Its basically a Dorian Scale with #4
F G A♭ B C D E♭ F
Don't know what to call it
According to this resource with lists of scale/mode names, some terms for this scale (with semitone groupings 2 1 3 1 2 1 2) include:
Mela Hemavati, Raga Desisimharavam, Maqam Nakriz, Tunisian, Dorian sharp 4, Misheberekh: Jewish, Nigriz, Pimenikos, Souzinak (Peiraiotikos Minor): Greece, Ukrainian Minor, Kaffa, Gnossiennes
This page suggests the name "Lydian Diminished" (which I personally find to be a curious designation) and has further possible terms and info.
In a normal Western context, I'd agree with Chris Mitchell's idea of Dorian with a sharp 4.
This is the the fourth mode of the harmonic minor scale, and is known as the Ukranian Dorian scale.
Every time you have a 1 tone and a half jump between two adjacent degrees of a scale (in this case between A♭ and B), you should think of some harmonic minor permutation ;)) - see the more common phrygian dominant.
As mentioned in other answers, more descriptive names may be dorian #4, or minor #4 natural6...
One notable use is in Erik Satie's Gnossienne no. 1: