According to Verneil Simmons, if Jesus died on the cross at midafternoon in Jerusalem, as recorded in the Gospels, and we allow for the eight [or nine] hours difference in time for this hemisphere (see illustration), the hour of his death would have been 7:00 a.m. [or 6:00 a.m.] in Zarahemla. Samuel had said the darkness would last from the moment of His death until He arose three days later. This would require darkness for all of Thursday, Friday, and Saturday, with light returning on Sunday morning. [Verneil W. Simmons, Peoples, Places and Prophecies, p. 205]
Helaman 14:20 From the time that he shall suffer death, for the space of three days, to the time he shall rise again from the dead (Illustration): The map below shows the time zones of the world as measured form the prime meridian at Greenwich, England. [Golden Press, The Golden Home and High School Encyclopedia, Vol. 18, p. 2560]
“There Shall Be No Light for the Space of Three Days”
According to Glen A. Ricks, Dr. Bruce Warren's articles in the Archaeological Digest (Volume II, issues II and III) and Dr. John Pratt's articles from the June/July 1985 Ensign present a convincing rationale in favor of the Friday Crucifixion. However, the possibility that the Savior was crucified on Thursday might be deduced from the Book of Mormon verses describing the relationship between the death and resurrection (which occurred on Sunday).
In Helaman 14:4 Samuel is explaining the sign that will be given at the Savior's birth, wherein he says the light "shall be one day and a night and a day, as if it were one day and there were no night." I interpret this to mean that Samuel defined the terms "day" and "night" like we use them today--"day" is a period of light and "night" is the period of darkness. In other words, Samuel did not interpret the term "day" like the Jews wherein a few hours could describe a 24-hour period of light and dark.
In Helaman 14:21 we find that Samuel says, "at the time that he shall yield up the ghost there shall be thunderings and lightnings," which can be interpreted to mean that the beginning of the great storm will coincide with the Savior's death. Helaman 14:20 supports this by saying that "in that day that he shall suffer death the sun shall be darkened and refuse to give his light unto you." But the key point is the last part of verse 20 wherein it states that "there shall be no light upon the face of this land, even from the time that he shall suffer death, for the space of three days, to the time that he shall rise again from the dead." I believe this means that there were three periods of daylight (defined as "days" to the Nephites) that were darkened, and they coincided with the time that the Savior was in the grave.
The time difference between Central America and Jerusalem is about 8 hours, and when the Savior died at about 3:00 p.m. in Jerusalem it was about 7:00 a.m. in Central America (the same day of the week). Thus the Nephites may have started to see the first light of the sky in the east when the great storm commenced. When the Savior arose early on Easter Sunday "while it was yet dark," it would have been Saturday evening in Central America. Thus the volcanic clouds and CO2 could have dissipated Saturday night, allowing them to finally light their fires and observe the dawn Sunday morning. A Thursday death allows Thursday, Friday, and Saturday to be the three days (periods of light) darkened as prophesied by Samuel. I cannot figure a way to make a Friday death satisfy Samuel's criteria of three days darkness if a "day" means the period that should have light and there was light in America on Sunday.
Another point not expanded upon by Drs. Warren and Pratt is John 19:31:
The Jews therefore, because it was the preparation, that the bodies should not remain upon the cross on the sabbath day, (for that sabbath day was an high day) besought Pilate that their legs might be broken, and that they might be taken away.
It appears that the Brethren who reviewed and approved the LDS edition footnotes also favored the Thursday death date, as evidenced by footnote 31c :
Cp. Lev. 23:7; Ex. 12:16; Mark 15:42. Jesus arose on the first day of the week. The previous day was the weekly Sabbath. The day before the Sabbath, being also the day after the Passover meal, could be the 'high' day. (although it is noted that a key word is "could.")
One last trivial point to pursue. I have always understood the Savior's triumphal entry to be on Sunday (the day after the Sabbath or "Palm Sunday"). The texts that support a Friday crucifixion are at a loss for Wednesday's activities, supposing that the Savior was "in seclusion in Bethany" or some other place. A Thursday death also allows documented activities for all of the days of the Savior's last week. (It is noted that Dr. Pratt lists the triumphal entry on Monday, which fills the entire week's activities and supports the Friday death date. Also, a day of solitude is not an unreasonable activity for the last week of the Savior's life.) [Glen A. Ricks, "One More Look at Dates," in The Book of Mormon Archaeological Digest, Volume II Issue IV, 1999, pp. 8-9, 13]