MLG FLC ENRTE MEM MUST DIVERT DUE TO WX. DISPATCH WANTS A DIVERT TO AN ARPT CREW IS UNABLE TO LOCATE ON HIGH ALT CHARTS. FUEL IS DEPLETING AS THEY WORK TO FINALLY DETERMINE IF THE ORIGINAL ALTERNATE PLANNED FOR PRIOR TO DEP IS THE BEST ONE. FLC EATS INTO THE REQUIRED RESERVE FUEL BY 200 LBS.

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AFTER CONSIDERABLE ENRTE DEV AROUND TSTMS I CONTACTED DISPATCH IN ORDER TO DECIDE WHETHER OR NOT TO DIVERT TO OUR ALTERNATE FOR ADDITIONAL FUEL. OUR ALTERNATE WAS CHANGED TO MKL WHICH WAS CLOSER TO OUR DEST (MEM) THAN OUR ORIGINAL ALTERNATE (LIT). UPON ARR IN THE MEM AREA; TSTMS WERE OVER THE FIELD AND WINDSHEAR AND MICROBURST AUTOMATED RPTS WERE RECEIVED. WE NEEDED TO DIVERT TO OUR ALTERNATE. IT WAS DECIDED THAT MKL WAS NOT SUITABLE FOR TURBOJET ACFT AND SO WE PROCEEDED TO THE NEAREST SUITABLE ARPT WHICH WAS LIT (OUR ORIGINAL ALTERNATE). BY THIS TIME WE HAD BURNED ENOUGH FUEL SO THAT IN ORDER TO REACH LIT WE HAD TO BURN 200 LBS OF OUR FAA REQUIRED RESERVE FUEL. MINIMUM FUEL WAS DECLARED WITH ATC AS A PRECAUTION. THIS WAS A VERY UNCOMFORTABLE SIT AND I SHOULD NEVER HAVE ACCEPTED MKL AS AN ALTERNATE TO MAKE THE FUEL NUMBERS WORK OUT TO ALLOW US TO CONTINUE TO MEM. MKL WAS A 'PAPER ALTERNATE.' THE DISPATCHER SHOULD HAVE INFORMED ME THAT WE WOULD ACTUALLY NEVER USE MKL. TO MAKE MATTERS WORSE; THE COPLT AND MYSELF HAD NO IDEA WHERE MKL WAS AS IT IS NOT ON OUR HIGH ALT CHARTS OR AREA ARR CHARTS FOR MEM.