40th Anniversary of the Palm Sunday Outbreak

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40th Anniversary of the Palm Sunday Outbreak

• How It Changed Tornado Preparedness Forecasting

Daniel McCarthy Warning Coordination
Meteorologist NOAA/NWS/NCEP Storm Prediction
Center
Photo by Paul Huffman, Elkhart Truth
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Typical Parameters for OH Tornadoes

• gt 80 kt Mid Level Jet over OK
• Coupled ULJ and LLJ
• Area underneath ULJ exit region
• Steep Lapse Rates over the Plains
• Advecting into area behind cold front or dryline
• BRN Shear gt 80
• Presence of Deep Layer Shear

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Fujita Attributed Outbreak to Several Facets

• Decrease in Best Lifted Index
• Pressure of best lifting
• Strong differential thermal advection
• Occurring with respect to the juxtoposition of
  intersecting jets
• First comprehensive aerial damage survey
• Led to theory of suction vortices
• Enhanced Super Outbreak

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April 11-12, 1965

• 47 Tornadoes
• 21 Killer Tornadoes
• 260 Fatalities
• 3,442 Injuries

Most significant outbreak since March 18, 1925.
-Fujita
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Fujitas Plot of Aerial Survey
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850 mb 11APR65/1800 CST
From Fujita, et. al, 1970
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500 mb 11APR65/1800 CST
From Fujita, et. al, 1970
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200 mb 11APR65/1800 CST
From Fujita, et. al, 1970
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Surface Analysis 1200 CST
From Fujita, et. al, 1970
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Isotherm Analysis 1200 CST
From Fujita, et. al, 1970
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Dayton Sounding 1200 UTC
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Flint, MI Sounding 1200 UTC
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Dayton, OH Sounding 0000 UTC
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DAY NAM 24 HR FCST Sounding
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LAN NAM 24 HR FCST Sounding
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TOL NAM 24 HR FCST Sounding
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NAM40 Surface
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SFC Td Mean RH
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500 mb Vorticity
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Upper Jet
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Low-Level Jet
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Composite
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Supercell Parameter

• Most Unstable CAPE (gt1000 Jkg-1)
• BRN Shear (gt40 kt)
• 0-3 km Storm Relative Helicity (gt100 m2s-2)

SCP MUCAPE BRN Shear SRH(0-3km)
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Supercell Parameters
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Differential Divergence
After Uccellini and Johnson, 1980
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Fujitas Aerial Survey
From Fujita, et. al, 1970
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Storm Data
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Storm Data
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Toledo Tornado
From Fujita, et. al, 1970
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Toledo Tornado
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IN into NW Ohio
From Fujita, et. al, 1970
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Bluffton Tornado
From Fujita, et. al, 1970
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Rockaway Tornado
From Fujita, et. al, 1970
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Strongsville Tornado
From Fujita, et. al, 1970
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From Weather Bureau Survey Team Report
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Problems Identified

• Tornado Forecast issued for 6 hours
• Those interviewed didnt know the difference
  between forecast and warning
• No real urgency until warnings were heard on
  radio and TV
• Radar coverage (WSR-57) inadequate
• Nothing in tornado-prone areas
• Poor communication with media sources

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Lessons Learned

• Watch/Warning terminology began
• Before 1966 were Tornado Forecasts
• Watches area definition simplified
• Use 4 or less points to define
• Circles, Triangles, portions of states (Florida
  South of line from Tampa to Melbourne, etc.
• Parallelograms implemented in 1970
• 60 miles either side of a line
• 60 miles north and south of a line

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Lessons Learned

• Hold Preparedness Meetings
• Spotter Talks now
• Saturate public with material on tornadoes
• Ready-Set-Go
• Outlook-Watch-Warning
• Doppler Radar
• Better coverage by NWS
• Private companies provide ability to local TV

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It Must Work!
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Thank You!!
Any Questions?
Web Site www.spc.noaa.gov
e-mail Daniel.McCarthy_at_noaa.gov