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Constantin Ardilouze, Lauriane Batté, Bertrand Decharme, and Michel Déqué

empirical studies have established a relationship between spring soil moisture and subsequent summer heat over many regions, including large parts of Europe, North and South America, and Australia ( Quesada et al. 2012 ; Mueller and Seneviratne 2012 ). The contribution of soil moisture to seasonal climate predictability is only relevant in those regions where the two legs of land–atmosphere coupling apply. The terrestrial leg corresponds to the dependence of the evaporative fraction to soil moisture

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John T. Abatzoglou, Renaud Barbero, and Nicholas J. Nauslar

1. Introduction The Santa Ana winds (SAW) of southwestern California are characterized by strong offshore foehn winds that develop in the lee of the Transverse and Peninsular Ranges that are locally intensified by channeling through mountain gaps (e.g., Burrows 1987 ). SAW generally are a cool season phenomenon that develop after the dissipation of the North American monsoon as radiative cooling over the high plateau of the Great Basin gives way to a thermal continental high pressure. This

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Sharanya J. Majumdar, Michael J. Brennan, and Kate Howard

23 August: “A mid-to-upper-level trough located east of North America will lift out within 24 hours…leaving a pronounced weakness in the ridge over the Bahamas.” From the same NHC discussion, it was also noted that 2–3 days into the forecast period, “the track of Irene appears to be sensitive to the timing and amplitude of several shortwave troughs moving eastward across the United States/Canadian border.” In Fig. 2a , the upper-level trough B was present over Saskatchewan, Canada, and the short

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Jeffrey D. Kelley, David M. Schultz, Russ S. Schumacher, and Dale R. Durran

2016. North American Mesoscale (NAM) model 6-h forecast of wind speed [kt (1 kt ≈ 0.51 m s −1 ); shaded according to scale] and streamlines, from 0600 UTC in (a) and 1800 UTC in (b). At the surface, this trough was associated with a surface cyclone which, during 23–25 December, moved onshore from the Pacific Ocean and then eastward through Nevada, Utah, and Colorado. At 1800 UTC 25 December, the occluded cyclone was over northeast Colorado with a central pressure of 986 hPa ( Fig. 2a ). A west

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Martin J. Murphy and Ronald L. Holle

the North American Lightning Detection Network (NALDN). The NLDN by itself has been used for a long time to study the climatology of CG lightning over the continental United States ( Orville 1991 ; Orville and Huffines 2001 ; Zajac and Rutledge 2001 ), and the first lightning climatologies involving Canada were published by Burrows et al. (2002) and Orville et al. (2002) . The aforementioned lightning climatologies have shown that the peak in CG flash activity within the nominal network

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Chiara Lepore, Michael K. Tippett, and John T. Allen

and tornado occurrence and their interannual variability. Here, monthly CFSv2 forecasts of these severe thunderstorm indices are evaluated to assess their skill in forecasting regimes that are supportive of severe thunderstorms during the upcoming month. To this end, we assess the skill of monthly CFSv2 forecasts of TEI and HEI, and their ingredients using storm report data and the North American Regional Reanalysis (NARR; Mesinger et al. 2006 ). 2. Data Tornado and hail reports are taken from

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Kelly A. Lombardo and Brian A. Colle

terrain on severe convection have been well documented ( Wasula et al. 2002 ; LaPenta et al. 2005 ; Bosart et al. 2006 ), we focused our larger-scale composites near the less well-studied coastal region. To evaluate the synoptic and thermodynamic conditions that support severe weather over the coastal zone, spatial composites were constructed using the North American Regional Reanalysis (NARR) at 32-km grid spacing ( Mesinger et al. 2006 ) for cellular (49 events), linear (45 events), and nonlinear

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Chad M. Shafer, Andrew E. Mercer, Michael B. Richman, Lance M. Leslie, and Charles A. Doswell III

(1200, 1500, 1800, … , 0900 UTC; see below). For example, if the median time of the reports was 2230 UTC, the 2100 UTC analysis was used as the valid time of the event. The North American Regional Reanalysis (NARR; Mesinger et al. 2006 ) dataset was used for this study, as in S10a . The NARR dataset is available from 1979 to the present, permitting a large number of cases (4057) to analyze for the period of record. NARR data have a horizontal grid spacing of 32 km, and 45 staggered layers in the

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Mehdi Rezapour and Tom E. Baldock

result, the accuracy of the calculated velocity is important for the model. The North Atlantic hurricane database (HURDAT; ) was chosen to calculate the forward speed C of the system. d. Individual and combined hazard indices The new combined hazard index includes the three hazards most typical of tropical cyclones: wind, surge, and rainfall. Each is represented by an individual subindex: 1) tropical cyclone wind index (TCWI), 2) tropical cyclone

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Larissa J. Reames

. Devenyi , J. M. Brown , G. A. Manikin , T. L. Smith , and T. G. Smirnova , 2004b : Improved moisture and PBL initialization in the RUC using METAR data. 22nd Conf. on Severe Local Storms , Hyannis, MA, Amer. Meteor. Soc., 17.3. [Available online at .] Benjamin , S. G. , and Coauthors , 2016 : A North American hourly assimilation and model forecast cycle: The Rapid Refresh . Mon. Wea. Rev. , 144 , 1669 – 1694 , doi: 10

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