"notably a" is a correct and usable phrase in written English.
It is generally used to introduce a particular example of something. For example, "She was an accomplished musician, notably a skilled pianist."
Sinclair is also, notably, a forgiving woman.
Most notably, a lack of linebacking talent.
He is, notably, a poet of the Pacific Rim.
What's more, education is notably a powerful antidote to conflict.
The public rooms have some 'splendid' stained glass, notably a depiction of Richelieu.
It is also, notably, a vision of and desire for greatness rather than the thing itself.
Notably, a period in 2000-2002 where he drove a forklift at a warehouse in Boston.
And perhaps most notably, a mandatory curfew exists at Reagan National Airport in Washington.
An assortment of natives preceded LoDuca, most notably a pitcher named Sandy Koufax.
Some of the supporting players (most notably a stricken Stellan Skarsgård) appear poignantly all at sea.
Nemicolopterus shares some features with other later pterosaurs, notably a toothless jaw.
