FLC OF AN MLG DROPPED BELOW GS DUE TO WINDSHEAR AT DECISION HT DURING AN APCH IN TSTM CONDITIONS.

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ENRTE TO CLT ON FLT FROM MEM TO CLT. ON APCH ENCOUNTERED VERY HVY RAIN ON SHORT FINAL TO RWY 18R ACFT WENT BELOW GS AFTER DECISION HT WAS REACHED. APCH LIGHTS WERE ALWAYS IN SIGHT. DSCNT BELOW GS WAS ARRESTED BY CAPT AND NORMAL LNDG PERFORMED. I RECOMMEND THAT BETTER COM BE ESTABLISHED BTWN FINAL APCH CTLR AND TWR WHEN WX CONDITIONS ARE DETERIORATING AS RAPIDLY AS WAS OCCURRING AND THIS INFO BE PASSED ON TO FLCS IN A MORE TIMELY MANNER. AT THE TIME THE DECISION WAS MADE TO COMMENCE THIS APCH; THE ATIS WAS RPTING 3000 FT SCATTERED; 6000 FT BROKEN; 15 MI VISIBILITY. THE ACARS WX FOR CLT AT TIME OF APCH SAID NO TDRW'S WITHIN 15 NM. WE WERE NEVER TOLD TO SWITCH TO TWR FREQ AND AS A RESULT WERE UNINFORMED THAT PREVIOUS 2 ACFT HAD GONE AROUND. HAD WE BEEN BETTER INFORMED OF THE SIT WE ALSO WOULD HAVE GONE AROUND ON THIS APCH. WHEN WX OF THIS INTENSITY IS MOVING DIRECTLY ON TO AN ARPT I FEEL THAT THE ARPT SHOULD BE SHUT DOWN UNTIL STORM HAS EITHER PASSED BY OR HAD A CHANCE TO BE STABILIZED OR STUDIED FURTHER BY GND BASED OBSERVATION. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THAT HE WAS CONCERNED THAT APCH CTL DID NOT PROVIDE THE LATEST WX INFO; AND THAT 2 OTHER ACFT HAD GONE AROUND DUE TO WX TSTM WINDSHEAR; OR TURN HIM OVER TO THE TWR EARLIER FOR THAT INFO FROM THE TWR. HE KNEW THAT THE TERMINAL DOPPLER WX RADAR SYS WAS OUT ACCORDING TO ATIS. THEREFORE; THE SEVERE TSTM WX WAS UNEXPECTED WHEN THE ACFT ACARS RPTED NO TSTMS WITHIN 15 MI. AT APPROX 600 FT ABOVE DECISION HT; WELL WITHIN THE OM; THE RPTR DID CHANGE ON HIS OWN TO TWR FREQ AND SUBSEQUENTLY HEARD THE TWR RPT TSTMS ALL QUADRANTS. AT APPROX THE SAME TIME; THE ACFT WENT INTO A WINDSHEAR CONDITION AND SANK BELOW THE GS AT APPROX 150 FT AGL. HE FURTHER STATED THAT HE BELIEVES THAT THE TWR COULD HELP SEE THE SEVERE WX AND CAUSE THE ARPT TO CLOSE UNTIL THE TSTM PASSED. HE ALSO STATED THAT THEIR ACARS HAS BEEN CHANGED TO NOT GIVE THE NO SEVERE WX WITHIN 15 MI WHEN THE TDWS SYS IS OTS; WHICH WAS VERY MISLEADING.