ACR X TCASII RA WITH ACFT DEVIATING AROUND WX. SYS ERROR.

Narrative

ACR X ON CLBOUT OF DFW. AFTER INITIAL LEVELOFF AT 10000 FT WE WERE CLRED TO CLB TO 17000 FT AND PROCEED DIRECT MILSAP. AT APPROX 10300 FT; CAPT NOTICED A TARGET ON TCASII SHOWING PLUS 300 FT AND CALLED IT OUT. IMMEDIATELY FOLLOWING THAT; WE HAD AN RA COMMANDING A 1500-2000 FPM DSCNT. THE TARGET SHOWED PLUS 200 FT IN OUR 1 O'CLOCK AND CLOSING. IMMEDIATE COMPLIANCE TO THE RA WAS INITIATED AND I STARTED A L TURN AWAY. THE CAPT ADVISED ATC OF THE RA AND OUR ACTIONS. ATC ISSUED A TURN TO 180 DEGS FOR TFC AVOIDANCE. THE TARGET SHOWED PLUS 100 FT OVERHEAD. WE NEVER SAW THE TFC. I REACHED APPROX 9500-9600 FT IN THE DSCNT. TCASII THEN SHOWED AN RA OF NO CLB AND SHORTLY THEREAFTER 'CLR OF CONFLICT.' WHEN WE ASKED ATC; THEY SAID THEY HAD TFC DEVIATING AROUND WX IN THE AREA AND THAT WE COULD RESUME OUR CLB TO 17000 FT AND COURSE TO MILSAP. THE EVENTS LEADING UP TO THIS AND PERTINENT POINTS I FEEL ARE AS FOLLOWS: 1) MASSIVE WX DELAYS AT DFW. WE SPENT A TOTAL OF 3.5 HRS IN TAXI AND SIT TIME ON TXWYS IN 2 ATTEMPTS IN ADDITION TO 2.5 HRS AT THE GATE BTWN THE ATTEMPTS TO FLY. DELAYS APPEARED TO AVERAGE 6-7 HRS. 2) AT OUR TKOF TIME FROM DFW-ELP; WE HAD BEEN ON DUTY FOR OVER 12 HRS. 3) PLT FATIGUE COUPLED WITH CTLR FATIGUE AND WX IS A SIT TO BE CONSIDERED. SUPPLEMENTAL INFO FROM ACN 301346: WE WERE CLRED FROM 10000 FT TO 17000 FT ON DEP WBOUND FROM DFW. CAPT NOTICED ANOTHER ACFT ON RADAR SCOPE/TCASII SHOWED PLUS 300 FT; 5 MI. CAPT INSTRUCTED FO TO DISCONTINUE CLB. TARGET ACFT IMMEDIATELY BECAME A TA ON TCASII FOLLOWED IMMEDIATELY BY RA AND COMMAND TO DSND AT 2000 FPM. WE NEVER PICKED UP TARGET VISUALLY. WE ADVISED CTLR OF OUR RA AND THAT WE WERE DSNDING; ASKED WHERE THE TFC WAS. DEP REPLIED NW OF YOU AT 11000 FT MSL. IT APPEARED ON TCASII THAT TARGET WENT ALMOST OVER US WITH VERT CLRNC SHOWN ON TARGET AS PLUS 100 FT.