ARTCC REQUESTS ACR TO SQUAWK EMER WHEN THEY ARE UNABLE TO FLY NEW CLRNC BECAUSE OF WX.

Narrative

ARRIVING TPA ON THE DARBS 1 ARR WITH CLRNC TO DEVIATE AS REQUIRED. WE WERE WORKING OUR WAY THROUGH CLOSELY SPACED CUMULO NIMBUS. ZJX CHANGED OUR ARR TO THE BLOND 2. AT THE TIME WE WERE VERY BUSY. I HAD DISENGAGED THE AUTOPLT TO GET MORE BANK ANGLE (30 DEGS) AND TURN RATE TO MANEUVER THROUGH TIGHTLY SPACED CELLS. THE FO WAS GETTING ALTERNATE WX (ORL) AS THE WX WAS DETERIORATING AT TPA. WE HAD JUST PASSED BTWN 2 CELLS ON A SE HDG WHEN ZJX REQUESTED WE TURN IMMEDIATELY BACK TOWARDS BLOND INTXN. A TURN IN EITHER DIRECTION WOULD HAVE PUT US INTO THE CELLS WE HAD JUST PASSED BTWN. THE CTLR THEN REQUESTED WE SQUAWK EMER AND INFORMED US WE WERE CONFLICTING WITH OTHER ARRS. NO ACFT WERE VISIBLE ON TCASII ON THE 20 NM SCALE AND WE WERE UNAWARE OF ANY ACFT AFFECTED BY OUR DEV. ZJX TURNED US OVER TO TPA APCH FOR A NORMAL RECOVERY. IT SEEMS IN RECENT YRS AS THE SYS HAS BECOME MORE COMPLEX (MORE ARRS AVAILABLE; MORE ACFT IN SYS) THAT CTLRS OFTEN CHANGE CLRNCS IN HIGH WORKLOAD SITS WITHOUT REGARD TO THE ADDITIONAL DEMANDS IT PLACES ON THE COCKPIT CREWS. THEY ASSUME THAT BECAUSE IT IS CHARTED; THAT IT IS DOABLE -- RIGHT NOW. THAT'S NOT ALWAYS THE CASE; AS IS SHOWN BY THE ABOVE INCIDENT.