B757-200
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Less Severe
Flight Crew Rejected Takeoff
Weather; Aircraft
While setting standard takeoff power; EICAS annunciated 'overspeed' with the associated aural warning momentarily (approximately 1 sec).   80 KTS airspeed check was missed during the distraction; and airspeed was compared at 110 KIAS.  Immediately at 110 KIAS; Captain's airspeed decreased to 30 KIAS; the lowest value on the indicator.  I elected to discontinue the takeoff at that time due to the lack of airspeed and the convective weather along the initial climb out and departure routing in the terminal area.  After the accomplishment of the rejected takeoff maneuver; the First Officer stated that the speed was 120 KIAS at the initiation of the reject maneuver.  V1 was 135 KIAS.  All associated checklists were accomplished after clearing the runway.  Brake energy was calculated to be under the caution zone.  After conferencing with [Operations and Maintenance]; and a 757 Check Airman who was jumpseating with us; the decision was made to reattempt the takeoff.  Prior to the second takeoff attempt; Tower issued a halt to all departures due to windshear alerts.  At about the same time; the Captain's PFD showed a flashing and sometimes steady yellow boxed ALT.  The decision was then made to terminate and return the aircraft to Maintenance.  Captain's airspeed indication loss for unknown reasons at the time.  Contributing factors were the momentary 'overspeed' warning; and the convective activity on the climb out and departure.
B757 Captain reported rejecting the takeoff attempt at approximately 120 KIAS when he experienced an airspeed indicator anomaly.