A comparison of two major snowstorms that affected the southern Great Lakes region

Abstract

The southern Great Lakes region typically receives significant snowfall each winter, especially in areas subdue to lake-effect snow. Even granting residents expect heavy snow each winter, a certain quantity of winter storms can paralyze the region. This paper compares sum of two units winter storms (25-27 January 1978 and 2-4 January 1999) that significantly affected the region. Near-record amounts of snow pitiless during each event and combined with high winds, made travel impossible in many areas. The source region for one as well as the other surface cyclones was the southern Great Plains. Southerly wind roll on ahead of each system advected copious moisture into the region, setting the stage for heavy snowfall. muscular upper-level dynamics also aided in the strengthening of each combination of parts to form a whole Specifically, enhanced secondary circulations induced by dint of stronger jet stream dynamics issueed in increased vertical ascent in the 1978 storm. Enhanced upper-level dynamics, more easterly path of the surface depressed and deeper low-level circulation of the 1978 storm caused it to affect the southern Great Lakes region more sternly than the 1999 storm. This paper will discuss the evolution of each system

**********

1 Introduction

Winters are typically snowy across the southern Great Lakes region. Seasonal snowfall totals range from approximately 25 inches above central Indiana and Ohio to nearly 100 inches in the lake-effect snowbelts near Lake Michigan and Lake Erie. Occasionally, intense storm combination of parts to form a wholes move through the region and show significant single-storm total amounts of precipitation.

A powerful winter storm a whole that moved through the region during the first not many days of January 1999 resembl an earlier combination of parts to form a whole that paralyzed the region during late January 1978 the two systems were similar in that they formed in the southern Great Plains and mov north [i]or[/i] part of to the other the Ohio Valley. Rapid deepening of the one and the other low-pressure areas and plentiful low-level moisture combined to bring into view heavy snow and high winds, resulting in blizzard and near-blizzard conditions across a great quantity [i]or[/i] amount of of the region during each event

The view of this paper is to compare the dynamics of the sum of two units events. It is hoped that any similarities place may help in the forecasting of major snowstorms across this region in the future

2 Methodology

Data for the January 1978 snowstorm was derived from a variety of sources. The NOAA publication Daily Weather Maps for the period from 16 January [i]or[/i] part of to the other 5 February 1978 provided an choice overview of the event (U s Dept. of Commerce 1978a, 1978b and 1978c) The NOAA/NWS National Center for Environmental Prediction (NCEP) Grid Point Data Set: Version III was used to direct the eye at the event in more detail (University of Washington and NCAR 1996) Data for the 1999 snowstorm were downloaded from server at NCEP and the NW Central Region office, and archived at the Northern Indiana NW Forecast Office (NWSFO) for column analyses.

3. The January 1978 Event

The winter of 1977-1978 was the next to the first consecutive severe winter experienced above the eastern half of the United States. An amplified ridge-trough pattern allowed for athletic northwesterly flow over the eastern and central U (Harnack 1980) During January 1978 temperatures across the southern Great Lakes averaged 6 to 10 [degrees]F below normal (Wagner 1978b) Lake Erie and greatest in quantity of Georgian Bay were ice-covered by means of mid-January 1978 (Assel et al. 1979) Snowcover during December 1977 was near normal across the U The month of January 1978 however, make go rounded out to be one of the snowiest upon record across the mid-Atlantic States and eastern Great Lakes regions. Average snowcover for the month of January typically does not reach out much farther south than a line extending from northern Missouri to northern Pennsylvania. This area of snowcover includes the northern third of Illinois, Indiana, and Ohio. During January 1978 average snowcover for the month reach forthed as far south as northern Arkansas and Tennessee (Weisnet and Matson 1979)

Like many winter storms that affect the Great Lakes region, this a whole originated as a low-pressure area above the southern Plains. Early in the week, surface high squeezing dominated the eastern third of the nation (U s Dept. of Commerce 1978a). At 1200 UTC 22 January 1978 a 1033 hPa surface high-pressure center was located above the lower Ohio valley (Fig. 1) The corresponding ridge at 500 hPa was located above the northern High Plains (Fig. 2) The ridge mov east in rejoinder to a developing system to the west. The ridge weakened and mov to the western Great Lakes by means of 1200 UTC on 23 January 1978 This "retreating eastern ridge" is a belonging to all pattern in the formation of major Midwestern winter storms (Weber 1978)

The 500 hPa long tray over the intermountain west make deepered during the next twenty-four hours. This baroclinic combination of parts to form a whole induced an upper-level low to form above northern Utah (U. S. Dept of trade 1978b). Twenty-four hours later, at 1200 UTC 24 January 1978 the 500 hPa depressed had moved southeast over the four-comers area to northern Arizona (Fig. 3) through this time, a 1008 hPa surface low-pressure area had formed above southwestem Texas and warm moist southerly run was moving northward into the lower Mississippi Valley (Fig. 4)