Mormon History, Jun 3, 1847. Thursday.

[William Clayton Journal] The morning cold with strong S.E. wind. The first division commenced ferrying over the river at 5 o'clock and took a wagon over every fifteen minutes. After breakfast I went over and wrote a letter for Elder Kimball to James Brown at Pueblo, then walked up to a high bluff on the N.W. to view the country, but not being able to see far from it I went to another over a mile farther N.W. Although this last was very high I could see nothing but a succession of high ranges of bluffs as far as I could see, except the narrow space through which the river winds its course. Seeing some heavy thunder clouds rising very rapidly from the N.W. I returned to camp and arrived just before the rain commenced. Elders A[masa] Lyman, Thomas Woolsey, John H. Tippets and Roswell Stevens started at 1/4 past 11 on horses and mules for Pueblo. President Young, Kimball, Richards and Pratt accompanied them to the Laramie Fork, and then held a council, kneeled down and dedicated them to God and blessed them. The four then forded the river and went on their journey, the others returned to Camp. At half past 1 it commenced raining heavy accompanied with hail, lightning and very loud thunder, which lasted till half past 3 o'clock. During the storm the horses were mostly secured in the old Fort. The ferrying ceased till it was fair again, and about 5 the first division were all over. The boat was then manned by the second division John S. Higbee Captain. They averaged a wagon across in 11 minutes 10 minutes and one in 10 minutes 20 secs. The quickest trip made by the first division was 13 minutes. About 7 o'clock it commenced raining again from the S.E. and rained heavy, consequently the brethren quit ferrying, leaving 3 companies of about 15 wagons on the other side. All the wagons would have been got over today if it had not been stormy.
There is a report come in that there are 2,000 wagons on the road to Oregon but a little distance behind, but we are satisfied the report is magnified. There are 18 wagons camped about 3 miles below and one of the men who has come to the fort says that they have counted over 500 wagons. They have lost 4 horses by the Caw Indians . . .

[source: George D. Smith, An Intimate Chronicle; The Journals of William Clayton, Signature Books in association with Smith Research Associates, Salt Lake City, 1995, http://amzn.to/william-clayton]