The T10331111 means
T=Temperature =1033 = 1=minus 03.3deg Celsius
(Dewpoint)= 1=minus 11.1 deg Celsius
hence the M03/M11 in the METAR.
for the 53031 I will look it up unless someone comes to your aid in the meantime.
[Edited to add]
I think 53031 means the 5=pressure tendency over the last 3 hours
3=?
031= change of 3.1 hpa in the last 3 hours (at 1751Z the pressure was 29.32 inreasing to 29.42" at 2051Z, but I may be wrong on that.
The other alternative is that is referring to a 5=turbulence report of 3=moderate in clear air, frequent, and 031= a height banding.
HTH
Last edited by TopBunk; 27th Dec 2010 at 21:20.