…The greatest rainfall in Pennsylvania during the century played its part [in the Flood] also. The records of the Franklin Institute and the United States Signal Service give the astounding record of the amounts of this rain and the area of greatest saturation. An unusual fall of rain was a feature of the last seven months of 1889. Beginning in May, heavy storms frequently passed over the state. Local rains and annoying drizzles were very frequent.
The Great Flood disrupted the collection of complete weather statistics for the year at Johnstown but local and unofficial diarists of the weather kept a fairly accurate account. George Spangler, night watchman of the First National Bank, recorded 110 days of rain and 26 days of snow for the year….1 C. C. Blough, another weather recorder, counted 168 days of precipitation for the entire year; and 132 days of rain from May 1 to December 31, 1889. Blough also claimed that 68-1/4 inches of rain fell in Johnstown in 1889.2 Spangler reported eleven days of rain in May. For the whole state of Pennsylvania, June had twenty-seven wet days.3
Following the heavy rains of May and June, the end of the year was a period of abnormal rainfall also. The Johnstown Tribune reported only three days without moisture for the period from November 1 to December 14.4 The spring waters around Johnstown were greatly augmented by a fourteen-inch snow on April 6 which melted almost immediately. Following this date, April had eight more days of rain during the month. May had eleven days of rain;5 one of which was a fall in excess of six inches. While the … average rainfall for the first six months was seventeen inches for the whole state, a total of twenty-one inches fell in the period,–four inches above average.6
…The Signal Service’s Monthly Weather Review devoted a separate article to the great storm at the end of May.9 The Report of the Secretary of Internal Affairs not only contained a separate article on the storm but also a carefully drawn map … with the figures for precipitation over the whole state. The duration of the storm at some stations was thirty-six hours.10
The great storm had its origin on the California coast on May 26.11 From the Pacific to the Atlantic seaboard, heavy rains accompanied the disturbance…. The storm had general characteristics which made it unusual for such an extensive change of weather. The storm moved at an unusually slow pace, and at a regular speed. High temperatures were shown in some areas; while low temperatures from frost to snow prevailed in others. Local storms in this vast cyclonic movement were unusually violent. Saturation was dense and rainfall enormous.
A pressure area over the Atlantic Ocean turned the winds to a south-to-east direction although they usually moved from south to west. The changed direction of the ocean winds, coupled with the normal west-to-east movement of the storm current, forced the winds with their huge rainfall into a comparatively small area over the crest of the Alleghenies,12 –three low pressure areas from the west, southwest, and southeast “met in a dire embrace upon the summits of the Allegheny mountains.”13 …
The Tribune on May 29 reported the barometric pressure at thirty, a temperature from forty-six to sixty-five, and humidity at sixty-nine percent. Since the following day, Thursday, May 30, would be Memorial Day and no paper would be published, the weather forecasts for the remainder of the month was also given in the Wednesday issue:
A Storm of considerable energy has developed in Southwestern Texas, which is now centered in the Mississippi Valley, moving northeastward. General rain has fallen within the track of the storm. Elsewhere fair weather has prevailed. The temperature is unusually low throughout the lake region, heavy frost having occurred in many places and light frosts are also reported from the county districts in this locality, with no perceptible damage, however. The temperature has risen slightly in all other districts. The barometer has fallen decidedly in the Mississippi Valley with manifestations of cyclonic disturbances, and is highest in the extreme Northwest.
Indications for Thursday: Threatening weather and rain, with conditions favorable for thunderstorms during the latter part of Thursday and Friday, slightly warmer.16
The heavy clouds in most localities held their rain until the services for Memorial Day had been completed. A territory from New Jersey to central West Virginia was the earliest areas to receive the rain, where it began at 1 a.m. May 30. By 3 p.m., northern West Virginia and a corner of Pennsylvania was under the storm. Four hours later, New York and Virginia had rain. At 11 p.m., the state of Pennsylvania was covered by the steady downpour from the storm.17
The great storm in Pennsylvania exhibited the local variations which made it memorable in all parts of the state. Although rain covered the whole state, a smaller area of about 12,000 square miles received the greatest burden of the storm. The densest rain extended over a territory from Harrisburg to Johnstown and from McConnellsburg to Tioga. Pittsburgh, 70 miles from Johnstown had only 1-1/2 inches of rain.18 Grampian Hills, less than 100 miles from Pittsburgh, had 8.6 inches of water in two days.
The magnitude of both the storm and Flood of 1889 can best be shown by describing the condition of the streams of Pennsylvania which were forced to carry the huge load of the storm. East of the Alleghenies, the Susquehanna was the principal stream draining from the continental divide. On the western side, the Allegheny and the Youghiogheny branch of the Monongahela drew off the water from the hills. In the highlands, the Juniata on the east and the Conemaugh on the west rose highest in the mountains and coursed through the narrowest ravines. In many of these streams, a three-inch rainfall would produce a flood. A six to eight-inch rain would produce the greatest flood that the state had ever known. The flood marks of 1786 and 1865 were surpassed in 1889; buildings built above the water lines were swept away by the surging [sic]…
…The destruction of bridges greatly impeded recovery from the flooding. From Renovo to Harrisburg, six large bridges were swept away while eight more were damaged. Six miles of railroad track was displaced; three miles of roadbed washed out; twenty-seven miles of telegraph lines destroyed. From Renovo to Clearfield, nine bridges were destroyed; six miles of roadbed washed out; fifteen miles of track overturned. On the Juniata, ten bridges were lost and four destroyed from Duncannon to Tyrone. With the storm causing damage in twenty-five counties in the state, innumerable county bridges and culverts were also torn loose.24
After the flood had passed its peak, the receding waters left a harrowing record of rain. Destroyed railroad track, bridges, and telegraph lines, accentuated the flood’s destruction. From the mouth of the Susquehanna, northward and westward, every tributary to the great river had created a trail of ruin and desolation. Reservoirs had been broken; wells and cisterns fouled with refuse and flood water. Streets were littered with wreckage and covered with slime. Floors and walls of homes and other buildings were covered with mud. Cellars stayed filled with water until they were pumped out. Dead animals, garbage, offal, and rubbish impeded the rich and poor alike as they wandered through the damp, reeking towns.
When communication lines had been patched for emergency service, the state and federal weather reporters sent their reports. Then the strength of the storm appeared through the measurements of rainfall at stations for the Susquehanna River system.
| City, County | Inches of rain | Hours of rain |
|---|---|---|
| Grampian Hills, Clearfield County | 8.6 inches | 48 hours (6 inches fell in just 7 hours) |
| Williamsport, Lycoming County | No measurements taken | 32 hours |
| Wellsboro, Tioga County | 9.8 inches | 31 hours (7.45 inches fell on June 1) |
| Harrisburg, Dauphin County | 8.2 | 34 hours |
| Altoona, Blair County | 5.33 inches | 30 hours |
| Huntingdon, Huntingdon County | 7.50 inches | 34 hours |
Table created from figures given in text
[Combining] … the United States Signal Service records with those of the Pennsylvania weather service showed the severity of the storm within a radius of fifty miles of the South Fork Dam. [Imagine South Fork at the intersection of the four sections on the following graph.]
|
NW 2.47 inches average Johnstown to Saltsburg to Indiana; but no records available for Johnstown after 10:44 a.m., May 31. |
NE
5.47 inches average Grampian Hill to Blue Knob |
|
SW 3.06 inches average Somerset to Greensburg |
SE
7.81 inches average Fulton and Bedford Counties |
Table created from figures given in text
The Signal Service recorded an average rainfall of six to eight inches for 24 hours. An eight-inch rainfall on the 12,000 square miles of densest storm put 5,760,000,000 tons of water on this surface. The 5,760,000,000 tons of water had to be carried off the 12,000 square miles by mountain streams which, in many places, ran through narrow valleys.25 …
…In the Conemaugh Valley the great storm began shortly after 4 p.m., May 30. The week previous to the Great Flood had brought five days of rain to the valley.26 The ground was saturated with moisture. The spring foliage had doubled its growth as a result of the showers. …
Excerpt from Nathan Daniel Shappee, History of Johnstown, Unpublished doctoral dissertation, University of Pittsburgh, 1940. Pages 232-242.
