5.424A In the band 2 900-3 100 MHz, stations in the radiolocation service shall not cause harmful interference to, nor claim protection from, radar systems in the radionavigation service. (WRC-03)
5.425 In the band 2 900-3 100 MHz, the use of the shipborne interrogator-transponder (SIT) system shall be confined to the sub-band 2 930 -2 950 MHz.
5.426 The use of the band 2 900-3 100 MHz by the aeronautical radionavigation service is limited to ground-based radars.
5.427 In the bands 2 900-3 100 MHz and 9 300-9 500 MHz, the response from radar transponders shall not be capable of being confused with the response from radar beacons (racons) and shall not cause interference to ship or aeronautical radars in the radionavigation service, having regard, however, to No. 4.9.
G56 Federal radiolocation in the bands 1215-1300, 2900-3100, 5350-5650 and 9300-9500 MHz is primarily for the military services; however, limited secondary use is permitted by other Federal agencies in support of experimentation and research programs. In addition, limited secondary use is permitted for survey operations in the band 2900-3100 MHz.
US44 In the band 2900-3100 MHz, the non-Federal radiolocation service may be authorized on the condition that no harmful interference is caused to Federal services.
US316 The band 2900-3000 MHz is also allocated to the meteorological aids service on a primary basis for Federal use. Operations in this service are limited to Next Generation Weather Radar (NEXRAD) systems where accommodation in the band 2700-2900 MHz is not technically practical and are subject to coordination with existing authorized stations.

Wiki entries

NEXRAD Weather Radar

Current Use 2700–3000 MHz NEXRAD Weather Radar

In the United States, NEXt-generation weather RADars (NEXRAD) operate in the band 2700-3000 MHz. The radars are WSR-88D (Weather Surveillance Radar - 1988 Doppler) models. According to the National Weather Service, there are 160 operational NEXRAD radars throughout the U.S. and at some overseas locations.
According to NTIA technical report 13-490, the lowest tuned frequency for any NEXRAD is 2705 MHz, and the radars have the following technical characteristics:

Peak transmitter power	750 kW
Transmitter type	klystron tube
Operational frequency range	2700-3000 MHz
Antenna type	9 m (28 ft) diameter parabolic reflector with microwave feed horn at power center
Antenna gain	45.5 dBi
Antenna height above ground	24 m (80 ft)
Antenna beam width	0.95 deg (3 dB width) 0.15 deg (boresight accuracy)
Antenna sidelobe levels	At least 27 dB below main-beam gain
Antenna beam scanning protocol	conical scan, +0.5 deg to +20 deg elevation
Antenna beam scanning rate	6 rpm (10 sec/scan revolution interval)
Transmitted pulse widths	short pulse: 1.6 microsec long Pulse: 4.5 microsec
Transmitted pulse modulation	P0N (unmodulated CW pulses)
Transmitted pulse repetition rates	short pulse: 318 to 1304 pulses/sec long pulse: 318 to 452 pulses/sec
Receiver bandwidth	0.795 MHz