Accession Number : ADA130649

Title :   Diagnosis of the Comma Cloud of 10 April 1979. Abridged Report.

Descriptive Note : Environmental research papers,

Corporate Author : AIR FORCE GEOPHYSICS LAB HANSCOM AFB MA

Personal Author(s) : Ridge,Daniel V

PDF Url : ADA130649

Report Date : 14 Dec 1982

Pagination or Media Count : 62

Abstract : On 10 April 1979 a comma cloud developed in association with a severe storm outbreak in Texas and Oklahoma during the AVE-SESAME 1 regional-scale experiment. With rather high time- and space-resolution rawinsonde data, plus GOES, radar, and surface data, a diagnosis was made of the structure and evolution of the disturbance which spawned the clouds. Vertical motion was computed by the kinematic method and from the quasi-geostrophic (QG) omega equation. An alternate partition of the GQ forcing function was tested. Five mesoscale waves in the mid- to high-troposphere strongly affected the weather patterns on 10 April 1979. These disturbances had wavelengths from 500 to 800 km, phase speeds of 20 to 33 m/s, and 500 mb height amplitudes around 30 m. They showed excellent time continuity in the 500 mb relative vorticity analyses. Both omega analyses showed 500 mb rising motion in eastern New Mexico six hours before a subsynoptic surface low and tornadic storms developed just to the east in Texas. Kinematic omegas indicated subsidence over the Texas coastal plain for six hours in the afternoon, evidently associated with maintenance of a surface pressure ridge and an intense low-level inversion which inhibited convection in that area. Because of its ageostrophic sensitivity and computational ease, kinematic omega is more useful than QG omega for operational purposes. However, the two methods make an independent and complementary pair for research purposes.

Descriptors :   *CLOUD PHYSICS, *ATMOSPHERIC MOTION, *CLOUDS, METEOROLOGICAL DATA, WEATHER FORECASTING, AIR MASS ANALYSIS, SYNOPTIC METEOROLOGY, BAROMETRIC PRESSURE, STORMS, VORTICES

Subject Categories : Meteorology

Distribution Statement : APPROVED FOR PUBLIC RELEASE