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Peter C. Banacos and David M. Schultz

-central Texas, with a narrow surface moist axis ( q ∼16 g kg −1 ) between the dryline and warm front. An attendant strong 500-mb short-wave trough was moving eastward from Colorado and New Mexico into the central plains states at this time (not shown). The upper-level forcing combined with instability and low-level moisture resulted in the development of isolated supercells beginning around 1815 UTC near the warm front in northeastern Kansas. Initiation of additional supercellular storms then occurred at

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Shawn M. Milrad, Eyad H. Atallah, and John R. Gyakum

et al. 2009 ; Razy et al. 2012 ) and can subsequently have an impact on the observed weather within the SLRV ( Roebber and Gyakum 2003 ; Razy et al. 2012 ). The bimodality is related to certain types of forcing mechanisms (sometimes referred to as wind channeling) within the valley ( Carrera et al. 2009 ; Razy et al. 2012 ). There are four forcing mechanisms for valley winds ( Whiteman and Doran 1993 ): thermal forcing, downward momentum transport, forced channeling, and pressure

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Corey G. Amiot, Lawrence D. Carey, William P. Roeder, Todd M. McNamara, and Richard J. Blakeslee

1. Introduction Wind warnings are the second-most-frequent advisory product issued by the U.S. Air Force’s 45th Weather Squadron (45WS), the organization responsible for providing weather support to America’s space program at Cape Canaveral Air Force Station and the National Aeronautics and Space Administration’s Kennedy Space Center (CCAFS/KSC) in Florida ( Roeder et al. 2014 ). The 45WS issues two warning levels for wind events: winds ≥ 35 kt (Threshold-1 or “threshold level”), with 30 min of

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Eric A. Hendricks, Yi Jin, Jonathan R. Moskaitis, James D. Doyle, Melinda S. Peng, Chun-Chieh Wu, and Hung-Chi Kuo

, leading to differences in the QPFs. Although there exists some sensitivity to these parameters, the results indicate that a multiply nested regional TC prediction model can provide an accurate QPF for large, highly asymmetric storms with multiscale interactions, such as Morakot. The enhanced predictability is likely due to the more predictable large-scale and topographic forcing. Acknowledgments The authors acknowledge the support of the Office of Naval Research (ONR) through Program Element (PE

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Gregory S. Poulos, Douglas A. Wesley, John S. Snook, and Michael P. Meyers

1. Introduction During 24–26 October 1997, a deep cutoff low pressure system moved eastward across the southern Colorado Rocky Mountains producing blizzard conditions along the Front Range from Wyoming to southern New Mexico. In addition, this storm caused easterly hurricane-force winds at the surface near Steamboat Springs, Colorado, which destroyed about 5300 ha (1 ha = ∼2.5 acres) of west-slope forest. Heavy snow also occurred in Nebraska and Kansas. The effects on the public of these

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Jongil Han, Marcin L. Witek, Joao Teixeira, Ruiyu Sun, Hua-Lu Pan, Jennifer K. Fletcher, and Christopher S. Bretherton

entrainment fluxes in the upper PBL. For diagnostic purposes, h is defined as Eq. (11) but without the thermal excess in Eq. (12) . A mass-flux mixing for momentum is also included but with the effect of the updraft-induced pressure gradient force ( Han and Pan 2006 ), which weakens the momentum exchange due to the vertical mass flux. This is similar to the nonlocal momentum mixing suggested by Frech and Mahrt (1995) , Brown and Grant (1997) , and Noh et al. (2003) in that the nonlocal mixing for

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Keith D. Sherburn, Matthew D. Parker, Jessica R. King, and Gary M. Lackmann

clearer depiction of what processes and features show operational utility at discriminating between events and nulls. The Northeast subset returns later as an independent verification dataset following the development of new forecasting techniques using the Southeast subset. There are several recurring themes in the Southeast cases. First, events are characterized by especially strong synoptic-scale forcing for ascent, including intense upper-level divergence and low-level convergence, a potent

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Conrad L. Ziegler and Erik N. Rasmussen

which CAPE and CIN values appeared to be favorable for convective initiation, yet where the LCL was within an elevated dry layer and storms did not develop. Although deep convection in such an environment is unlikely, storms could conceivably be initiated given localized mesoscale convergence extreme enough to dominate small-scale turbulent mixing and force large volumes of moist boundary layer air up to the LFC. The dryline was probed by east–west traverses of the NSSL-2 mobile mesonet during

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Justin Sharp and Clifford F. Mass

approaching from the west producing a westward pressure gradient force across the gorge. Thus, easterly gap flow and precipitation often occur on the same day. In contrast to precipitation (mostly rainfall), the KPDX snowfall climatology exhibits a strong correlation between east to southeast surface winds at KPDX and increased snowfall amount ( Fig. 10b ) and snowfall frequency (not shown). Almost 70% of days with snowfall occur when the daily resultant wind direction is between 79° and 147°. This

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Kyle M. Nardi, Cory F. Baggett, Elizabeth A. Barnes, Eric D. Maloney, Daniel S. Harnos, and Laura M. Ciasto

-D-15-0502.1 . 10.1175/JCLI-D-15-0502.1 Hendon , H. , and S. Abhik , 2018 : Differences in vertical structure of the Madden-Julian Oscillation associated with the quasi-biennial oscillation . Geophys. Res. Lett. , 45 , 4419 – 4428 , https://doi.org/10.1029/2018GL077207 . 10.1029/2018GL077207 Higgins , R. , J. Schemm , W. Shi , and A. Leetmaa , 2000 : Extreme precipitation events in the western United States related to tropical forcing . J. Climate , 13 , 793 – 820 , https

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