1. USACE Extreme Storm Team Update
(May 2011 MR-T Flood Storm Maximization)
Chuck McWilliams
Meteorologist
USACE, Omaha District
20 February 2013

2. History
1991 – ER “Use HMR’s or request site-specific studies through NWS Hydro-met”
2004 – NWS discontinues PMP services
2005 – Agreement between COE & USBR for USBR to temporarily provide PMP services
2008 – Interagency Federal Work Group established
2010 – USACE Work Group established

3. Extreme Storm Events Work Group
Interagency Federal Work Group established by SOH (Subcommittee on Hydrology) of the ACWI (Advisory Committee on Water Information)
Purpose: Coordinate Studies & Databases used to develop Extreme Design Storms up to PMP
Current Membership: NRC, USBR, NWS, USACE, FEMA, FERC, USGS, NRCS, NHWC
Kickoff Meeting: Sep 4, 2008
ACWI: Advisory Committee on Water Information
SOH: Subcommittee on Hydrology
NHWC: National Hydrologic Warning Council

4. USACE Extreme Storm Team
Funding from Dam Safety
Virtual Team
Meteorologists
Hydro Engineers experienced in PMP/PMF
GIS Specialist
Webmaster
Products
Extreme Storm Database
PMP studies for Dam Safety Risk Assessments
Provide Technical Review of PMP studies
HMR Updates

5. USACE Extreme Storm Team
Matt Fleming, Hydraulic Engineer, HEC
Larry Schick, Meteorologist, NWS
Angela Duren, Hydrologist, SPK
Marian Baker, Hydrologist/Meteorologist, NWK
David Williams, Hydraulic Engineer, SWT
Doug Clemetson, Hydraulic Engineer, NWO
Chuck McWilliams, Meteorologist, NWO
George Hayes, Geographer, NWO

6. USACE Extreme Storm Data Needs
Site-Specific Probable Maximum Precipitation Studies
Hydrometeorological Reports (HMR’s) updates
Data Archiving & Analysis of Extreme Storm Events
Update Standard Project Storm Criteria
Standard Project Storm Criteria: approximately ½ of PMF

7. Location of USACE Dams HMR Regional Coverage
HMR 51 and 52 are likely first HMRs to be updated!

8. Extreme Storm Catalog
No storms since 1973!

9. Data Archiving and Analysis System
Original Isohyetal Map
Bucket Survey Form
Digitized Isohyetal Map
GIS for Transposition Studies

10. Radar Estimates of Precipitation
Stage III
MPE
ABRFC
May 1993-Dec 2004
Jun 2003-Sep 2005
APRFC
Jul 2002-Sep 2005
CBRFC
Sep 1996-Mar 2002
Feb 2002-Sep 2005
CNRFC
Sep 1996-Jan 2005
May 2003-Sep 2005
LMRFC
Apr 1996-Aug 2003
Aug 2003-Sep 2005
MARFC
Oct 1995-Dec 2001
Oct 1999-Sep 2005
MBRFC
Nov 1994-Jun 2003
Jan 2003-Sep 2005
NCRFC
Dec 1994-Apr 2002
NERFC
Feb 1996-Aug 2002
Aug 2002-Sep 2005
NWRFC
Jan 1996-Nov 2002
Nov 2002-Sep 2005
OHRFC
Dec 1995-Jun 2003
Dec 2001-Sep 2005
SERFC
Dec 1995-Sep 2002
Jan 2002-Sep 2005
Radar Data can be downloaded from the NWS

11. Extreme Storm Database
Highest recorded rainfall
Total Storm
Storm ID
Basic assignment number (if given)
Date of storm
Approximate location of storm center
Total rainfall (in)
Storm duration (hr)
Storm area (mi2)
Max average depth of rainfall (in)
24-hr, 100 mi2 rainfall (in) 1
MR 1-1
16-20 Dec 1895
Phillipsburg, MO
12.20 96
110000
5.6
7.2 2
MR 1-3A
6-7 Jul 1898
Blanchard, IA
12.50 30
7200
4.2
10.9 3
MR 1-3B
7-8 Jul 1898
Edgehill, MO
8.30
20000
3.2
7.8 4
MR 1-5
14-17 Jul 1900
Primghar, IA
13.60 78
100000
3.9
11.8 5
MR 1-6
4-8 Sep 1901
Ness City, KS
9.10
114
63000
3.5
8.3 6
MR 1-8
20-24 Sep 1902
Wakeeney, KS
8.10
108
81600
4.0
6.2
Area within 2-in isohyetal (mi2)
Area within 4-in isohyetal (mi2)
Latitude
Longitude
Storm Dew point
Max Dewpoint
In-place moisture adjustment
Wind Vector
Elevation
Links to Depth-Area-Duration Curves, Isohyetal Map, Scanned
Images of Original Data, GIS Shapefiles, DSS files

12. Current & Recent Projects
Update Extreme Storm Catalog
Digitize Historic Storm Isohyetal Maps
Convert Radar Imagery
Compute Depth Area Duration
Chena Basin Site Specific PMP Study
Incorporate HMR51/52 into HEC-HMS
Afghanistan PMP/PMF Criteria
Review Wyoming Statewide PMP Study
Review MR&T Project Design Flood

13. Max Precipitation 33 inches
Project Design Storm (58A): combination of 3 Historic Storm shapefiles: January 1937 increased by 10%, January 1950 transposed 90 miles northward and rotated 20% and February 1938
Max Precipitation 33 inches

14. Data used: NWS Multisensor Precipitation Estimator Data – 384 hourly XMRG files. XMRG files from LMRFC Lower Mississippi River Forecast Center – inches
384 hr/16 day - NWS Multisensor Precipitation Estimator Data (hourly radar) - Max Precipitation inches

15. Obtain Storm Representative Dew Point Temperature
Storm Of Interest
Representative Dew Point Temps
Moisture Source
Manual on Estimation of Probable Maximum Precipitation (WMO/2009); Page 12
Notes
Representative Dew Points should be outside of “rainfall area”
Minimum of two stations to be used (homogeneous air mass)
Stations need to be along the inflow trajectory
Consider time needed to transport moisture to rainfall site
Consider avoiding “intervening barrier”, if possible
Stations must show observations for more than half of the 12-hour period under consideration

16. Obtain Storm Representative Dew Point Temperature (Surface Analysis)
12Z 19 April 2011
12Z 20 April 2011
12Z 21 April 2011
12Z 22 April 2011
12Z 23 April 2011
12Z 24 April 2011
Notes/Observations
Frontal boundary across region… some shifting north/south
Strong/severe thunderstorms… periodic outflow boundaries
Steady fetch of moist air from Gulf of Mexico (southerly winds)
Little or no “intervening barriers” from moisture source to rainfall area
Graphics courtesy of NOAA/NWS

17. Obtain Storm Representative Dew Point Temperature (Surface Analysis)
12Z 25 April 2011
12Z 26 April 2011
12Z 27 April 2011
12Z 28 April 2011
***Two Distinct Air Masses***
Notes/Observations
Frontal boundary becomes progressive after 12Z 27 April 2011
Strong/severe thunderstorms… periodic outflow boundaries continue
Southerly winds continue from eastern Texas across Louisiana into heavy rainfall region
Frontal passage complete by 12Z 28 April 2011… followed by cooler/drier air mass
Graphics courtesy of NOAA/NWS

18. Obtain Storm Representative Dew Point Temperature (Surface Analysis)
12Z 29 April 2011
12Z 30 April 2011
12Z 01 May 2011
12Z 02 May 2011
12Z 03 May 2011
12Z 04 May 2011
Notes/Observations
Cyclogenesis across Central U.S. with another frontal system
Warm/moist southerly winds return to region by 12Z 30 April 2011
Front from “second system” more progressive than previous front
Moisture inflow shut off by 12Z 03 May 2011
Graphics courtesy of NOAA/NWS

19. Obtain Storm Representative Dew Point Temperature (Streamlines)
12Z 20 April 2011
12Z 21 April 2011
12Z 22 April 2011
12Z 23 April 2011
12Z 24 April 2011
12Z 25 April 2011
Notes/Observations
Flow of moisture from central Gulf of Mexico inland to rainfall center
Far eastern Texas… Louisiana… southwestern Mississippi general path
Graphics courtesy of Plymouth State Weather Center

20. Obtain Storm Representative Dew Point Temperature (NOAA HYSPLIT Model)
12Z 23 April 2011
12Z 24 April 2011
12Z 25 April 2011
Surface Winds
550 meters AGL Winds
1300 meters AGL Winds
Notes/Observations
MOISTURE INFLOW FOR April 2011
Storm moisture from central Gulf of Mexico
SE Texas-Louisiana-SW Mississippi along path
Graphics courtesy of NOAA

21. Graphics courtesy of Plymouth State Weather Center and NOAA
Obtain Storm Representative Dew Point Temperature (Streamlines & HYSPLIT)
12Z 30 April 2011
12Z 01 May 2011
12Z 02 May 2011
12Z 03 May 2011
00Z 01 May 2011
12Z 01 May 2011
00Z 02 May 2011
Surface Winds
550 meters AGL Winds
1300 meters AGL Winds
Notes/Observations
Flow of moisture from central Gulf of Mexico inland to rainfall center
Far eastern Texas… Louisiana… southwestern Mississippi general path
Graphics courtesy of Plymouth State Weather Center and NOAA

22. Obtain Storm Representative Dew Point Temperature
Notes/Observations
INFLOW FOR 29 April – 4 May2011
Storm moisture from central Gulf of Mexico
SE Texas-southern Louisiana along path
Notes/Observations
Diagram from HMR 34 (1956)
Moisture inflow pattern similar to 19 April – 4 May storms

23. Obtaining Storm Representative Dew Point Temperature
Notes
Reduce Td to 1000 millibars pseudo-adiabatically
Adjustment = 2.4° F per 1,000 feet of elevation
Then average…
Moist Lapse Rate
Height (meters)
Td (Celsius)
Manual on Estimation of Probable Maximum Precipitation (WMO/2009); Page 11
STATE
CITY
21 April 05Z
21 April 06Z
21 April 07Z
21 April 08Z
21 April 09Z
21 April 10Z
21 April 11Z
21 April 12Z
21 April 13Z
21 April 14Z
21 April 15Z
21 April 16Z
Adjusted (°F)
Texas
Jasper 73 72 70 69
Louisiana
DeRidder
Lake Charles 71
Lafayette 68
Patterson
Baton Rouge 74
Mississippi
McComb
New Orleans
Average
12-hr Persisting
STATE
CITY
1 May 04Z
1 May 05Z
1 May 06Z
1 May 07Z
1 May 08Z
1 May 09Z
1 May 10Z
1 May 11Z
1 May 12Z
1 May 13Z
1 May 14Z
1 May 15Z
Adjusted (°F)
Texas
Jasper 73 74
Port Arthur 72 71
Louisiana
Lake Charles 70
Fort Polk
Alexandria 69
Lafayette
Patterson
Baton Rouge 68
Average
12-hr Persisting
12-Hour Persisting Td = 72° F : April 2011
12-Hour Persisting Td = 71° F : 29 April – 4 May 2011

24. Obtain Storm Maximum Dew Point Temperature
April
Maximum Persisting
12-Hour 1000-mb DewPoints (°F)
(19-28 April 2011)
April = 74.5° F
May = 77.0° F
21 April = 75° F
06 May** = 76° F
Maximum Persisting
12-Hour 1000-mb DewPoints (°F)
(29 April-04 May 2011)
April = 74.5° F
May = 77.0° F
01 May = 76° F
16 May** = 77° F
May
**Adjusting 15 days toward seasonal maximum
Climatic Atlas of the United States (Page 59); Environmental Data Services

25. In Place Maximization Adjustment Time Period In-Place Adjustment
Steps
Locate the Dew Point Temperature (x-axis)
Go down (y-axis)
Note the corresponding precipitable waters (PW)
The ratio is the in-place maximization adjustment
Maximum Td = 76
Storm Td = 72
Example for April
PW(76) = 3.04 inches
PW(72) = 2.50 inches
Ratio = 3.04/2.50 = 1.22
PW(76) = 3.04”
PW(72) = 2.50”
Time Period
12-Hour Persisting Dew Point Temperature (°F)
Observed Storm Td
Maximum Td
(Climate Atlas)
15 Days “Warmer”
19-28 April 72 75 76
29 April-4 May 71 77
Time Period
In-Place Adjustment
(15 days “warmer”)
April
1.16
1.22
29 April - 4 May
1.28
1.34
Hydrometeorological Report No. 55A (NOAA/1988)
Appendix C, Page 242
Note: There’s approximately a 6% increase due to “seasonal” adjustment”

26. Data used: NWS Multisensor Precipitation Estimator Data – 384 hourly XMRG files. XMRG files from LMRFC Lower Mississippi River Forecast Center -15 days closer to warm season- Dew Point maximization for April Dew Point 29 April-04 May High Precip ”
Dew Point maximization April days closer to the warm season Dew Point maximization 29 April-04 May days closer to the warm season
Note: Max Precipitation = 29.08” (previously 23.47”)

27. Depth Area Duration Curve: Project Design Storm (58A) and 2011 Storm – Mississippi Basin

28. Depth Area Duration Curve: Comparing- Project Design Storm (58A) , 2011 Storm – Mississippi Basin, 2011 Storm – Mississippi Basin with increased Dew Point of 1.16 for 04/19/2011 – 04/28/2011 and 1.28 for 04/29/ /04/2011, 2011 Storm – Mississippi Basin with increased Dew Point of 1.22 for 04/19/2011 – 04/28/2011 and 1.34 for 04/29/ /04/2011

29. Future Projects Update SPS Criteria (EM1110-2-1411)
Update IDF Criteria (ER )
Other Site-Specific PMP studies
Review of District PMP studies
Review of AE prepared PMP studies
Combine Database with USBR and others
Set up Web Site to Disseminate Data
SPS: Standard Project Storm
IDF: Inflow Design Flood

30. Questions ??