AMBER

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AMBER

• Areal Mean Basin Estimated Rainfall
• COMAP Symposium
• Heavy Precipitation and Flash Floods
• Robert S. Davis, Pittsburgh WFO

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AMBER Overview

• All watersheds in county warning area are
  defined to a Minimum Basin Area (MBA) of 2 mi2 to
  show spatial rainfall distribution.
• The WSR-88D polar grid (1o by 1 km) is mapped to
  the defined watersheds.
• Average Basin Rainfall (ABR) is computed for each
  watershed every volume scan.
• An hourly ABR rate is determined from the single
  volume scan (5-6 min.) of ABR.

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Stream Basin Definitions
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National Basin Delineation

• 30Sep1999 NWS agrees to fund the AMBER National
  Basin Delineation project by NSSL for all of the
  United States.
• ArcInfo used to define the watershed boundaries.
• USGS 1 arc second (30 m) DEM data supplied by
  EROS Data Center.
• www.nssl.noaa.gov/teams/western/basins

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AMBER Watershed Division

• All watersheds in the county warning area are
  divided into hydrologic segments no larger than
  10 mi2.
• A Minimum Basin Area of 2 mi2 is used in the
  initial NSSL stream creation procedure.
• Each forecast office may modify the NSSL stream
  database (subdivide or aggregate).

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Patchel Run
Allegheny River
Rocky Grove
French Creek
Franklin
River Gage
Franklin Airport
Allegheny River
0
2km
7
Allegheny River at Franklin, PA
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French Creek from 13th Street Bridge Franklin, PA
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Patchel Run
A
5624
French Creek
Rocky Grove
62mm
5623
5632
65mm
Franklin
Franklin
60mm
B
Franklin Airport
5622
C
61mm
Allegheny River
5618
0
2km
42mm
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5662
5663
Patchel Run(1)
Patchel Run(2)
31mm
35mm
5661
48mm
Patchel Run
French Creek
Allegheny River
Rocky Grove
5632
60mm
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ABR vs. FFG

• Determining the Flash Flood Threat

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Flash Flood Guidance (FFG)

• ABR in a specific time period (1, 3 hours) to
  initiate flooding on streams.
• Assumes stream at low flow level.
• Assumes no rainfall since data cutoff
• FFG is the amount of ABR needed to produce
  threshold runoff (climatic average runoff needed
  to start flooding of streams)

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FF Scale for Flash FloodingABR in inches

• FF0 ABR FFG to lt FFG 0.5
• FF1 ABR FFG 0.5 to lt FFG 1.5
• FF2 ABR FFG 1.5 to lt FFG 2.5
• FF3 ABR FFG 2.5 to lt FFG 3.5
• FF4 ABR FFG 3.5 to lt FFG 4.5
• FF5 ABR FFG 4.5 to gt FFG 4.5

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Graphical Radar Rainfall

• OHP One hour rainfall
• STP Storm total rainfall
• THP Three hour rainfall

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Storm Total Rainfall
19 May1999
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Digital Radar Rainfall

• DPA Digital Precipitation Array
• DHR Digital Hybrid Scan Reflectivity

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Digital Rainfall Estimate
2130 2135 UTC Rainfall (mm)
9.6
7.4
3.6
7.5
4.1
10.4
9.8
9.4
5.0
6.2
Grid size 1km x 1km
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ABR and ABR Rate Computations
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Digital Rainfall Estimate
2130 2135 UTC Rainfall (mm)
9.6
7.4
3.6
7.5
4.1
10.4
9.8
9.4
5.0
6.2
Grid size 1km x 1km
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Average Basin Rainfall 7.3 mm
2130 2135 UTC Rainfall (mm)
7.3
7.3
7.3
7.3
7.3
7.3
7.3
7.3
7.3
7.3
Grid size 1km x 1km
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Average Basin Rainfall 7.3 mm
2130 2135 UTC Rainfall (mm)
9.6
7.4
3.6
7.5
4.1
10.4
9.8
9.4
5.0
6.2
Grid size 1km x 1km
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Average Basin Rainfall 7.3 mm
2130 2135 UTC Rainfall (mm)
9.3
6.4
6.4
9.3
5.2
9.3
9.3
6.4
6.4
5.2
Grid size 1km x 1km
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History of NWS Digital Rainfall Products

• Manually Digitized Radar
• (MDR1975-1993) 40 km grid / 1 hour
• RADAP-II digital rainfall (1977-1993)
• 10-12 offices. Polar grid (2o x 2.2 km / 10 min.)
• WSR-88D Digital Precipitation Array
• (DPA1993-current) 4 km grid - 1 hour
• WSR-88D Digital Hybrid Scan Reflectivity
• (DHR1999-current) Polar grid (1o x 1 km / 5
  min.)

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Grid size 40 km x 40 km 1,600 km2
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Digital Precipitation Array (DPA)

• Time interval (1 hour)
• Data grid size (4 km x 4 km grid 16 km2)
• Rainfall estimates in the WSR-88D polar grid (1o
  x 2 km) are averaged to produce a single rainfall
  estimate in each grid box.
• Used for RFC Stage 1-3 precipitation estimation
  and for FFMP(AWIPS Build 5.0)

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Digital Hybrid Scan Reflectivity (DHR)

• Time interval (5-6 minutes)
• Grid size (1 degree x 1 km)
• Reflectivity to the nearest 0.5 dBZ

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DHR Grid Area (km2) vs. Radar Range (km)
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AMBER DHR Grid Assignment Classes

• DHR grid is mapped to all defined watershed
  segments. This allows ABR computation in 5-6
  minute time steps.
• DHR grid is mapped to all urban areas to compute
  ABR urban rainfall.
• Single 1km DHR bins are assigned to location of
  all rain gages, allowing gage comparison with
  radar estimated rainfall.

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Patchel Run
A
5624
French Creek
Rocky Grove
62mm
5623
5632
65mm
Franklin
Franklin
60mm
B
Franklin Airport
5622
C
61mm
Allegheny River
5618
0
2km
42mm
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x
x
16.5o 103.5km
x
17.5o 103.5km
x
x
Rocky Grove
French Creek
x
x
x
x
x
x
5632
Franklin
x
17.5o 100.5km
x
x
16.5o 99.5km
18.5o 100.5km
x
Franklin Airport
0
2km
x
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Radar Rainfall Data

• Radar provides 3 rainfall measurements, location,
  time, and quantitative estimate.
• Radar grid size determines the minimum basin
  area (MBA) for ABR computations.
• Sample rate determines time interval, but product
  time interval may be larger.
• Z/R relationship determines rainfall estimate.
  (Sources of error important!!)

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Scale of Flash Flood Storms

• Thunderstorms producing heavy rainfall (gt25 mm
  hr-1) are small in area and short in time
  duration.
• Cell lifetime generally lt 30 minutes.
• Areal coverage is Z/R dependent, larger areas
  with Tropical Z/R, smaller areas with standard
  convective Z/R.

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Davis, R. S., 2001 Flash Flood Forecast and
Detection Methods. Severe Convective Storms,
Meteor. Monogr., 28, no. 50, Amer. Meteor.
Soc., in press.
36
Davis, R. S., 2001 Flash Flood Forecast and
Detection Methods. Severe Convective Storms,
Meteor. Monogr., 28, no. 50, Amer. Meteor.
Soc., in press.
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AMBER Localization

• Modifications to the NSSL database done at the
  NWSFO

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AMBER Localization

• Subdivide defined NSSL watersheds
• Add smaller watersheds
• Add urban areas
• Create rain gage database
• Modify FFG for individual streams

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French Creek
13th Street
Liberty Street
Area 2.5km2 MBA 5 km2
Chubb Run
15th Street
Route 62
Localization Add small watersheds
Route 8
0
1km
Franklin Airport
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Key West Subs and Pizza, at 15th St and Route 62
15th Street Hill
Water was up to the hoods of the cars in the
parking lot.
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French Creek
13th Street
Liberty Street
Area 2.5km2 MBA 5 km2
Chubb Run
15th Street
Route 62
Localization Add small watersheds
Key West
Route 8
0
1km
Franklin Airport
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15th Street and Route 62
Chubb Run outflow beneath Route 62
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15th Street Hill on descent into Franklin, PA
5 Grade
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Chubb Run, at 15th and Eagle St (looking upstream)
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French Creek
13th Street
Liberty Street
Area 2.5km2 MBA 5 km2
Chubb Run
15th Street
Route 62
Localization Add small watersheds
Route 8
0
1km
Franklin Airport
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Chubb Run at 15th Street and Eagle Street,
looking downstream
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Localization Add urban areas.
Oak Hill 442 m
French Creek
Rocky Grove
5632
Galena Hill 460m
Franklin
Franklin Airport
0
2km
48
Galena Hill 460 m
Modify FFG for urbanization
450 m
400 m
15th Street Liberty Street
River Bank
350 m
Franklin
300 m
0
0.5
1.0
1.5 km
49
450 m
Modify FFG for steep terrain
Oak Hill 445 m
400 m
River Bank
Atlantic St.
Pacific St.
Grant St.
350 m
300 m
Rocky Grove
0
0.5
1.0 km
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Haylett Furniture Store, Grant Street (300 Block)
Water was chest deep in the parking lot.
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B.L.T. Café, Grant Street (300 block) 5 houses
east of Haylett furniture.
Water filled the basement and flooded the parking
lot.
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Rain Gage Verification of Z/R

• Include all rain gages in AMBER database
• Latitude/Longitude of gage only needed.
• Single DHR bin with gage used for WSR-88D
  rainfall estimate.

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Gage Franklin Airport 105921-22 June 2001
2331-0040 UTC
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AMBERGIS Graphic Products

• ABR Rate Time Lapse
• 30 minute ABR Time Lapse
• 120 minute ABR Total
• Graphics produced for 15, 30, 60, 90, 120 and 180
  minutes. (User selectable).
• ABR/ABR Rate line graphs.

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ABR Rate

• 21 June 2001 2311 UTC to
• 22 June 2001 0045 UTC

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30 Minute ABR

• 21 June 2001 2326 UTC to
• 22 June 2001 0040 UTC

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Two Hour ABR

• ending
• 22 June 2001 0105 UTC

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Three Hour ABR

• ending
• 22 June 2001 0129 UTC

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ABR French Creek 563221-22 June 2001 2331-0040
UTC
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ABR Allegheny River(67) 562321-22 June 2001
2331-0040 UTC
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ABR Patchel Run Sum21-22 June 2001 2331-0040 UTC
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AMBER Summary

• ABR provides basin specific rainfall to determine
  flash flood risk (ABR-FFG)
• ABR rate focuses forecaster attention on critical
  streams before flooding occurs.
• History of ABR helpful in adjusting FFG for
  multiple rainfall events.
• Basin specific ABR allows forecaster to mention
  threat area in warning text.

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Flood Damage Path

• Stream Specific Warnings

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Route 322
French Creek
3rd Ward
Route 322
5632
Chubb Run
15th St
Route 8
Franklin Airport
Route 62
0
2km
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AMBER Data Sources

• ArcView and the spatial analyst extension.
  www.esri.com
• USGS Data (3 arc second DEM data)
  edcwww.cr.usgs.gov
• EPA Data (RF3 data files) www.epa.gov/OST/BASINS/g
  isdata.html
• Ami Arthur aarthur_at_enterprise.nssl.noaa.gov
• Paul.Jendrowski_at_noaa.gov (SOO KHNL)

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AMBER Case Studieson COMET Website

• buff.ppt 13Jul96
• epgh99.ppt 18May99
• pitcairn.ppt 01Jul97
• zion.ppt 27Jul98
• ohio98.ppt 26Jun98
• redbank.ppt 19Jul96
• dallas95.ppt 05May95
• ftc97.ppt 28Jul97
• kc1998.ppt 05Oct98

• Buffalo Creek, CO
• Pittsburgh, PA
• Pittsburgh, PA
• Cedar City, UT
• Eastern Ohio
• Brookville, PA
• Dallas, TX
• Fort Collins, CO
• Kansas City, MO Tropical
  Z/R Cases