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Using The Short Fuse Composite to Forecast Severe Convection:

Using The Short Fuse Composite to Forecast Severe Convection:. Part I– Ancient History; The AFOS Era. By Jim Johnson & Mike Umscheid NWS Dodge City, KS. Using The Short Fuse Composite to Forecast Severe Convection:. - - - The Dark Ages - - -

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Using The Short Fuse Composite to Forecast Severe Convection:

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  1. Using The Short Fuse Composite to Forecast Severe Convection: Part I– Ancient History; The AFOS Era By Jim Johnson & Mike Umscheid NWS Dodge City, KS

  2. Using The Short Fuse Composite to Forecast Severe Convection: • - - - The Dark Ages - - - • Phil Bothwell's ADAP (NWS SR-114) piped in from AFOS node in 1985. • Watched hourly ADAP charts for May 7, 1986 Canadian, TX F-3. • A few base charts selected by spring season of 1987. STA, SMC, SSL and SSC. • Charts watched for 18 TX, KS and CO Tornadoes 1987 - 1990. Epiphany!! Nov. 15, 1988 TOP • Empirical values noted by parameter - composite the charts and define a threat area.

  3. Using The Short Fuse Composite to Forecast Severe Convection: Parameters: Flux Divergence of Surface Mixing Ratio Potential Temperature Advection Surface to 500 hPa Lifted Index Convective Cap Streamlines of Surface wind direction Thru 1996 total of 63 cases – 81% success in first hour from composite time – 62% in second hour…

  4. Using The Short Fuse Composite to Forecast Severe Convection: The Short Fuse Threat Area • Down-wind of the positive Theta advection axis. (ex. - Burgess, et al. BAMS, 1994) • Within the 1.5g/kg/hr SMFC isopleth. (Waldstreicher, NWA Dig.,14, 1989) • On axis of maximum instability • Convective “cap” 2 degrees Celsius or less. Tornado Symposium III 1990 – AGU Monograph 79 Went online in 1996 – heavy use by chasers

  5. Using The Short Fuse Composite to Forecast Severe Convection:

  6. Using The Short Fuse Composite to Forecast Severe Convection:

  7. Using The Short Fuse Composite to Forecast Severe Convection:

  8. Using The Short Fuse Composite to Forecast Severe Convection:

  9. Using The Short Fuse Composite to Forecast Severe Convection: *TORN 1 S Amorita OK 25/0045Z *TORN 3 ENE Amorita OK 25/0050Z *TORN 8 E Amorita OK 25/0055z-0105Z *TORN 6 W Medford OK 25/0146Z-0153Z Total 15 Tornadoes – Cyclic Supercell?

  10. Using The Short Fuse Composite to Forecast Severe Convection: • Change to AWIPS and associated problems – MSAS and LAPS aren’t same as ADAP! • AWIPS can’t do O.A. of raw data!! • When AFOS was unplugged, so was the composite! • Had to find a way to apply the technique to AWIPS product sets - recalling that the previously arrived at empirical values were no longer valid……..

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