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Published byHope Daniels Modified over 9 years ago
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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
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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.
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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…
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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
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Using The Short Fuse Composite to Forecast Severe Convection:
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*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?
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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a way to apply the technique to AWIPS product sets - recalling that the previously arrived at empirical values were no longer valid……..
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