Search Results

You are looking at 131 - 140 of 1,536 items for :

  • Weather and Forecasting x
  • Refine by Access: All Content x
Clear All
Christopher A. Hiemstra, Glen E. Liston, Roger A. Pielke Sr., Daniel L. Birkenheuer, and Steven C. Albers

1. Introduction The use of meteorological forcing data to drive land surface/hydrological models is an active area of investigation. Advances in Land Data Assimilation Systems (LDAS) at global ( Rodell et al. 2004 ) and continental scales ( Mitchell et al. 2004 ) have illustrated the utility of merging atmospheric and surface process models. Similar studies are needed at local and regional scales. Gridded local and regional meteorological fields are necessary to drive many of the spatial models

Full access
M. Laura Guimarães Rodrigues and Rita Yuri Ynoue

. Also determined from the reanalysis were the fields of convergence of specific humidity at 850 and 700 hPa, temperature advection at 850 hPa, and advection of relative vorticity at 500 hPa. The moisture divergence on the 850-hPa surface was obtained from the continuity equation for the water vapor, where q is the specific humidity and v is the horizontal wind, calculated as ∇ ⋅ ( q v ). The vertical forcings from quasigeostrophic theory ( Holton 2004 ) have been used in studies of

Full access
Mark D. Powell, Peter P. Dodge, and Michael L. Black

values measured by reconnaissanceaircraft at the same location relative to the storm over water. Despite relatively rapid increases in the centralsea-level pressure and decreases in the mean circulation as Hugo progressed inland, hurricane-force wind gustsextended Hugo's damage pattern well past Charlotte, North Carolina, 4330 km inland. Accurate determination of surface wind distribution in land-falling hurricanes is dependent upon the spatialdensity and quality of surface wind measurements and

Full access
David B. Gilhousen

more rapid cyclogenesis on 12 March 1993 than was forecast by numerical weather prediction(NWP) models. Observations demonstrated a closed circulation with gale-force winds shortly after the stormentered the Gulf of Mexico. Pressure measurements at two buoys off the Texas coast were 4-6 hPa lower thanthe 12-h NWP forecasts, a significant forecast error. Observations from NDBC's moored buoys and CoastalMarine Automated Network stations revealed that the developing storm was significantly deeper than

Full access
Luca Mathias, Volker Ermert, Fanni D. Kelemen, Patrick Ludwig, and Joaquim G. Pinto

shows the location of NRW (shaded in orange) in western Europe. Mesoscale convective systems (MCSs) occur more frequently during the summer months and can produce hazardous weather events, such as flash floods, large hail, and storm-force wind gusts that can occasionally reach hurricane-force levels. Wind gusts accompanying MCSs are induced by strong downdrafts and by the associated pressure gradients within their convective cells. The necessary ingredients for well-organized MCSs are sufficient

Full access
Rita D. Roberts and Steven Rutledge

boundary layer forcing in the form of convergence boundaries in conditionally unstable environments ( Wilson and Schreiber 1986 ; Wilson and Mueller 1993 ; Mueller et al. 1993 ) with more intense thunderstorms resulting from a combination of boundary layer and weak synoptic-scale forcing ( Doswell 1980 ; Szoke et al. 1984 ; Roberts and Wilson 1995 ). Although Dye et al. (1989) and Gremillion and Orville (1999) , among others, have shown that onset of storm electrification generally occurs >5 min

Full access
Kenneth J. Westrick, Pascal Storck, and Clifford F. Mass

western (upwind) side of the Cascade Mountain barrier. A procedure to remove this bias prior to forcing the hydrologic model is discussed in the appendix . b. Hydrologic model The hydrologic model used in this project is the DHSVM, which is a physically based distributed hydrologic model designed for use in a variety of geographical and environmental settings ( Wigmosta et al. 1994 ) that has been extensively tested in regions of complex terrain ( Bowling et al. 2000 ; Storck et al. 1995 ). The

Full access
A. James Wagner

from a series of seasonal 700 mb lag autocorrelationfields going back as far as 2 1 / 1 years. Numerical weather prediction products do not enter into the seasonalforecast, but boundary forcing by sea surface temperature anomalies, particularly in the Pacific, is consideredduring the seasons these factors have been shown to have a significant effect on the mean circulation. Extensiveuse is made of teleconnections to obtain a consistent overall qualitative concept of the expected pattern. Mean

Full access
Jing Xu and Yuqing Wang

.1175/1520-0493(1984)112<1408:ACOLAS>2.0.CO;2 . Pendergrass, A. G. , and Willoughby H. E. , 2009 : Diabatically induced secondary flows in tropical cyclones. Part I: Quasi-steady forcing . Mon. Wea. Rev. , 137 , 805 – 821 , doi: 10.1175/2008MWR2657.1 . Rogers, R. , Reasor P. , and Lorsolo S. , 2013 : Airborne Doppler observations of the inner-core structural differences between intensifying and steady-state tropical cyclones . Mon. Wea. Rev. , 141 , 2970 – 2991 , doi: 10.1175/MWR-D-12-00357.1 . Schubert W. H

Full access
Barry E. Schwartz, Charles F. Chappell, William E. Togstad, and Xiao-Ping Zhong

, areemployed to identify the large-scale forcing that set the stage for the development of mesoscale convection.Surface mesoanalysis identified a significant outflow boundary and mesohigh-pressure system produced fromafternoon thunderstorms over east-central Minnesota and western Wisconsin. This outflow boundary becamestationary over Minneapolis-St. Paul (the Twin Cities), providing a convergence zone that acted to focus thunderstorm development. Satellite imagery shows that the thunderstorms associated

Full access