Severe Weather in the Southeast and Heavy Rain in the Northeast

Low pressure and a trailing cold front will cross the Eastern U.S. through this evening. Severe thunderstorms will be most common in the Southeast states where an Enhanced Risk exists over the Carolinas for a threat of damaging winds. Heavy rain will bring an elevated potential for flash flooding from the upper Ohio River Valley into northern Vermont where Flash Flood Watches are in effect. Read More >

LOADING...

Short Fuse Composite Charts
objective meso-analysis using hourly FSL LAPS analysis grids and FSL/NWS GFE software

Chart #1: Surface-based Moisture Convergence, Warm Theta Advection, Theta-E

Mouseover links to view previous hours

2300 UTC
2200 UTC
2100 UTC
2000 UTC
1900 UTC
1800 UTC
1700 UTC
1600 UTC
1500 UTC
1400 UTC
1300 UTC
1200 UTC
1100 UTC
1000 UTC
0900 UTC
0800 UTC
0700 UTC
0600 UTC
0500 UTC
0400 UTC
0300 UTC
0200 UTC
0100 UTC
0000 UTC

Chart #2: Surface-based CAPE, Low Level Lapse Rate (0-2.5km 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 (0-2.5km 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.
- Discussion of the old and new technique is offered HERE.

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).
Latest Changes & Recent Events:
- (6/20/2005) We have changed Chart 2 to remove surface-based CIN and use, instead, 0-2.5km AGL low level lapse rate. A discussion on this change can be found HERE
- (10/5/2005) A two-part Powerpoint presentation "Using the Short Fuse Composite to Forecast Severe Convection" is now available which was presented at the 2005 9th Annual High Plains Conference.
  Part I - "History of the SFC in the AFOS Era"
  Part II - "The Next Generation SFC" which includes Case Study examples from April 10, June 9, July 3, and August 19 2005.

Questions or comments regarding the graphics can be directed to Mike Umscheid (application developer).

Follow us on Twitter

Follow us on Facebook

Follow us on YouTube

DDC RSS Feed