The Squall Line and Massachusetts Tornadoes of June 9, 1953

VOL. 36, No. 3, MARCH, 1955 109

SAMUEL PENN, CHARLES PIERCE AND JAMES K. MCGUIRE U. S. Weather Bureau, Boston, Mass.

(Manuscript received April 25, 1954)

ABSTRACT Some features of the squall line situation of June 9, 1953 and accompanying tornadoes in central and eastern Massachusetts are discussed. From radarscope photographs, it is pointed out (1) that the Worcester tornado and the Franklin-Wrentham tornado each occurred in the right-rear quadrant of a squall-line thunderstorm cell, and (2) that this relative position, with an associated tail or hook in the radar echo, is similar to that of the Illinois tornado of April 9, 1953. A tentative explanation is suggested for tornado formation in this position.

INTRODUCTION storms, violent in spots, were general over New ON the afternoon of June 9, 1953, two se- England. These disturbances accompanied the vere tornadoes roared through central and passage of a prefrontal squall line which developed eastern Massachusetts, while a third struck early that afternoon as a low pressure system Exeter, N. H. In addition, a "baby twister" was moved into the New England area. On the two reported from Rollinsford, N. H., and thunder- preceding days, squall line developments in the

FIG. 1. Paths of the two Massachusetts tornadoes of June 9, 1953. Path widths exaggerated to show regions of maximum intensity. Dashed tracks indicate "skipping."

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FIG. 2. Photograph of tornado taken about 1625E 6 miles east of Worcester by Robert P. Resch, 2nd, of Westboro, Mass. Funnel estimated % mile away.

FIG. 3. Surface chart for 1330E June 7, 1953.

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FIG. 4. Surface chart for 1930E June 8, 1953.

same region of the Low generated tornadic ac- the fact that echoes from the thunderstorms as- tivity in the Great Plains, Mid-West and Great sociated with the Massachusetts tornadoes were Lakes regions. observed on radar sets operated by the Depart- In this paper, attention will be concentrated on ment of Meteorology of the Massachusetts In- the two Massachusets tornadoes whose paths are stitute of Technology, at Cambridge, Mass., un- given in FIGURE 1, and primarily on the first and der contract with the U. S. Army Signal Corps more devastating of these, the "Worcester tor- Engineering Laboratories, and by Project Lincoln nado". This storm, a photograph of which is of M.I.T. at Lexington, Mass. Through the shown in FIGURE 2, ranks among the most de- courtesy of these organizations, photographs of structive storms of its type on record for the radar echoes obtained on the afternoon of June 9 United States. The other Massachusetts tornado, were made available. It is proposed, then, to the so-called Franklin-Wrentham storm, was some- point out some of the features of the tornado situa- what less intense but still of major magnitude. tion on that date as revealed by a study of the Considerable information on both of these was synoptic background, the squall-line activity, and collected at the New England Climatological Sec- the radar scope photographs. tion Center of the U. S. Weather Bureau. In par- ticular, it was possible to construct detailed maps SYNOPTIC BACKGROUND of the paths of the tornadoes and to obtain a num- As is often the case, large-scale surface analysis ber of reliable time-checks on their movement. yielded few clues as to the mechanism of either the The value of such information is enhanced by squall line or the associated tornadoes. The fol-

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FIG. 5. Surface chart for 1330E June 9, 1953. lowing brief description gives the main sequence the first of the day's tornadoes occurred only five of events leading up to the disastrous Massachu- hours afterwards, and a squall line associated setts storms. with tornado activity is a feature of the 1930E The 1930E map of June 6 showed a Pacific map (FIG. 4). The widespread nature of this ac- front moving into the Rockies, whose northern tivity, however, suggests that more than one portion was occupied by a broad area of low squall line was involved, a conclusion which may pressure. On the morning of June 7, as the Pa- also be drawn from a synoptic study of the situa- cific front crossed over to the eastern side of the tion earlier on June 8. range, a well-defined Low formed in Eastern This same feature—violent activity following Colorado. That afternoon, tornadoes broke out quickly from a relatively quiescent situation—was in northeastern Colorado, western Nebraska and repeated on June 9. The night of the 8-9th and Iowa, some of these occurring in the vicinity of the morning of the 9th showed little or nothing in the pre-cold-frontal squall line which appears on the way of squall line weather as the system passed the 1330E map (FIG. 3) of June 7. During the over Pennsylvania and New York. On the early late afternoon and evening of the following day, afternoon of the 9th, however, squall line activity with the regeneration of squall line activity, south- developed afresh in west-central New England. eastern Michigan and northwestern Ohio experi- Violent hailstorms broke out in the northwestern enced widespread tornadic activity. The 1330E Massachusetts-southeastern Vermont-southwestern map of June 8 showed practically no showers or New Hampshire border region. Fanning out from thunderstorms in advance of the cold front, though this center, hailstorms developed during the course

Unauthenticated | Downloaded 10/08/21 09:01 PM UTC VOL. 36, No. 3, MARCH, 1955 113 of the afternoon in two bands along the squall line. the property losses were caused by the first tor- One hail track extended eastward to the New nado, mainly in and around Worcester. Here the Hampshire coast, while the other led southeast- twister attained its greatest intensity and its maxi- ward across Massachusetts to Cape Cod. It is mum width, almost one mile. worth noting that the tornadoes occurred on the The 1330E, 1630E and 1930E sectional surface same segments of the squall line that produced maps of the 9th, given in FIGURES 5-7, delineate these hailstorms. the progress of the squall line across New Eng- The first tornado struck in Petersham, Mass., land. The first of these charts coincides closely shortly before 1525E and moved forty-six miles, with the outbreak of the hailstorms. The second as shown in FIGURE 1, to its point of dissolution map is near the time of the ending of the Wor- in Southborough about 1645E. The second cester tornado, the occurrence of the Exeter struck Exeter, N. H., around 1620E, while the twister, and the beginning of the second Massa- third (see FIG. 1) travelled a twenty-nine-mile chusetts tornado. The 1930E chart represents path, starting in Sutton, Mass., about 1630E and conditions after the tornadic activity had ended ending in Mansfield at 1737E. These three and the squall line, in other respects still vigorous, storms combined to take ninety lives, inflict over had swept east of New England except for Cape 400 major and close to 900 minor injuries, and Cod and northeastern Maine. Over Cape Cod destroy an estimated $60,000,000 in property. All that evening there was a magnificent display of the fatalities, most of the injuries, and the bulk of vivid, continuous lightning for nearly three hours.

FIG. 6. Surface chart for 1630E June 9, 1953.

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FIG. 7. Surface chart for 1930E June 9, 1953.

FIG. 8. 850-mb chart for 1030E June 7, 1953. FIG. 9. 850-mb chart for 1030E June 8, 1953.

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FIG. 10. 850-mb chart for 1030E June 9, 1953.

THE SQUALL LINE The synoptic parameter most closely associated FIG. 11. Plotted raob sounding for Mt. Clemens, Mich., with the squall line in this case was warm-air 1030E June 7 and 8, 1953. advection in the lowest layers of the atmosphere. This statement is not meant to offer the advection as a mechanism for the squall line, but to point out its importance as a means of affecting the thermal stratification of the air in advance of the cold front. Several investigators have called attention to relationships between squall lines and various types of advection. Newton [1] mentions that a warm tongue at 850 mb is very often found in advance of a pre-colcl-frontal squall line, and states that the squall line will dissipate upon reaching the axis of the warm tongue. According to Crawford [2] and MacDonald [3], a squall line develops along the axis of an 850-mb warm tongue, in conjunction with certain features of 700-mb cold-air advection. In the case under examination, the squall line on June 7th lay immediately to the west of the 850-mb warm tongue. The squall lines that developed on the next two days appeared in the same relative position. FIGURES 8-10 give the 850-mb charts for June 7, 8 and 9; FIGURE 11 contains the Mount Clemens, Mich., raobs for the 7th and 8th; FIGURE 12 shows the Portland, Me., and FIGURE 13 the Hempstead, N. Y., raobs for the 8th and 9th. These clearly indicate the effect FIG. 12. Plotted raob soundings for Portland, Me., for of warm-air advection below approximately 10,- 1030E June 8 and 9, 1953.

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June 9).* Thus there was an almost spontaneous build-up of cumulus clouds to very high levels, to at least 50,000 feet. M.I.T. radar observations actually showed build-ups reaching above this height over Massachusetts on the afternoon of the 9th. The hodographs for Mount Clemens at 1000E of the 8th (FIG. 14) and for Hempstead at the same hour on the 9th (FIG. 15) confirm the presence of low-level advection of warm air. Ad- vective cooling is shown at Mount Clemens in the layer from 10,000 to 14,000 feet, but such cooling must have been short-lived or counteracted since the same layer had a slightly higher temperature twelve hours later. Similarly, the Hempstead hodograph indicates slight cooling from 10,000 to 18,000 feet.

FIG. 13. Plotted raob soundings for Hempstead, N. Y., for 1030E June 8 and 9, 1953.

000 feet. The steep lapse rates of the upper and middle troposphere have been extended surface- ward up to the time of the soundings (1000E). Further lowering undoubtedly continued up to the afternoon tornado occurrences. The inversion cap was apparently eliminated during the afternoon as surface temperatures reached the middle FIG. 15. Hodograph for Hempstead, N. Y., for 1030E 80's (see FIG. 13, Hempstead raob for 1030E of June 9, 1953.

In summary, the squall-line activity appears to have been intimately linked with the 850-mb warm tongue. Clear-cut evidence for or against other relationships was not found in this case, although the upper-level cooling, while slight, may have been significant to tornado formation.

THE RADARSCOPE PHOTOGRAPHS As mentioned in the introduction, the squall line thunderstorms over Massachusetts on the afternoon of June 9 were detected by radar sets at M.I.T. (Cambridge) and Project Lincoln in Lexington. It has thus been possible to study the associated tornadoes with the aid of the best observational tool available for spotting such local- ized storms and tracking their movements. FIG. 14. Hodograph for Mt. Clemens, Mich., for 1030E June 8, 1953. * Boston's maximum on the 9th was 85°.

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FIG. 16. Radar PPI-scope picture taken at 1527E by Radar Research Laboratory, Department of Meteorology, M.I.T.

The position of a tornado funnel with reference twister are, with rare exceptions, too busy seek- to a parent cloud mass has never been satisfactorily ing shelter to make the necessary observations, established. People along or near the path of a and even a meteorologist who happens to witness

FIG. 17. Radar picture taken at 1535E June 9, 1953 by Radar Research Laboratory.

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FIG. 18. Radar picture taken at 1553E by Radar Research Laboratory. a funnel cloud is handicapped in drawing pertinent This year, meteorological knowledge of the conclusions because his radius of observation is so position of tornado funnels relative to the ac- limited that he does not see the entire surrounding companying thunderstorm cells has been increased picture. by the spotting on radar screens of echoes linked

FIG. 19. Radar picture taken at 1557E by Radar Research Laboratory.

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FIG. 20. Radar picture taken at 1650E by Radar Research Laboratory. with tornado activity in at least four separate The M.I.T. 10-cm radar set, located on the situations. The first of these consists of the ob- campus at Cambridge, Mass., was inoperative dur- servations made in central Illinois on April 9, 1953 ing the final stages of the Worcester tornado. by the radar weather unit of the Illinois State Good radarscope photographs, however, were ob- Water Survey. The second and third of these tained of the echoes associated with its early his- occurred in Texas in the Spring of 1953, and tory. Photographs of the echoes accompanying have been reported on by J. C. Freeman, Jr., in the other Massachusetts tornado, the Franklin- November 1953 at the Austin, Texas, meeting of Wrentham storm, were also made but did not prove the American Meteorological Society. The fourth as clear as in the case of the earlier one. The tornado situation detected by radar will be de- scribed here.

FIG. 22. Radar picture taken at 1556E by Project Lin- FIG. 21. Radar picture taken at 1555E June 9, 1953, by coln ; 40-mile range with 10-mile range photo superim- Project Lincoln of M.I.T.; 40-mile range. posed (double exposure).

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radar site. The axis of this cell lies 100°-280°, though it has a neck connecting it with a smaller cell adjoining to the north. Subsequent photographs revealed that this neck became increasingly diffuse and eventually disappeared. The motion of the large cell was from about 290°, though the cells in the northern portion of the line of echoes moved from 270°. At the time of this photograph, the first or Worcester tornado was over Petersham, Mass., bearing 278°, distance 53 miles from M.I.T. in Cambridge. Facing in the direction of movement

FIG. 23. Radar picture taken at 1558E by Project Lincoln.

Project Lincoln radar secured excellent photographs of the Worcester storm. Geological Survey charts of the tornado-stricken areas in Massachusetts were used to prepare a detailed track for both tornadoes. Field surveys, interviews with eye witness, and reports from town officials provided reliable positions and time- checks during the course of each storm. It was thus possible to examine the various radarscope photographs for features indicating the associated tornado activity. FIGURE 16 shows the M.I.T. radar picture for 1527E. (Clock in all radar pictures indicates Eastern Daylight Time; range markers are for 20-mile intervals in M.I.T. set.) An organized line of individual echoes extends northeast-southwest in the northwestern quadrant of the scope. Close to the southern end of this line a large echo may be identified at 282° about 50 miles from the

FIG. 25. Vertical cross section through mature thunderstorm cell after the illustration taken from the report by the thunderstorm project.

of the cell just discussed, this position puts the surface location of the funnel on the edge of the echo in the right rear quadrant of the thunderstorm. Such a position agrees with that found in the Illinois case. At 1535E (see FIG. 17) the tornado was situated fifty miles from Cambridge, bearing 276°, which places it in the right rear edge of the large echo where a diffuse tail appears. After 1535E, a break in the M.I.T. radarscope sequence occurred. At 1553E, however, the time of FIGURE 18, the tornado's relative position re- FIG. 24. Radar picture taken at 1601E by Project Lin- mains very much the same. This is also the case coln; multiple exposure (10 scans). at 1557E (see FIG. 19), when the last good radar-

Unauthenticated | Downloaded 10/08/21 09:01 PM UTC VOL. 36, No. 3, MARCH, 1955 121 scope photograph of the Worcester tornado was with severe thunderstorms, and a partial and ten- taken at M.I.T. The tornado's surface position tative explanation suggests itself from a considera- continues to be on the right-rear edge of the large tion of the horizontal wind shear near the base and echo. sides of a thunderstorm cell. Downdrafts pre- Though the M.I.T. sequence ends at this time, dominate in this region in the cell's mature state; with reference to the Worcester storm, later as the downdrafts strike the surface their vertical photographs were taken of echoes associated with motion is transformed into the horizontal. Hence the second Massachusetts tornado. In FIGURE 19, a gusty surface current is established, representing it will be noted that a rather large and elongated an outflow of air from all sides of the thunder- cell is located southwest of the one that has hith- storm. While most of the deflection from vertical erto been followed. This southwestern echo, com- to horizontal motion occurs near the surface, the pared to earlier photographs, has shown an in- outward deflection of the downdraft is likely to crease along its main axis, whereas the cells in the start somewhat higher, near the cloud base, in the northern portion of the squall line have shown manner suggested in FIGURE 25. At the south- no development. The Franklin-Wrentham tornado formed along the southwestern edge of this developing cell. At 1650E (see FIG. 20) its surface position was 237° and 30 miles from M.I.T. This position is associated with a tail seen at the right-rear end of the echo, so that there is a common feature between the location of this tornado and the earlier one. This point—the presence of a hook on the echo associated with tornado activity—is confirmed very clearly by the radarscope photographs taken by Project Lincoln at Lincoln, Mass. Four of these are shown in FIGURES 21-24. The first picture was taken at 1555E, the second one minute later, the third three minutes later, and the fourth at 160IE. They show the echoes associated with the first or Worcester tornado, which during this six-minute interval was moving through Holden. Very striking is the ring of precipitataion located at the right rear side of the thunderstorm cell, in FIG. 26. Horizontal cross section near base of mature the same relative position as the hook in the thunderstorm cell showing shear resulting from down- M.I.T. photos. Though rather diffuse on its for- draft effect. ward side, the ring shows up in all of the four photographs and shows the full form of the hook or tail noted on the M.I.T. series. Ground checks western edge of the cell, this outflow would result placed the tornado on the hook shown in FIGURES in some loss in the westerly component of the 21-24. There is a close similarity between these horizontal wind, thereby establishing a region of radarscope pictures and those taken of the Illinois cyclonic shear between air emerging from the tornado of April 9, 1953 [4], especially with re- thunderstorm and that surrounding it, as shown gard to the position of the tornado in the right in FIGURE 26. By analogous reasoning the shear rear quadrant of the thunderstorm. would also be cyclonic in the northeast edge and An important question therefore arises, namely, anticyclonic at the southeastern and northwestern how to explain the location of the cyclonic vortices edges in FIGURE 26. in the position, relative to the parent cells, shown It might thus be argued that a region located on the radar photographs? on the edge of the rear right-hand or left-front Obviously, a satisfactory answer must await the quadrant of a thunderstorm offers the most favor- accumulation of additional observational evidence able opportunity for the initiation of a cyclonically- and a better understanding of the tornado mecha- rotating tornado circulation. At any rate, the fact nism. Tornadoes usually occur in connection that both the Massachusetts storms of June 9th

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were located in the right-rear position offers a REFERENCES clue which may prove significant to the problem [1] Newton, C. W., 1950: "Structure and Mechanism of of tornado formation. the Prefrontal Squall Line," Journal of Meteor- ology, Vol. 7, No. 3. [2] Crawford, M. E., 1950: "A Synoptic Study of Squall ACKNOWLEDGMENTS Lines," Bulletin of the American Meteorological Society, Vol. 31, No. 10. The authors wish to express their appreciation [3] MacDonald, J. D., 1952: "On the Formation of of the cooperation received from the U. S. Army Squall Lines," Bulletin of the American Meteoro- Signal Corps Engineering Laboratories, Project logical Society, Vol. 33, No. 6. [4] Stout, G. E., and Huff, F. A., 1953: "Radar Records Lincoln, and the members of the Radar-meteorol- Illinois Tornadogenesis," Bulletin of the American ogy group at M.I.T. Meteorological Society, Vol. 34, No. 6.

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