Transcript By Christopher Gitro NWS Binghamton, NY  Flash flooding remains the number 1 weather killer across the US  29 flash flood related fatalities in.

By Christopher Gitro
NWS Binghamton, NY
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Flash flooding remains the number 1 weather killer
across the US
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29 flash flood related fatalities in BGM’s CWA since
Jan 1996
◦ Most Recent: 01 Oct 10
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Knowledge of favorable synoptic patterns responsible
for significant flash flooding → higher situational
awareness →Pattern Recognition
First local attempt to classify large scale flash flood
episodes based on large scale synoptic patterns
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Main Goal: Classify historically significant past flash flood
episodes by the Maddox Synoptic classification scheme
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Flash flood events from the winter of 1996 through present were
examined
◦ 42 total Events
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An event was classified if any of the following three occurred:
 1) 5 or more flash flood reports from a single event
 2) $500K crop/property damage
 3) Fatality(ies) occurred
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For synoptic environments in which the synoptic pattern did not
reflect the traditional patterns as described by Maddox et al.
(1979), the events were labeled as “Unclassified”
If a flash flood event resulted from a remnant tropical circulation
moving across the area, the event was classified as “Tropical”
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Archived H50 (SPC, HPC)
00Z/12Z Maps
Archived HPC analyzed
surface maps
Radar animations analyzed
through GR Analyst
NAM BUFKIT Proximity
Soundings
◦ Sounding was selected by
picking the hour from closest
NAM forecast point to time of
initial flash flood report
◦ (LLJ winds (BUFKIT defined),
Cloud Layer Winds, MBE
Speeds, Warm Cloud Depth,
etc)
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Anomaly departures derived
from NCEP/NCAR Reanalysis
data
Synoptic
Frontal
Meso High
All images
from Maddox
et al. (1979)
Flash Flood Event Classification
25
20
20
15
10
5
0
7
10
2
3
Flash Flood Synoptic Type by
Percentage
42 Total Events
Tropical,
Meso High,
4.76%
7.14%
Frontal,
16.67%
Synoptic
Unclassified
23.81%
Frontal
Synoptic
47.62%
Unclassified
Meso High
Tropical
Events by Month
7
7
6
7
6
5
5
4
3
3
3
3
3
3
2
2
1
0
0
Jan
Feb
Mar
Apr
May
Jun
0
Jul
Aug
Sep
Oct
Nov
Dec
Type by Season
8
7
6
5
4
Winter
3
2
1
0
Spring
Summer
Fall
LLJ Wind Speeds (kts)
80
70
60
50
Q1
Min
40
Median
Max
30
Q3
20
10
0
Frontal
Synoptic
Unclassified
Meso High
Tropical
LLJ Winds (kts) - All Events
80
70
60
50
Q1
Min
40
Median
Max
30
20
10
0
Q3
MBE Speed (kts)
60
50
40
Q1
Min
30
Median
Max
20
Q3
10
0
Frontal
Synoptic
Unclassified
Meso High
Tropical
PWAT vs Climo (% of normal)
500
450
400
350
Q1
300
Min
250
Median
Max
200
Q3
150
100
50
0
Frontal
Synoptic
Unclassifed
Meso High
Tropical
Warm Cloud Layer Depth (ft)
16000
14000
12000
10000
Q1
Min
8000
Median
Max
6000
Q3
4000
2000
0
Frontal
Synoptic
Unclassified
Meso High
Tropical
H50 Height (m)
MSLP
Sfc Air Temp
PWAT
H85 Meridional Winds
H50 Height (m)
MSLP
Sfc Air Temp
PWAT
H85 Meridional Winds
H50 Height (m)
MSLP
Sfc Air Temp
PWAT
H85 Meridional Winds
H50 Height (m)
MSLP
Sfc Air Temp
PWAT
H85 Meridional Winds
1200 UTC 28 May 2002 SPC H50
Analysis (NAM)
1500 UTC 28 May 2002 HPC
Analyzed SFC Analysis
• $5 Million Property Damage
1200 UTC 25 Jan 2010 SPC H50
Analysis (NAM)
1500 UTC 25 Jan 2010 HPC
Analyzed SFC Analysis
1200 UTC 19 June 2007 NCEP
H50 Analysis
2100 UTC 19 June 2007 HPC
Analyzed SFC Analysis
• $30 Million
Property Damage
• 4 Fatalities
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The BGM HSA is susceptible to all 3 eastern US
Maddox Flash Flood types
Synoptic type flash flood producing
environments most common (20 cases)
Not all synoptic patterns cleanly fit into the
Maddox classification scheme (10 unclassified,
3 tropical)
Frontal/Meso High less common but
potentially devastating considering BGM’s
highly variable terrain (terrain anchoring)
◦ Both Meso High cases had fatalities
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Synoptic flash flood producing environments
showed the most variable spread (LLJ, Cloud
Layer Winds, MBE Speeds)
Weaker forced frontal/meso high
environments displayed less variable spread
◦ Smaller sample size
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The use of anomaly departure information
can heighten a forecaster’s SA of a potential
high impact flash flood producing
environment 24-48 hrs out
Maddox, R. A., C. F. Chappell and L. R. Hoxit, 1979: Synoptic and
meso-α scale aspects of flash flood events. Bull. Amer. Meteor.
Soc., 60, 115-123.