On why we are observing the Solemnity of St. Joseph today (and not March 19) this year.

Paragraph 60 of the Universal Norms on the Liturgical Year and Calendar reads:

If several celebrations fall on the same day, the one that holds the highest rank according to the preceding Table of Liturgical Days is observed. But a solemnity impeded by a liturgical day that takes precedence over it should be transferred to the closest day not listed in nos. 1-8 in the table of precedence; the rule of no. 5 remains in effect. Other celebrations are omitted that year.

In the Table of Liturgical Days According to Their Order of Precedence, the Sundays of Lent (at number 2) rank higher than Solemnities inscribed in the General Calendar (at number 3). Therefore yesterday was rightly observed as the Third Sunday of Lent.  But, being a solemnity, St. Joseph was not completely bumped (as, say. St. Patrick will be in 2019 when March 17 falls on a Sunday) but rather moved to the closest available day, today!

St. Joseph, pray for us.