Flash Flood Case Study : June 24, 2006

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Flash Flood Case Study June 24, 2006

• Ray Kruzdlo
• Severe Weather Warning Technology Workshop
• Stories From the Field
• Norman, Oklahoma
• July 10-12, 2007

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Synoptic Setup (18z/24)
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Synoptic Setup (12z/24)
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Synoptic Setup (18z/24)
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Synoptic Setup (00z/25)
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Regional Radar (19z/24)
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Regional Radar (23z/24)
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RFC 1 Hr Flash Flood Guidance
Bucks Co 1.88 Montgomery Co 2.51
Monmouth Co 2.27
Burlington Co 2.94 Camden Co 2.94 Gloucester Co
3.06
Chester Co 2.27
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KDIX STP (2258z)
Mainly 1 inch or less with embedded areas of 1
to 3 inches.
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KDOX STP (2256z)
Mainly 1 to 2.5 inches with embedded areas 3 to 4
inches.
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FFMP FFG and the 80 Rule
1.89/2.2882.8
Chester Co 1 Hr FFG hit 80 at 1902z Event
verified at 1930z 28 minute LT
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Monmouth County, NJ
Warning issued at 2021z 2026z image Ratio 32
1.15/3.1136.9
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Monmouth County, NJ
Event verified at 2200z 2159z Image Ratio
34 Highest ratio during event 47 at 2047z
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Storm Data Entry
Poor drainage, street, and small creek flooding
was reported especially across the southern
portion of the county.
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Gloucester County, NJ
Numbers dont add up
Warning issued at 2217z 2216z image Ratio 45
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Gloucester County, NJ
Event verified at 2220z 2220z Image Ratio
51 Highest ratio during event 67 at 2237z
Ratio and Diff dont add up 1.54/2.4862
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Camden County, NJ
Warning issued at 2217z 2216z image Ratio 55
1.76/2.9559.6
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Camden County, NJ
Numbers add up, but not elsewhere
Event verified at 2235z 2233z Image Ratio
55 Highest ratio during event 59 at 2224z
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Burlington County, NJ
Warning issued at 2217z 2216z image Ratio 24
.78/1.8941.2
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Burlington County, NJ
Event verified at 2300z 2258z Image Ratio
40 Highest ratio during event 42 at 2241z
1.32/1.8969.8
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Storm Data Entries
Thunderstorms with heavy rain caused flooding of
roadways and small streams from central
Gloucester County northeast through central
portions of Burlington County. In Gloucester
County, several roads were closed in and around
Pitman with up to three feet of water on them.
Roadway closures in Burlington County occurred in
Burlington, Pemberton, and Southampton Townships.
Measured storm totals included 4.20 in Glassboro
(Gloucester County), 2.89 inches in Medford
(Burlington County) and 2.59 inches in
Wrightstown (Burlington County).
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Hydrologic Warning Shortcomings
Urbanization - Urban flash flooding 15 to 30
minutes Types of precipitation - Warm rain
processes Radar issues - Blockage, distance, Z-R
relationship, FFMP Using multiple radars one
too high, the other too low FFMP Reliance on
radar and FFG, inconsistent values In this
example, using only a method related to FFMP
would have led to more missed events or events
with zero lead time. The 80 rule did not work
well. Was it because FFG was too high or STP
inaccurate?
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Addressing the Shortcomings
Unrelated to FFMP Understand meteorological
event Questions related to FFMP Should FFG be
issued more than 4 times a day when
necessary? Could FFG be partially automated and
recalibrated during an event? Hourly basis? Could
observation data be ingested to supplement and/or
correct radar based data? Can radar based data
be improved? (dual pol and hail)