amber areal mean basin estimated rainfall comap symposium heavy precipitation and flash floods...
DESCRIPTION
Stream Basin DefinitionsTRANSCRIPT
AMBERAMBERAreal Mean Basin Estimated Rainfall
COMAP SymposiumHeavy Precipitation and Flash Floods
Robert S. Davis, Pittsburgh WFO
AMBER OverviewAMBER 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.
Stream Basin Stream Basin DefinitionsDefinitions
National Basin DelineationNational 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
AMBER Watershed DivisionAMBER 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).
FrenchCreek
AlleghenyRiver
0 2km
AlleghenyRiver
PatchelRun
FranklinAirport
Franklin
RockyGrove
RiverGage
FrenchCreek
0 2km
AlleghenyRiver
PatchelRun
FranklinAirport
Franklin
RockyGrove
5632
5624
5623
5618
5622
A
B
C
Franklin60mm
61mm
42mm
65mm
62mm
AlleghenyRiver
FrenchCreek
56625663
5661
5632RockyGrove
PatchelRun
PatchelRun(2)
PatchelRun(1)
48mm
31mm
35mm
60mm
ABR vs FFGDetermining the Flash Flood Threat
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)
FF Scale for Flash FloodingFF Scale for Flash FloodingABR in inchesABR in inches
• FF0 ABR = FFG to < FFG + 0.5• FF1 ABR = FFG + 0.5 to < FFG + 1.5• FF2 ABR = FFG + 1.5 to < FFG + 2.5 • FF3 ABR = FFG + 2.5 to < FFG + 3.5 • FF4 ABR = FFG + 3.5 to < FFG + 4.5 • FF5 ABR = FFG + 4.5 to > FFG + 4.5
Graphical Radar Graphical Radar RainfallRainfall
OHP – One hour rainfallSTP – Storm total rainfallTHP – Three hour rainfall
Digital Radar Digital Radar RainfallRainfall
DPA – Digital Precipitation ArrayDHR – Digital Hybrid Scan
Reflectivity
Digital Rainfall Estimate2130 – 2135 UTC Rainfall (mm)
10.4
9.6
9.8 9.4
7.4 3.6
5.0
7.54.1
6.2
Grid size 1km x 1km
ABR and ABR Rate ABR and ABR Rate
ComputationsComputations
Digital Rainfall Estimate2130 – 2135 UTC Rainfall (mm)
10.4
9.6
9.8 9.4
7.4 3.6
5.0
7.54.1
6.2
Grid size 1km x 1km
Average Basin Rainfall = 7.3 mm2130 – 2135 UTC Rainfall (mm)
7.3
7.3
7.3 7.3
7.3 7.3
7.3
7.37.3
7.3
Grid size 1km x 1km
Average Basin Rainfall = 7.3 mm2130 – 2135 UTC Rainfall (mm)
10.4
9.6
9.8 9.4
7.4 3.6
5.0
7.54.1
6.2
Grid size 1km x 1km
Average Basin Rainfall = 7.3 mm2130 – 2135 UTC Rainfall (mm)
9.3
9.3
9.3 6.4
6.4 6.4
6.4
9.35.2
5.2
Grid size 1km x 1km
History of NWS Digital History of NWS Digital Rainfall ProductsRainfall Products
• Manually Digitized Radar(MDR:1975-1993) 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(DPA:1993-current) 4 km grid - 1 hour• WSR-88D Digital Hybrid Scan Reflectivity(DHR:1999-current) Polar grid: (1o x 1 km / 5 min.)
ABCDEFGH
JI
KLMNOPQRSTUVWXY
A B C D E F G H I J K L M N O P Q R S T U V W X Y
250nm
125nm
MDR
GRIDRadar inBox MM
LJ352
3 5 2
ROB DigitalReport:
Grid size 40 km x 40 km = 1,600 km2
Digital Precipitation Array Digital Precipitation Array (DPA)(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)
MDR vs. HRAP 4kmAllegheny County, PA
Pine Creek
HRAP 4kmGrid
Little Pine Creek
4.2km at 40oN
727 mi2
68 mi2
6 mi2
Manually Digitized Radar
Digital Hybrid Scan Digital Hybrid Scan Reflectivity (DHR)Reflectivity (DHR)
• Time interval (5-6 minutes)• Grid size (1 degree x 1 km)• Reflectivity to the nearest 0.5 dBZ
DHR Grid Area (kmDHR Grid Area (km22) ) vs. Radar Range (km)vs. Radar Range (km)
0
0.5
1
1.5
2
2.5
3
3.5
4
0 50 100 150 200
AMBER DHR Grid AMBER DHR Grid Assignment ClassesAssignment 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.
FrenchCreek
0 2km
AlleghenyRiver
PatchelRun
FranklinAirport
Franklin
RockyGrove
5632
5624
5623
5618
5622
A
B
C
Franklin60mm
61mm
42mm
65mm
62mm
RockyGrove
Franklin
0 2kmFranklinAirport
5632x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x16.5o 99.5km
16.5o 103.5km
17.5o 103.5km
18.5o 100.5km
17.5o 100.5km
FrenchCreek
Radar Rainfall DataRadar 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!!)
Scale of Flash Flood Storms
• Thunderstorms producing heavy rainfall (>25 mm hr-1) are small in area and short in time duration.
• Cell lifetime generally < 30 minutes.• Areal coverage is Z/R dependent, larger
areas with Tropical Z/R, smaller areas with standard convective Z/R.
40 dBZ
0 10 km
20km25km270km2
2575
125
Rainfall RateStandard Z/R mm hr-1Z = 300 R 1.4
Davis, R. S., 2001: Flash Flood Forecast and Detection Methods. Severe Convective
Storms, Meteor. Monogr., 28, no. 50, Amer. Meteor. Soc., in press.
40 dBZ
0 10 km
32km2
40km2
80km2
2575
125
Rainfall RateTropical Z/R mm hr-1
Z = 250 R 1.2
Davis, R. S., 2001: Flash Flood Forecast and Detection Methods. Severe Convective
Storms, Meteor. Monogr., 28, no. 50, Amer. Meteor. Soc., in press.
AMBER Localization
Modifications to the NSSL database done at the NWSFO
AMBER Localization
• Subdivide defined NSSL watersheds• Add smaller watersheds• Add urban areas• Create rain gage database• Modify FFG for individual streams
15th
Street
13th
Street
FranklinAirport
LibertyStreet
Route 8
Route 62
French Creek
ChubbRun
0 1km
LocalizationAdd small watersheds
Area 2.5km2
MBA 5 km2
RockyGrove
Franklin
0 2kmFranklinAirport
FrenchCreek
5632Galena
Hill460m
OakHill
442 m
LocalizationAdd urban areas.
Franklin
Galena Hill460 m
RiverBank
0 0.5 1.0 1.5 km300 m
350 m
400 m
450 m
15th Street &Liberty Street
Modify FFGfor urbanization
Oak Hill445 m
RiverBank
0 0.5 1.0 km300 m
350 m
400 m
450 m
Atla
ntic
St.
Gra
n t S
t .
Paci
fic S
t.
Rocky Grove
Modify FFGfor steep terrain
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.
Gage: Franklin Airport #105921-22 June 2001 2331-0040 UTC
0
20
40
60
80
100
120
140
2331
2336
2341
2346
2351
2355
0002
0007
0011
0016
0021
0026
0035
0040
ABR RateABR
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.
ABR French Creek #563221-22 June 2001 2331-0040 UTC
0
20
40
60
80
100
120
2331
2336
2341
2346
2351
2355
0002
0007
0011
0016
0021
0026
0035
0040
ABR RateABR
ABR Allegheny River(67) #562321-22 June 2001 2331-0040 UTC
0
20
40
60
80
100
120
140
2331
2336
2341
2346
2351
2355
0002
0007
0011
0016
0021
0026
0035
0040
ABR RateABR
ABR Patchel Run Sum21-22 June 2001 2331-0040 UTC
01020304050607080
2331
2336
2341
2346
2351
2355
0002
0007
0011
0016
0021
0026
0035
0040
ABR RateABR
AMBER SummaryAMBER 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.
Flood Damage Path
Stream Specific Warnings
3rd Ward
0 2kmFranklinAirport
FrenchCreek
5632
Route 322
Route322
Route 62Route 8
15th StChubb Run
AMBER Data SourcesAMBER 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/gisdata.html• Ami Arthur [email protected]• [email protected] (SOO KHNL)
AMBER Case StudiesAMBER Case Studieson COMET Websiteon 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