet Moderate Flood Stage = 22 Feet Minor Flood Stage = 22 Feet

Union, MO30

20

10




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)


Union, MO

--NWS Major FS

30

20

10

30

20

10



Uncertainty in River

Forecasting starts

with forcings

Increases with

atmospheric

instability

QPF uncertainties

Quantity

Placement

Timing

Type

Dangers of Forecast Rainfall





Valley Park, MO

40

30

20





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



Lost Communication


Union, MO30

20

10



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



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




Risk communication products



Know Your NWS POC

https://www.weather.gov/contact




Closing the loop

Observation

Keep your RFC informed!

Need data

Need feedback

Need to be informed



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

http://www.wpc.ncep.noaa.gov/pqpf/conus_hpc_pqpf.php

http://www.weather.gov/ncrfc/LMI_ncrfc_forecast_products

http://www.weather.gov/crh/rfc_ensemble


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