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Thomas W. Schmidlin

Abstract

R. J. Leffler recently presented regression equations to estimate average monthly temperatures of Appalachian summits based on the long-term average temperatures on Mt. Washington, New Hampshire, and temperature lapse rates as a function of latitude and elevation. The data used to derive his equations came from eight summits in northern New England and from Virginia southward. Long-term average monthly temperatures are derived here from 8-14 years of data for four summit locations in New York to evaluate Leffler's equations where they have not previously been tested. The average monthly temperatures estimated by Leffler's equations for the four New York summits are generally within 0.6°C of the long-term averages and Leffler's equations may therefore be applied with reasonable accuracy in New York.

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Thomas W. Schmidlin

State minimum temperature records were set or tied in Indiana (−37.8°C) and Kentucky (−38.3°C) in January 1994, and in Illinois (−37.2°C), Iowa (−43.9°C), Minnesota (−51.1°C), and Wisconsin (−48.3°C) in February 1996. The veracity of these temperatures was examined in the context of the large-scale synoptic situation, station location and history, observer, local terrain, instrumentation, and other factors related to extreme temperatures. New state minimum temperature records for states listed above were found to be acceptable; however, a state minimum initially reported for Michigan (−46.7°C) in January 1994 was found to be unreliable and not accepted as a state record.

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Thomas W. Schmidlin

Abstract

December 1989 was the coldest December in over 100 years in the Lake Erie snowbelt of Ohio, Pennsylvania, and New York. Mean temperatures of −9°C were 7°C lower than average and extreme minima reached −30°C. Snow fell on 20 to 25 days of the month and snowfall totals of 100 to 200 cm were twice the December average. Some locations reported record snowfalls and the greatest snow depths of this century. Several segments of society were studied to assess the impacts of this severe winter weather.

The severe weather had minimal impacts on school districts. Over half (54%) of the districts had no closures due to snow but costs for snow removal increased for schools. Ski centers reported a 50% to 100% increase in revenues over December 1988 and the best December skiing in many years. Lake ports had higher operating costs and loss of shipments. Costs for snow and ice control on Interstate 90 (I-90) in the snowbelt increased at least $1326 km−1 over December 1988, but traffic flow was maintained. Person-hours spent on snow and ice control on I-90 increased 59%. An average of 111 000 kg km−1 (200 tons mile−1) of salt and grit was spread on I-90, an increase of 50 000 kg km−1 (89 tons mile−1) over December 1988. Colleges, airports, agriculture, hospitals, urban mass transit, electric utilities, and government agencies had only minor disruptions due to the severe winter weather.

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Thomas W. Schmidlin

Abstract

The water equivalent of snow on the ground (SWE) has been measured daily since 1952 at National Weather Service first-order stations whenever snow depth exceeded 5 cm (2 in). These data are used in snowmelt analyses, snow climatology, and snow load design calculations for budding codes. Problems with this measurement that may affect data quality include 1) inconsistent methods of measurement among stations and within many stations' records, 2) unrepresentative and inconsistent locations of measurement, 3) a six-hour lag between daily measurement of snow depth and SWE, and 4) numerous errors in the climatic record of extreme SWE values. These data have not been viewed critically in the literature and are not subjected to rigorous quality control at the National Climatic Data Center. Suggestions are made for improving the quality of SWE data.

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Barbara Hammer and Thomas W. Schmidlin

Abstract

Residents of homes that sustained F4 or F5 damage in the deadliest of the 3 May 1999 tornadoes were surveyed to determine their responses to the tornado warning, reasons for their responses, and relative injury rates. There were 190 people in 65 surveyed houses at the time that warnings were issued. Television was the most commonly cited source of the warning (89%), followed by a telephone call (37%), sirens (37%), and AM/FM radio (25%), and 55% received the warning from more than one source. Nearly one-half (47%) of the residents fled their homes before the tornado struck. Of those who fled, 65% went to a tornado shelter, of whom 70% ran to the shelter (median distance 30 m) and 30% drove to the shelter (median distance 4.8 km). About one-half (53%) of those who fled their homes left in a vehicle. None of those who fled their homes, by foot or by vehicle, were injured. Of those who stayed in the home, 39% sought shelter in a bathroom, 38% in a closet, 9% in a hallway, and 15% in other rooms. Reasons for not leaving included believing the storm would not strike their house, believing it was too late or too dangerous to leave, having no transportation available, or having no alternative shelter available. Thirty percent of those who remained in their homes were injured and 1% killed. The rate of serious injury was not significantly different for those in a closet (14%), hallway (20%), or bathroom (23%). Tornado preparedness and warning programs should recognize that long tornado warning lead times and street-level television coverage allow residents to make reasoned decisions to minimize risk and that those decisions may include driving out of the path of the tornado.

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Thomas W. Schmidlin and James Kosarik

A 6-day lake effect snow event produced a reported 68.9 in. (175.0 cm) of snowfall in Hambden Township, Geauga County, Ohio, during 9–14 November 1996. This exceeded the previous Ohio single-storm snowfall record of 42 in. The purpose of this research is to describe the meteorological situation that caused the record snowfall, document the site of the record snow and the methods of the measurement, describe the societal impacts of the storm, and assess the validity of the record. A persistent deep trough in the midtroposphere provided cold advection across Lake Erie into northeast Ohio. This combined with a very unstable lower atmosphere to allow deep, moist convection and a prolonged period of heavy snowfall. The observer and site were selected in 1994 for a federal study of lake effect snowfalls and the observer was a “snow spotter” for the National Weather Service office in Cleveland in November 1996. A review of snowfall data from the event indicates the reported snowfall is consistent with respect to snow depths, nearby reported snowfall, the synoptic situation, and societal impacts of the snow. The authors suggest the 68.9 in. of snowfall should be accepted as a new state record single-storm snowfall. In addition, the 76.7 in. (195 cm) of snowfall recorded at this site in November 1996 is a new monthly snowfall record for Ohio.

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Robert M. Schwartz and Thomas W. Schmidlin

Abstract

A blizzard is defined by the U.S. National Weather Service as winds over 16 m s−1 and falling or blowing snow causing visibility less than 400 m lasting for at least 3 h. Blizzard occurrence by county was tallied from Storm Data for the 41 winters from 1959/60 to 1999/2000. This revealed 438 blizzards for an annual average of 10.7, ranging from 1 blizzard in 1980/81 to 27 blizzards in 1996/97. The average area affected per blizzard was 150 492 km2 and the average number of people in affected counties was 2 462 949 per blizzard. There was a significant linear increase in the number of blizzards but no linear trend in the total area affected by blizzards or the population in affected counties during the period. Blizzards were most common in a “blizzard zone” of North Dakota, South Dakota, and western Minnesota where each county had 41 or more blizzards in these 41 winters and the annual probability of a blizzard in each county exceeded 50%. Monthly occurrence of blizzards peaked during January in most areas, but during December in the Sierra Nevada, during March in the central Great Plains, and during April in Montana. There was weak correlation between the ENSO phase and the number of blizzards, with a tendency for more blizzards during La Niña and fewer during El Niño.

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Thomas J. Ballinger, Thomas W. Schmidlin, and Daniel F. Steinhoff

Abstract

As an additional classification to Köppen’s climate classification for polar (E) climates, the Polar Marine (EM) climate was presented nearly five decades ago and is revisited in this paper. The EM climate was traced to the North Atlantic, North Pacific, and Southern Ocean and recognized as wet, cloudy, and windy, especially during winter. These areas by definition are encompassed by monthly mean air temperatures of −6.7°C (20°F) and 10°C (50°F) in the coldest and warmest months of the annual cycle, respectively. Here three global reanalyses [ECMWF Interim Re-Analysis (ERA-Interim), Climate Forecast System Reanalysis (CFSR), and Japan Meteorological Agency (JMA) 25-yr reanalysis (JRA-25)] are used to produce a modern depiction of EM climate. General agreement is found between original and new EM boundaries, for which the poleward boundary can be approximated by the winter sea ice maximum and the equatorward boundary by the warmest month SSTs. Variability of these parameters is shown to largely dictate the EM area. A downward trend in global EM areal extent for 1979–2010 (−42.4 × 109 m2 yr−1) is dominated by the negative Northern Hemisphere (NH) EM trend (−45.7 × 109 m2 yr−1), whereas the Southern Hemisphere (SH) EM areal trend is insignificant. This observed reduction in NH EM areal extent of roughly 20% over the past three decades, largely from losses at the equatorward boundaries of these biologically rich EM zones, may not be fully compensated by poleward shifts in the EM environment due to projected warming and sea ice decline in the twenty-first century.

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Gary McManus, Thomas W. Schmidlin, and Christopher A. Fiebrich

A minimum temperature of −31°F (−35°C) was recorded at Nowata, Oklahoma, on 10 February 2011. This exceeded the previous record minimum temperature for Oklahoma of −27°F (−32.8°C). The Nowata station is in the Oklahoma Mesonet network. High pressure was centered over Oklahoma on the morning of the record with clear skies, calm winds, and a fresh snow cover of 38 cm at Nowata. A State Climate Extremes Committee (SCEC) examined the record, including the siting of the station, calibration of the thermometer, and depth of snow. The SCEC voted unanimously to approve the reading as the new lowest minimum temperature record for Oklahoma.

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L. Baker Perry, Charles E. Konrad, and Thomas W. Schmidlin

Abstract

Northwest flow snow (NWFS) events are common occurrences at higher elevations and on windward slopes in the southern Appalachians. Low temperatures and considerable blowing and drifting of snow, coupled with significant spatial variability of snowfall, substantially increase societal impacts. This paper develops a synoptic classification of NWFS events in the southern Appalachians using 72-h antecedent upstream (backward) air-trajectory analyses. Hourly observations from first-order stations and daily snowfall data from cooperative observer stations are used to define snowfall events. NCEP–NCAR reanalysis data are utilized to identify NWFS events on the basis of 850-hPa northwest flow (270°–360°) at the event maturation hour. The NOAA Hybrid Single-Particle Lagrangian Integrated Trajectory tool is used to calculate 72-h backward air trajectories at the event maturation hour and composite trajectories are mapped in a geographic information systems format. Analyses of vertical soundings are coupled with NCEP–NCAR reanalysis data to determine the synoptic characteristics associated with each trajectory class. Significant variability of trajectories and synoptic patterns is evident from the analyses, resulting in four distinct backward air-trajectory classes. Trajectories with a Great Lakes connection result in higher composite mean and maximum snowfall totals along portions of the higher-elevation windward slopes when compared with other northwest trajectories, but little effect of the Great Lakes is noted at lower elevations and on leeward slopes.

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