I have a question regarding where the makhraj of "yaa" comes from in the mouth.

Question
Assalamualykom   I have a question regarding where the makhraj of "yaa" comes from in the mouth. I have hardly found it on the net and where I have it says that it's pronounced by the tongue touching the palette (just like "jeem") which I think is inaccurate and wrong because it doesn't..
 Salaam

Answer
Wa alaikum assalaam wa rahmatullahi wa barakaatuh
Imam Ibn Al-Jazaree the famous scholar of tajweed (died 833 h) said  وَالْوَسْطُ فَجِيمُ الشِّينُ يَـا

so all three of these letters come from the middle of the tongue and the opposing roof of the mouth but with their characteristics, some close off the articulation point more than others.  The جيم completely closes off the articulation point, the شين less on the unlengthened ياءless.  So although you may not feel it, since it doesn't close off completely, you should be able to feel it if you say it with a shaddah.  If there is a ya' saakinah preceded by a kasrah, then the articulation point is from the empty space in the mouth and the throat.
The video link below should help you understand, if you can understand the Arabic.
https://www.youtube.com/watch?v=lOXBbeXOJjA
Wa alakum assalaam wa rahmatullah