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Manual of Downburst Identification for Project NIMROD.

PB286048

Publication Date	1978
Personal Author	Fujita, T. T.
Page Count	118
Abstract	The evidence of downbursts available as of this date are presented. Straight-line winds, often preceded by an awesome-looking roll cloud, can induce widespread wind damage in and around thunderstorm areas. Extensive aerial photography and mapping of the areas swept by straight-line winds has revealed the existence of diverging patterns of damage embedded inside of overall straight-line flows. A major breakthrough in this study was the analysis of the Independence Day, 1977 storms in Northern Wisconsin. At least 25 locations of divergent downburst flow were mapped from a low-flying aircraft. Microscale downbursts (microbursts), less than 3 miles in outflow diameter, were found in other parts of the country. Four aircraft accidents in 1975-77 and one more in 1956 have been related to microbursts whose sizes were comparable to the length of runways. Damaging winds of a microburst last only for a few minutes. Downburst damage is often highly localized, resembling that of tornadoes. Insight into operational applications of these findings are presented. These assessments should be useful in ascertaining whether or not storm damage is tornado or downburst related.
Keywords	Thunderstorms Wind(Meteorology) Damage assessment Tornadoes Infrared mapping Aerial photography Manuals Aviation safety Divergence Aviation accidents Assessments Size determination NIMROD project Downbursts
Source Agency	National Oceanic and Atmospheric Administration National Aeronautics and Space Administration
NTIS Subject Category	55B - Dynamic Meteorology 55C - Meteorological Data Collection, Analysis, & Weather Forecasting
Corporate Authors	Chicago Univ., Ill. Dept. of the Geophysical Sciences.; National Aeronautics and Space Administration, Washington, D.C.; National Weather Service, Silver Spring, MD.; Nuclear Regulatory Commission, Washington, D.C.
Supplemental Notes	Sponsored in part by National Aeronautics and Space Administration, Washington, D.C. Grant NGR-14-001-008. Report on Satellite and Mesometeorology Research Project.
Document Type	Technical Report
Title Note	Research paper.
NTIS Issue Number	197825
Contract Number	NRC-04-74-239

Manual of Downburst Identification for Project NIMROD.

Manual of Downburst Identification for Project NIMROD.
PB286048

Publication Date	1978
Personal Author	Fujita, T. T.
Page Count	118
Abstract	The evidence of downbursts available as of this date are presented. Straight-line winds, often preceded by an awesome-looking roll cloud, can induce widespread wind damage in and around thunderstorm areas. Extensive aerial photography and mapping of the areas swept by straight-line winds has revealed the existence of diverging patterns of damage embedded inside of overall straight-line flows. A major breakthrough in this study was the analysis of the Independence Day, 1977 storms in Northern Wisconsin. At least 25 locations of divergent downburst flow were mapped from a low-flying aircraft. Microscale downbursts (microbursts), less than 3 miles in outflow diameter, were found in other parts of the country. Four aircraft accidents in 1975-77 and one more in 1956 have been related to microbursts whose sizes were comparable to the length of runways. Damaging winds of a microburst last only for a few minutes. Downburst damage is often highly localized, resembling that of tornadoes. Insight into operational applications of these findings are presented. These assessments should be useful in ascertaining whether or not storm damage is tornado or downburst related.
Keywords	Thunderstorms Wind(Meteorology) Damage assessment Tornadoes Infrared mapping Aerial photography Manuals Aviation safety Divergence Aviation accidents Assessments Size determination NIMROD project Downbursts
Source Agency	National Oceanic and Atmospheric Administration National Aeronautics and Space Administration
NTIS Subject Category	55B - Dynamic Meteorology 55C - Meteorological Data Collection, Analysis, & Weather Forecasting
Corporate Authors	Chicago Univ., Ill. Dept. of the Geophysical Sciences.; National Aeronautics and Space Administration, Washington, D.C.; National Weather Service, Silver Spring, MD.; Nuclear Regulatory Commission, Washington, D.C.
Supplemental Notes	Sponsored in part by National Aeronautics and Space Administration, Washington, D.C. Grant NGR-14-001-008. Report on Satellite and Mesometeorology Research Project.
Document Type	Technical Report
Title Note	Research paper.
NTIS Issue Number	197825
Contract Number	NRC-04-74-239