The Paraguay attacker's move to Atlanta United was rubberstamped on Thursday.
Ahead of Saturday's clash with Fulham, Howe said this morning: "Very special player, very special person. He's going to be greatly missed by everyone connected with us.
"Miggy was what you saw. Bubbly, bright personality. Behind the scenes, very professional. Always recovering, looking after himself.
"You can't have enough of those players who set the right standards. He'll be greatly missed.
"People are negotiating behind the scenes. I think it's a deal that suits the club and and suits Miggy. I think it's a good time for him to get a fresh challenge and a club obviously that he knows very well, he's got a great relationship with, so I think he goes into very good hands the other way.
"But as I've said many times this month, it's a deal that we needed to do. We're a little bit short in respect of that position and attacking areas currently where Harvey's (Barnes) injured and Callum's (Wilson) injured. We're certainly stretched in that area - but it's a deal that we needed to do."
Asked if he can see more players leaving before next week's deadline, Howe continued: "As we stand now, currently I don't
- but things can change.
"As we stand at the moment, I expect the squad to remain the same."
On replacing Almiron, he said: "We knew - barring something huge happening - that we didn't expect it to be a window that we could recruit. I've said that right from from the outset and despite being linked with numerous players, that's still the case.
"We're not actively looking to bring players in but hopefully the squad's in a decent place if we can get Callum and Harvey back fit and firing within a few weeks. I think the the squad will look good.
"It's probably not ideal for us in this moment to be light in that position but it is what it is and I've always said I've got no problems dealing with that. I'm trying to make the best of the situation, so we'll look at solutions and players in different positions if we need to.
"That's my job to try and find a solution if that happens."
Fulham beat Newcastle 3-1 in London earlier this season, a match Howe branded as a "tough day".
He recalled: "Yeah, it was a tough day. We didn't perform anywhere near what we can and we know that that was a phase where we were struggling to reach our best form
"But you know in the Premier League that every team has really strong qualities and I think Fulham played very well, they really deserve to win.
"We learned a lot of lessons from that from that game that we tried to take forward and we're still trying to take forward and improve our game. They're a very good side, very good manager, very well coached team."