B737 FO FAILS TO ADVOCATE FOR GAR WHEN CAP ACCEPTS A LAHSO CLRNC FOR RWY 22R AT ORD. WINDS WERE OUT OF LIMITS FOR THE LAHSO.

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ON APCH TO ORD IN VMC; ON A VECTOR (ESSENTIALLY R BASE FOR RWY 22R); THE APCH CTLR SAID THEY 'LOST THE WINDS' FOR LAHSO FOR RWY 22R. ATIS WINDS WERE 310 DEGS AT 7 KTS GUSTING TO 16 KTS. SOON AFTER THAT; HE SWITCHED US TO TWR. TWR CLRED US TO LAND WITH 'LAHSO RWY 27L' INSTRUCTIONS. I ASKED THE CAPT IF HE WANTED ME TO REACH BACK AND ACCEPT THE LAHSO; HE SAID YES. I HAD USED ACARS TO PULL UP THE LNDG DATA WHICH SHOWED BRAKES 'MAX' OR 'OFF' AS THE FULL LENGTH BRAKING OPTIONS AND WINDS WITH 0 DEGS HEADWIND/10(?) DEG KT DIRECT XWIND. AT 1000 FT I STATED 'INSTS XCHKED; GS APCHING 1 DOT LOW.' AT 500 FT I STATED '500 FT; 1 DOT LOW.' AROUND 100-200 FT (I'M NOT SURE) I STATED 'GS APCHING 2 DOTS LOW' AFTER WHICH POINT WE GOT AN AUDIBLE 'GS' WARNING FROM THE GPWS. IT WAS AT THAT POINT I REALIZED FLYING THE GS 1 DOT LOW HAD BEEN THE PLAN. I'M A LITTLE DENSE SOMETIMES AND HADN'T REALIZED THAT WAS THE CAPT'S WAY TO ASSURE COMPLYING WITH THE LAHSO INSTRUCTION. THE CAPT LANDED; USED MAX BRAKING; COMPLIED WITH LAHSO AND MADE THE A1 TURNOFF. I NOW BELIEVE THE WINDS HAD SHIFTED TO 320 DEGS OR MORE NORTHERLY AND THAT THERE HAD BEEN A TAILWIND ON APCH WHICH WOULD HAVE PREVENTED US FROM ACCEPTING A LAHSO. I ALSO BELIEVE THE TWR CTLR KNEW THIS BUT DIDN'T ADVISE US. HOW ELSE WOULD THE APCH CTLR HAVE KNOWN? I WAS HESITANT TO CALL FOR A GAR BELOW 200 FT WHEN WE GOT THE WARNING BECAUSE OF: 1) HE'S THE CAPT AND HAD A PLAN. 2) WE WERE VMC IN GOOD WX. 3) A GAR WITH INTERSECTING RWY DEP PATHS MIGHT BE LESS SAFE THAN BEING LOW ON GS. 4) LNDG ON THE RWY WAS ASSURED. I ALSO THINK THAT REQUESTING A WIND CHK MIGHT HAVE FORCED THE CTLR'S HAND BY REQUIRING HIM TO TELL US THE CURRENT WINDS (WHICH I SUSPECT WERE BEYOND LAHSO LIMITS). I WAS TOO PREOCCUPIED WITH BEING BELOW GS AND HAVING A 'NOT SO GOOD' GUT FEELING TO REQUEST A WIND CHK.