What would be considered a prophecy alert? I consider a prophecy alert, anything that would pertain to the scripture Matthew 24: 3-12
3 And as he sat upon the mount of Olives, the disciples came unto him privately, saying, Tell us, when shall these things be? and what shall be the sign of thy coming, and of the end of the world?
4 And Jesus answered and said unto them, Take heed that no man deceive you.
5 For many shall come in my name, saying, I am Christ; and shall deceive many.
6 And ye shall hear of wars and rumours of wars: see that ye be not troubled: for all these things must come to pass, but the end is not yet.
7 For nation shall rise against nation, and kingdom against kingdom: and there shall be famines, and pestilences, and earthquakes, in divers places.
8 All these are the beginning of sorrows.
9 Then shall they deliver you up to be afflicted, and shall kill you: and ye shall be hated of all nations for my name's sake.
10 And then shall many be offended, and shall betray one another, and shall hate one another.
11 And many false prophets shall rise, and shall deceive many.
12 And because iniquity shall abound, the love of many shall wax cold.
Luke 21: 6-36 tells us the same things that Matthew tells us but in Luke's words.
Notice when reading Matthew, he tells you what to expect when the end is near and when Luke speaks he tells us a little more of what is going to happen to the people..
In Verse 20-24, Luke mentions Israel:
20 And when ye shall see Jerusalem compassed with armies, then know that the desolation thereof is nigh.
21 Then let them which are in Judaea flee to the mountains; and let them which are in the midst of it depart out; and let not them that are in the countries enter thereinto.
22 For these be the days of vengeance, that all things which are written may be fulfilled.
23 But woe unto them that are with child, and to them that give suck, in those days! for there shall be great distress in the land, and wrath upon this people.
24 And they shall fall by the edge of the sword, and shall be led away captive into all nations: and Jerusalem shall be trodden down of the Gentiles, until the times of the Gentiles be fulfilled.
Verses 26-28 Luke tells us also of the second coming..
26 Men's hearts failing them for fear, and for looking after those things which are coming on the earth: for the powers of heaven shall be shaken.
27 And then shall they see the Son of man coming in a cloud with power and great glory.
28 And when these things begin to come to pass, then look up, and lift up your heads; for your redemption draweth nigh.
Verse 32 also tells us that when all these signs are seen, that this generation will not pass until Jesus returns..
32 Verily I say unto you, This generation shall not pass away, till all be fulfilled.
Verses 34-36 Luke warns us not to be consumed with sin and worries of this life because the second coming of Jesus will catch you unaware if you are not looking and waiting.
34 And take heed to yourselves, lest at any time your hearts be overcharged with surfeiting, and drunkenness, and cares of this life, and so that day come upon you unawares.
35 For as a snare shall it come on all them that dwell on the face of the whole earth.
36 Watch ye therefore, and pray always, that ye may be accounted worthy to escape all these things that shall come to pass, and to stand before the Son of man. These are just some of the signs to look for in the days to come before the return of Jesus Christ. With several prophecy books took look at, the study of prophecy can be quite exciting.