The Life Cycle of Thunderstorm Gust Fronts as Viewed with Doppler Radar and Rawinsonde Data

Two Severe Local Storms as Observed in the Arid Area of Northwest China

“…Considering that the horizontal distance between the centers of the AWSs, which was at almost the same place as the divergence center, and that each AWS was less than 4km away, and that the wind speeds observed at the AWSs were more than 10m s-1, this type of strong downdraft may be called a microburst as defined by Fujita (1981). The preceding convergence may have been caused by the leading edge of diverging downdraft wind, which formed a squall line nose, just as shown in the cross section of Doppler wind velocity pattern of the downdraft observed at Chicago reported by Wakimoto (1982). This rain storm passed away from this triangle at about 16:30 BST and all the wind directions became parallel after this time.…”

Evolution and structure of a cold front in an Alpine valley as revealed by a Doppler lidar

“…This uncertainty results in a relatively large range of density current speeds, in our case approximately 2 ≤ u d ≤ 12 m s −1 . Further, slightly different values for a and b appear in the literature with a variation of about ±10 to 20% (Thorpe, et al, 1980;Wakimoto, 1982;Smith and Reeder, 1988). Moreover, Eq.…”

“…Hence, the data spacing normal to the beam is about 10 m at a distance of 1 km from the lidar site and 100 m at a distance of 10 km, respectively. For the derivation of the 'full' wind field, radial velocities are interpolated on to a Cartesian grid with a horizontal and vertical mesh size of 100 m. We use a similar procedure to that applied in previous studies (Wakimoto, 1982;Intrieri, et al, 1990;Banta, et al, 1992) to derive the along-valley wind component u and the vertical wind component w from the radial wind velocity u r . We assume that the flow is along the valley in the direction of the lidar beam with a cross-valley wind component v = 0.…”

“…As shown by the scale analysis of Wakimoto (1982) this is a suitable approximation as long as the depth of the considered layer is not much more than 2 km. In order to solve Eq.…”

Okayama Downbursts on 27 June 1991

“…12. Such rolling-up clouds are considered to be precipitation rolls which indicate that a downward motion has been occurring from a thunderstorm behind the rolls (Wakimoto 1982). Considering (1) the existence of a downward motion was indicated by the expansion of the gust front (DL-II) and the arc-shaped rolling-up clouds and (2) the maximum wind speed (26m/s) over 10m/s under heavy rainfall, we concluded that it was a wet downburst with strong northwesterly wind at 1329 JST (Downburst-III) which caused Gust-III.…”