Short Fuse Composite Charts

Objective meso-analysis using hourly FSL LAPS analysis grids and FSL/NWS GFE software

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Chart #1:  Surface-based Moisture

Convergence, Warm Theta Advection, ThetaE

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Chart #2:  Surface-based CAPE

Low Level Lapse Rate (0-2.5 km AGL)

  • LAPS/GFE Short Fuse Composite "Threat Area" (critical threshold values will be devloped in the future upon testing this spring)
    • Within the maximum of surface moisture convergence
    • Immediately downwind of the warm theta advection axis
    • Within the axis of highest surface based instability (CAPE and Theta-E)
    • Within the region of lowest surface based convective inhibition (0-2.5 km AGL lapse rate)
    • Temporal and spatial continuity of at least 3 hours of all of the above
  • More information on the original Short Fuse Composite and its utility in nowcasting initiation and location of the most intense convective storms (that can lead to potential tornado development) can be found in this paper:
    • Jim Johnson, 1993: The "Short Fuse" Composite: An Operational Analysis Technique for Tornado Forecasting.  In The Tornado: Its Structure, Dynamics, Prediction, and Hazards (C. Church, D. Burgess, C. Doswell, and R. Davies_Jones, eds.). Geophysical Monograph 79, American Geophysical Union, Washington, D.C. pp. 605-610.   Click HERE! to read document in .pdf format.
  • Some information on the generation of these graphics:
    • The charts are currently updating at :35 past the hour.  (Future plans are to hopefully run LAPS earlier to get the valid time graphics updated perhaps as early as :20 past the hour.
    • The surface moisture flux convergence graphic is computed locally using MSAS hourly analysis wind fields (instead of LAPS).  MSAS uses a better quality control algorithm to filter out poor wind observations, versus the LAPS analysis scheme.  Testing has concluded that the moisture convergence field offered a better signal using MSAS winds in most convective events.
    • Warm Theta Advection, Theta-E, and CAPE graphics are all the internally calculated grids from within LAPS itself.  (Future plans are to also calculate Theta Advection using MSAS winds, but the "potential temperature advection" grid from LAPS itself tends to have less noise than moisture convergence).
Information from this page originated from WFO Dodge City. Questions or Comments regarding the graphics can be directed to Mike Umscheid (application developer) is the U.S. government's official web portal to all federal, state and local government web resources and services.