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

, westerly shear being correlated with severe weather ( Hagemeyer and Schmocker 1991 ). Easterly shear can also result in high-level anvil clouds over the space launch and landing facilities of the John F. Kennedy Space Center (KSC) and Cape Canaveral Air Force Station (CCAFS) on Florida's east coast, originating from convective systems over the Atlantic Ocean. Caniaux et al. (1994) used the term “forward anvil clouds” to describe the westward-propagating anvil of a tropical squall line in easterly

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James L. Wiesmueller and Steven M. Zubrick

1985 ) was around the middle 1980s. Q -vector diagnosis as a method for estimating quasigeostrophic forcing had been a topic of study and discussion in the literature since the late 1970s (see Trenberth 1978 ) and was available in limited diagnostic programs in the operational community by the late 1980s (see Foster 1988 ). It was not widely used, however, in the operational community until these fields became available in model-derived forecasts via advanced workstations such as the prototype

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Jeffrey D. Duda and William A. Gallus Jr.

1. Introduction Mesoscale convective systems produce a significant portion of warm-season rainfall ( Fritsch et al. 1986 ) and a large amount of severe weather ( Doswell et al. 1996 ; Wheatley et al. 2006 ; Wakimoto et al. 2006 ; Gallus et al. 2008 ; Duda and Gallus 2010 ). Many mesoscale convective systems (MCSs) also spawn mesoscale convective vortices (MCVs) that can serve later as focal points for the development of new convection that may not be tied to any other large-scale forcing

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Russell L. Elsberry and Peter J. Kirchoffer

SEPTEMBER 1988 RUSSELL L. ELSBERY AND PETER J. KIRCHOFFER 205Upper-Level Forcing of Explosive Cyclogenesis over the Ocean Based on Operationally Analyzed Fields RUSSELL L. ELSBERRY AND PETER J. KIRCHOFFERDepartment of Meteorology, Naval Postgraduate School, Monterey, California(Manuscript received 29 September 1987, in final form I March 1988)ABSTRACT Some of the recent research studies of

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Donald W. McCann

correct some of the misconceptions. First I want to review some basic parcel dynamics. There are three major forces in the atmosphere that can act on a parcel. The forces in the vertical are the pressure gradient force and gravity. In the horizontal they are again the pressure gradient force and the Coriolis force. Meteorologists call the balance of these vertical forces “hydrostatic” balance and the balance of these horizontal forces “geostrophic” balance. Imbalances occur when the pressure gradient

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Michael J. Brennan, Hugh D. Cobb III, and Richard D. Knabb

1. Introduction The National Hurricane Center (NHC) has high seas forecast and warning responsibility for portions of the eastern tropical Pacific Ocean, including the Gulf of Tehuantepec ( Fig. 1 ). These responsibilities are carried out by NHC’s Tropical Analysis and Forecast Branch (TAFB). Gap wind events that occur in the Gulf of Tehuantepec ( Fig. 2 ) are the most frequently observed storm-force (48 kt or greater) wind events that occur outside of tropical cyclones in this region. The Gulf

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Florian Pappenberger and Roberto Buizza


In this paper the suitability of ECMWF forecasts for hydrological applications is evaluated. This study focuses on three spatial scales: the upper Danube (which is upstream of Bratislava, Slovakia), the entire Danube catchment, and the whole of Europe. Two variables, 2-m temperature and total precipitation, are analyzed. The analysis shows that precipitation forecasts follow largely in pattern the observations. The timing of the peaks between forecasted and observed precipitation and temperature is good although precipitation amounts are often underestimated. The catchment scale influences the skill scores significantly. Small catchments exhibit a larger variance as well as larger extremes. A water balance analysis suggest a 10% underestimation by the ensemble mean and an overestimation by the high-resolution forecast over the past few years. Precipitation and temperature predictions are skillful up to days 5–7. Forecasts accumulated over a longer time frame are largely more skillful than forecasts accumulated over short time periods.

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Charles R. Sampson, James S. Goerss, John A. Knaff, Brian R. Strahl, Edward M. Fukada, and Efren A. Serra

, . Knaff , J. A. , and C. R. Sampson , 2015 : After a decade are Atlantic tropical cyclone gale force wind radii forecasts now skillful? Wea. Forecasting , 30 , 702 – 709 , . 10.1175/WAF-D-14-00149.1 Knaff , J. A. , C. R. Sampson , M. DeMaria , T. P. Marchok , J. M. Gross , and C. J. McAdie , 2007 : Statistical tropical cyclone wind radii prediction using climatology

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Lawrence B. Dunn

-vector analysis; and 3) a look at possible ageostrophic fomingin excess of, or operating on smaller scales than those expected from a purely quasi-geostrophic (QG) framework.Additionally, an examination &the atmosphere's potential response to forcing was attempted via a conditionalsymmetric instability analysis. The results show a failure of both the conventional approach and the purely QG forcing analysis in explainingthe heavy snowband, although Q-vectors did much better than 500 mb PVA on the

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Suzanne W. Wetzel and Jonathan E. Martin

winter precipitation event diagnosed by the technique presented here are quasigeostrophic forcing for ascent, moisture, instability (i.e., gravitational, inertial, or slantwise instability), precipitation efficiency (specifically, cloud microphysical properties), and temperature. Section 2 provides a general introduction to the IM for winter weather forecasting, including a brief history of the ingredients-based methodology, a discussion of our definition of an ingredient, and a rationale for the

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