Is it possible?

Is it possible via a macro to cast a ground based AOE spell such as Blizzard centered on your current target rather than have to place and click the floor?

If you have a programmable keyboard or mouse, you can make a keybind that combines the pressing of a key and the mouse click so it is done in one motion. https://www.youtube.com/watch?v=5q1J28vyq-c

Not directly from the Blizzard API that’s available for macros. We just don’t have access or control over this.

I found this list on Wowhead: http://www.wowhead.com/forums&topic=78483

There seems to be many threads with asking about what Macros can do what. This thread was made as a sort of remedy for said threads. Just scroll down, and see which section best fits your situation.

Macros
1. Cast X and Y spell at the same time.
Macros can’t do this, simply because of the Global Cooldown.
There are a few ways around this.

  1. If a spell isn't on the GCD, it can be used in a macro along with other spells not on the GCD and at most one spell on the GCD
  2. <li>    If a spell is classed as "Next Melee" (like Rune Strike, Heroic Strike, etc.), then it can be used after a GCD spell is used</li>
    

    .

2. Cast X spell if you have enough Mana/Energy/Rage/RP, else cast Y spell.
This is not possible. It would be playing the game for you, and Macros can’t do that.

3. Cast X spell if you have Y buff, else cast Z spell.
Not possible. Although UnitBuff() (which checks buffs on a unit) is usable by macros, CastSpell() (which casts spells) isn’t, meaning you can’t use this code to cast spells.

4. Cast X spell without pressing a button.
Macros cannot be used with no user input (pressing a key). (Thanks HighFive)

5. Target something by icon.

Can’t. /target (the command used to target a unit) can’t recognise icons mobs are maked with.(Thanks Paolo)

6. Cast X when Y is on cooldown.
Can’t do it. Macros can’t check for Cooldown on any spells.

7. Cast an AoE spell, without selecting a target area.

No. Although Macros can click on frames, it can’t click on the WorldFrame (the ground, sky, everything you see in WoW that isn’t part of the UI).

8. Click X object.
Nope. Macros can’t click on objects.

9. Cast X, then wait for Y amount of time, then cast Z.

Good news, there is a /in command.
Bad news, it doesn’t work with spells.

Addons.
1. Walk me from X location to Y location.
NO. You absolutely CANNOT do this. It’s actually a bot, and is against Blizzard’s Terms of Service. If caught, you face a swing of the banhammer. The name of a bot is even censored on Wowhead forums.

2. Make me look like a Tauren, instead of a Gnome.
Nope. Again, it’s against Blizzard’s ToS, but carries a lighter sentence. Ask yourself this:

Can I modelchange? Yes, you can. May I modelchange? No, you may not

GS-E can work around some of these but as a rule of thumb these be the rules.