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Paul J. Kocin

A collection of detailed surface weather observations is used to construct an analysis of the legendary “Blizzard of '88,” an intense cyclone that was accompanied by unusually heavy snowfall, high winds and cold temperatures across the northeastern United States from 11 to 14 March 1888. The analysis follows the cyclone from genesis along a slow-moving frontal system, through rapid development and occlusion along the Middle Atlantic and southern New England coasts. Unusual aspects of the cyclone are highlighted. These include the limited areal extent of heavy snow accumulations, the establishment of very cold air across western New England and the Middle Atlantic states, a persistent stationary frontal zone across central New England that separated frigid continental air from maritime air, and the slow movement and rapid warming associated with the decay of the storm.

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Paul J. Kocin and Louis W. Uccellini

A Northeast snowfall impact scale (NESIS) is presented to convey a measure of the impact of heavy snowfall in the Northeast urban corridor, a region that extends from southern Virginia to New England. The scale is derived from a synoptic climatology of 30 major snowstorms in the Northeast urban corridor and applied to the snowfall distribution of 70 snowstorms east of the Rocky Mountains. NESIS is similar in concept to other meteorological scales that are designed to simplify complex phenomena into an easily understood range of values. The Fujita scale for tornadoes and the Saffir–Simpson scale for hurricanes measure the potential for destruction to property and loss of life by wind-related damage (and storm surge for Saffir–Simpson) through use of a categorical ranking (0 or 1–5).

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Louis W. Uccellini, Paul J. Kocin, Russell S. Schneider, Paul M. Stokols, and Russell A. Dorr

This paper describes the decision-making process used by the forecasters in the National Meteorological Center's Meteorological Operations Division and in Weather Forecast Offices of the National Weather Service to provide the successful forecasts of the superstorm of 12–14 March 1993. This review illustrates 1) the difficult decisions forecasters faced when using sometimes conflicting model guidance, 2) the forecasters' success in recognizing the mesoscale aspects of the storm as it began to develop and move along the Gulf and East Coasts of the United States, and 3) their ability to produce one of the most successful heavy snow and blizzard forecasts ever for a major winter storm that affected the eastern third of the United States.

The successful aspects of the forecasts include the following. 1) Cyclogenesis was predicted up to 5 days prior to its onset. 2) The unusual intensity of the storm was predicted three days in advance, allowing forecasters, government officials, and the media ample time to prepare the public, marine, and aviation interests to take precautions for the protection of life and property. 3) The excessive amounts and areal distribution of snowfall were predicted two days in advance of its onset. 4) An extensive number of blizzard watches and warnings were issued throughout the eastern United States with unprecedented lead times. 5) The coordination of forecasts within the National Weather Service and between the National Weather Service, private forecasters, and media meteorologists was perhaps the most extensive in recent history.

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Paul J. Kocin, Philip N. Schumacher, Ronald F. Morales Jr., and Louis W. Uccellini

An extratropical cyclone of unusual intensity and areal extent affected much of the Gulf and East Coasts of the United States on 12–14 March 1993. In this paper, the many effects of the storm will be highlighted, including perhaps the most widespread distribution of heavy snowfall of any recent East Coast storm, severe coastal flooding, and an outbreak of 11 confirmed tornadoes. A meteorological description of the storm is also presented, including a synoptic overview and a mesoscale analysis that focuses on the rapid development of the cyclone over the Gulf of Mexico. This is the first part of a three-paper series that also addresses the performance of the operational numerical models and assesses the forecasting decisions made at the National Meteorological Center and National Weather Service local forecast offices in the eastern United States.

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Louis W. Uccellini, Keith F. Brill, Ralph A. Petersen, Daniel Keyser, Robert Aune, Paul J. Kocin, and Mary des Jardins

The synoptic-scale weather conditions preceding and following the ill-fated Space Shuttle Challenger launch are documented, with particular emphasis on the upper-level winds for central and northern Florida. Operational radiosonde data collected by the National Weather Service, visible and infrared imagery from the Geostationary Operational Environmental Satellite, and water-vapor imagery from the VISSR (Visible Infrared Spin Scan Radiometer) Atmospheric Sounder, ozone data collected by the Total Ozone Mapping Spectrometer aboard the Nimbus-7, and soundings collected at Cape Canaveral (XMR) are described. Analyses derived from these data sets point to the juxtaposition of two distinct jet-stream systems (a polar-front jet [PFJ] and a subtropical jet [STJ]) over north-central Florida on the morning of the launch. Both jets were characterized by regions of significant vertical wind shear, which was especially strong above and below the core of the STJ.

Data from a radiosonde released at Cape Canaveral 10 min after the shuttle accident combined with radiosonde and jimsphere wind measurements before the shuttle launch reveal that, over XMR, the magnitude of the maximum wind in the PFJ was increasing with time while the magnitude of the STJ was decreasing. Even with the decreasing magnitude of wind speeds in the core of the STJ over XMR, large vertical wind shears and low Richardson numbers were still diagnosed near the PFJ and beneath the core of the STJ at the time of launch (1639 GMT). The low Richardson numbers associated with the presence of vertical wind shear indicate that conditions were favorable for shear-induced turbulence at the time of the shuttle explosion.

The results from the analyses of the synoptic radiosonde data are inconclusive due to the poor temporal and horizontal spatial resolution of the observational data base and the large number of missing data reports at numerous stations in the southeastern United States (including XMR). In an attempt to overcome this deficiency, numerical simulations of the atmospheric conditions were conducted using a mesoscale numerical model. The simulations initialized at 1200 GMT 28 January confirm the juxtaposition of two distinct jet systems over north-central Florida at the time of the shuttle launch and the presence of large vertical wind shears and low Richardson numbers associated with these jets.

Given the rapid temporal evolution of atmospheric flow regimes which involve strong wind shears, we recommend that consideration should be given to 1) augmenting the observations (both in time and space) upstream and around the Cape Canaveral launch facility, 2) enhancing the analysis and display capabilities of these data, and 3) using numerical-model output to provide the best possible diagnosis and forecast of the meteorological conditions for future shuttle launches.

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Walter F. Dabberdt, Jeremy Hales, Steven Zubrick, Andrew Crook, Witold Krajewski, J. Christopher Doran, Cynthia Mueller, Clark King, Ronald N. Keener, Robert Bornstein, David Rodenhuis, Paul Kocin, Michael A. Rossetti, Fred Sharrocks, and Ellis M. Stanley Sr.

The 10th Prospectus Development Team (PDT-10) of the U.S. Weather Research Program was charged with identifying research needs and opportunities related to the short-term prediction of weather and air quality in urban forecast zones. Weather has special and significant impacts on large numbers of the U.S. population who live in major urban areas. It is recognized that urban users have different weather information needs than do their rural counterparts. Further, large urban areas can impact local weather and hydrologic processes in various ways. The recommendations of the team emphasize that human life and well-being in urban areas can be protected and enjoyed to a significantly greater degree. In particular, PDT-10 supports the need for 1) improved access to real-time weather information, 2) improved tailoring of weather data to the specific needs of individual user groups, and 3) more user-specific forecasts of weather and air quality. Specific recommendations fall within nine thematic areas: 1) development of a user-oriented weather database; 2) focused research on the impacts of visibility and icing on transportation; 3) improved understanding and forecasting of winter storms; 4) improved understanding and forecasting of convective storms; 5) improved forecasting of intense/severe lightning; 6) further research into the impacts of large urban areas on the location and intensity of urban convection; 7) focused research on the application of mesoscale forecasting in support of emergency response and air quality; 8) quantification and reduction of uncertainty in hydrological, meteorological, and air quality modeling; and 9) the need for improved observing systems. An overarching recommendation of PDT-10 is that research into understanding and predicting weather impacts in urban areas should receive increased emphasis by the atmospheric science community at large, and that urban weather should be a focal point of the U.S. Weather Research Program.

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