RPTR WAS CONCERNED THAT A DEVELOPING CONVECTIVE TSTM SYS WAS NOT OBSERVED ON THEIR SAT LONG RANGE RADAR SITE. RPTR STATES THAT NWS RADAR WAS SHOWING LEVEL 4 TO 5 TSTM ACTIVITY IN THAT AREA; BUT A FACILITY DIRECTIVE PROHIBITS ATC FROM USING THIS INFO.

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ON MAR/XX/96 AT XX09Z (GENERAL TIME; THIS PROB WAS ONGOING FOR A FEW HRS) A LINE OF TSTMS WAS NW OF SAT (SEE ENCLOSED DEPICTION) WITH EMBEDDED LEVEL 4 AND 5 STORMS. OUR RADAR SCOPE FOR THE AREA DEPICTED SHOWED NO PRECIPITATION; THOUGH THE NWS RADAR WAS SHOWING AS DEPICTED ON THE ENCLOSURE. IFR PLTS TRYING TO GET INTO SAT SHOWED CONCERN (MAINLY SINGLE ENG; NON WX RADAR EQUIPPED) WITH REF TO THE DEVELOPING LINE OF STORMS N OF SAT. WE HAVE IN THE AREA UP-TO-DATE WX RADAR VIA MONITORS FROM THE NWS. THIS EQUIP IS CALLED METEOROLOGIST WX PROCESSOR (MWP). WE HAVE AN ORDER ZHU 71104.104F APPENDIX 6 WHICH STATES: ATCS (CTLRS) SHALL NOT: 1) PROVIDE PLTS WITH ANY SPECIFIC WX DATA TAKEN FROM THE MWP EQUIP. 2) PROVIDE WX RADAR ADVISORIES OR ACFT VECTORS BASED ON DATA TAKEN FROM THE MWP EQUIP. 3) USE SATELLITE PRODUCTS. 4) USE GRAPHIC PRODUCTS THAT REQUIRE INTERP. BECAUSE OF THE ABOVE; MANY CTLRS DISREGARD THE MWP AND ADVISE ACFT THAT NO PRECIPITATION IS SHOWN ON OUR RADAR IN THE AREA OF CONCERN. THIS TENDS TO LEAD THE PLTS ON A FALSE SENSE OF SECURITY FOR THEIR RTE OF FLT. IN CLOSING; I HAVE UP-TO- DATE WX AVAILABLE; BUT I CAN'T INTERPRET IT; THUS I HAVE TO RELY ON OUR NARROW BAND RADAR WHICH SHOWS LINES FOR MODERATE; H FOR HVY. THIS DEPENDS ON WHERE THE WX IS IN RELATION TO OUR LONG RANGE RADAR SITE.