B737-300 CREW WAS DENIED A TURN TO AVOID WX IN THE ZDV CLASS E AIRSPACE. THE CREW AND CTLR THEN HAD A MISCOM ABOUT CLRED ALT.

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AT XA15; 30 MI SW OF DEN; CLBING TO FL230; ON AN ASSIGNED HDG OF 190 DEGS. THIS HDG POINTED US AT WX WITH A STEEP GRADIENT OF GREEN TO RED. WE REQUESTED TO COME RIGHT TO AVOID AND WAS THEN TOLD UNABLE BY ATC WITH NO OTHER INFO. APPROX 1 MIN LATER WE REQUESTED TO COME R AGAIN. WE WERE TOLD UNABLE BY ATC. WE THEN INFORMED ATC THAT WE WERE LEVELING AT 15000 FT TO AVOID WX; AS WE COULD SEE THE GND EVEN THOUGH VIRGA AND HVY RAIN WERE COMING OUT OF THE LARGE BUILDUPS WITH BASES AT 16000 FT. ATC SAID THIS WOULD RUN US INTO THE MOUNTAINS. HE THEN GAVE US A TURN TO 310 DEGS (TOWARDS THE TERRAIN). WE STARTED A CLBING TURN TO FL230 AND HDG 310 DEGS. ATC THEN SAID DON'T CLB; OUR CLRNC WAS 15000 FT. WE IMMEDIATELY STARTED (AT 15500 FT) TO RETURN TO 15000 FT. WE THEN RECEIVED AN RA FOR TFC ABOVE US; IMMEDIATELY FOLLOWED BY CLR OF CONFLICT. SOON THEREAFTER WE CHANGED FREQ WITH ALL ELSE UNEVENTFUL. CONCERNS: NO FEEDBACK FROM ATC ON NOT ALLOWING R DEV. CONFLICTING INFO FROM ATC REGARDING THE RISK OF TERRAIN AVOIDANCE VERSUS TFC AVOIDANCE. THE CAPT HAD TO USE HIS AUTH (AND I AGREED) IN ORDER TO AVOID SEVERE WX AS WELL AS TERRAIN.