How to plot lines extending to the right?

The chart below is very messy. I'd like to plot those lines starting from the point the circles appear on the chart and to be extended to the right, not both right and left. So, I'd like to start from the time the circle is there and keep going on the same price level to the right with the date going forward.

My current code:

for i in alert_df['Close']:
    plt.axhline(i, color ="blue", lw=1)

current plot