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Jiuhua Feng and Yi-Leng Chen

and rain-cooled air from the downdraft outflow, whereas on the upper slopes, the extensive orographic clouds reduce the infrared radiation heat loss and cause a slower temperature decrease than in dry cases. As a result, on wet days, the katabatic flow onset is earlier on the windward lowlands and coastal regions, but later on the upper slopes. Carbone et al. (1995) also found that thermal forcing is important for the flow reversal on the windward slope. Nevertheless, they attributed evaporative

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Richard E. Passarelli Jr. and Hannah Boehme

1062 MONTHLY WEATHER REVIEW VOLUME 111The Orographic Modulation of Pre-Warm-Front Precipitation in Southern New England RICHARD E. PASSARELLI, JR., AND HANNAH BOEHMEMassachusetts Institute of Technology, Department of Meteorology and Physical Oceanography, Cambridge, MA 02139(Manuscript received 8 June 1982, in final form 20 January 1983)ABSTRACT Topographic forcing over

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Cheng-Ku Yu, Ben Jong-Dao Jou, and David P. Jorgensen

forcing terms and buoyancy forcing terms (not shown) reveal that the dynamic forcing originated from the interaction between cross-line wind shear and updraft [term B2 in (4) ]. Thermal buoyancy forcing [term D in (4) ] is also a contributor to this midlevel downshear low. The environmental shear exhibited pronounced cross-line shear (cf. Fig. 1 ) and in-cloud vertical velocities also reached a maximum (cf. Fig. 8 ) at the midlevel, both of which may explain the increased importance of the dynamic

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Charles Cohen and William M. Frank

stable state, but generally will not reach it because some conditional instability is required to overcome dissipative processes andto drive the passive portions of the circulation (divergence and compensating subsidence). This is the equilibrium state characterized by Arakawa and Schubert(1974) as a balance between destabilization by largescale forcing and stabilization by convection. Chimonas and Rossi (1987) showed that the tropopause height is determined by undilute clouds, andthat the

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Seon Tae Kim, Jin-Yi Yu, Arun Kumar, and Hui Wang

that the weaker CP ENSO in the CFS model is also partly due to unrealistically weak zonal advective feedback in the equatorial Pacific. By analyzing the mean SST, SLP, and surface wind produced in the CFS model, we notice that the unrealistically weak extratropical forcing (and also zonal advective feedback) may be linked to the model deficiency in simulating the marine stratus clouds in the eastern Pacific. The underestimation of the amount and/or the optical thickness of these clouds may produce

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Walter Fernandez and Alan J. Thorpe

-Miller model overestimates it. Raymond's model is poor whenthe cloud bases are very low. This result indicates that over tropical oceans wave-CISK models cannotgive good results unless the mass flux due to the plumes, which is equated to the mass flux across cloudbase, is treated in a more realistic way. The Moncrieff-Miller model gives better results if the mean windcomponent along the direction of motion is used rather than the mid-level wind. The wave-CISK model and steady-state models of storm

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Da-Lin Zhang, Wei-Zhong Zheng, and Yong-Kang Xue

studies revealed that the hydrometeorological cycle would be enhanced in a warm climate setting with large variability in weather conditions ( Houghton et al. 1996 ; Wetzel et al. 1996 ; Paegle et al. 1996 ). Despite the importance of cloud and precipitation in the regional water cycle, the progress in warm-season quantitative precipitation forecasts (QPFs) has been slow due to the dominant weak dynamical forcing in the synoptic-scale environments and subgrid-scale meteorological forcing and surface

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M. Inoue, G. Matheou, and J. Teixeira

1. Introduction Large-eddy simulation (LES) has been used to examine detailed turbulence processes in atmospheric boundary layers (ABLs). Our focus is a realistic LES of a spatially developing ABL, specifically an application to the stratocumulus to shallow cumulus cloud (Sc–Cu) transition, but the application of the method presented here is not restricted to this particular case. The Sc–Cu transition is one of the key cloud processes over the subtropical ocean and has been extensively studied

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Chee-Pong Cheng and Robert A. Houze Jr.

precipitatinganvil clouds in GATE cloud clusters. About 40% of the total precipitation in GATE fell in these mesoscale regions. The remaining rainfall fell in the convective regions. Only very small amounts of convectiverain fell from echoes <5 km in maximum height. Increasing amounts of convective precipitation wer~associated with echoes of increasing maximum height, from the very small amounts in echoes ~5 kmto a maximum amount from echoes with maximum tops of ~12 kin. A secondary maximum of rain

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David A. Rahn and Thomas R. Parish

the cloud cover and the progression of the northward movement of the CTWR along the coast is encouraging and provides reason to believe that the model is able to simulate key forcing mechanisms. Figure 6 shows the 996-hPa heights, winds, and temperatures from WRF that are coincident with the images and simulation results shown in Fig. 5 with an additional nighttime image at 0800 UTC. This level was selected since it corresponds to the primary isobaric level at which the UWKA collected data on

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