Is the Genesis creation account consistent with the Big Bang theory according to Catholic theology?

To answer the question of whether "the Genesis story of creation is consistent with the Big bang theory solely from a Catholic point of view" we must define exactly the Catholic point of view and the Big Bang theory.

The Catholic point of view is stated in the Catechism of the Catholic Church, points 290, 293 and 296. By the first and last, quoted by Andrew Leach in his response, to be an orthodox Catholic you must believe that God created freely and out of nothing, from a beginning of time (i.e. not from an infinite past), the totality of what exists outside of Himself. This is stated more succintly but with much greater magisterial weight in the Constitution "Dei Filius" of The Ecumenical Council Vatican I, Chapter 1 "On God the creator of all things" (quoted by Catechism #293):

This only true God, of his own goodness and almighty power, not to increase his happiness, nor to acquire it, but to manifest his perfection by the goods which he bestows on creatures, with absolute freedom of counsel, created out of nothing, from the beginning of time, both the spiritual and the corporeal creature, to wit, the angelical and the mundane,

Hic solus verus Deus bonitate sua et omnipotenti virtute non ad augendam suam beatitudinem, nec ad acquirendam, sed ad manifestandam perfectionem suam per bona, quæ creaturis impertitur, liberrimo consilio simul ab initio temporis utramque de nihilo condidit creaturam, spiritualem et corporalem, angelicam videlicet et mundanam,

http://www.ccel.org/ccel/schaff/creeds2.v.ii.i.html

http://www.ewtn.com/library/COUNCILS/V1.HTM

As only the EWTN link shows, this passage of "Dei Filius" quotes in turn from a canon of the Fourth Lateran Council, 1215:

We firmly believe and openly confess that there is only one true God, [...] Creator of all things invisible and visible, spiritual and corporeal, who from the beginning of time and by His omnipotent power made from nothing creatures both spiritual and corporeal, angelic, namely, and mundane,

http://legacy.fordham.edu/halsall/basis/lateran4.asp

Therefore, Catholic doctrine requires you to believe the essentials of the Genesis account as stated above, but not the details. You are not required to believe that the six days were current 24-hour intervals or that plants and trees were actually created before the sun was.

Holding then the essentials of the Genesis account as required by Catholic doctrine, and not those details which contradict the findings of natural science, the account is consistent with "Big Bang Theory" as long as you impose on the latter the constraint of an absolute beginning, t=0.

Now, I placed "Big Bang Theory" (BBT) in scare quotes on purpose, because the meaning of the term is no longer univocal. If you are not interested in the subject, you can leave it at that. Otherwise, go on reading.

Today, the precise meaning of BBT requires making explicit the role of cosmological inflation. Historically, the first version of BBT, around 1930, was:

1. Hot BB from singularity (no inflation).

The Catholic-consistent flavor of that is creation ex-nihilo of the singularity, a state of extreme density. Now, to account for observations of flatness and h*m*geneity while avoiding theism-favoring extremely special initial conditions, atheist scientists developed the hypothesis of cosmological inflation, resulting in the second version of BBT, around 1980:

2. Hot BB from singularity, inflation to near emptiness, reheating.

With the Catholic-consistent flavor thereof being the same as above. As the hypothesis of inflation makes a number of observational predictions which make it falsifiable, and as those predictions have been all verified by observations, the hypothesis currently enjoys a status of very high plausibility. The new problem is that, of the several possible models of inflation, current observations strongly favor inflation models which themselves require extremely special initial conditions to get started, which specifically exclude a previous "hot" initial state. Which allows a third plausible version of BBT, which is Catholic-consistent by design:

3. Creation at the start of inflation, inflation, "reheating".

The beauty of this (currently wholly plausible) version is that it is consistent not only with the essentials of the Genesis account, but also with the details of days 1 and 2. It is described here:

http://speculativethinking.blogspot.com/2015/08/concordance-between-narrative-of_26.html

The "problems" (not for Christians!) that make this version plausible are explained in my June 14 comment at the bottom of the discussion under this article: http://www.wall.org/~aron/blog/physics-culture-and-theistic-cosmology-models/

The 1909 Pontifical Biblical Commission said:

The word “day” [םוי = yom] need not be taken in the literal sense of a natural day of 24 hours, but can also be understood in the improper sense of a longer space of time.

See this for more info. So for Catholics there is no inconsistency.

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Pope Pius XII spoke of the compatibility of the Catholic faith and the Big Bang theory in his 22 November 1951 speech to the Pontifical Academy of Sciences. (Unfortunately, I don't know of an English translation of it, but this machine translation isn't too bad.)

The Catechism of the Catholic Church has

289 Among all the Scriptural texts about creation, the first three chapters of Genesis occupy a unique place. From a literary standpoint these texts may have had diverse sources. the inspired authors have placed them at the beginning of Scripture to express in their solemn language the truths of creation — its origin and its end in God, its order and goodness, the vocation of man, and finally the drama of sin and the hope of salvation. Read in the light of Christ, within the unity of Sacred Scripture and in the living Tradition of the Church, these texts remain the principal source for catechesis on the mysteries of the "beginning": creation, fall, and promise of salvation.

290 "In the beginning God created the heavens and the earth":¹²⁸ three things are affirmed in these first words of Scripture: the eternal God gave a beginning to all that exists outside of himself; he alone is Creator (the verb "create" — Hebrew bara — always has God for its subject). the totality of what exists (expressed by the formula "the heavens and the earth") depends on the One who gives it being.

295 We believe that God created the world according to his wisdom.¹⁴¹ It is not the product of any necessity whatever, nor of blind fate or chance. We believe that it proceeds from God's free will; he wanted to make his creatures share in his being, wisdom and goodness: "For you created all things, and by your will they existed and were created."¹⁴² Therefore the Psalmist exclaims: "O LORD, how manifold are your works! In wisdom you have made them all"; and "The LORD is good to all, and his compassion is over all that he has made."¹⁴³ God creates "out of nothing".

296 We believe that God needs no pre-existent thing or any help in order to create, nor is creation any sort of necessary emanation from the divine substance.¹⁴⁴ God creates freely "out of nothing".¹⁴⁵

Thus it may be seen that Catholic teaching, expressed in the Catechism, does not depend on the literal truth (or not) of Genesis 1. Other than a few brief words of literary analysis, it expresses no opinion — although St Augustine of Hippo certainly did. What is important is that Genesis 1 testifies that God created all that exists, and did so from nothing.

Although God is continually revealing himself and his methods, scientists have not reached the origin of creation, either by observation of the deep universe or by theoretical calculation. Even if one posits that the Big Bang was the means by which creation was effected, it is thought that everything emanated from a singularity: a point of infinite density and zero size — nothing.

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128: Gen 1.1
141: Cf Wis 9:9
142: Rev 4:11
143: Pss 104:24; 145:9
144: Cf Dei Filius, cann 2–4 (1869)
145: Lateran Council IV (1215)