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Wyndam R. Lewis, W. James Steenburgh, Trevor I. Alcott, and Jonathan J. Rutz

western North America: A Lagrangian analysis . Mon. Wea. Rev. , 143 , 1924 – 1944 , doi: 10.1175/MWR-D-14-00288.1 . 10.1175/MWR-D-14-00288.1 Schaefer , J. T. , 1990 : The critical success index as an indicator of warning skill . Wea. Forecasting , 5 , 570 – 575 , doi: 10.1175/1520-0434(1990)005<0570:TCSIAA>2.0.CO;2 . 10.1175/1520-0434(1990)005<0570:TCSIAA>2.0.CO;2 Scheuerer , M. , and T. M. Hamill , 2015 : Statistical postprocessing of ensemble precipitation forecasts by fitting censored

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Christopher D. McCray, John R. Gyakum, and Eyad H. Atallah

and Environmental Sciences, University at Albany, State University of New York, 149 pp . Changnon , S. A. , 2003 : Characteristics of ice storms in the United States . J. Appl. Meteor. , 42 , 630 – 639 ,<0630:COISIT>2.0.CO;2 . 10.1175/1520-0450(2003)042<0630:COISIT>2.0.CO;2 Cortinas , J. , 2000 : A climatology of freezing rain in the Great Lakes region of North America . Mon. Wea. Rev. , 128 , 3574 – 3588 ,

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Nathan G. Korfe and Brian A. Colle

Colle (2009) verified the intensity and position of cyclones around North America and its adjacent oceans using the National Weather Service (NWS) Short-Range Ensemble Forecast system (SREF) for the 2004–07 cool seasons (October–March). The 15-member SREF mean provided a better overall forecast than its various subgroups for cyclone displacement and cyclone central pressure along the East Coast and the western Atlantic. The SREF intensity bias along the U.S East Coast from hours 3–15 is slightly

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Heather Dawn Reeves, Kimberly L. Elmore, Geoffrey S. Manikin, and David J. Stensrud

1. Introduction Valley cold pools (VCPs), which are shallow layers of cold air trapped in a valley or basin ( Whiteman et al. 2001 ), are common in the western United States during winter. Numerical forecasts of basic variables, such as temperature and humidity, are known to be problematic during VCPs, which makes for difficulty in anticipating the various forms of hazardous weather, such as fog or freezing rain that can occur. In this study, the North American Mesoscale Model (NAM) forecasts

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Taylor A. Gowan and John D. Horel

( Fig. 9c , previously shown in Fig. 1c ). Since the QM IMERG-E QPEs were calculated only within the state of Alaska, no precipitation is shown in Canada in Fig. 9b . The reduction of the IMERG-E wet bias as a result of the regional quantile mapping is evident by comparing Figs. 9a and 9b . The overall precipitation patterns are generally similar between the IMERG-E and APRFC estimates. However, the APRFC analysis appears to miss the north-south band of precipitation west of the Alaska

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Sean Stelten and William A. Gallus Jr.

-ARW model with 4-km horizontal grid spacing and 50 vertical levels. The domain spanned 1200 km × 1200 km and was centered on the initiation location of the observed PNCI. Initial and lateral boundary conditions were provided every 6 h from 12-km North American Mesoscale Forecast System (NAM) analyses. Runs began at 1200 UTC the day of the nocturnal initiation event, to capture the diurnal evolution of the boundary layer prior to the nocturnal events. The four PBL schemes used included two local mixing

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Alexandra K. Anderson-Frey, Yvette P. Richardson, Andrew R. Dean, Richard L. Thompson, and Bryan T. Smith
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Christopher M. Hill, Patrick J. Fitzpatrick, James H. Corbin, Yee H. Lau, and Sachin K. Bhate

regime using land and offshore in situ observations ( Hawkins 1977 ; Sheng et al. 2009 ) or with radar data. In particular, few climatology studies exist that document the SBC and land-breeze circulation (LBC) cycle along the north-central coast of the Gulf of Mexico (hereafter NCGC) using such a network. Regional lightning studies present 24-h ( Reap 1994 ) and annual ( Steiger and Orville 2003 ) flash data along the NCGC (which serve as a surrogate for convection) but do not convey the daily

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William A. Gallus Jr., Nathan A. Snook, and Elise V. Johnson


Radar data during the period 1 April–31 August 2002 were used to classify all convective storms occurring in a 10-state region of the central United States into nine predominant morphologies, and the severe weather reports associated with each morphology were then analyzed. The morphologies included three types of cellular convection (individual cells, clusters of cells, and broken squall lines), five types of linear systems (bow echoes, squall lines with trailing stratiform rain, lines with leading stratiform rain, lines with parallel stratiform rain, and lines with no stratiform rain), and nonlinear systems. Because linear systems with leading and line-parallel stratiform rainfall were relatively rare in the 2002 sample of 925 events, 24 additional cases of these morphologies from 1996 and 1997 identified by Parker and Johnson were included in the sample.

All morphologies were found to pose some risk of severe weather, but substantial differences existed between the number and types of severe weather reports and the different morphologies. Normalizing results per event, nonlinear systems produced the fewest reports of hail, and were relatively inactive for all types of severe weather compared to the other morphologies. Linear systems generated large numbers of reports from all categories of severe weather. Among linear systems, the hail and tornado threat was particularly enhanced in systems having leading and line-parallel stratiform rain. Bow echoes were found to produce far more severe wind reports than any other morphology. The flooding threat was largest in broken lines and linear systems having trailing and line-parallel stratiform rain. Cellular storms, despite much smaller areal coverage, also were abundant producers of severe hail and tornadoes, particularly in broken squall lines.

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Richard M. Mosier, Courtney Schumacher, Richard E. Orville, and Lawrence D. Carey

isotherm as the best predictor combination. Using those criteria produced an average CSI of 0.51 in this study. For most predictor combinations in this study, 40 dB Z had significantly lower CSIs than either 30 or 35 dB Z , while the CSI values when using 30 and 35 dB Z were similar. This difference suggests 1) cells reaching 40 dB Z occur less frequently over Houston than either Florida [the location of Gremillion and Orville (1999) ] or North Carolina [the location of Vincent et al. (2004) ] and

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