Bulletin of the American Meteorological Society/Volume 27/Issue 8/The Tornado at Montgomery, Alabama, February 12, 1945

by Floyd C. Pate

The Tornado at Montgomery, Alabama, February 12, 1945

F. C. Pate

U. S. Weather Bureau, Montgomery, Ala.

A tornado, perhaps the most officially observed one in history, passed one half mile northwest of the Montgomery Weather Bureau Office at 4:22 P.M., Central Standard Time, on February 12, 1945. During the afternoon, six other tornadoes were reported in middle Alabama from Mississippi to Georgia. They were all warm-sector storms which occurred at such random times as to exclude any apparent likelihood of direct connection or association with any kind of single front. Their distribution is shown in Figure 2. The Montgomery storm was within sight of four government weather observing stations, with no one of them more than two miles from the path of the storm. Figure 1 gives the location of these stations with respect to the path, which was 13 miles long.

Figure 1.

The width of the path of the Montgomery tornado was uniformly about 100 yards except that it momentarily spread out to about 350 yards as it struck the high bank of the river northeast of the Union Station, where the force was much weakened. The bottom regained full energy and destructive force crossing the open field about a mile beyond, and was 100 yards wide from there on. There was also previously a very brief weakening at the surface as it moved across the Army Reconsignment Depot, between the Weather Bureau Airport Station at Dannelly Field and Maxwell Field. It plowed deeply at first, but became less severe as the last of the closely spaced warehouses were passed. Destruction along the path was typical of any fully developed tornado, and amounted to about $1,700,000. Twenty-six persons were killed.

Figure 2.

The speed of the storm determined by Maxwell Field radar, was 49 miles per hour, and the elevation of the top of the clouds associated with it was 28,000 feet. The funnel spout from the ground to where it spread out was estimated 4,000 feet high by the angle subtended to the eye when it was about two miles away. This estimation had to be made after allowing for the roll collar of cloud surrounding the tornado.

When first seen from the roof of the Post Office building in which the Weather Bureau Office is located, the storm was approaching and was about two miles away. A collar of roll cloud around the sharply defined rotating column reached to within four or five hundred feet of the ground, with shreds of it not over one or two hundred feet above the ground, but as the storm passed two minutes later, it reached the surface. Large pieces of debris and miscellaneous building materials emerged from the roll cloud immediately ahead of the cyclone at heights of two or three hundred feet. When the storm was first seen, WSW of the Weather Bureau Airport Station, where it was seven miles away from the City Office, the roll collar had not formed, and the entire tornado was visible. The whirling column tapered from the cloud to the ground and did not appear appreciably bent by wind shear aloft, but there was a slight lag at the ground. As the storm was last seen near the horizon in the northeast, the collar appeared to have lifted faster than the whirl, which at that stage had left the ground.

A rather light thunder shower occurred from 3:33 P.M. to 4:10 P.M., with the thunder near and east of the station, before the tornado passed a 4:22 P.M. Twenty-one minutes after the tornado passed, a shower began again, and thunder was heard near by at 4:45 P.M. The last shower ended at 5:30 P.M. Rainfall during the two showers was 0.03 inch and 0.23 inch, respectively. No thunder or precipitation accompanied the immediate passage of the tornado, but as it receded on the horizon toward the northeast, a rain shower could be seen falling over a small area to its right and rear so that the right side of the funnel was obscured. Lifting of the core began soon after precipitation began falling from the storm cloud.

At Gunter Field, 0.20 inch of rain fell in showers between 3:57 P.M. and 5:47 P.M. Showers were recorded from 3:24 P.M. to 6:09 P.M. at the Weather Bureau Airport Station. One shower at the station was briefly heavy at 4:55 P.M. The amount of rain at the Weather Bureau Airport Station during the afternoon was 0.31 inch.

During the warm part of the afternoon, many rather small-scale scattered convective showers and thunderstorms could be seen in different directions in the distance, and in the early part of the night distant lightning was seen in numerous directions. Except in two showers mentioned above, no other precipitation occurred at the station between the time the warm front passed at 12:15 P.M. and the time of beginning of pre-cold front rain at 1:25 A.M. on the 13th.

The sky was broken, becoming overcast shortly before the tornado occurred. The predominating cloud type during the afternoon was fast moving altostratus-like sheets which spread out from the passing showers and were variable in height, so that the showers appeared to be sagging areas in these clouds. Only small amounts of lower clouds were underneath, and they were formless and did not choose any particular level. Soon after sundown, the shower clouds gradually lifted to form what appeared to be rather high common layer similar to the overcast left after summer thunderstorm. This layer of clouds disappeared by 8:30 P.M. The directions of the clouds depended on the heights as shown by the wind directions in Figure 3.

The wind was from the southeast during the afternoon, and gradually became southerly by 4:00 P.M. It continued from that direction until near midnight, except when briefly deflected and accelerated as parts of the circular wind when the tornado passed.

Except from the momentary dip of 0.04 to 0.06 inch accompanying the tornado passage at each of the four stations in the vicinity, the barograph tendency during the afternoon was slowly downward, with the variations or irregularities that usually accom

Fig. 3. Wind, temperature and moisture conditions aloft accompanying tornado passing Montgomery, Alabama, at 4:22 P.M. CST, February 12, 1945.

pany showers and thunderstorms, and there was no change in trend after the tornado had passed.

Figure 3 gives all the available local information from soundings aloft. The rawin data for 3:00 P.M. and 9:00 P.M. and local observations on the ground indicated little change in the rather simple general airmass structure in the interim. The only raob available in approximately the same air mass was Lake Charles at 9:00 A.M. The data from this sounding are plotted in this diagram to give some idea of the starting point for the modifications during the day brought about by the wind system and diurnal changes.

Although Montgomery was in the line of flow of air at high levels only from the direction of Lake Charles, surface temperature and moisture conditions on the coast in the line of flow from the south were similar to the surface conditions at Lake Charles. The surface dew-point at Montgomery at the time of the tornado was the same as given in the Lake Charles morning raob. The surface temperate at the time of the storm was 23°C, and an ascent curve for a surface heated parcel (dry up to saturation point, wet above) was drawn on the diagram for that surface temperature and dew point.

The speed of movement of the tornado was the same as that of the wind between 3,000 feet and 5,000 feet, while its direction was the same as that of the wind at an altitude of about 13,000 feet.

From Figure 3, it is seen that the freezing level was at about 14,000 feet. There was no hail reported anywhere, however. Notice the estimated height (4000 ft) of the tornado plotted on this diagram.