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David A. Short, James E. Sardonia, Winifred C. Lambert, and Mark M. Wheeler

1. Introduction Anvil clouds are formed in the upper troposphere from a supply of water vapor, supercooled cloud droplets, and ice crystals that is carried aloft by the deep convective updrafts of thunderstorms (e.g., Heymsfield 1986 ). Anvil cirrus is perhaps the most familiar term used for the upper portion of mature and dissipating thunderstorms with incus, or anvil, features. However, a variety of terms are in common usage, varying to fit descriptions of the environment and life history

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James T. Moore, Charles E. Graves, Sam Ng, and Jamie L. Smith

extensive, yet relatively narrow, snowband and destabilizing the atmosphere for the present storm. Finally, section 5 summarizes the results and presents a schematic diagram that highlights the major processes acting in the storm in the context of three-dimensional airstreams. 2. Processes important to the production of narrow snowbands a. Atmospheric airstreams and conveyor belts Analysis of an animated loop of water vapor channel imagery readily reveals that atmospheric flow tends to be concentrated

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Haldun Karan, Patrick J. Fitzpatrick, Christopher M. Hill, Yongzuo Li, Qingnong Xiao, and Eunha Lim

system. As concluded from a numerical study by Droegemeier and Wilhelmson (1987) and an observational study by Koch et al. (1991) , CI along the CBZ is highly dependent on wind shear and on temperature and water vapor profiles. Convective lines are also linked to the intensification of thermally direct circulations that transverse a CF. Koch (1984) found that the leading edge of a cloud-free zone was often collocated with initial squall-line development, and that the CF squall line developed as

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Andrea B. Schumacher, Mark DeMaria, and John A. Knaff

probability scheme for real-time use over multiple tropical basins. A linear discriminant analysis is applied to the NCEP Global Forecasting System (GFS) model analysis fields and water vapor (6.7 μ m) imagery from several geostationary satellites covering the North Atlantic, eastern North Pacific, and western North Pacific tropical cyclone basins. However, unlike PL86 and HH03 , this study uses convective parameters in combination with environmental parameters in lieu of limiting analysis to existing

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Stephen J. Harrison, John R. Mecikalski, and Kevin R. Knupp

°, wind speed increase of ≥3 m s −1 , or pressure p increase of >0.1 hPa. For the 915 measurements, an intense OB is defined if one of the following is analyzed: 1) vertical velocity w of >2 m s −1 , 2) spectrum width of >2 m s −1 , or 3) signal-to-noise (SNR) increase of 10 dB. For the MPR measurements an intense boundary is classified if the water vapor density increase at 1 and 2 km AGL exceeds 1.5 and 1.0 g m −3 , respectively. The water vapor density increase was determined by finding the

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Giovanni Leoncini, Roger A. Pielke Sr., and Philip Gabriel

et al. 2006 ), the Arctic Oscillation ( Thompson and Wallace 2000 ), the predictability of seasonal means ( Schubert et al. 2002 ), the relation between surface-level humidity and column-integrated water vapor ( Liu et al. 1991 ), the impact of microphysics parameterization on a cloud property retrieval algorithm ( Biggerstaff et al. 2006 ), and to approximate the difference in the reflectance of the O 2 A band obtained from a multiscattering line-by-line code and a two-stream representation

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Charles A. Doswell III, Harold E. Brooks, and Robert A. Maddox

sustained high rainfall rates. In turn, high rainfall ratesinvolve the rapid ascent of air containing substantial water vapor and also depend on the precipitation efficiency.The duration of an event is associated with its speed of movement and the size of the system causing the eventalong the direction of system movement. This leads naturally to a consideration of the meteorological processes by which these basic ingredients arebrought together. A description of those processes and of the types of heavy

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Tsing-Chang Chen, Ming-Cheng Yen, Jenq-Dar Tsay, Jordan Alpert, and Nguyen Thi Tan Thanh

the same time, the intensity of the explosive cyclone measured by sea level pressure, the North Pacific anticyclone, and the HRF cyclone reached their maxima. Three monsoon (30–60, 12–24, and 5 day) modes were identified by the spectral analysis of zonal winds to the north and south around the HRF event center. The HRF event occurred when the three monsoon modes were in phase, constructively interfering with the water vapor transport and convergence of water vapor flux by these three monsoon modes

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Peter C. Banacos and David M. Schultz

, conceptual models of how MFC or horizontal mass convergence can be applied to CI are constructed and are used as a pretext for discussing an elevated (i.e., convective updrafts not rooted in the local boundary layer) severe thunderstorm case study in section 6 . Finally, section 7 provides a summary and concluding discussion. 2. Physical expression The expression for MFC can be derived from the conservation of water vapor in pressure ( p ) coordinates: where u , υ , and ω represent the

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William A. Gallus Jr. and Moti Segal

adjustment might suggest that with both of the convective schemes, the precipitation is particularly sensitive to the amount of water vapor present, since the onion adjustment results in a removal of water vapor at lower levels. Despite the absolute changes in ETSs being small for the cold pool initialization, the paired t test indicated significance of the changes at the 95% confidence level for several thresholds. The statistical significance is assisted by small variance in the ETS differences

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