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Gary M. Barnes

1989 ). The typical subdivisions of the boundary layer include the surface, mixed, transition, cloud, and inversion layers for the trade wind regions. How this vertical thermodynamic structure evolves in a tropical cyclone (TC) is not well documented. Omega dropwindsondes (ODWs) did show some aspects of the boundary layer ( Franklin et al. 1988 ; Powell 1990 ; Bogner et al. 2000 ; Barnes and Bogner 2001 ), but their quality demanded averaging over tens of meters. The hygristor often stayed wet

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Thomas J. Perrone and Paul R. Lowe

at 950, 700, 500 and 200 mb to forecast tropical storm formation (genesis). NationalOceanographic and Atmospheric Administration tropical mosaic visible satellite images and the Joint (UnitedStates Navy and Air Force) Typhoon Warning Center's Post-Season Best Track analyses of tropical storms wereused to select a representative collection of tropical cloud clusters, some of which became tropical storms (GOcases), others of which did not (NO GO cases). Navy Fleet Numerical Oceanography Central

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CHARLES F. BROOKS

Roniebimcs experienced in flying tluough such regione. Clouds, rain, and fog all contribute t,o tlie discomfort and danger of flyinq. I)erhxps tlie most interesting are tlie experiences in the thimder- storm and tlie up-and-down wjnda which accompany such storms. AR tlie driving wedge of cold air a t the Hurface advances ahead of the st,orni, the air into which the shrni is moving is forced upward. The Iimxinium t,urbulence is found in the region of the sguzll cloud, but t!ie force of the rising air

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N. C. G. Hart, C. J. C. Reason, and N. Fauchereau

into the temperate latitudes, had amplified the upper-level trough as it moved over southern Africa ( Fig. 5d ), increasing curvature in the upper-level flow. This wave growth intensified the upper-level divergence favoring convection and was further reinforced by the upper-level divergent response to convective activity already occurring in the cloud band. Heavy showers, supported by the intensified large-scale forcing, continued to fall over much of South Africa on 6 January, although generally

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Qing-Hong Zhang, Kai-Hon Lau, Ying-Hwa Kuo, and Shou-Jun Chen

in the subtropics. Nagata and Ogura (1991) conducted a modeling study of an intensive MCS along the baiu front. They simulated a localized LLJ with a horizontal scale of ≈500 km associated with a mesoscale low. The localized LLJ was accelerated by the pressure gradient force toward the convectively induced low. Kato (1998) studied the maintenance and enhancement of the LLJ in the simulation of a torrential rain case over Japan. He found that the core of the localized LLJ is maintained through

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James W. Wilson, R. E. Carbone, J. D. Tuttle, and T. D. Keenan

Simpson (1984, 1989) have used numerical simulations to examine the merging process and the role of storm low-level outflows in establishing “bridge clouds” between neighboring cumulonimbi. The authors are unaware of any dual-Doppler studies that have examined the merger process in detail. As shown in section 4 the merging and growth of storms was a very important process in the growth of Hector; this was typically triggered by gust fronts as postulated by Simpson et al. (1980, 1993) . Carbone et

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Chung-Chieh Wang, George Tai-Jen Chen, and Shin-Yi Huang

initiated by frontal uplift, topographic uplift, dynamical forcing (of synoptic or mesoscale) associated with the front, or a combination of these processes (e.g., Chen 1993 ; Li et al. 1997 ). The topography of Taiwan, with a length of about 350 km and the highest peak reaching almost 4 km ( Fig. 1 ), often exerts a significant blocking effect on the prevailing low-level flow. The blocking effect can result in flow deceleration and deflection (e.g., Banta 1990 ; Baines 1995 ), localized barrier jet

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Ying-Hwa Kuo, M. A. Shapiro, and Evelyn G. Donall

, suggesting the presence of deep baroclinic forcing during the evolution of the storm. The full-physicssimulation produced major cyclogenesis with a central pressure of 967 rab and a deepening of 37 mb in 24 h.The model simulated the development of comma-sha~nxl cloud patterns, which compared favorably with satelliteobservafons of the storm. Further analysis showed that the rapid cyclogenesis was strongly related to moistfrontogenesis at the warm front. During rapid storm intensification, the heavy

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Robert J. Trapp and Morris L. Weisman

magnitude at t = 4 h 50 min is added to the time-integrated pressure-gradient force terms to allow for comparison with V H . Note that the time domain of (b) is half that of (a) Fig . 20. Vertical and horizontal structure, at t = 5 h, of the convective systems simulated with (a), (b) 10/2.5/ f and (c), (d) 30/5/ f . In (a) and (c), vertical cross sections of north–south-averaged [centered about y = 70 km and y = 54 km, respectively, as indicated in (b) and (d)] wind vectors and cloud water

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Andrew J. Negri and Thomas H. Vonder Haar

visible channel data were used to derive low-level windfields by tracking small cumulus clouds on NASA's Atmospheric and Oceanographic InformationProcessing System (AOIPS). The satellite-derived wind fields were combined with surface mixing ratiosto derive horizontal moisture convergence in the pre-storm environment of 24 April 1975. Storms begandeveloping in an area extending from southwest Oklahoma to eastern Tennessee 2 h subsequent to thetime of the derived fields. The maximum moisture convergence

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