No it is not a Poisson distribution, which is discrete, takes integer values, and is potentially unlimited in value. This question is a continuous distribution and cannot take a value greater than a $\frac14$ of an hour.
Suppose the forecast was only on the hour. Then the distribution of waiting times to the start of the next forecast would essentially be uniform on the interval $[0,1)$.
The intervals are in fact $\frac16, \frac14, \frac{1}{12}, \frac14, \frac16, \frac{1}{12}$ of hours. So the distribution is uniform on each of the equal-length waiting time intervals $\left[0, \frac{1}{12}\right), \left[\frac{1}{12}, \frac16\right), \left[\frac16, \frac14\right)$ but you are three times as likely to have a waiting time in the first as in the third, and twice as likely in the second than the third.
I will leave it to you to adjust the three densities to give a total probability of $1$; it is not difficult, especially if you sketch the densities.