Lesson 1
Meteorological Satellite Orbits
Lesson 2
Review of Radiative Transfer
Lesson 3
Visible Image Interpretation
Lesson 4
Infrared Image Interpretation
Lesson 5
Multispectral Image Interpretation
Lesson 6
Fires & Aerosols
Lesson 7
Winds
Lesson 8
Sounders
Lesson 9
Fog and Stratus
Lesson 10
Thunderstorm
Lesson 11
Energy Budget
Lesson 12
Hurricanes
Lesson 13
Global Circulation
Lesson 14
Synoptic Scale
Lesson 15
Local Circulation
Lesson 16
Satellite Oceanography
Lesson 17
Precipitation

Lesson 10: Thunderstorms

enhanced V

The enhanced-V is a pattern seen on satellite infrared images of thunderstorms; a thunderstorm anvil exhibits a V-shaped region of colder cloud tops extending downwind from the thunderstorm updraft. The enhanced-V indicates a very strong updraft, and therefore a higher potential for severe weather.

A V-shaped cold plume extends downstream from the coldest IR temperature, which is associated with the overshooting cloud top associated with the intense storm updraft. The V-shape results from advection by the strong winds near the tropopause.

A warmer "wake" is seen downstream, and the intense overshooting top can be quantified by the IR temperatures of a cold and a warm pixel (cold-warm couplet). Typically, cloud top temperatures are related to height due to the atmospheric lapse rates such that the higher the cloud the colder the IR temperature. However, with overshooting convective cloud tops the cloud top temperature relates to the parcel temperature which cools moist adiabatically as it rises.

Use the applet below to determine the enhanced-V and warmer wake in an IR satellite image.


QuizImage

Studies (e.g. McCann, 1981) have demonstrated the value of real-time satellite data in detecting and monitoring severe thunderstorms using the enhanced-V. Median lead time is approximately 30 minutes.

Some References:

  • McCann, D.W., 1981: The enhanced-V, a satellite observable severe storm signature. IN:United States National Oceanic and Atmospheric Administration, National Weather Service, Wash., DC., Technical Memorandum (NOAA TM NWS NSSFC-4), March 1981. 31 p., 33, 5-257.
  • McCann, D.W., 1983: The enhanced-V, a satellite observable severe storm signature. Mon. Wea. Rev., 111, 887-894.
  • Heymsfield, G.M., Blackmer, R., Jr., and Schotz, S., 1983: Upper level structure of Oklahoma tornadic storms on 2 May 1979, Part 1 Radar and Satellite observations. Journal of the Atmospheric Sciences, Boston, 40(7): 1740-1755.
  • Heymsfield, 1983: Upper level structure of Oklahoma tornadic storms on 2 May 1979, Part 2, Proposed explanation of V pattern and internal warm region in infrared observations, Journal of the Atmospheric Sciences, Boston, 40(7): 1756-1767.


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